The weather in Lapland varies a lot depending on the season. In the following there are some typical characteristics of the different seasons.
Summer (approx. June-August) in Lapland is usually mild with mean temperatures between +10 to +16 °C. There is no particular rain season in the summer, but there is a small chance of occational thunderstorms. The nights can be cold but the temperatures rarely fall below zero during summer. In daytime, the temperature quite typically reaches +20 °C. The winds over the fells can be gusty at times throughout the year.
Lasting for about two months (approx. September-October), the mean temperatures in autumn lie around -3 and +9 °C. The weather can be wet at times with rainy days for up to 15 days per month. The amount of daylight starts dropping after Equinox. The nights become frosty and the ground starts to freeze towards the end of the season. Thanks to the beneficial weather type, the autumn colors are especially impressive in Lapland.
This is the longest season of the four (approx. November-March), lasting for up to 200 days in Lapland. The mean temperature lies around -10 and -18 °C. Occationally the temperature may fall as low as to -30 °C or below. The winters are usually dry with the lowest amount of precipitation of the year. The real feel of the coldness is affected by the wind. The conditions may sound harsh, but adequate clothing allows working outdoors throughout the winter.
The mean temperatures of the spring season (approx. April-May) vary between a few degrees below zero and a few degrees above zero. The snow cover has to a large part melted away and the last remains of the snow will disappear around late April / early May. Spring is fairly dry with an average precipitation of 20-30 mm of rain per month.
More information on Finnish seasons and the weather can be found through the Finnish Meteorological Institute.