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Preliminary Climate Summary for September

Preliminary Climate Summary for September:

Mostly warmer than normal weather dominated our September weather with nearly two-thirds of all days bringing above average temperatures. Overall, most climate stations will report an average monthly temperature from 2°F to 4°F above normal. Extremes for the month ranged from 99°F at Lamberton (Redwood County) on the 21st to 21°F at Brimson (St Louis County) on the 28th. Over 50 climate stations reported at least one day with a maximum temperature of 90°F or greater. Within the state climate network during the month 49 daily high maximum temperature records were tied or broken. Despite the overall warmer than normal month, at least 70 climate stations reported frost over September 28-29, including as far south as Austin (Mower County). About a hundred climate stations have yet to report first frost.

Rainfall was less than normal across the state except for some northeastern and north-central counties. Grand Portage (Cook County) reported the most with 5.04 inches, but many areas reported between 1 and 2 inches. Some climate stations reported less than 1 inch of total rainfall, a near record or record low amount. Some of these included:
MSP 0.23 inches record driest
Theilman (Wabasha County) 0.68 inches, record driest
Farmington (Dakota County) 0.22 inches, 2nd driest
Minnesota City (Winona County) 0.29 inches, 2nd driest
Wheaton (Traverse County) 0.22 inches, 5th driest
Redwood Falls (Redwood County) 0.41 inches, 5th driest
New Ulm (Brown County) 0.44 inches, 7th driest
Austin (Mower County) 0.60 inches, 6th driest

As a result of the drier areas of the state getting drier in September, the regions of Severe Drought centered around the Twin Cities and extending southwest, expanded a bit, but the region of Moderate Drought expanded more to the west and northwest and now encompass about a quarter of the state landscape.

Wind conditions in September were on a par with earlier months of the year. Wind gusts of 30 mph or greater prevailed anywhere from 13 to 15 days during the month.

Weekly Weather Potpourri:

The biggest weather news of the week was Hurricane Ian and its powerful impact on the state of Florida when it came ashore on September 28th just north of Fort Myers. As one of the strongest hurricanes to hit the SE USA, it brought record setting winds, tidal surges, and rainfall amounts to many areas. Many areas reported sustained wind speeds of 80 mph or greater and some reported sustained winds of 120 mph or greater. Many climate stations reported rainfall amounts between 10 and 20 inches. Kissimmee (Osceola County) in central Florida just south of Orlando reported a new all-time rainfall for September 29th of 18.60 inches, while Union Park (Orange County) between Orlando and Cape Canaveral reported a record 17 inches. Many Florida rivers also went to record flood stage. The Weather Underground filed many reports on this hurricane.

Meanwhile, Canadians in the Atlantic Province are still reeling from the impacts of Storm Fiona last weekend. There was widespread coastal damage to property and infrastructure, with estimate insured losses ranging from 300 to 700 million Canadian dollars. According to Reuters the Environment Canada Agency may need to reconsider more aggressive climate adaptation strategies for their upcoming November report.

In the Western Pacific Ocean Typhoon Noru brought severe weather to the Philippines, and then to portions of Vietnam and Thailand. This typhoon brought 8-12 inches of rainfall to many places and was reported on by the BBC.

MPR listener question:

Can you comment on any expected weather pattern changes that might come to us in Minnesota as a result of the passage of Hurricane Ian this week over the southeastern USA?


There is no 100 percent correlation between hurricane striking the southeastern states and impacts on weather patterns across Minnesota. There are however historical cases where the landfall of strong hurricanes produced significant weather impacts in Minnesota. Sometimes when strong hurricanes come ashore in Texas or Louisiana, residual moisture aloft migrates as far north as Minnesota and brings us significant rainfall. In addition there have been cases when strong hurricanes coming ashore in other southeastern states (MS, AL, GA, or FL) have produced a change in the jet stream pattern which allows for cold air intrusion from Canada to migrate further south across Minnesota, bringing us several days of below normal temperatures.

Twin Cities Almanac for September 30th:

The average MSP high temperature for this date is 67 degrees F (plus or minus 10 degrees F standard deviation), while the average low is 48 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for September 30th:

MSP records for this date: highest daily maximum temperature of 87 degrees F in 1897; lowest daily maximum temperature of 44 degrees F in 1985; lowest daily minimum temperature of 26 degrees F in 1939; highest daily minimum temperature of 68 degrees F in 1878; record precipitation of 1.06 inches in 2007. Record snowfall is 0.1 inches in 1961..

Average dew point for September 30th is 43°F; the maximum dew point on this date is 66°F in 1971; and the minimum dew point on this date is 18 degrees F in 1974 .

All-time state records for September 30th:

The state record high temperature for this date is 93 degrees F at Montevideo (Lac Qui Parle County) in 1897. The state record low temperature for this date is 10 degrees F at Big Falls (Koochiching County) in 1930. The state record precipitation for this date is 5.00 inches at Cook (St Louis County) in 1995. Record snowfall is 3.0 inches at Isabella (Lake County) in 1985.

Past Weather Features:

Very warm weather on September 30, 1897 blanketed Minnesota. Temperatures were in the 70s and 80s F on most places, and nine southern and western counties reported afternoon highs in the 90s F.

September 30, 1930 brought a hard freeze to many northern areas of the state where low temperatures ranges from 10°F to 17°F. It froze as far south as New Ulm (Brown County) ending the growing season.

A somewhat rare early snowstorm crossed northern Minnesota over September 30 to October 1 of 1985. It dropped 2 to 6 inches across many northeastern counties. Isabella (Lake County) residents were shoveling snow on October 1st as 11.5 inches had fallen. Whew!

Slow moving thunderstorms brought heavy rains to northern Minnesota communities over September 30 to October 1 of 1995. Many observers reported 2 to 4 inches of rainfall, with some street flooding. Cook (St Louis County) reported a record 5 inches on September 30th, the largest single day rainfall in their climate record.


Warm and dry for Saturday through Monday. Chance for rain on Tuesday and then much cooler for Wednesday through Friday of next week, with another chance for frosts.

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