Deviation of mean annual and monthly air temperatures in the period 1775–2020

Circular diagrams above represent mean annual and monthly air temperature deviations from annual and monthly average in the period 1961-1990. Dark red indicates significantly above-average temperature, dark blue shows below-average values. Annual mean is represented by the color of the circle center, monthly means are represented by the wedge-like sectors as shown in the legend on the right. The color legend is shown separately for monthly and annual means – the deviations are higher in case of the monthly means.
Absolutely coldest was the year 1829 (mean: 4.4°C, deviation: -2.9°C), warmest being the year 2018 (mean: 10.0°C, deviation +2.7°C). Coldest month in terms of absolute values was December 1788 (-12.7°C), while the warmest was August 1807 (+21.6°C). Month with highest negative deviation is December 1788 (mean: -12.7°C, deviation: -11.6°C). In contrast, highest positive deviation was observed in January 2007 (mean: +3.2°C, deviation: +6.1°C).
It is also interesting to note that in each year there was at least one above-average month, however, in some years, there was no month with below-average monthly mean (2015 and 1934). Five warmest and coldest years are 2018, 2019, 2015, 2014 and 2020, and 1829, 1789, 1799, 1785 and 1805, respectively.