September Climate Normals; Long range forecast for September; and a look at first fall freeze dates for the Northland

September 1st marks the beginning of Meteorological fall, or the three month period of September, October and November.

The official start of Fall 2021 is on September 22.

Here’s a look at the climate normals and records at Duluth, Minnesota for the month of September.

Normal high on the 1st: 73
Normal high on the 30th: 61

Normal low on the 1st: 52
Normal low on the 30th: 42

Average monthly temperature for September: 57.3 degrees
Warmest September on record: 62.6 degrees set in 1897
Coldest September on record: 47.8 degrees set in 1974

Normal precipitation: 3.48″
Wettest September on record: 11.52″ set in 1881
Driest September on record: 0.19″ set in 1952

Normal snowfall: 0.1″
Snowiest September on record: 2.4″ set in 1991

Duluth averages 2 days at or above 80 in September (record is 10 days in Sep 1908)
Duluth averages 1 day at or below 32 in September (record is 7 days in Sep 1974)

Mean date for last 80 degree day in Duluth is September 11th. The latest last 80 in Duluth was on October 21, 1901. Last year’s final 80 degree day in Duluth was on October 9.

Mean date for first 32 degree or colder temperature in Duluth is September 30. The earliest first 32 degree or colder temperature in Duluth occurred on August 27, 1986, and the latest first 32 degree or colder temperature in Duluth was on November 6, 1900. Last year’s first 32 degree or colder temperature in Duluth came on September 17.

Astronomical Data for Duluth, Minnesota

Days continue to get shorter in September

Sunrise on the 1st: 6:28 AM CDT
Sunrise on the 30th: 7:06 AM CDT

Sunset on the 1st: 7:47 PM CDT
Sunset on the 30th: 6:49 PM CDT

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Much of the Northland typically sees their first frost and freeze of the season during the month of September, although it usually happens a little later near Lake Superior.

Mean date for first freeze (32 F)

International Falls, MN: September 14
Hibbing, MN: September 15
Ashland, WI: September 18
Brainerd, MN: September 21
Duluth, MN: September 30

Note: In 2020, Duluth recorded its first 32 F or lower temperature on September 17th.

Mean date for first freeze (28 F)

International Falls, MN: September 26
Hibbing, MN: September 29
Ashland, WI: September 29
Brainerd, MN: October 2
Duluth, MN: October 12

Note: In 2020, Duluth recorded its first 28 F or lower temperature on September 18th.

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The long range outlook for September 2021 calls for above average temperatures in northeast Minnesota and northwest Wisconsin per CFS model forecast.

The long range outlook for September 2021 calls for above average precipitation in all of northeast Minnesota, and near normal to above average precipitation in northwest Wisconsin per CFS model forecast.

Tim

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