August 25-27, 2013 Heat Wave

Records Heat Indices Heat Index Climatology

An unusually late season heat wave impacted the Upper Mississippi River Valley Sunday, August 25th through Tuesday, August 27th.  Daily high temperatures reached the upper 80s to mid 90s, and the dew points ranged from the upper 60s to mid 70s.  As a result, heat indices topped out between 95 and 110. Heat Advisories were issued for southeast Minnesota, northeast Iowa, and southwest into central Wisconsin. Drier soils along the river valleys led to warmer temperatures, especially from La Crosse northward, where an Excessive Heat Warning was issued.

During the heat wave there were 52 temperature records tied or broken, which included:

  • 17 record high temperatures (7 tied and 10 new records)
  • 35 record warmest minimum temperatures (7 tied and 28 new records).  
  • La Crosse, WI tied its overall warmest August low temperature (79 degrees). Only 5 other days (any day of year) have had a warmer low temperature. It was also the warmest low temperature so late in the calendar year.

Records Established: 

Rochester, Minnesota

Type of Record

Date

Record

Previous Record

Warmest Minimum Temperature

8/25

73

73 (1948)

Warmest Minimum Temperature

8/26

73

70 (1993)

La Crosse, Wisconsin

Type of Record

Date

Record

Previous Record

High Temperature

8/26

97

96 (1991)

High Temperature

8/27

96

95 (1973)

Warmest Minimum Temperature

8/26

76

76 (1948)

Warmest Minimum Temperature

8/27

79

74 (1948)

Warmest Average Temperature

8/26

87

85 (1948)

Warmest Average Temperature

8/27

88

84 (1990)

Highest Dew Point Temperature

8/26

75

73 (1973, 1980)

August Warmest Minimum Temperature

8/27

79

79 (8/3/2005, 8/7/2001, 8/17/1988, 8/16/1988, 8/1/1988, 8/2/1964 and 8/24/1948)

 Records Established at Cooperative Observer Sites:

Records for Monday, August 26th:
 

Location

Type of Record

Record

Previous Record

 
Alma Dam 4

High Temperature

94

92 in 1949

New Record

Austin WWTP, MN

Warmest Minimum Temperature

70

69 in 1993

New Record

Byron, MN

Warmest Minimum Temperature

73

67 in 1993

New Record

Friendship, WI

High Temperature

92

92 in 1930

Tied

Friendship, WI

Warmest Minimum Temperature

73

67 in 2004

New Record

Genoa Dam 8

Warmest Minimum Temperature

77

75 in 1948

New Record

Grand Meadow, MN

Warmest Minimum Temperature

71

70 in 1948

New Record

La Crescent Dam

High Temperature

97

86 in 1974

New Record

Lancaster, WI

Warmest Minimum Temperature

70

70 in 1993

Tied

Lynxville Dam 9, WI

Warmest Minimum Temperature

75

74 in 1948

New Record

Mather 3NW, WI

Warmest Minimum Temperature

73

70 in 1959

New Record

Mauston 1SE, WI

Warmest Minimum Temperature

74

72 in 1959

New Record

Minnesota City Dam 5, MN

High Temperature

94

94 in 1993

Tied

Minnesota City Dam 5, MN

Warmest Minimum Temperature

74

74 in 1993

Tied

Neillsville 3SW, WI

Warmest Minimum Temperature

72

69 in 1973

New Record

Owen 3W, WI

Warmest Minimum Temperature

69

66 in 1991

New Record

Prairie du Chien

Warmest Minimum Temperature

73

73 in 1959

Tied

Theilman, MN

Warmest Minimum Temperature

74

73 in 1991

New Record

Trempealeau Dam 6

Warmest Minimum Temperature

77

76 in 1948

New Record

Winona Dam 5 A, MN

High Temperature

92

92 in 1994

Tied

Winona Dam 5 A, MN

Warmest Minimum Temperature

76

72 in 1991

New Record

Records for Tuesday, August 27th:

Location

Type of Record

Record

Previous Record

 
Alma Dam 4, WI

Warmest Minimum Temperature

78

75 in 1977

New Record

Boscobel, WI

High Temperature

95

89 in 2012

New Record

Boscobel, WI

Warmest Minimum Temperature

71

65 in 2004

New Record

Byron

High Temperature

91

90 in 1993

New Record

Byron

Warmest Minimum Temperature

72

66 in 1995

New Record

Cresco 1NE, IA

Warmest Minimum Temperature

72

71 in 1993

New Record

Friendship, WI

High Temperature

92

92 in 2003

Tied

Friendship, WI

Warmest Minimum Temperature

73

63 in 2005

New Record

Genoa Dam 8, WI

Warmest Minimum Temperature

77

75 in 1993

New Record

Grand Meadow, MN

Warmest Minimum Temperature

71

70 in 1973

New Record

Guttenberg L&D 10, IA

High Temperature

95

95 in 1956

Tied

La Crescent Dam 7, MN

High Temperature

93

93 in 1977

Tied

Mather 3NW, WI

Warmest Minimum Temperature

73

69 in 1993

New Record

Mauston 1SE, WI

Warmest Minimum Temperature

75

74 in 1909

New Record

Minnesota City Dam 5, MN

High Temperature

95

88 in 1997

New Record

Minnesota City Dam 5, MN

Warmest Minimum Temperature

75

72 in 1993

New Record

Prairie du Chien, WI

Warmest Minimum Temperature

74

74 in 1993

Tied

Preston, MN

High Temperature

92

92 in 2003

Tied

Preston, MN

Warmest Minimum Temperature

74

73 in 1977

New Record

Soldiers Grove, WI

High Temperature

92

83 in 2011

New Record

Soldiers Grove, WI

Warmest Minimum Temperature

69

61 in 2012

New Record

Theilman, MN

High Temperature

95

94 in 1991

New Record

Theilman, MN

Warmest Minimum Temperature

71

71 in 1993

Tied

Winona Dam 5A, MN

High Temperature

94

93 in 1993

New Record

Winona Dam 5A, MN

Warmest Minimum Temperature

75

74 in 1991

New Record


 

Heat Indices from August 25 - 27, 2013

The table below lists the daily highest heat indices:

Date

Highest Heat Index

Location

Sunday, August 26th

108

Lake City, MN (Wabasha County)
Onalaska, WI (La Crosse County)

Monday, August 27th

109

Near Dubuque IA in southern Grant County
Eyota MN (Olmsted County)
Mauston, WI (Juneau County)
Waterville, IA (Allamakee County)

Tuesday, August 28th

107

Waterville, IA (Allamakee County)


 Heat Index Climatology

 

 

 


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