Regional weather and climates of the British Isles – Part 3: The Midlands

Authors


Correspondence to: Ian Phillips: i.d.phillips@bham.ac.uk

In this article, the Midlands comprise Shropshire, Herefordshire, Worcestershire, Warwickshire, West Midlands, Staffordshire, Derbyshire (apart from the High Peak), Nottinghamshire, Lincolnshire, Leicestershire, Rutland and Northamptonshire (Figure 1). Kings and Giles (1997) likened the Midlands to a shallow bowl with a subdued central dome. The bowl's edges are the Welsh Marches, the Cotswolds, the Northamptonshire Jurassic escarpment, the Derbyshire Peak and the Staffordshire Moorlands. The subdued central dome is the Birmingham Plateau (>120 m), which acts as the watershed between rivers that drain southwest into the Severn and Avon and those that drain northeast into the Trent. In the west, isolated ranges of hills such as the Malverns and the Long Mynd rise out of the Midland Plain.

Figure 1.

The Midlands region and the location of places mentioned in the text.

Stations within the region with long records include Raunds (Northamptonshire), where records began in the 1850 s, Ross-on-Wye and, from 1793, Birmingham. The re-opening of the climatological station at Ross-on-Wye in 1985 is a particularly welcome addition to the observing network, as it extends a record that originally commenced at a site elsewhere in the town in 1859 and sustained observations at the current site from 1914 until 1975 (Parsons, 1975). The well-known Central England Temperature (CET) series has always included one station from the Midlands, as well as extending more widely into northwest and southeast England. It is the world's longest instrumental record, starting in 1659 as a monthly series, and is currently defined by the Met Office's Hadley Centre as the average of Rothamsted (Hertfordshire), Pershore College (Worcestershire) and Stonyhurst (Lancashire). Also worthy of note are the voluntary observing sites at Bablake School in Coventry, at Newtown Linford (Leicestershire) – where records started in 1959 – and at Middleton (in the Peak District of Derbyshire at 321 m), the data for which are used extensively in this article.

Temperature

Table 1 provides mean monthly temperatures. Given that the influence of the sea is minimal and therefore the region's climate is as ‘continental’ in character as is possible in the British Isles, temperatures respond more quickly to changes in radiation than in other regions. Mean maximum and minimum temperatures are at their highest in July at all sites (Table 1); this contrasts with South West England, where temperatures do not usually peak until August because of the delayed warming of the sea. Mean maxima are at their lowest in January at most sites, though they are very similar in December.

Table 1. Mean monthly maximum and minimum temperatures (°C) for the period 1981–2010
 Alt (m)JFMAMJJASOND
Ashover1786.36.79.312.215.718.520.920.417.313.29.26.5
(Derbyshire) 1.10.82.53.96.69.511.711.59.46.73.71.5
Waddington686.57.09.812.415.918.721.321.118.013.89.46.6
(Lincolnshire) 1.51.32.94.47.210.212.412.310.37.34.21.9
Shawbury727.17.410.012.616.018.821.020.617.913.89.97.0
(Shropshire) 1.10.82.43.56.49.311.311.19.16.43.41.3
Coventry Bablake1197.17.510.313.216.619.622.021.618.514.210.07.2
(Warwickshire) 1.71.43.24.67.510.512.612.310.27.24.11.9
Newtown Linford1196.36.59.812.816.219.021.621.218.113.89.36.3
(Leicestershire) 1.51.42.63.26.09.211.211.19.36.73.91.9
Ross-on-Wye677.78.110.813.717.120.022.221.718.814.510.67.8
(Herefordshire) 2.01.73.44.67.610.412.412.310.17.44.32.1

In general, the warmest winter days occur in the southwest of the region close to the Severn Valley, with temperatures declining to the northeast. This is different from the summer, when the warmest conditions are more likely to occur in the east Midlands (especially in Northamptonshire) because this area is less exposed to maritime southwesterlies, lies more firmly in the dominant rain shadow and so experiences less cloud cover. At all six sites in Table 1, February records the lowest mean minimum temperatures. Whereas winter days tend to be warmer in the western half of the Midlands, these counties are more prone to very cold winter nights; Kings and Giles (1997) attributed this to cold-air drainage along the Severn, Wye and Avon valleys. This is illustrated by Shawbury, which records the lowest mean minima of these sites from September to December inclusive and again in March. The winter of 1981/1982 brought the coldest night on record for the whole of England (−26.1 °C at Newport (Shropshire) on 10 January 1982) and the lowest December reading (−25.2 °C at Shawbury on 13 December 1981). Shawbury's coldest November night occurred more recently: in 2010, when −13.2 °C was recorded on the 28th (Burt and Brugge, 2011).

At the other end of the temperature spectrum, and referring to the CET but recalling its regional definition as noted above, July 2006 with 19.7 °C is noteworthy because it was the warmest month in this record (Prior and Beswick, 2007). The mean sea-level pressure (MSLP) for that month was 7 mbar above average in the southern Baltic and 7 mbar below average in the mid-Atlantic (Eden, 2006); this led to a persistent southerly airflow over Britain, with a mean monthly 1000–500 mbar thickness anomaly of +8dam. After a seven-day anticyclonic spell, temperatures peaked on the 19th, when maxima widely exceeded 34 °C in the south Midlands. This day was thought to be the seventh warmest day of the CET series (Prior and Beswick, 2007): the six warmest days occurred in July 1808, July 1948, July 1976 and August 1995.

The current UK national daily temperature record was set in August 2003, but that month's CET was 1.4 degC lower than it was in July 2006. The 2003 heatwave was most intense in South East England, with temperatures just topping 38 °C on the 10th, but an eastward-moving cold front prevented temperatures in the Midlands from rising above 30 °C on that day: the hot spell here had peaked a day earlier, when Leicester University and Wellesbourne recorded 35.1 °C and 35.0 °C respectively (Burt, 2004).

Frost in the Midlands

As the region holds the record minimum English temperature (see above), frost is a particular characteristic of the Midlands’ climate worthy of closer attention.

Between 1981 and 2010, there was an average of 48 and 41 air frosts per year at Ashover and Coventry (Bablake) respectively. The incidence of air frost was slightly higher in February than in December and January. No air frosts were recorded at any Midlands’ Climatological Observers Link (COL) station in July and August; at the more vulnerable sites, an air frost occurs at most once every five years in May and September. Frosts are favoured by radiative cooling, a dry soil and cold-air drainage, all factors that are in this region exaggerated by the relatively limited maritime influence. In addition, the east Midlands is more prone to frost because the area's sandy soils dissipate residual summer warmth more quickly than do the heavier clay soils further west (Kings and Giles, 1997). Ground frosts are around twice as frequent as air frosts (nearly 60% of winter (December to February) nights at Ashover and Coventry experienced a ground frost between 1981 and 2010) and can occur throughout the year.

Connolly (2008) examined trends in hourly night-time temperatures and the number of frost hours at 13 sites in England, including four in the Midlands (Shawbury, Elmdon, Watnall and Waddington). Between 1971 and 2006, the annual number of frost hours had declined at the four Midlands sites, but none of the trends were statistically significant (even at p = 0.1), although there was a significant (p <0.01) reduction in frost frequency at 0200 and 0300 utc at Elmdon. Table 2 shows that in the west frosts are more abundant in northerly and easterly airstreams, whilst in eastern districts westerlies are more frost-prone (due to lower cloud amounts).

Table 2. The total number of frost hours for each wind direction quadrant at four Midlands sites, 1971–2006
 Shawbury (Shrop)Elmdon (West Mids)Watnall (Notts)Waddington (Lincs)
Northerly6443658747813465
Easterly3679326934813554
Southerly1667282414102422
Westerly3030205136983618
Source: Connolly, 2008.

Precipitation

In most of the Midlands, mean annual rainfall totals are of the order of 600–800 mm (Table 3). The wettest areas, with over 1000 mm, are along the Welsh border and in the Derbyshire Peak. The driest areas, with slightly less than 600 mm, are mainly in the east: the Lincolnshire Fens around Spalding, the Nene valley downstream of Northampton and the Trent Valley downstream of Newark. However, owing to the rain-shadow effect of the Welsh mountains, locations in the western Midlands are much drier than would have been the case if Wales were a flat plain: means are less than 700 mm around Hereford and to the east of Shrewsbury, and small areas of the Avon valley around Stratford and Warwick even record less than 600 mm (Kings and Giles, 1997). Local precipitation maxima are evident in areas of higher ground such as the Birmingham Plateau, and accordingly parts of southwest Birmingham record just over 800 mm compared to just under 700 mm at Coventry. Totals also increase as the Cotswolds are approached to the southeast of Evesham.

Table 3. Mean monthly and annual precipitation totals (mm) for the period 1981–2010
 Alt (m)JFMAMJJASONDYear
Ashover17886.265.366.169.359.176.957.468.070.088.787.493.3887.7
Waddington6850.136.641.246.647.657.558.960.453.456.355.049.1612.7
Shawbury7256.138.946.448.953.653.353.259.457.267.961.262.3658.4
Coventry (Bablake)11959.844.247.452.355.759.459.162.959.467.862.661.6692.2
Newtown Linford11961.047.550.556.653.859.460.265.364.369.364.566.0718.4
Ross-on-Wye6775.350.951.353.154.751.549.458.659.081.872.574.7732.7

In western Britain and Ireland there is a clear winter maximum in precipitation, whereas many locations in East Anglia display a summer peak that is driven by convection. Reflecting its situation between these two areas, rainfall in the Midlands is more evenly distributed across the seasons: at the six sites in Table 3, each season contributes between 21 and 30% of the station's mean annual precipitation. Despite this greater uniformity, a subtle seasonal rhythm is still evident. Spring and autumn are the driest and wettest seasons respectively, with the only exception being Waddington (significantly located in the far east of the region and closer to East Anglia) where the summer is wetter than the autumn. August is Waddington's wettest month, October is the wettest at Shawbury, Coventry, Newtown Linford and Ross-on-Wye, and December is the wettest at Ashover. These statistics are consistent with Kings and Giles’ (1997, p. 119) observation that locations in western and central areas of the Midlands have a tendency for a [precipitation] maximum in the second half of the year. In hilly areas (Peak District and near the Welsh border) where orographic enhancement of frontal rainfall is important, December and January are the wettest months. As the westerlies decline in strength and frequency in late winter and spring, drier conditions affect the Midlands and February is the driest month (has the lowest mean daily rainfall) at four sites. With a greater exposure to moisture-laden tropical maritime air masses than the other five sites, Ross-on-Wye's precipitation regime is more akin to that of western Britain and Ireland: October, December and January are the wettest months, and July is the driest.

Between 1981 and 2010, the annual number of wet days (totals of 1 mm or more) at Ashover and Coventry were 134 and 119 respectively. In the winter, precipitation falls over longer periods of time (hence more wet days), whereas summer rainfall tends to occur at higher intensities (hence fewer wet days). Thunder is heard on between 10 and 14 days in an average year at most Midlands sites, with the frequency highest in the summer (generally greater than two days per month) and lowest in the winter (less than 0.5 day per month) reflecting the greater degree of surface warming in the former season (Figure 2).

Figure 2.

Mean monthly frequency of days when thunder was heard for the period 1981–2010.

Table 4 shows the precipitation yields for selected weather types in the Midlands. Hand (2005) produced a climatology of shower frequency in the British Isles. For the Midlands, he showed that: (i) in northerly airflows, showers are infrequent during the winter, but become more common in spring as strong insolation destabilises the air; (ii) in a northwesterly, showers generated over the North Channel and Irish Sea are funnelled into the northwest Midlands through the Cheshire Gap (Figure 3), and (iii) in southwesterlies there is a notable inland penetration of afternoon showers from Monmouthshire to Warwickshire.

Table 4. The variation in mean daily precipitation totals in the Midlands for non-directional anticyclonic and cyclonic, and directional Lamb weather types (LWT) over about 40 years
 Non-directional LWT
Anticyclonic<0.5mm everywhere
CyclonicUp to 5mm in Herefordshire, 4.5mm in north Derbyshire and 4mm in Lincolnshire. Drier elsewhere.
 Directional LWT
NortherlyWettest along Lincolnshire coast (2mm), with around 1mm in Birmingham.
NortheasterlyWettest in Northamptonshire (2.5mm), with 2mm in a band from Lincolnshire to Worcestershire. Less than 2mm in Peak District and Welsh Marches.
EasterlyWetter in west (2.5mm) and drier in east Midlands (<2mm).
SoutheasterlyBetween 2 and 3mm in west and <2mm in east Midlands.
SoutherlyWettest in Herefordshire (>3.5mm) and driest in Lincolnshire (<2mm).
SouthwesterlyFrom around 4mm in Welsh Marches and Peak District to <2mm in Lincolnshire.
WesterlyWettest in north Shropshire, north Staffordshire and north Derbyshire, and in Herefordshire (>2.5mm). Driest on Lincolnshire coast (1.5mm).
NorthwesterlyWettest in north Shropshire and north Staffordshire (1.5mm).
Source: Abstracted from maps in Sweeney and O'Hare (1992).
Figure 3.

Showers moving through the Cheshire Gap in a northwesterly airstream at 0445 utc on 2 March 2006.

Floods

Several major floods have affected the Midlands since 1997, the most notable being those of Easter 1998, autumn 2000 and summer 2007. In the Easter 1998 flood, two-day rainfall totals widely exceeded 70 mm in a band stretching from Herefordshire to Northamptonshire (see Figure 7 of Galvin and Pike, 2001). With low pressure centred in the English Channel on 9 April, the heavy rainfall was caused by the forced ascent of warm, moist, conditionally unstable air that had become trapped between colder air to the north and south. Five people were killed. Holt (2000) examined the flood's effects on Northampton, where around 2500 properties were inundated. There was extensive flooding along the River Severn in autumn 2000, with water levels in Shrewsbury and Worcester at their highest since 1947 (Eden, 2001). On 20 July 2007, Worcestershire's daily rainfall record was broken, with 120.8 mm recorded at Pershore College (Prior and Beswick, 2008). There was widespread flooding in Evesham as the River Avon burst its banks.

There have been other notable floods in recent decades. Four localised flood events in southwest Birmingham between 1998 and 2000 were analysed by Phillips (2003), but one of the region's most notable floods was at Louth (Lincolnshire) in 1920 (Clark and Vetere Arellano, 2004). The flood killed 23 people and cut gullies about 1.5 m deep in solid chalk. A soil survey and estimates of river discharge were used to deduce catchment rainfall intensities of 90–108mmh−1. The erosive powers of floodwater were also demonstrated at Ashow (Warwickshire) after 24.5 mm of rainfall fell in only 30 minutes on 20 August 1996; Harrison and Foster (1999) calculated that around 790 tonnes of sediment was eroded from two fields near the village.

Snow

Heavy snow can be caused by unstable Arctic or polar maritime airstreams (especially when polar lows are embedded in the flow) and when low-pressure areas move east across southern England (Kings and Giles, 1997). The Derbyshire Peak and Staffordshire Moorlands record the most snowfall. Elevated areas of the Welsh Marches also experience significantly more snowfall than the regional average. At Middleton (Derbyshire) at 321 m ASL, snow or sleet fell on 48 days per year on average compared to only 18 days at Bablake at a more modest 119 m (Figure 4(a)). There were 26 and 13 days of lying snow at 0900 utc at Middleton and Bablake respectively (Figure 4(b)). On low ground, more snow falls in the east Midlands than further west because of its proximity to the North Sea and exposure to north to northeasterly snow-bearing airstreams. The least snowfall occurs in Worcestershire. The region's snow season is from November to April: January and February are the snowiest months, with February having the highest probability of snowfall. Snow has been recorded in the Derbyshire Peak in May, June and October, but it rarely settles; an exception was 2 June 1975 when snow blanketed Buxton, during a county championship cricket match. It seldom snows at low elevation sites in these three months, and at Bablake it only snows on average on one day every ten years in May.

Figure 4.

(a) Mean monthly frequency of days with snow or sleet falling at two sites for the period 1981–2010. (b) Mean monthly frequency of days with snow lying at 0900 utc at two sites for the period 1981–2010.

During the recent cold winters of 2009/2010 and 2010/2011, the Midlands largely escaped the worst snowfall. However, a disruptive event did occur on 18 December 2010, with snow depths in excess of 20 cm in eastern Worcestershire and parts of south Warwickshire. At Evesham, it started to snow at 0600 utc and by 1730 a depth of 28 cm was recorded (Webb, 2011). The snow was caused by a complex low-pressure area that developed in deep cold air (the 1000–500 mbar thickness was less than 516dam). As the 500 mbar winds became light, the surface low in the northern Irish Sea and a trough remained quasi-stationary, thus prolonging the snow over the south Midlands. The snow could not have come at a worse time for retailers, with many shops in Birmingham City Centre having to close early on the last Saturday before Christmas (McCaskill and Hudson, 2011). Unexpected rain before a snowfall can make matters worse, as was demonstrated by Thornes’ (2005) account of the chaos on Birmingham's roads on 28 January 2004. Two cold fronts moved south over the Midlands between 1500 and 1600 utc; the first one unexpectedly produced up to 30 minutes of heavy rain, which washed much of the salt off the roads. As the second cold front crossed, the rain rapidly turned to snow, settled and turned the roads into an ice rink. Many drivers abandoned their cars and slept in their offices overnight.

Sunshine

Within the region, the main sunshine contrast is between the cloudier north and west and the sunnier south and east, with Shawbury and Ross-on-Wye recording the lowest and highest annual number of sunshine hours respectively. The mean monthly sunshine statistics for 1981–2010 (Table 5) show a predictable seasonal rhythm, with the highest totals in July and the lowest totals in December. There is one anomaly, however: Waddington and Shawbury record more sunshine per day in May than June. Despite being further south, Ross-on-Wye records less sunshine than Waddington from October to March inclusive because of its greater exposure to Atlantic depressions. Ross-on-Wye is, however, the sunniest of the six sites from June to September; over these four months, sunshine totals at Ross-on-Wye exceed those at Waddington by about 50 hours. Sunshine records were broken in July 2006 (the month with the highest CET), with Waddington recording its highest July total (304.5 hours) since 1947 (Prior and Beswick, 2007).

Table 5. Mean monthly and annual sunshine totals (hours) for the period 1981–2010
 Alt (m)JFMAMJJASONDYear
Middleton32155.168.096.5128.2164.6160.0172.1158.0114.787.758.249.01312.1
Waddington6860.982.3115.6156.5198.8180.0199.9187.4140.3111.270.554.81558.2
Shawbury7250.766.995.9132.0164.3154.9165.4161.3117.390.656.642.61298.5
Coventry (Bablake)11962.978.4114.2152.2190.5186.4200.9185.2137.4105.366.255.71535.3
Newtown Linford11956.373.1103.3138.0171.4167.9183.9173.3132.1102.363.951.61417.1
Ross-on-Wye6754.075.0114.0163.1194.9201.6214.8198.1142.8104.563.445.01571.1

There is also a contrast between urban and rural areas. In the early 1950s, cities usually recorded less sunshine than surrounding rural areas on winter days. With the decline of heavy smokestack industry and the introduction of air quality legislation, cities such as Birmingham often now enjoy fine weather when the low-lying areas of the Severn and Avon valleys are shrouded in mist and fog.

Wind

Using mean hourly wind speeds from 1980 to 1995, Kings and Giles (1997) summarised the frequency of occurrence of each Beaufort Force at Birmingham. The city's highest speeds, in common with that in other regions, are most likely to occur between December and March: the cumulative frequency of Forces 6–12 varies from 0.6% in July to 10.5% in February. However, the most remarkable wind event in recent years happened during the summer and was the south Birmingham tornado of 28 July 2005 (Figure 5). Twenty people were injured, and around 1000 houses were damaged in the Sparkbrook, King's Heath and Moseley districts of the city. James Ball from Moseley said (quoted in Britten, 2005, p. 2): Within a split second the sky went black [at around 1345 utc] and the wind was howling…Roof tiles were being thrown around and the air was full of swirling debris. The Birmingham tornado was ranked T4 on the TORRO scale with estimated wind speeds of 115–136mph (Eden, 2005). On this day, low pressure was centred off the coast of Cornwall, with warm, moist air being advected northwards across southern Britain (Figure 6), and an active front brought intense thunderstorms across the West Midlands. The July 2005 tornado occurred a few hundred metres west of the site of another tornado on 14 June 1931, and it is noteworthy that the synoptic situations on both days were almost identical.

Figure 5.

The effects of the Birmingham tornado of 28 July 2005 (Source: Birmingham Mail.)

Figure 6.

The synoptic situation at 0000 utc on 28 July 2005. (Crown copyright, Met Office.)

Despite being largely a landlocked region, sea breezes still merit consideration. In ideal conditions, sea breezes that develop along the Lincolnshire coast can sometimes reach as far inland as Nottingham and Mansfield by early evening (Meteorological Office, 1993). In Lincolnshire, Bennett (1997) determined that the sea breeze is able to penetrate at least 23 km inland by 1400 utc on about 50% of summer days with otherwise light pressure-gradient winds. North Sea breezes are likely to penetrate furthest inland in early summer when the sea is still cool and the land is rapidly gaining its summer heat. In an extreme case, Galvin (1997) noted how 30 June 1995 was exceptional because the sea-breeze front reached Birmingham. He attributed this to a large land-sea temperature gradient (from 30 °C in the central Midlands to 12 °C in the North Sea) and a ‘heat low’ that developed with a southward-moving cold front. When the sea-breeze front reached Wellesbourne (Warwickshire) at 1845 utc, the wind changed from calm to 15kn and the temperature fell by 6 degC. Sea breezes are also capable of reaching the Midlands from the Irish Sea, working through the Staffordshire lowlands from the Wirral and Cheshire.

Concluding remarks

The Midlands is a region of thermal transition between southern and northern England, and between the wetter west and drier east of Britain. It is the most ‘continental’ of all our regions. The Welsh mountains help to create a rain-shadow across the Midlands and so reduce the difference in rainfall between the west Midlands and east Midlands. In terms of extremes, the region's tendency for hot summer days and cold winter nights is perhaps the most noteworthy feature, together with the high frequency of flooding along the rivers Severn, Trent and Avon, with their extensive flood plains spreading over the low-lying terrain that characterises much of this, the ‘heart’ of England.

Acknowledgements

The author would like to thank the series editors Julian Mayes and Dennis Wheeler for their comments on the first draft. I would also like to thank the two reviewers for their suggestions. Thanks go to Mrs Anne Ankcorn, School of Geography, University of Birmingham, for drawing Figures 1, 2 and 4.

Ancillary