Near-surface meteorological observations and rawinsonde soundings from Arctic cruises with the German icebreaker RV Polarstern during August 1996, 2001, and 2007 are compared with each other and with ERA-Interim reanalyses. Although the observations are usually applied in the reanalysis, they differ considerably from ERA data. ERA overestimates the relative humidity and temperature in the atmospheric boundary layer and the base height of the capping inversion. Warm biases of ERA near-surface temperatures amount up to 2 K. The melting point of snow is the most frequent near-surface temperature in ERA, while the observed value is the sea water freezing temperature. Both observations and ERA show that above 400 m, in the North Atlantic sector 0–90 E, the warmest August occurred in 2001, and August 2007 had the highest humidity. In the Eastern Siberian and Beaufort Sea region ERA temperatures along 80 and 85 N were highest in 2007.