The Record Warmth of March 2012

March 2012 will be remembered for its record-breaking warmth, particularly across the Upper Midwest. Long stretches of record highs and record warm lows were set, a lot of them significantly (10 degrees or more), including all-time March records. Record warmth was not only found in the Upper Mississippi River Valley, but across the entire Midwest.  According to the Midwestern Regional Climate Center, "The average temperature for the nine-state Midwest region was 50.3 degrees Fahrenheit, which broke the previous record of 46.9 degrees set over 100 years ago in 1910.  Each of the nine Midwest states also set statewide records for the warmest March.  Statewide records go back to 1895, and the existing records were all from the early to mid-20th century.

Daily Temperature Anomalies for March 2012 (Courtesy of the Midwestern Regional Climate Center)

Preliminary statewide average temperatures for March:

Throughout the month, over 6,400 daily record temperatures were set or tied (including both warmest minimum and maximum temperature), with over 650 of them also setting records for the warmest temperature for any day in March.  A majority of the records were set during the middle of the month, from the 14th through the 24th of March, when hundreds of records fell each day.

March average temperatures ranged from 10 degrees above average in Kentucky to 17 degrees above average in northwest Iowa, southern Minnesota, and western Wisconsin.  During the record-breaking period from March 14 to 24, temperature departures ranged from at least 13 degrees above average in southwest Missouri to just over 29 degrees above average in central Wisconsin and northern Michigan. 

Why So Warm?

The culprit was an unseasonably warm pattern over the Upper Mississippi River Valley region that took hold on March 10th. Aiding in this stretch was the lack of snow cover along and south of Interstate 94. The warmth and humidity intensified over the weekend of the 17th and 18th, in response to a deepening low pressure system over Montana. A slow cool down then ensued as more clouds and occasional precipitation moved across the region, associated with the low pressure system's cold front. Toward the end of the month, a slight warm up into the 70s set some new records, but temperatures dropped back to normal readings for the last few days of the month.

All-Time Warmest March Across The Upper Mississippi River Valley

• La Crosse Municipal Airport had an average temperature of 50.4 degrees.  This was 15.9 degrees above the 1981-2010 March normal of 34.5 degrees.  This easily surpassed the previous record of 47.1 degrees in 1878.  March of 2012 was even 2.6 degrees warmer than the 1981-2010 April average.  Only 30 April's were warmer than this March (monthly records date back to 1873: 139 April's).
• Rochester International Airport had an average temperature of 49.1 degrees.  This was 16.7 degrees above the 1981-2010 March normal of 32.4 degrees.  This smashed the previous record by over 6 degrees (42.9 degrees in 1910).  March of 2012 was even 4.4 degrees warmer than the 1981-2010 April average.  Only 13 April's were warmer than this March (monthly records date back to 1886:  96 April's).

In addition to the record warmth at both La Crosse and Rochester, March of 2012 was the warmest at the following cooperative observing sites:

Northeast Iowa...

                       2012 March       Previous Record      Records
                       Avg. Temp.          for March          Began
                       ----------       ---------------      -------
Cascade              50.1 degrees*   43.3 degrees in 1973     1948
Charles City         49.8 degrees    44.4 degrees in 1910     1893
Cresco 1NE           48.0 degrees    42.2 degrees in 1946     1893
Decorah              50.9 degrees    43.7 degrees in 1910     1893
Elkader              47.5 degrees*   45.8 degrees in 1910     1893
Fayette              48.8 degrees    45.0 degrees in 1910     1893
Guttenberg Dam 10    51.4 degrees    43.7 degrees in 1973     1937
New Hampton          47.3 degrees*   44.2 degrees in 1910     1897
Oelwein+             48.5 degrees    44.8 degrees in 1945     1923
Osage                48.1 degrees    46.5 degrees in 1910     1899
Waukon               46.8 degrees*   42.4 degrees in 1945     1934

Southeast Minnesota...

                       2012 March       Previous Record      Records
                       Avg. Temp.          for March          Began
                       ----------       ---------------      -------
Austin WWTP          46.4 degrees    43.8 degrees in 1946     1938
Byron                46.0 degrees    38.2 degrees in 2000     1993
Caledonia            46.9 degrees*   41.0 degrees in 1973     1893
Grand Meadow         45.8 degrees    44.5 degrees in 1910     1891
Preston              48.6 degrees    40.6 degrees in 1973     1953
Theilman             48.0 degrees*   39.6 degrees in 2010     1963
Winona               49.1 degrees    46.5 degrees in 1910     1893
Zumbrota             47.1 degrees    44.6 degrees in 1910     1896


Western Wisconsin...

                       2012 March       Previous Record      Records
                       Avg. Temp.          for March          Began
                       ----------       ---------------      -------
Alma Dam 4           49.6 degrees*   41.2 degrees in 2000     1939
Blair                47.4 degrees    45.4 degrees in 1910     1896
Friendship           47.7 degrees    41.7 degrees in 1945     1930
Genoa Dam 8          51.0 degrees    44.5 degrees in 1946     1939
La Crosse NWS        49.1 degrees    39.9 degrees in 2000     1996
Lancaster 4WSW       50.7 degrees    45.6 degrees in 1945     1893
Lone Rock Tri Co AP  50.6 degrees    42.6 degrees in 1973     1948
Lynxville Dam 9      51.6 degrees    45.2 degrees in 1945     1940
Mauston 1SE          48.7 degrees    40.7 degrees in 1973     1905
Medford              43.2 degrees    41.1 degrees in 1910     1893
Necedah 2SE          47.1 degrees    41.4 degrees in 2000     1954
Neillsville 3SW      46.0 degrees    39.0 degrees in 1973     1893
Owen 3W              44.3 degrees*   37.7 degrees in 2000     1947
Prairie du Chien     50.5 degrees    45.8 degrees in 1945     1893
Richland Center      48.5 degrees    44.1 degrees in 1945     1908
Soldiers Grove       49.1 degrees    39.2 degrees in 2010     2010
Sparta               49.0 degrees*   42.5 degrees in 1945     1893
Trempealeau Dam 6    50.6 degrees    41.4 degrees in 2000     1937
Viroqua              46.5 degrees*   45.9 degrees in 1910     1893

* Missing 1 to 3 days of temperature data, so the monthly temperature average is preliminary.

 Listing Of Daily Temperature Records Set During March 2012:

March 2012 Temperatures In La Crosse,WI & Rochester, MN:

La Crosse, WI High and Low Temperatures	Rochester, MN High and Low Temperatures

Other Interesting Climate Factoids:

La Crosse, WI

• On March 20th at 1:53 a.m. CDT, the dew point at the La Crosse Municipal Airport climbed to 62 degrees.  This breaks the previous record of 61 degrees set on March 17, 2012 and March 23, 1936 for the highest March dew point.  Dew point records for La Crosse date back to 1933.
• The 83 degree high temperature on March 17th was the earliest occurrence of an 83 degree day in a year. The high temperature was 1 degree shy of the all-time March temperature of 84 set on the 29th of 1986.
• Between March 17th and March 20th, average temperature departures from normal were 30 or more degrees.  March 17th saw the largest departure from normal, a whopping 38 degrees!
• Between March 14th and 22nd, 70 degree or higher temperatures were observed (9 consecutive days). This broke the longest string of 70 degrees or higher temperatures in March. The previous record occurred between March 23rd and 29th of 1910.

Rochester, MN:

• On March 16th at 11:54 a.m. CDT and March 17th from 10:54 a.m. through 12:54 p.m., the dew point at the Rochester International Airport climbed to 62 degrees.  This surpassed the previous March record of 56 degrees set on March 25, 2007.  Prior to this year, the earliest 60 degree dew point was April 24th in 1990.  Dew point records for Rochester date back to 1948.
• The 81 degree high temperature on March 17th was the earliest occurrence of an 80 degree day in a year. The previous record was March 24th of 1910.  The high temperature was 1 degree shy of the all-time March temperature of 82 degrees, also set on the 24th in 1910.
• Between March 17th and March 20th, average temperature departures from normal were 30 or more degrees. March 18th saw the largest departure from normal, a whopping 38 degrees!
• Between March 14th and 19th, 70 degree or higher temperatures were observed for 6 consecutive days. This is the second longest string of 70 degrees or higher temperatures in March. The record is 7 days between March 24 and 30th of 1910.

Mississippi River:

• Water temperatures responded dramatically to the unprecedented warmth as well. At La Crescent Dam 7, the water temperature rose from 36 degrees at 7 a.m. on March 10th to 50 degrees at 7 a.m. on the March 20th.  The water temperature topped out at 52 degrees on March 26th.
   

  
  
  Mississippi Water Temperatures
  at La Crescent, MN during Match 2012

Phenology:

Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate.

The record warmth resulted in the growing season starting well ahead of normal.  Soil temperatures quickly climbed from 31 degrees on March 9th to 58 degrees on March 18th.  They topped out at 59 degrees on March 22nd.  As clouds and precipitation moved into the area during the last week, they cooled off into the mid and upper 40s.

NWS La Crosse 2" Soil Temperatures for March 2012

In addition, the accumulated growing degree days climbed rapidly during the month.  Areas along and north of the Interstate 94 corridor saw anywhere from 100 to 150.  Meanwhile the remainder of the area accumulated between 150 and 210.  Normally, we do not start accumulating growing degree days until after April 1st.  The image below illustrates how the growing degree days quickly accumulated from March 13th through March 27th.

With the unusually warm soils and well above normal growing degree days, the growing season is well ahead of schedule.  Forsythia bushes and spring flowers (crocuses, hyacinths, and tulips) were flowering anywhere from two weeks to a month ahead of schedule.  Meanwhile fruit trees and rose bushes were at least a month to 6 weeks ahead of schedule.  There were even some mushrooms at the end of March (usually not seen until May).  The pictures below are from West Salem, WI.

March 18, 2012:

Rose bush beginning to leaf out	Forsythia bush flowering	Magnolia bush flowering
Crocuses blooming	Crocuses blooming	Spring flowers blooming

March 26, 2012:

Rose bush fully leafed out	Forsythia bush fully leafed	Bleeding Hearts flowering
Crocuses blooming	Hyacinths blooming	Azalia bushes blooming

March 31, 2012:

Mushrooms	Double Flowering Dogwood in full bloom	Weeping Dogwood about ready to bloom
Blueberry bush getting ready to leaf out	Maple tree beginning to leaf out	Tulips

Additional Climate Information: