Present Climate Conditions


Warm Streak Stopped Cold

Graph of May 2017 temperatures and departures in the Twin Cities
May 2017 temperatures and departures in the Twin Cities

 

Bouts of chilly air during May 2017 put the brakes on the longest known warm spell in Minnesota history.

May started with snow showers and temperatures 15-20 degrees below average. It took almost two weeks of mild and even warm weather to undo the temperature deficits from May 1 and 2. The eventual warmth of mid-May gave way to a run of cool weather, which proved to be the deciding factor. Even though most locations had 17 or 18 warm days, compared to just 13 or 14 cool ones, the depth of the cold was great enough to finish below-normal at virtually all stations in Minnesota.

The slightly cool month ends an incredible run of warmth. For 20 straight months, September 2015 through April 2017, stations throughout southern and central Minnesota remained warmer than 1981-2010 normals. The second longest streak in history came just five years earlier, in 2011 and 2012, when many stations logged 16 straight warm months.

If the climate were truly stable, then any month would have equal chances of being warmer or cooler than normal. Using basic probability theory, the chance of 20 straight warm months is about one-ten-thousandth of one percent, and even the chance of 16 straight warm months is still between one and two one-thousandths of a percent--highly unlikely!  Indeed, the whole of Minnesota has been warming rapidly since about 1970, making above-normal temperatures more likely than below-normal ones, even as the baseline "normal" values are updated to reflect the warmer conditions. 

It is impossible to know when the next warm streak will begin, and we will require over a year-and-a-half of continued warmth after that first warm month before we can talk about challenging this impressive record!

Below is some information about the temperature characteristics in the Twin Cities since September 2015.  

Twin Cities Average Monthly Temperatures

                Avg    Dept. from
Month     Year  Temp   1981-2010 Normal
---------------------------------------------
September 2015  67.9   + 5.9  
October   2015  52.1   + 3.2
November  2015  41.3   + 7.6
December  2015  30.2   +10.5
January   2016  17.6   + 2.0
February  2016  24.9   + 4.0
March     2016  41.3   + 8.5
April     2016  48.1   + 0.6
May       2016  61.3   + 2.2
June      2016  71.3   + 2.4
July      2016  75.2   + 1.4
August    2016  73.4   + 2.2
September 2016  66.1   + 4.1
October   2016  52.9   + 4.0
November  2016  44.1   +10.4
December  2016  20.9   + 1.2
January   2017  20.9   + 5.3
February  2017  31.2   +10.3
March     2017  34.0   + 1.2
April     2017  50.5   + 3.0
May       2017  58.5   - 0.6 Streak Ended


Last modified: June 1, 2017
For more information contact: climate@umn.edu