Upper Mississippi River Climate Summary for September 2025:
Temperatures - Near to Above Normal
- During September 2025, average temperatures ranged from 60.5°F at Medford Taylor County Airport (AWOS) to 67.1°F at Decorah, IA (COOP).
- Temperature anomalies ranged from near normal to 3°F warmer-than-normal.
- There was a 61°F difference between the warmest and coldest temperatures in the Upper Mississippi River Valley.
- The warmest temperature was 91°F at Austin Municipal Airport, WI (AWOS); New Hampton, IA (COOP); Northeast Iowa Regional Airport, IA (AWOS); and Oelwein Municipal Airport, IA (AWOS) on September 13. Meanwhile, the coldest temperature was 32°F at Sparta Fort McCoy, WI (ASOS) on September 7.
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Rainfall - Highly Variable
- Rainfall totals varied from 0.81" near Byron, MN (CoCoRaHS) to 5.06" near Warrens, WI (CoCoRaHS).
- Rainfall anomalies ranged from 4" drier than normal to 2" wetter than normal.
- The highest one-day precipitation was 3.28" at Rochester International Airport on September 22.
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Below are the September 2025 climate summaries for La Crosse, WI, and Rochester, MN.
La Crosse, WI
September 2025 was Warmer and Slightly Wetter than Normal for La Crosse, WI
...September 2025 Highlights...
Temperatures - 19th Warmest
- During September 2025, the average temperature at La Crosse Regional Airport was 66.8°F.
- This was 2°F warmer than the 1991-2020 average of 64.8°F.
- This was the 19th warmest September.
- During the past decade, 6 out of the 10 warmest Septembers have occurred.
- 11 out of 19 warmest Septembers have occurred since 2005. This includes the warmest (2015 - 69.3°F), 2nd warmest (2019 - 69.1°F), 3rd warmest (2017 - 68.8°F - tied with 1998), 5th warmest (2023 - 68.6°F), 8th warmest (2024 - 68°F), 11th warmest (2016 - 67.7°F), 14th warmest (2004 & 2021 - 67.2°F), 16th warmest (2013 - 67°F - tied with 1884), and 19th warmest (2025 - 66.8°F). Below are the 20 warmest Septembers.
- Below are the 20 warmest Septembers.
20 Warmest Septembers
in La Crosse, WI
1873-2025
Average
Rank Temperature Year
---- ----------- ----
1 69.3°F 2015
2 69.1°F 2019
3 68.8°F 2017
68.8°F 1998
5 68.6°F 2023
6 68.5°F 1931
7 68.3°F 1978
8 68.0°F 2024
9 67.9°F 1908
10 67.8°F 1897
11 67.7°F 2016
12 67.6°F 1895
13 67.4°F 1891
14 67.2°F 2021
67.2°F 2004
16 67.1°F 2005
17 67.0°F 2013
67.0°F 1884
19 66.8°F 2025
20 66.6°F 1906
- The average high temperature was 77.3°F. This was 1.7°F warmer than the 1991-2020 normal of 75.5°F. This was tied with 1933 for the 17th warmest.
- The average low temperature was 56.2°F. This was 2.1°F warmer than the 1991-2020 normal of 54.1°F. This was tied for the 18th warmest with 1998.
- The warmest high temperature was 87°F on September 14, September 16, and September 29.
- The coldest high temperature was 63°F on September 5.
- The warmest low temperature was 68°F on September 13 and September 15.
- The coldest low temperature was 40°F on September 7.
Rainfall - Slightly Wetter than Normal
- A total of 3.72" of rain fell. This was 0.09" wetter than the 1991-2020 average of 3.63".
- The wettest day occurred on September 22 when 1.70" of rain fell.
- Measurable rain fell on 12 days (40%) and trace amounts fell on another 3 days (10%).
...September 2025 Records...
- September 7 - Record Low - 40°F - Tied with 1956, 1986, and 2024 - This was only the 4th daily cold record (coldest high or coldest low) this century. In contrast, there have been 59 daily warm records (record high or warmest low) this century.
- September 22 - Record Rain - 1.70" - Tied with 1959
- September 29 - Record High - 87°F - Tied with 1898
...Looking Ahead to October...
- The normal high temperature in La Crosse starts off at 69°F on October 1st and falls to 54°F by the end of the month. The normal low temperature starts off at 47°F on the 1st and falls to 36°F by the end of the month. The warmest October temperature on record is 93°F on October 6, 1963, and the coldest is 6°F on October 25, 1887.
- The normal mean temperature for October is 51.7°F. La Crosse’s warmest October occurred in 1963 with an average temperature of 61.2°F, and its coldest October occurred in 1917 with an average temperature of 39.4°F.
- The normal October precipitation is 2.49". The wettest October occurred in 1881 with 12.09" of precipitation (second wettest month - only August 2007 was wetter with 13.75") and the driest October occurred in 1952 with only 0.02" of precipitation (third driest month - only November 1976 with a trace and December 1943 with 0.01" were drier). The wettest October day occurred on October 28, 1900, when 4.89" of rain fell (4th wettest calendar day). Normally, there are 2 days with thunderstorms.
- The normal October snowfall is 0.3". The snowiest October occurred in 1917 with 7" of snow. The snowiest October day occurred on October 28, 1917, when 4.7" of snow fell.
Rochester, MN
September 2025 was Warmer and Wetter than Normal for Rochester, MN
...September 2025 Highlights...
Temperatures - Tied for the 10th Warmest with 1998, 2004, and 2016
- During September 2025, the average temperature at Rochester International Airport was 64.4°F.
- This was 3.3°F warmer than the 1991-2020 average of 61.1°F.
- This was tied for the 10th warmest September with 1998, 2004, and 2016.
- During the past decade, 5 out of the 10 warmest Septembers have occurred. 11 out of 18 warmest Septembers have occurred since 2005. This includes the 3rd warmest (2023 - 66.3°F), 4th warmest (2015 - 66.2°F), 5th warmest (2024 - 65.4°F), 8th warmest (2019 - 65.1°F), 9th warmest (2005 - 64.7°F), 10th warmest (tied with 1998, 2005, 2016, and 2025 - 64.4°F), 14th warmest (2017 - 64.1°F), 15th warmest (2013 - 64°F), and 19th warmest (2007 - 63.9°F).
- The table below contains the 20 warmest Septembers for Rochester, MN.
20 Warmest Septembers
in Rochester MN
1886-2025
Average
Rank Temperature Year
---- ----------- ----
1 69.6°F 1908
2 66.9°F 1931
3 66.3°F 2023
4 66.2°F 2015
5 65.4°F 2024
6 65.3°F 1948
7 65.2°F 1933
8 65.1°F 2019
9 64.7°F 2005
10 64.4°F 2025
64.4°F 2016
64.4°F 2004
64.4°F 1998
14 64.1°F 2017
15 64.0°F 2013
64.0°F 1939
64.0°F 1919
18 63.9°F 2007
19 63.7°F 1978
20 63.6°F 1936
- The average high temperature was 75°F. This was 3.2°F warmer than the 1991-2020 normal of 71.8°F. This was tied for the 19th warmest with 1919 and 1936.
- The average low temperature was 53.8°F. This was 3.5°F warmer than the 1991-2020 normal of 50.4°F. This was the 9th warmest.
- The warmest high temperature was 88°F on September 14 and September 16.
- The coldest high temperature was 58°F on September 5.
- The warmest low temperature was 67°F on September 15.
- The coldest low temperature was 41°F on September 4, September 6, and September 7.
Rainfall - Wetter than Normal
- A total of 4.15" of rain fell. This was 0.55" wetter than the 1991-2020 average of 3.60".
- The wettest day occurred on September 22 when 3.28" of rain fell. This was the 6th wettest September day. The only wetter September days were September 12, 1978 (5.98"); September 23, 2010 (4.34"); September 14, 2004 (4.04"); September 21, 2016 (3.60"), and September 4, 2018 (3.32").
- Measurable rain fell on 11 days (36.7%) and trace amounts fell on another 2 days (6.7%).
...September 2025 Records...
- September 5 - Record Low Maximum - 58°F - Previous Record was 59°F in 1956
- September 22 - Record Rain - 3.28" - Previous Record was 1.57" in 2010
...Looking Ahead to October...
- The normal high temperature in Rochester starts off at 66°F on October 1st and falls to 50°F by the end of the month. The normal low temperature starts off at 44°F on the 1st and falls to 32°F by the end of the month. The warmest October temperature on record was 93°F on October 3, 1997, and the coldest was -6°F on October 25, 1887.
- The normal mean temperature for October is 47.9°F. Rochester’s warmest October occurred in 1963 with an average temperature of 58.1°F, and its coldest October occurred in 1917 with an average temperature of 37.6°F.
- The normal October precipitation is 2.43". The wettest October occurred in 1911 with 9.11" of precipitation and the driest October occurred in 1952 with only 0.01" of precipitation. The wettest October day occurred on October 6, 1911, when 2.85" of precipitation fell. Normally, there are 2 days with thunderstorms.
- The normal October snowfall is 0.9". The snowiest October occurred in 2009 with 7.9" of snow. The snowiest October day occurred on October 22, 1979, when 5" of snow fell.