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August Climate Summary

August Climate Summary:

Mean August temperature values from around the state were generally 2 to 4 degrees F cooler than normal. Only the second cooler than normal month in 2017 (May was the other). Extreme temperatures for the month ranged from 93 degrees F at Granite Falls (Yellow Medicine County) on August 1st, and just 30 degrees F at Embarrass, Brimson, and Crane Lake on the 25th. Some observers in St Louis, Lake, Cook, and Koochiching Counties reported frosts during the month. Minnesota did not report the nation's lowest on any date this month.

The most noteworthy climate attribute of August was the rainfall. Overall the statewide average rainfall was over 5 inches, ranking as the 11th wettest month of August in state history. Some western and southern communities reported their wettest August in history with total rainfall values over 10 inches. Redwood Falls topped the state network reports with over 13 inches. They reported the largest ever 1-day rainfall on August 17th in state history with a measurement of 8.12 inches. In addition over 40 climate stations in the state reported at least one new daily rainfall record during the month.

Destruction from Harvey may be the weather story of the year:

Large and slow-moving Hurricane Harvey (later Tropical Storm Harvey) brought widespread flooding and devastation to many parts of southeastern Texas last weekend and earlier this week, most especially the Houston Metropolitan Area. Many communities in Jefferson, Galveston, and Harris Counties reported over 40 inches of rain from this storm, topped by 51.88 inches in the Cedar Bayou-Mont Belvieu area of the Eastern Metro Area, a value that is the largest amount of rainfall ever measured from a Tropical Storm. Flooding issues were compounded in Beaumont, TX (pop 120,000) when there water supply pumps failed, preventing access to fresh water for all the residents there. More recently over Wednesday-Thursday Harvey brought 10 to 20 inches of rainfall to portions of western and southern Louisiana. Over the coming Labor Day weekend remnants of Harvey as a low pressure system will move northeast, not affecting Minnesota but ending up on the North Atlantic Ocean. Further coverage on Harvey can be found at the Weather Underground web site.

State Fair Weather Quiz:

The Annual Minnesota State Fair continues through Labor Day (September 4th). We had a good time on August 29th broadcasting the Annual Minnesota Weather Quiz from the MPR Booth (corner of Judson and Nelson on the fairgrounds). For those who would like to take the quiz (so far nearly 600 people have taken it), it is still available online at the MPR web site.

Weekly Weather Potpourri:

This week, the United Kingdom Met Office provided a brief climate summary of the summer season (June-August) noting that it has been very wet and warmer than usual in 2017. For Scotland it has been their 5th wettest summer historically.

Also this week NOAA's Jake Crouch presents an analysis of the climate patterns across the USA so far this year. He makes some interesting observations about severe weather and the pattern of warm and dry years versus the pattern of wet and cool years. You can read more at NOAA web site.

Following all of the attention on Hurricane and Tropical Storm Harvey this week, the NOAA National Hurricane Center is tracking Hurricane Irma in the Eastern Atlantic Ocean. It is expected to strengthen to a Category 4 hurricane as it travels westward across the Atlantic Ocean towards Puerto Rico next week. This system will be closely monitored all of next week. Elsewhere in the Eastern Pacific Ocean, Tropical Storm Lidia was being monitored a may bring heavy rains and wind to portions of Mexico and Baja California over the weekend, while in the Western Pacific Ocean, Typhoon Sanvu was growing stronger and may bring rain and high seas to portions of Japan over the weekend.

With the school year starting, many science teachers are looking for engaging materials to use with their students. NOAA's Data in the Classroom Program provides some great real-time data for students to better understand atmospheric and ocean sciences. There are curricula materials on El Nino and Sea Level variations, Coral Bleaching, Ocean Acidification, and Water Quality.

A recent paper appearing in the Proceedings of the National Academy of Sciences documents how climate change will alter the seasonality and geographic distribution of peak electricity loads across Europe. Southern portions of Europe will eventually use more electricity than northern Europe, and summer peak loads will be higher than those of winter. This is an interesting result of the disparity in climate change impacts across the European nations.

MPR listener question:

You mentioned during the State Fair broadcast of the Minnesota Weather Quiz this week that "rain begets rain" and that "drought begets drought." That sparked a conversation in our family that produced these two questions: What is the longest streak of consecutive days with measurable rainfall in the Twin Cities? Also, what is the longest streak of days with no precipitation in the Twin Cities?


The longest stretch of consecutive days with measurable rain is from a long time ago, May 30, 1883 to June 9, 1883, 11 days. It rained at least .03 inches each day, with an 11 day total of 3.95 inches in the Twin Cities. No flooding was reported, but a lightning storm took out the telegraph lines across southern Minnesota during this interval. The most recent exceptionally long streak of consecutive days with precipitation was April 5 to April 14, 2013 (10 days) when a mixture of rain and/or snow occurred each day, totaling 6.8 inches of snow and 2.73 inches of precipitation.

The longest stretch of days when no measurable precipitation occurred was from November 15, 1943 to January 4, 1944, a period of 51 days. There were some dates in this interval when a trace of precipitation was reported. The most recent long spell of dry weather was September 26 to October 22, 2010, a period of 27 days.

Twin Cities Almanac for September 1st:

The average MSP high temperature for this date is 77 degrees F (plus or minus 9 degrees F standard deviation), while the average low is 59 degrees F (plus or minus 8 degrees F standard deviation).

MSP Local Records for September 1st:

MSP records for this date include: highest daily maximum temperature of 97 degrees F in 1913; lowest daily maximum temperature of 59 degrees F in 1951; lowest daily minimum temperature of 36 degrees F in 1974; highest daily minimum temperature of 74 degrees F in 1937 and 1953; record precipitation of 3.29 inches in 1942. No snowfall has occurred on this date.

Average dew point for September 1st is 56F; the maximum dew point on this date is 75F in 1997; and the minimum dew point on this date is 30F in 1946.

All-time state records for September 1st:

The all-time state high temperature for today's date is 101 degrees F at Beardsley (Big Stone County) in 1913; the all-time state low for today's date is 23 degrees F at Tower (St Louis County) in 1974. The all-time state record precipitation for this date is 7.70 inches at Nett Lake (St Louis County) in 1973. No snow has fallen on this date.

Past Weather Features:

The warmest ever September 1st came in 1913 when most areas of the state saw afternoon temperatures climb into the 90s F. Five locations surpassed 100 degrees F. St Peter started the day with a cool morning of 52 degrees F, but under sunny skies warmed up to 98 degrees F by 4pm.

Very strong thunderstorms moved across the state over August 31 and September 1, 1973 bringing very heavy rains and flash flooding to portions of northern. Rainfall totals from 4 to 8 inches occurred in portions of Clay, Mahnomen, Polk, and St Louis Counties. An unusual tornado passed between Big Falls and Little Fork in Koochiching Counties, destroying many farm buildings and some mobile homes.

By far the coldest September 1st in state history was in 1974. Many parts of the state saw widespread frosts. Over 40 climate stations reported freezing temperatures in the morning, representing 23 of Minnesota's 87 counties. Frost damage to crops, both corn and soybeans, was widespread as well.


Mostly sunny weekend with near normal temperatures. Chance of showers later in the day in the north on Labor Day. Cooler temperatures and chance for showers on Tuesday, and continuing cooler than normal temperatures for much of next week.

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