During May 2021, temperatures were near-normal across the Upper Mississippi River Valley. Monthly average temperatures ranged from 52°F at Medford, WI to 60.8°F at La Crosse Regional Airport.
Precipitation totals were up to 1.50” wetter-than-normal along and north of Interstate 90 and up to 2.00” drier-than-normal across northeast Iowa and southwest Wisconsin. Precipitation totals ranged from 1.73” near Oelwein, IA to 6.24” in Rochester, MN.
On the morning of May 28, late season snow fell across northern Buffalo, northern Trempealeau, southern Clark, and northern Jackson counties in west-central and central Wisconsin. Snow amounts ranged from a trace to a few tenths of an inch of snow. The latest date for snow in the La Crosse County Warning Area is June 2 (1910) in Medford, WI. This same system produced snow in northeast Minnesota, northern Wisconsin, and the western half of Upper Michigan. Snow pellets even fell in Chicago on this date. Most places only received a trace of snow. The only measurable amounts were 0.2” in Marquette, MI and Chatham, MI.
The graphics below show the May 2021 temperature and precipitation anomalies
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| Temperature Anomalies | Precipitation Anomalies |
...May 2021 Highlights...
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May 2021 was slightly cooler than normal. The mean temperature was 60.8°F. This was 0.2°F cooler than the 1991-2020 normal of 61 degrees. However, in reality the temperatures were quite variable. Over a third (13 days) of the month saw departures of at least 10°F or more from normal. There were 7 days which were much warmer than normal and 6 days which were much colder than normal. The largest departure was 17°F warmer than normal on the 2nd.
The hottest temperature was 91°F on the 1st and the coldest temperature was 32°F on the 11th. |
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Scattered to widespread frosts occurred on the mornings of the 8th, 11th, and 29th. The low temperature was 35°F on the 29th. This tied 1965 and 1984 for the 2nd latest date in a spring for a temperature of 35°F or colder. The latest date was June 1st in 1897 (33°F).
A total of 4.74” of rain fell during the month. This was 0.41” wetter than the 1991-2020 normal of 4.33”. This was the first month to see wetter-than-normal precipitation since November 2020. This resulted in a moderate drought (D1) developing in April 2021 and this continued through the month of May.
...Records...
May 1 - High Temp - 91°F - previous record 89°F in 1992
...May 2021 Highlights...
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May 2021 had normal temperatures. The mean temperature was 57.6°F. This was normal. However, in reality the temperatures were quite variable. Over a third of the month (12 days) saw departures of at least 10°F or more from normal. There were 7 days which were much warmer than normal and 5 days which were much colder than normal. The largest departure was 19°F warmer than normal on the 1st and 2nd.
The hottest temperature was 91°F on the 1st and the coldest temperature was 33°F on the 11th. |
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Scattered to widespread frosts occurred on the mornings of the 5th, 8th, 9th, 11th, and 12th.
A total of 4.10” of rain fell during the month. This was 0.25” drier than the 1991-2020 normal of 4.33”. Abnormally dry (D0) to moderate (D1) drought conditions persisted through the month.
...Records...
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