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Preliminary Climate Summary for September 2018

Preliminary Climate Summary for September 2018:

September continued a trend of warmer than normal months. Most climate stations reported a mean monthly temperature from 1 to 3 degrees F warmer than normal. Over 60 climate stations reported at least one day with a 90 degrees F temperature or higher, while Marshall topped the state with a reading of 100 degrees F on the 15th. Many northern communities reported overnight lows in the 20s F the first and third weeks of the month. Brimson reported a low of 26 degrees F on the 22nd, but there may be colder readings yet for this coming weekend.

For the third year in a row Minnesota has seen abundant rainfall during the month of September. Furthermore, this time around it appears that September will be the wettest month on the calendar for many climate stations in the state during 2018. This is unusual, but not unprecedented. For south-central and southeastern counties September of 2018 will rank among the wettest five in history. Many climate stations have reported total rainfall for the month that is two or three times normal (6-9 inches), while some communities in southern counties have reported over 10 inches, the wettest September since that of 2010. Overall with Minnesota’s statewide climate network at least 72 new daily rainfall records were set during the month. In some areas farmers will have to wait for fields to dry out before beginning harvest of soybeans or corn.

Last Call for "Learning Life Series"

Next week on the evening of October 4th at 7pm I will be giving a lecture for the U of M College of Continuing Education “Learning LifeSeries.” I am calling it “Climate Change in Our Own Backyards: Evidence and Implications.” I believe there may still be some tickets available, not just for my lecture but for other wonderful lectures in the series. Hope to see you there.

Weekly Weather Potpourri:

NOAA scientists publishing in the journal Science this week noted that their research shows with continued warming in the North Atlantic Ocean Basin, category 3 or stronger hurricanes will become more frequent in occurrence.

Also this week NOAA scientists provided an update on the Arctic Sea Ice minimum for 2018. It occurred on September 19th and ranked as the 6th lowest amount observed in the 40 year record. Warm water from the North Pacific enters the Arctic Ocean through the Bering Strait, and in recent decades this warm water has exerted a strong influence on the decline in Arctic Sea Ice.

In the Western Pacific Ocean Typhoon Trami was slowly making its way towards southern Japan where it is expected to make landfall late in the weekend. Trami is producing winds up to 110 mph and sea wave heights over 35 feet.

MPR listener question:

Seeing the cold forecast for the coming weekend, do you think any places in Minnesota will see some snow, and isn’t that unusual for September?


Indeed portions of Koochiching, Roseau, Lake of the Woods, and Kittson Counties could see some snow flurries mixed with rain showers this weekend. But no accumulations are expected. Historically across the southern half of Minnesota September snowfall is rare, but in some northern areas like International Falls, Roseau, and Kabetogama snow comes in September about 20 percent of the time.

Twin Cities Almanac for September 28th

The average MSP high temperature for this date is 66 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 47 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for September 28th:

MSP weather records for this date include: highest daily maximum temperature of 91 degrees F in 1898; lowest daily maximum temperature of 43 degrees F in 1908; lowest daily minimum temperature of 26 F in 1942; highest daily minimum temperature of 64 F in 1905; and record precipitation of 1.21 inches in 1891; and a trace of snow fell in 1945..

Average dew point for September 28th is 44 degrees F, with a maximum of 70 degrees F in 1971 and a minimum of 24 degrees F in 1942.

All-time state records for September 28th:

The state record high temperature for this date is 97 degrees F at Argyle (Marshall County) in 1952. The state record low temperature for this date is 15 degrees F at Alborn (St Louis County) in 1942. State record precipitation for this date is 3.65 inches at St Peter (Nicollet County) in 1901; and record snowfall is 2.0 inches at Ada (Norman County) in 1899.

Past Weather Features:

A spell of very warm weather brought an end to the month of September in 1898. Over a dozen climate stations reported daytime highs in the 90s F on the 28th. The overnight temperature never fell below 65 degrees F at St Cloud.

One of the wettest conclusions to September came in 1901 when five consecutive days of rain brought 2-3 inches to many parts of the state. A number of dirt roads were washed out in Nicollet and Sibley Counties.

Following an early snow storm on the 26th frigid air closed out the month of September in 1942 across Minnesota. Most climate stations saw morning lows in the 20s F, and a number of communities in northern counties reported temperatures in the teens.


Cold Canadian high pressure will settle over the state this weekend bringing much below normal temperature conditions. Widespread frosts are likely, except perhaps for the Twin Cities inner core. Widespread readings in the 20s F will prevail across the north, but daytime highs will warm into the 40s and 50s F. Some chance for light, scattered showers over the weekend as well. There will be some moderation in temperatures with increased cloudiness for next Monday through Wednesday, and a chance for showers as well.

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