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Wet Start to September

Wet Start to September:

After a wetter than normal July and August, September is following trend and beginning wetter than normal for many areas of the state thanks in large part to some strong thunderstorms that crossed the state over September 4-7. Several areas of the state have reported over 2 inches of rainfall so far this month. Many climate stations are already reporting rainfall totals which are near the monthly average for September, and some locations have already surpassed the monthly normal rainfall values. A partial list of these locations:

Mabel (Fillmore County) 5.54"
Caledonia (Houston County) 4.69"
Spring Valley (Fillmore County) 4.14"
Spring Grove (Houston County) 4.03"
Lanesboro (Fillmore County) 3.40"
Worthington (Nobles County) 2.86"
Wright (Carlton County) 3.93"
Brainerd (Crow Wing County) 2.90"
Ottertail (Otter Tail County) 2.52"
Eveleth (St Lous County) 3.20"
Pokegama Dam (Itasca County) 3.52"
Ada (Norman County) 2.97"
Roseau (Roseau County) 2.65"

Some of these thunderstorms produced new daily rainfall records for many observers. Some of these new record values included:
For September 5th: 1.03" at Amboy, 1.92" at Redwood Falls, 2.65" at Roseau, 1.41" at Floodwood, 2.02" at Argyle, 1.42" at Isabella, and 1.37" at Thief River Falls.
For September 6th: 2.78" at Pokegama Dam, 1.96" at Eveleth, and 0.89" at Grand Portage
For September 7th: 4.41" at Caledonia, 2.95" at Harmony, 3.35" at Spring Valley, 2.00" at Theilman, 1.47" at Grand Rapids, 1.27" at Zumbrota, 1.20" at Owatonna, 3.89" at Spring Grove, and 2.32" at Houston.

In addition, the thunderstorms on the evening of September 7th produced a tornado caused that caused some damage at Camp Ripley (Morrison County) The State Climatology Office wrote a report about this.

Thankfully the weather looks to be cooler and drier for much of next week.

Weather Associated with the Record State Fair Attendance:

The12-day run of the Minnesota State Fair (August 25-September 5) set a new attendance record this year with 1,943,719. Three dates brought record daily attendance: Friday, August 26; Friday, September 2nd; and Saturday, September 3rd (all-time daily attendance record set with 260,374). So what was the weather like and did it help promote this record attendance? Yes, likely. Here is the daily attendance and associated weather description for each day of the State Fair (* denotes record attendance for the day):
Thursday, August 25, 111,902, cooler than normal and breezy
Friday, August 26, 141,023*, cooler than normal, with low relative humidity
Saturday, August 27, 180,567, cloudy and humid day
Sunday, August 28, 177,906, warm and humid day, afternoon temperatures in the mid-80s F
Monday, August 29, 119,522, warm and humid with Heat Index near 90F, and rain at night
Tuesday, August 30, 126,354, early morning rain, cloudy
Wednesday, August 31, 118,042, near normal weather, partly cloudy
Thursday, September 1, 133,773, near normal weather
Friday, September 2, 182,926*, very sunny, with low relative humidity, pleasant temperatures
Saturday, September 3, 260,374*, sunny, breezy, and low relative humidity
Sunday, September 4, 233,303, cloudy and breezy
Monday, September 5, 158,027, early morning rain, very humid, warm and cloudy

Weekly Weather Potpourri:

As a follow up to the dialogue we had last week during the broadcast of the MPR State Fair Weather Quiz, I found reference to the two modern era Grandstand Shows that were washed out by wet weather. The first one was the concert by Mac Davis on August 30, 1977 when over 4 inches of rain fell at the Fairgrounds, the 2nd one was the evening of August 26, 1982 when a half inch of wind-whipped rain fell, getting all of the sound equipment wet and canceling the Willie Nelson concert. My wife Cindy vividly remembered that one as we had tickets to attend.

In a NOAA press release earlier this week scientists offered an assessment of the devastating floods in Louisiana during August. Over August 11-17 many areas around Baton Rouge reported over 20 inches of rainfall, setting records for the most rain ever. Widespread flooding resulted in over 60,000 homes being damaged, 30,000 people being evacuated, and the loss of 13 lives. The scientific assessment of this event concluded that climate change likely helped magnify the atmospheric conditions that produced such rainfalls.

NOAA also recently announced a new climate data search tool that simply uses your zip code. You can retrieve daily climate data for any historically measured time period by going to the Climate Data Online Search Page. Specific instructions for doing this can be found at the NOAA Climate web site.

The BBC reported this week on a new study of weather-related pain that is making use of a cell phone app. Over 9000 people have signed up for this study in the United Kingdom which will examine the correlations between pain and various weather conditions and patterns. They hope to learn more about what types of weather trigger different kinds of pain.

MPR listener question:

I am writing to you from rural Fillmore County where I have farmed since 1957. So far this month we have recorded about 5 inches of rain. Over coffee this morning we wondered what has been the wettest September in history for our area of the state, over 10 inches perhaps?


The wettest September for Fillmore County was in 1965. Numerous heavy thunderstorms delivered over 10 inches of rain to many communities, including 13.43" at Harmony, 12.74" at Preston, and 10.87" at Lanesboro. The most recent wet September was in 2010 when Rushford received 10.42 inches. That same year the all-time state record wettest September was reported from Zumbrota (Goodhue County), where 14.57" of rain fell.

Twin Cities Almanac for September 9th:

The average MSP high temperature for this date is 75 degrees F (plus or minus 9 degrees F standard deviation), while the average low is 56 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for September 9th:

MSP weather records for this date include: highest daily maximum temperature of 95 degrees F in 1947; lowest daily maximum temperature of 55 degrees F in 1929; lowest daily minimum temperature is 38 degrees F in 1883; highest daily minimum temperature of 76 degrees F in 1931; record precipitation of 1.79 inches in 1900; and no snowfall has occurred on this date.

Average dew point for September 9th is 55 degrees F, with a maximum of 75 degrees F in 1964 and a minimum of 33 degrees F in 1976.

All-time state records for September 9th:

The state record high temperature for this date is 105 degrees F at Beardsley (Big Stone County) in 1931. The state record low temperature for this date is 19 degrees F at Embarrass (St Louis County) in 2006. State record precipitation for this date is 4.75 inches at Gunflint Lake (Cook County) in 1977 and no measurable snowfall has occurred on this date.

Past Weather Features:

Strong thunderstorms brought heavy rains and widespread flash flooding to many parts of the state over September 8-11, 1900. Many climate stations reported from 4 to 7 inches of rain, along with strong winds. Bird Island reported nearly 8 inches. Farmers could not resume harvesting crops for nearly two weeks.

A hard freeze ended the growing season for many parts of northwester Minnesota on September 9, 1917. Low temperatures ranged from 22F to 30F across many parts of the Red River Valley, setting record early dates for frost.

By far the warmest September 9th in state history was in 1931. Only Grand Marais Harbor and Two Harbors along the Lake Superior shoreline failed to reach the 90F temperature mark. Over 35 communities reported a daytime high of 100F or greater. Temperatures did not fall to near seasonal normals until September 15th that year.


Slightly cooler than normal temperatures throughout the weekend under mostly sunny skies. There will be a chance for showers later on Monday into early Tuesday. Cooler and drier the rest of next week.

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