2021 Summer Climate Assessment:
August ended up as the 7th warmest in history on a statewide basis, continuing the significantly warmer than normal monthly temperature streak that started in June. In terms of rainfall, about a third of the state saw below normal rainfall during August, but the month delivered above normal amounts to over 60 percent of the state, helping to mitigate the drought situation. According to the September 2nd release from the US Drought Monitor, the area of Minnesota landscape in Extreme to Exceptional Drought shrunk by roughly 35 percent over the last week of August. As we start September this week about two-thirds of the state remains in Severe, Extreme, or Exceptional Drought. More details on the Drought of 2021 can be found at the Minnesota State Climatology Office web site:
If we look at the statewide mean monthly temperatures for June through August, 70.6°F, this trails only the summer of 1988, 70.7°F on a statewide basis for hottest summer in state history. For some individual climate stations, 2021 brought the hottest summer in their climate history, including MSP, Duluth, Brainerd, Grand Rapids, Roseau, and Park Rapids.
Despite the surplus rainfall that fell in many places during August, most areas of Minnesota recorded a much drier than normal summer. Many climate stations reported less than 5 inches of rainfall for the June-August period. And for some it was indeed record-setting dryness. Minneota (Lyon County) reported just 4.28 inches of rain, a record dry summer there. Likewise Embarrass (St Louis County) with 4.53 inches and Ely (St Louis County) with 4.86 inches were record dry as well.
There are some large disparities in the historical rankings of summer’s climate based on general state geography. We can see this in the table below:
Geographic Region: Historical Ranking of Jun-Aug Temperature and Rainfall Table:
Temperature Rainfall
Northwest (Climate Division 1) 2nd warmest 10th driest
North-Central (Climate Division 2) 1st warmest 6th driest
Northeast (Climate Division 3) 1st warmest 7th driest
West-Central (Climate Division 4) 2nd warmest 41st driest
Central (Climate Division 5) 2nd warmest 16th driest
East-Central (Climate Division 6) 1st warmest 8th driest
Southwest (Climate Division 7) 3rd warmest 20th driest
South-Central (Climate Division 8) 9th warmest 36th driest
Southeast (Climate Division 9) 5th warmest 34thwettest
All geographic areas of the state were drier than normal this summer with the exception of the southeastern counties which received abundant rainfall during the last then days of August. From a temperature standpoint the Northeast, East-Central, and North-Central Counties were the hottest this summer relative to their historical climatology.
25th Annual MPR Minnesota State Fair Weather Quiz:
Despite the fact that Minnesota Public Radio will not be broadcasting programs from the Minnesota State Fair this year, we will broadcast the 25th edition of the MPR Minnesota State Fair Weather Quiz from noon to 1pm on Friday, September 3rd (MPR Day at the Fair). Tom Crann will host from the St Paul radio studios and I will participate remotely. I always look forward to this program and will do my best to provide some interesting, entertaining, educational, and downright nerdy weather questions for you to consider. FM 91,1 in the Twin Cities and check your local FM radio listings for Greater Minnesota.
Weekly Weather Potpourri:
Hurricane Ida brought a great deal of destruction to portions of Louisiana over August 29-30, then remnants of the storm brought flooding rains to many northeastern states over September 1-2. In New York, areas around Central Park, La Guardia, and Westchester reported rainfalls of 6-7 inches, while in New Jersey, areas around Newark and Harrison reported 8-9 inches. Street flooding was widespread. Up to 45 deaths were blamed on the storm according to the BBC. The New York City Office of the National Weather Service provided more details.
El Pais reported on the intense and heavy rains that fell over portions of Spain on Wednesday this week causing widespread flash flooding. The State Meteorological Service of Spain (AEMET) reported rainfall rates of over 3 inches in 30 minutes, with some daily totals that exceeded 10 inches. Many roads and highways were washed out and there were power outages.
A recent study from the National Center for Atmospheric Research (NCAR) suggests that future flooding patterns may change significantly, as climate change impacts the frequencies of both drought and intense storms that cause flash flooding. The study's findings could have significant implications for infrastructure design and flood risk mitigation strategies. The study appears in the journal Communications Earth and Environment.
MPR listener question:
As we continue to be concerned about the drought of 2021 can you remind us what is the average rainfall in September, and what are the extremes for the state?Answer:
Average or normal rainfall for September across Minnesota ranges from 2.25 inches in some western counties to 3.50 inches in some southeastern counties. Historical extremes have ranged from over 14 inches at Hallock, Zumbrota, Caledonia, Waseca, Windom, and Spring Grove) to just a trace which was recorded at Beardsley (Big Stone County) in September of 1918. Many areas of the state have seen less than a quarter of an inch of rainfall in September historically. The current NOAA outlook actually gives equal chances for above or below normal rainfall across Minnesota during this September.Twin Cities Almanac for September 3rd:
The average MSP high temperature for this date is 77 degrees F (plus or minus 9 degrees F standard deviation), while the average low is 58 degrees F (plus or minus 7 degrees F standard deviation).MSP Local Records for September 3rd:
MSP records for this date: highest daily maximum temperature of 97 degrees F in 1925; lowest daily maximum temperature of 58 degrees F in 1934; lowest daily minimum temperature of 32 degrees F in 1974; highest daily minimum temperature of 73 degrees F in 1960; record precipitation of 1.08 inches in 1887. No snowfall has occurred on this date.
Average dew point for September 3rd is 55°F; the maximum dew point on this date is 74°F in 1964; and the minimum dew point on this date is 31 degrees F in 1974.
All-time state records for September 3rd:
The state record high temperature for this date is 103 degrees F at New Ulm (Brown County) in 1925. The state record low temperature for this date is 20 degrees F at Tower (St Louis County) in 1997. The state record precipitation for this date is 5.44 inches at Mankato (Blue Earth County) in 1996. No snowfall on this date.Past Weather Features:
The hottest September 3rd in state history was in 1925 when over half of Minnesota saw afternoon temperatures in the 90s F. Six climate stations reported a high of 100°F or greater.
Heavy rains dominated the state over the first three days of September in 1926. Many areas reported 2-4 inches of rain, while Little Falls in central Minnesota reported over 5 inches. It turned out to be a very wet month (7-10 inches of rain in many places) and a difficult harvest season for Minnesota farmers.
The coldest September 3rd was in 1974 when widespread frosts occurred, encompassing about half of the state. Over 40 climate stations reported morning lows in the 20s F. Even the Twin Cities reported frost, and one of the earliest endings to a growing season in history
Outlook:
Cool and pleasant over the weekend and on Labor Day. Sunny skies, cooler than normal temperatures and relatively low humidity will prevail. There will be a chance for showers later on Monday and into early Tuesday. Then the rest of nextweek should be dry and cool.
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