Upper Mississippi River Climate Summary for Astronomical Summer 2024: Temperatures - Near to Above Normal Temperatures

During Astronomical Summer (June 21 through September 21) 2024, average temperatures ranged from 64.8°F at Medford Taylor County Airport (AWOS) to 72.9°F at Decorah, IA (COOP). Temperature anomalies were within 2°F of normal. There was a 68°F difference between the warmest and coldest temperatures in the Upper Mississippi River Valley. The warmest temperature was 98°F at Mondovi, WI (COOP) on August 26 and Decorah, IA (COOP) on August 27. Meanwhile, the coldest temperature was 30°F at Sparta Fort McCoy, WI (ASOS) on June 11.

Precipitation - Wetter than Normal

Rainfall totals varied from 10.07" near Postville, IA (CoCoRaHS) to 22.89" near Winona, MN (CoCoRaHS). Rainfall anomalies ranged from 4" drier than normal to 8" wetter than normal. The highest one-day precipitation was 5.61" near Wykoff, MN (CoCoRaHS) on June 22. There were unofficial rainfall totals of 6 to 6.5" from southern Winona County (MN) to eastern Jackson County (WI) from August 29-30.

Below are the climate summaries for the 2024 astronomical spring in La Crosse, WI, and Rochester, MN

La Crosse, WI

 2024 Astronomical Summer was Warmer and Wetter than Average in La Crosse WI
 

During the astronomical summer of 2024 (June 20 through September 21), it was warmer and wetter than average at La Crosse Regional Airport. Records date back to 1873.

Temperatures - Warmer than Average During astronomical summer, La Crosse Regional Airport had an average temperature of 72.1°F. This was 1.8°F warmer than the long-term average of 70.3°F. This was the 15th consecutive astronomical summer to be warmer than average. The last summer to be cooler than average was 2009 with an average temperature of 68.8°F. The average maximum temperature was 82.5°F. This was 2°F warmer than the long-term average of 80.5°F. The was the 21st warmest. The average minimum temperature was 61.7°F. This was 1.6°F warmer than the long-term average of 60.1°F.

• Other temperature tidbits this summer...
  
  The hottest temperature was 97°F on August 26.
  The coldest high temperature was 68°F on July 2 and September 7.
  
  The warmest low temperature was 76°F on August 26.
  The coldest low temperature was 40°F on September 7. Tied the record low for the date. This was the first cold record since February 15, 2021.
  
  The temperature climbed to or exceeded 90°F on 9 days. Normally, there are 13 days in summer.  

Rainfall - Wetter-than-Average

• During the astronomical summer, La Crosse Regional Airport received 14.04" of rain which was 2.03" wetter than the long-term normal of 12.01".
• The wettest calendar day occurred on August 29 when 2.02" of rain fell.
• Measurable rain fell on 26 days (27.7%) and trace amounts fell on another 15 days (16%).
• Here is a breakdown of the summer rain...
  
  None             53 days - 56.4%
  Trace            15 days - 16.0%
  0.01-0.09 inches 10 days - 10.6%
  0.10-0.24 inches  5 days -  5.3%
  0.25-0.49 inches   1 day -  1.1%
  0.50-0.99 inches  4 days -  4.3%
  1.00-1.99 inches  4 days -  4.3%
  2.00-2.99 inches  2 days -  2.1%
  3.00 inches +     0 day  -  0.0%

Rochester, MN  
 

Astronomical Summer was Slightly Warmer and Much Wetter than the Long-Term Average in Rochester MN

During the astronomical summer of 2024 (June 20 through September 21), it was warmer and much wetter (14th wettest) than the long-term average at Rochester International Airport. Records date back to 1887. More details on these statistics can be found below.

Temperatures - Warmer than Average During astronomical summer, Rochester International Airport had an average temperature of 68.8°F. This was 0.7°F warmer than the long-term average of 68.1°F.   The average maximum temperature was 79.1°F. This was the same as the average of 79.1°F.   The average minimum temperature was 58.5°F. This was 1.4°F warmer than the long-term average of 57.1°F.

• Other temperature tidbits this summer...
  
  The hottest temperature was 91°F on August 26.
  The coldest high temperature was 67°F on September 6.
  
  The warmest low temperature was 71°F on August 26.
  The coldest temperature was 43°F on September 7.
  
  The temperature climbed to or exceeded 90°F on 1 day. Normally, there are 9 days per summer.  

Precipitation - 14th Wettest Summer

• During the astronomical summer, Rochester International Airport received 16.24" of rain which was 4.27" wetter than the long-term normal of 11.97".
• This was the 14th wettest astronomical summer.

Wettest Astronomical Summers
     in Rochester MN
        1886-2024

Rank    Rainfall    Year
----    --------    ----
  1   24.13 inches  1978
  2   22.68 inches  2019
      22.68 inches  1938
  4   22.37 inches  1986
  5   21.74 inches  1942
  6   21.17 inches  2016
  7   19.99 inches  2007
  8   19.28 inches  1990
  9   18.83 inches  1981
 10   18.19 inches  1913
 11   17.58 inches  1959
 12   17.32 inches  1999
 13   17.02 inches  1951
 14   16.24 inches  2024
 15   16.08 inches  2010
 16   16.07 inches  1983
 17   15.85 inches  1952
 18   15.57 inches  2018
 19   15.29 inches  1993
 20   15.03 inches  1997

• 8 out of the last 11 summers have been wetter than the long-term normal. This includes the 2nd wettest (2019 - tied with 1938), 6th wettest (2016), 14th wettest (2024) and 18th wettest (2018).
• The wettest day occurred on June 22 when 2.51 inches of rain fell.
• Measurable rain fell on 31 days (33%) and trace amounts fell on another 10 days (10.6%).
• Here is a breakdown of the summer rain...

None             53 days - 56.4%
Trace            10 days - 10.6%
0.01-0.09 inches 12 days - 12.8%
0.10-0.24 inches  6 days -  6.4%
0.25-0.49 inches  1 days -  1.1%
0.50-0.99 inches  4 days -  4.3%
1.00-1.99 inches  6 days -  6.4%
2.00-2.99 inches  2 days -  2.1%
3.00 inches +     0 days -  0.0%