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Highest Dew Points of the Summer With Thunderstorms

Highest Dew Points of the Summer With Thunderstorms:

Heat and humidity dominated the state this week, but some thunderstorms also brought hail and heavy rains to a few places. Hallock (Kittson County), Theilman (Wabasha County), Zumbrota (Goodhue County), Kimball (Stearns County), Jordan (Scott County), and Brownton (McLeod County) all reported over 2 inches of rainfall this week. Also portions of Dakota and Washington Counties reported over 2 inches. The DNR State Climatology Office web site presents a comprehensive analysis of the storms of July 25-26.

Their summary showed that some areas received over 3 inches from these storms. Despite the rains, the majority of the state landscape remains locked in the grip of Moderate to Severe Drought.

Also, thunderstorms brought hail on July 22, 24, and 25th. Large hail was reported from portions of Cook, Lake, Itasca, Pope, Grant, Lincoln, Lyon, Redwood, Cottonwood, Nobles, Sherburne, Olmsted, Goodhue, Dakota, Dodge, Anoka, and Wright Counties. Strong, damaging winds were also reported from Sherburne, Stearns Pope, Stevens, Traverse, Polk, Morrison, Redwood, Cook, Ramsey, and Washington counties with measured gusts over 60 mph in many places.

Dew points in the 70s F pushed the afternoon Heat Index Values over 95°F in many places on Wednesday and Thursday afternoons. Some communities reported Heat Index Values ranging from 102°F to 108° F (Tracy). With the high dew points overnight low temperatures remained in the mid 60s F to low 70s F at many locations. Canby reported a high temperature of 102°F this week. Overall temperatures during the week averaged 4 to 8 degrees F above normal.

A NOTE ON DEW POINTS: For many areas of the state Wednesday and Thursday brought a long period of dew points that were 70°F or higher. MSP reported over 25 hours of dew points that high this week. In addition, some climate stations reported record high dew points on July 26th, including 81°F at Tracy (Lyon County) and 82°F at both Thief River Falls (Pennington County) and Hallock (Kittson County) where the early evening Heat Index reached 111°F. On Thursday, July 27 more high dew points and temperatures in the 90s F pushed the Heat Index Values even higher for many places ranging from 100°F to 112°F (Granite Falls). Tracy (Lyon County) at 3:30 pm in the afternoon reported a temperature of 95°F with a dew point of 81°F and a Heat Index value of 116°F. This is the highest Heat Index ever measured at Tracy and the highest measured in the state this year.

Weekly Weather Potpourri:

Jonathan Erdman writing for the Weather Underground provided a nice summary of all the heat records being set this month across the Northern Hemisphere. It has been unprecedented for how widespread the record-setting heat has been across North America, Europe, and Asia.

This week the BBC Weather Center provided a synopsis of a United Nations briefing which shows data to suggests that this July will likely be the warmest month globally in thousands of years. Positive temperature anomalies really dominate much of the Northern Hemisphere, over both oceans and lands, and sections of the Southern Hemisphere are anomalously warm as well.

The Joint Typhoon Warning Center was tracking Typhoon Doksuri this week as it headed towards Taiwan and southeastern China. The typhoon was producing sustained winds over 125 mph and sea wave heights between 35 and 40 feet. Doksuri was expected to skirt Taiwan but come ashore in southeastern China early this weekend.

Scientists from the University of Denmark reported on a study of Arctic phenology in the journal Current Biology this week. Their study found no directional shift or trend towards earlier spring seasons, but a large change in year to year variability of the onset of spring. This study corresponds to other evidence that suggests spring seasons are showing a higher degree of variability as the overall climate drivers of seasonal change become more variable in their behavior.

MPR listener question:

With all of the reports of hail this week, we wondered what part of the state of Minnesota reports the most hail from a climate history perspective?


Numerous studies by climatologists have reported that the highest frequency of hail reports historically comes form southwestern Minnesota, south of the Minnesota River Valley and east as far as St James and Fairmont. This is also associated with the atmospheric lift provided by the Buffalo Ridge topography in that area of the state. Peak hail season is May and June for Minnesota, although there have been more reports in July of this year and they have been much more widespread geographically.

Twin Cities Almanac for July 28th:

The average MSP high temperature for this date is 83 degrees F (plus or minus 7 degrees F standard deviation), while the average low is 65 degrees F (plus or minus 6 degrees F standard deviation).

MSP Local Records for July 28th:

MSP records for this date: highest daily maximum temperature of 100 degrees F in 1955; lowest daily maximum temperature of 64 degrees F in 1991; lowest daily minimum temperature of 50 degrees F in 1981; highest daily minimum temperature of 76 degrees F in 2006; record precipitation of 1.48 inches in 1942. No snowfall on this date.

Average dew point for July 28th is 61°F; the maximum dew point on this date is 76°F in 1955; and the minimum dew point on this date is 40 degrees F in 1937.

All-time state records for July 28th:

The state record high temperature for this date is 113 degrees F at Beardsley (Big Stone County) in 1917. The state record low temperature for this date is 31 degrees F at Kelliher (Beltrami County) in 2009. The state record precipitation for this date is 5.01 inches at Pine River Dam (Crow Wing County) in 1972. No snowfall has been reported on this date.

Past Weather:

A relatively short-lived Heat Wave brought extreme high temperatures to many parts of Minnesota on July 28, 1917. Over 40 Minnesota climate stations reported an afternoon high temperature of 100°F or greater, with 113°F reported at Beardsley. The overnight low did not drop below 80°F at New London and Virginia.

Campers in northern Minnesota woke up to a cool, crisp morning on July 28, 1934 with many areas reporting morning low temperatures in the 30s F. The afternoon high temperature at Mizpah (south of International Falls) only reached 65°F.

In the drought year of 1976, July 28th brought the largest rains of the year to many parts of eastern Minnesota. Several observers reported from 2 to 3 inches, while Elgin in Wabasha County reported nearly 5 inches with flash flooding.


Sunny and cooler over the weekend, with temperatures a few degrees below normal. Increasing cloudiness on Sunday night with a chance for showers or thunderstorms., especially in southern areas of the state. Slight chances for showers Monday and Tuesday as temperatures warm to near seasonal normal levels. Warming trend towards the end of next week will push temperatures back to above normal levels.
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