Historically Hot Start to September

Historically Hot Start to September:

The first five days of September brought a Heat Wave to Minnesota that surpassed all previous climate records for the same period of time. MSP reported five consecutive days of afternoon high temperatures in the 90s F, tying records for maximum temperature on consecutive days (September 3-4) with readings of 97°F and 98°F, respectively. In addition MSP recorded over the same dates consecutive record warm minimum temperatures with readings of 75°F and 74°F. Over the same first five dates of the month the climate observer at Theilman, MN (Wabasha County) recorded daily high temperatures of 92°F, 103°F, 102°F, 104°F, and 95°F, setting records at that location as well. The reading of 104°F was the highest September temperature ever recorded in September for Wabasha County. During the first 5 days of the month there were 24 reports of 100°F maximum temperatures or greater within the state climate network.

Within the state climate network, September 1-5 produced 95 record hot maximum daily temperatures, including 93°F at Gunflint Lake on the 5th, and 49 record warm daily minimum temperatures. Overall, the average temperature for those five days across the state was nearly 13°F above normal, the warmest in state history for this period. Some individual climate stations reported temperature readings that were over 20 degrees above normal. The heat was accompanied by moderate to strong winds as many climate stations reported wind gusts of 30 mph or greater on most days.

The start to September was hot, sunny, windy, and dry, with some rainfall finally arriving for many locations late in the day on the 5th. The heaviest rainfall was across the northern third of Minnesota, where many observers reported over 1 inch. A few northeastern Minnesota climate stations reported over 2 inches of rainfall, including Duluth which received a new record amount for September 5th of 2.77 inches. Much of the southern two-thirds of the state received less than half an inch of rain or no rain at all.

The Heat Wave aggravated the drought situation across the state. The update from the U.S. Drought Monitor showed some expansion of Extreme Drought across central Minnesota from Wadena County east to Carlton County, as well as in the southeast from Freeborn County east to Houston County. Much of the eastern half of the state remains in at least the Severe Drought category. The NOAA Drought Outlook for the autumn season, released at the end of August calls for persistence of drought across much of Minnesota through at least November 30th.

Weekly Weather Potpourri:

According to a new State of the Climate report released by NOAA scientists this week greenhouse gas concentrations, global sea level and ocean heat content reached record highs in 2022. Carbon dioxide, methane, and nitrous oxide concentrations in Earth’s atmosphere all continue to climb to new high levels during 2022. Global ocean heat content (from the surface down to 2000 meters also reached a record high value, as did global sea level rise. Many climate stations in Europe recorded all-time high temperatures during the summer of 2022 as well.

The BBC reported this week that tropical rainfalls in Hong Kong and southern China caused flash flooding and landslides in many areas. Record-setting rains occurred their this week with some areas reporting rainfall intensity of up to 6 inches in one hour, and rainfall totals over 19 inches.

New research from scientists at Cornell and Princeton Universities explores the possibilities for greenhouse gas emissions to be drastically reduced in the global food system. This work is published this week in the PLOS Climate online journal. The researchers find that The most promising technologies for achieving net negative greenhouse gas emissions include hydrogen-powered fertilizer production, livestock feeds, organic and inorganic soil amendments, agroforestry, and sustainable seafood harvesting practices.

MPR listener question:

With the dry weather pattern expected to prevail this fall, do you see any signs of an early frost for us?

Answer:

Indeed, historically a dry autumn might be expected to produce more loss of heat as the nights get longer and certainly risk of frost. But the climate outlooks all favor a warmer than normal temperature pattern continuing across Minnesota deep into October. In this context, I would suspect we will not see an earlier than normal frost for most of the state.

Twin Cities Almanac for September 8th:

The average MSP high temperature for this date is 76 degrees F (plus or minus 10 degrees F standard deviation), while the average low is 57 degrees F (plus or minus 7 degrees F standard deviation).

MSP Local Records for September 8th:

MSP records for this date: highest daily maximum temperature of 99 degrees F in 1931; lowest daily maximum temperature of 54 degrees F in 1929; lowest daily minimum temperature of 36 degrees F in 1883; highest daily minimum temperature of 74 degrees F in 1931; record precipitation of 1.52 inches in 1885. No snowfall on this date.

Average dew point for September 8th is 55°F; the maximum dew point on this date is 73°F in 1947; and the minimum dew point on this date is 25 degrees F in 1995.

All-time state records for September 8th:

The state record high temperature for this date is 105 degrees F at New Ulm (Brown County) in 1931. The state record low temperature for this date is 20 degrees F at Tower (St Louis County) in 1995. The state record precipitation for this date is 5.54 inches at Young America (Carver County) in 1991. No snowfall has been reported on this date.

Past Weather:

The hottest September 8th in history occurred in 1931 when almost all locations in Minnesota reported afternoon high temperatures in the 90s F or greater. Thirty climate stations reported a maximum temperature of 100°F or greater. 

Thunderstorms brought heavy rains and flash flooding to much of central Minnesota over September 7-8 in 1991. Many areas reported 4 to 6 inches of rain. Elk River (Sherburne County) reported over 7 inches of rain, while New London (Kandiyohi County) reported over 10 inches. Many roads and highways were flooded, as well as several farm fields.

Frosts were widespread across northern Minnesota on September 8, 1995. Frost was even reported at Lamberton (Redwood County) in southwestern Minnesota. Morning lows in the upper 30s F were common across southern Minnesota near the Iowa border.

Outlook:

Temperatures will warm over the weekend with chances for showers on Saturday and Sunday. Then near normal to cooler than normal temperatures prevail much of next week which looks to be generally dry across the area. Warming temperatures towards next weekend.