Skip to main content

Preliminary Climate Summary for September

Preliminary Climate Summary for September

Average September temperatures reported by observers around the state ranged from 2 to 5 degrees F above normal. Several days early in the month hit 90 degrees F or higher, with high dewpoints (70 F) pushing the Heat Index Values between 98 F and 102 F on September 9th. The highest temperature for the month was 97 degrees F at Preston on the 7th, while the lowest was 26 degrees F at Embarrass on the 17th and at Brimson on the 22nd. Numerous frosts occurred in northeastern and north-central counties, while the rest of the state escaped a September frost, which was good for crop maturation and drying. Corn harvesting had begun in some areas of the state.

Precipitation for September was below normal for most observers, especially the northwestern and southern counties which reported just 5 or less days with rainfall. Most observers reported between 1 and 2 inches. Some of the driest spots in the state were Argyle (Marshall County) with just 0.11 inches (their driest September ever surpassing 0.16 inches in 1948), Roseau with 0.18 inches (2nd driest September to 0.07 inches in 2012), Blue Earth (Faribault County) with 0.58 inches (2nd driest September to 0.55 inches in 2000), Winnebago (Blue Earth County) with 0.76 inches (4th driest September), and Austin with 0.82 inches (9th driest September). Thanks to some widely scattered but intense thunderstorms a few spots reported above normal rainfall for the month including 4.44 inches at Grand Portage, 4.04 inches at Kabetogama, 5.03 inches at Ottertail, 5.65 inches at Fergus Falls, 4.67 inches at Pelican Rapids, 5.14 inches at Long Prairie, and 4.49 inches at Big Lake. Thunderstorms brought large hail and strong winds (50-75 mph) to parts of central Minnesota on the 19th.

With September being the 3rd consecutive drier than normal month for the state, many more counties returned to the drought status of earlier in the year, with over half the state landscape designated to be in moderate to severe drought by month's end.

September 1807 in Minnesota

Alexander Henry was an explorer and trapper for the old Northwest Fur Trade Company at the beginning of the 19th Century. He explored and lived in the Red River Valley of Minnesota and North Dakota from 1800 to 1808, establishing camps and building temporary forts in many places along the river, including near Pembina and Drayton, ND as well as Warren, Oslo, and Red Lake Falls, MN. Thanks to his daily weather journal, one of the oldest in our region, we have a daily written record of the weather in northwestern Minnesota for the period from September 1807 to June 1808.. September, 1807 according to Henry was highly variable. Very sunny and warm early in the month with several days in the 80s F. Then it turned cool and showery by mid-month with a number of frosts and a hard freeze on the 16th (28 F). Fall coloration and leaf drop came about mid-month, and he observed the migration of geese and swans heading south. September 18th brought every kind of weather according to Henry's journal...."strong winds, heavy rain, hail, and even two inches of snow!" This was followed by another hard freeze on the 20th (27 F). The month concluded with yet another freeze on the 28th, followed by light showers and foggy weather through the end of the month.

Henry's journal is a treasure to a historian or climatologist as it is one of the few written records of the daily weather from such an early time period, before settlement of the Red River Valley. He documents a number of spring snow melt floods in the region and remarks about how the floods used to drown hundreds of buffalo which would graze the numerous islands. The 1800-1808 period is still encompassed by the northern hemisphere's Little Ice Age that extended to roughly 1850. In this context it is not unexpected to find that Alexander Henry recorded snows in September and winter snow cover persisting well into the month of May in northern Minnesota.

Coming up, October a favorite month for many

I came across this commentary about October's weather in an 1895 edition of the Minneapolis Journal...."October is generally a kingly month in Minnesota. It opens with the usual affluence of sunshine and quickening, bracing air, which [is} stimulating to the senses. Day after day, the transformation of summer greenery into the royal and gorgeous tones of autumn will go on and summer's silent fingering will be overwoven with pageantry of color which no human art can call into being. The recessional of the year is grander than the processional...."

From numerous conversations with weather observers and other friends, I have drawn the conclusion that many of us cherish October as a favorite month. Some of the memories shared include:
A pageantry of landscape color for outdoor weddings, harvest festivals, Oktoberfest dinners...visits to the apple house and glasses of fresh cider..picking out hay rides...filling the pantry with the garden harvest including homemade pickles and apple sauce...frosty morning bike rides under clear, blue skies...wearing handmade sweaters and embroidered sweatshirts...a bonfire rally...the last boat trip...migrating bird formations...drying and arranging the last of the cut and soccer games...and of course MPR's fall pledge drive (which starts October 10).

Climate Change Adaptation Conference at the Science Museum on November 7, 2013

Several organizations are partnering to host the first statewide conference on Climate Change Adaptation, Planning and Practice. It will take place at the Science Museum of Minnesota in downtown St Paul on November 7, 2013. Registration for the all day program is only $50. Sessions will be devoted to city planning, agriculture, transportation, natural resources (including watershed management), and public health.

Weekly Weather potpourri

The highly anticipated AR5 report from the IPCC was partly released on Friday (September 27th), the remainder of the report will be released on Monday (Sept 30). IPCC scientists emphasized that confidence about the human fingerprint on climate change has grown to 95 percent. Specific environmental features that are clearly related to human activity include increasing frequency of severe thunderstorms and heat waves, as well as continued loss of Arctic sea ice and sea level rise. The summary for policymakers and the final AR5 report will be available for reading here.

Researchers from the University of Missouri this week published a study of the fossil evidence recovered from Tanzania representing the Late Cretaceous Period (90 million years ago) and determined that when the Earth's atmosphere contained up to 1000 ppm of carbon dioxide there were no continental ice sheets present. You can read more about this study here.

Another study from Stanford researchers and published in the Proceedings of the National Academy of Science suggests that continued climate change will lead to a higher frequency of severe thunderstorms across the USA. Models of the future changes in climate show an increase in convective available potential energy (CAPE), a measure of energy correlated with the development of severe thunderstorms. You can read more about this study here.

Portions of Vietnam, Thailand, and Laos, already plagued by flooding and heavy rains this month are expected to see even heavier rainfall from Tropical Storm Wutip in the Western Pacific Ocean. This storm is expected to make landfall late in the weekend and early next week bringing several inches of rain to the area.

NOAA National Weather Service expects the first significant autumn snowfall to occur in portions of WY, MT, and ID Friday and Saturday, with up to a foot of snow in the Wind River Range of western Wyoming. It will be short-lived as temperatures warm into the 40s and 50s F later in the weekend.

Some drought notes this week from Brad Rippey with the USDA World Agricultural Outlook Board:
-During the drought-monitoring period ending September 24, U.S. severe to exceptional drought (D2 to D4) coverage fell from 28.35 to 25.33%; extreme to exceptional drought (D3 to D4) coverage fell from 6.85 to 4.33%; and exceptional (D4) drought coverage fell from 0.43 to 0.31%. In all three cases (D2 to D4, D3 to D4, and D4), drought coverage stood at its lowest level since June 2012.
- For the week ending September 24, corn and soybeans in drought [across the USA] were down one percentage point, with 54 and 44% of the respective production areas categorized as being in moderate drought (D1) or worse. There were two percentage point decreases apiece in drought coverage for cattle (51% in drought) and hay (37%). Forty percent of the U.S. winter wheat production area was in drought on September 24, down three percentage points from a week ago.

MPR listener question

I haven't heard you talk about stored soil moisture values in a long time. With this recent sequence of dry months and return of drought how much moisture is stored in the soil this fall?

Answer: Good question, and of course the answer varies with geography. In southwestern Minnesota at Lamberton a measurement made last week showed just 1.49 inches of moisture available in the top 5 feet of soil. That's very dry (average for this time of year is about 4 inches) but not as low as last year at this time (0.72 inches). At Waseca, in south-central Minnesota, a recent measurement shows over 7 inches of stored moisture remaining in the top 5 feet of the soil profile (slightly above normal for this time of year), and well above last year when only about 2 inches was stored. Elsewhere estimate ranging from 2 to 4 inches are pretty common.

Twin Cities Almanac for September 27th

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 46 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for September 27th

MSP weather records for this date include: highest daily maximum temperature of 88 degrees F in 1987; lowest daily maximum temperature of 40 degrees F in 1942; lowest daily minimum temperature is 29 degrees F in 1942 and 1991; highest daily minimum temperature of 64 F in 1891; and record precipitation of 0.54 inches in 1947; and no snow has fallen on this date.

Average dew point for September 27th is 45 degrees F, with a maximum of 67 degrees F in 1905 and a minimum of 24 degrees F in 1951.

All-time state records for September 27th

The state record high temperature for this date is 97 degrees F at Beardsley (Big Stone County) in 1894, at Hallock (Kittson County) and Wheaton (Traverse County) in 1952, and at Canby (Yellow Medicine County) in 1956. The state record low temperature for this date is 13 degrees F at Beardsley (Big Stone County) in 1893. State record precipitation for this date is 3.50 inches at Wolf Ridge Environmental Learning Center (Lake County) in 1996; and state record snowfall for this date is 6.0 inches at Benson (Swift County) in 1942.

Past Weather Features:

September 27-28, 1894 brought a fall Heat Wave to many parts of Minnesota with low to mid 90s F. A strong cold front caused temperatures to plummet into the 30s by the evening of the 29th.

September 26-27, 1942 brought an early season snow storm to Minnesota. A heavy wet storm made travel difficult in rural areas. Bird Island reported 8 inches, Long Prairie 7.5 inches, Detroit Lakes, Benson and Willmar reported 6 inches, New Ulm 5.5 inches, and Grand Meadow 5 inches. The snow was short-lived as temperatures warmed into the 50s and 60s F by the end of the month.

Thunderstorms brought heavy rain to northern Minnesota communities on September 27, 1996. Lutsen Mountain received nearly two inches of rain and many other areas reported well over an inch. Wolf Ridge Environmental Learning Center near Finland on the North Shore reported an all-time September rainfall record of 3.50 inches.


 Mostly cloudy and showery on Saturday with somewhat cooler temperatures and strong winds. Dry and sunny on Sunday and Monday with warmer temperatures. Generally dry and warm next week with a chance for showers and thunderstorms by late Thursday and Friday.
Print Friendly and PDF