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Multiple Frosts This Month

 Multiple Frosts This Month:

Many climate stations are reporting multiple frosts this month, especially in the northern third of the state. Some places have seen 5-6 morning frosts. Minimum temperatures from 20°F (Embarrass, Babbitt, and Cotton) to 29°F have been reported from portions of Koochiching, Cook, Lake, St Louis, Carlton, Hubbard, Marshall, Clearwater, Lake of the Woods, Cass, Chisago, and Beltrami Counties. Some parts of these counties have already reported up to 50 percent autumn leaf color change according to the DNR.

Much of the southern half of Minnesota has yet to see a frost this month, and most of the next two weeks looks to be frost free according to the NOAA outlook models. The outlook for harvesting of crops looks good too with a general absence of rainfall over the remainder of the month, and good field dry-down rates expected for crops.

Weekly Weather Potpourri:

According to NOAA Hurricane Sally brought massive amounts of rainfall to portions of coastal Alabama and the pan handle of Florida this week. Close to 500,000 people were without power, and at least two deaths were blamed on the storm. Many rainfall reports from the Florida panhandle ranged from 15 to 24 inches, while along coastal Alabama reports ranged from 12-14 inches of rain. The Weather Channel filed a detailed report on the storm.

The NOAA National Hurricane Center was tracking yet another Tropical Depression that had formed on Thursday in the Gulf of Mexico. It may mature into a Tropical Storm and affect the Texas Gulf Coast next week.

The BBC reports this week that an unusual tropical storm has formed in the Mediterranean Sea. This storm is called a Medi-cane. It is threatening to bring very heavy rains (8-12 inches) to Greece by the end of the week.

A team of international scientists have published an estimate of the contribution of melting polar ice to the rise in sea level over the rest of this century. Estimates of total sea rise due to melting in Antarctica and Greenland range from 16 to 20 inches, but this does not include continual sea level rise due to thermal (heat) expansion of the oceans. You can read more from Science Daily.

MPR listener question:

It seems to have excessively windy in the Twin Cities, this summer. I can’t recall any recent year where my gardens have been repeatedly damaged by strong wind gusts. Can you please comment on the reason for the wind and also put it in a historical context?


Looking at the climate data for May through August in the Twin Cities shows that 2020 did generally bring higher average daily wind speeds, and a higher than normal frequency of days with wind gusts over 30 mph. Only the month of July brought less than average daily wind speeds on most days. June was the windiest month of the summer and had 23 days with wind gusts over 30 mph. There were 21 days during the growing season when wind gusts exceeded 40 mph, and on August 10th and 14th wind gusts peaked briefly over 60 mph. These are indeed higher numbers and may partially be caused by the polar jet stream taking up position over the Minnesota landscape more frequently this summer.

Twin Cities Almanac for September 18th:

The average MSP high temperature for this date is 71 degrees F (plus or minus 10 degrees F standard deviation), while the average low is 51 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for September 18th:

MSP records for this date include: highest daily maximum temperature of 93 degrees F in 1891; lowest daily maximum temperature of 47 degrees F in 1991; lowest daily minimum temperature of 32 degrees F in 1929; highest daily minimum temperature of 71 degrees F in 1955; record precipitation of 3.75 inches in 1905. No snowfall has been reported on this date.

Average dew point for September 18th is 52°F; the maximum dew point on this date is 73°F in 1947; and the minimum dew point on this date is 23°F in 1929.

All-time state records for September 18th:

The state record high temperature for this date is 100 degrees F at Montevideo (Chippewa County) in 1891. The state record low temperature for this date is 12 degrees F at Littlefork (Koochiching County) in 1929. The state record precipitation for this date is 7.25 inches at Albert Lea (Freeborn County) in 1926. Record snowfall for this date is 2.4 inches at Duluth (St Louis County) in 1991.

Past Weather Features:

September 18, 1891 brought summer heat to most parts of Minnesota with daytime temperature readings in the 90s F. Montevideo (Chippewa County) reached a high of 100 degrees F by 3pm after starting out in the morning at just 51°F.

September 18, 1929 was the coldest in history statewide with many climate stations reporting minimum temperatures in the teens and twenties. Nearly every spot in the state reported frost. The daytime high in northern Minnesota only reached the mid-40s F.

September 18, 1991 brought snow to many parts of western and northern Minnesota. Most climate stations just reported a trace of snow, but in portions of Marshall and Saint Louis Counties measurable snowfall was reported, with up to 2.4 inches at Duluth.


Generally sunny and dry with a warming trend beginning this Saturday. Temperatures will average warmer than normal Sunday through Thursday with mostly sunny skies.

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