Solar Radiation, measured in Langleys, for September 1 to November 30 from the U of M St. Paul Campus.
September through November 2018 was quite gloomy across Minnesota. In fact, looking at solar radiation records at the U of M St. Paul Campus Climate Observatory it was the least sunny meteorological autumn since 1983 and the 4th gloomiest autumn on record. There were 40 days of mostly cloudy to cloudy conditions for the three month period, a number that sounds impressive until one sees that the average number of cloudy days for the period is 43. The difference is the lack of clear days. From September through November there is on average 25 clear days, For 2018 there were only 18. Only two of those clear days were in November.
Meteorological Autumn for the Twin Cities finished cool, with the cold October and November outweighing the mild September. The three month average departure from normal was -1.8 degrees. November finished slightly below normal for precipitation, but September was 3.79 inches above normal and October was nearly and inch above normal so the three month period finished 4.44 inches above normal.
With the cold October and November conditions, lake ice freeze up was about ten days ahead of the median.