How to read the map:
Frost day is defined as a day with an average temperature below 0 ºC.
Stations with positive trends are in blue and stations with negative trend are in red colour. When stations are in green colour trends are not statistically significant at 25% level.
Positive values indicate cooling trend (increase in frequency) and negative values indicate a warming trend (decrease in frequency). The circle size depicts the magnitude of change in temperature per decade. Geographical coverage note: Europe