Hot start to July

Hot start to July:

The first few days of July have averaged 4°F to 7°F above normal in most places around the state. Observers in 9 counties have reported afternoon highs of 90°F or higher so far. In addition, dew points have climbed into the 70s F, producing stressful Heat Index Values over 100°F. The National Weather Service has already had to issue some Heat Advisories for portions of Minnesota. NOAA outlook models continue to favor warmer than normal temperatures across Minnesota for much of the month of July, so I suspect that there will be more Heat Advisories and Excessive Heat Warnings issued during the month. 

July 4th Climatology:

The 4th of July holiday in Minnesota is usually hot with a chance for showers and thunderstorms.

There have even been significant derechos (straight-line thunderstorm winds) that have caused damage in the state, most notably in 1977, 1983, and 1995. Speaking of thunderstorms, an intense one brought nearly 10 inches of rain of Milan (Chippewa County) on July 4 of 1995, producing widespread flash flooding.

There have been several July 4th holidays that produced high Heat Index Values across Minnesota due to the combination of high temperature and high dew point. Such was the case in the Twin Cities in 1949 (110°F Heat Index), 1977 (103°F Heat Index, 1999 (109°F Heat Index), and 2012 (108°F Heat Index.

Last year, 2024 was a challenging 4th of July in the Twin Cities because of rain during the evening when most fireworks displays were planned. There is much more about the history of the weather during the 4th of July holiday in Minnesota on the State Climatology Office web page. 

Weekly Weather Potpourri:

The BBC reports this week on the recent Heat Wave affecting so many parts of Western Europe. Many areas have reported daytime temperatures of 104°F to 110°F. Meanwhile, wildfires have been burning out of control in areas of Greece and Crete, fouling the air and causing evacuations. These extreme conditions have caused many European citizens to alter their summer vacation plans.

MPR listener question:

We were wondering if we have seen a higher frequency of 70°F dew points on the 4th of July here in the Twin Cities over recent decades? We have live here since 1969 and it sure seems like. 

Answer:

You are correct. Checking the 36 years from 1945 to 1980, there were 7 years when the July 4th holiday recorded a 70°F dew point in the Twin Cities. Over the period from 1986 to 2022, another 36 years, there were 12 4th of Julys that brought such dew points. Most recently the holiday in 2018, 2019, 2020, and 2022 all brought dew points of 72°F, highly uncomfortable. 

Twin Cities Almanac for July 4th:

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 4th:

MSP records for this date: highest daily maximum temperature of 101 degrees F in 2012; lowest daily maximum temperature of 58 degrees F in 1967; lowest daily minimum temperature of 43 degrees F in 1972; highest daily minimum temperature of 81 degrees F in 2012; and record precipitation of 2.27 inches in 1900. There has not been any snowfall on this date.

Average dew point for July 4th is 59°F; the maximum dew point on this date is 79°F in 1999 and the minimum dew point on this date is 40 degrees F in 1942. 

All-time state records for July 4th:

The state record high temperature for this date is 107 degrees F at Worthington (Nobles County) in 1936. The state record low temperature for this date is 27 degrees F at Tower (St Louis County) in 1972. The state record precipitation for this date is 9.78 inches at Milan (Chippewa County) in 1995. No snowfall has occurred on this date. 

Past Weather:

Morning frost was reported from many northern Minnesota communities on July 4 of 1972. Tower reported just 27°F a statewide low temperature for the 4th of July. The afternoon high at Two Harbors only reached 60°F.

Strong thunderstorms brought 3 to 5 inches of rain to portions of central and western Minnesota over July 3-4 of 1995. There were road closures due to flash flooding, and many crop fields were washed out.

July 4 of 2012 was downright hot, with many communities reporting afternoon temperatures I the mid to upper 90s F. There were six counties where the maximum temperature reached 100°F or higher. The overnight low temperature in the Twin Cities was a very uncomfortable 81°F. 

Outlook:

Much cooler temperatures over the weekend with a chance for showers and thunderstorms on Saturday. Generally dry on Sunday. Slightly below normal temperatures next week, with a chance for showers and thunderstorms Tuesday through Thursday.