To predict the effects of temperature changes on plant growth and performance, it is crucial to understand the impact of thermal history on leaf morphology, anatomy and physiology. Here, we document a comprehensive range of leaf phenotypes in 25/20 °C-grown Arabidopsis thaliana plants that were shifted to 5 °C for up to 2 months. When warm-grown, pre-existing (PE) leaves were exposed to cold, leaf thickness increased due to an increase in mesophyll cell size. Leaves that were entirely cold-developed (CD) were twice as thick (eight cell layers) as their warm-developed (WD) counterparts (six layers), and also had higher epidermal and stomatal cell densities. After 4 d of cold, PE leaves accumulated high levels of total non-structural carbohydrates (TNC). However, glucose and starch levels declined thereafter, and after 45 d in the cold, PE leaves exhibited similar TNC to CD leaves. A similar phenomenon was observed in δ13C and a range of photosynthetic parameters. In cold-treated PE leaves, an increase in respiration (Rdark) with cold exposure time was evident when measured at 25 °C but not 5 °C. Cold acclimation was associated with a large increase in the ratio of leaf Rdark to photosynthesis. The data highlight the importance of understanding developmental thermal history in determining individual phenotypic traits.