Midwest Overview - December 2012

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Warm Month Brings an End to a Warm Year

December got off to a very warm start and despite cooling late in the month, monthly temperatures were only moderated slightly (Indianapolis for example, Figure 1). Temperatures ranged from near normal in northwest Minnesota to as much as 6° to 7°F above normal in large parts of Illinois and Indiana (Figure 2). December daily temperature records were dominated by record highs (over 800 for the month compared to just 5 record lows) especially from the 2nd to 4th and 15th to 17th (Figure 3).

Annual temperatures for 2012 were among the warmest on record. January to December temperatures averaged from 1° to 5°F above normal across the Midwest (Figure 4). The nine-state region as a whole experienced its warmest year dating back to 1895 with a temperature of 52.1°F (based on preliminary estimates) topping the old record of 51.9 °F in 1931. Each of the nine states ranked among the top 3 warmest in the same time period. Missouri set a new statewide record (58.5°F vs. 57.6°F in 1938) in 2012 while Illinois and Ohio tied their existing record. Many cities across the Midwest also set new annual temperature records as shown in the table below.

City	State	2012 Annual Temperature (°F)	Previous Record (°F)	Year of Previous Record	Records Began
Chicago	IL	54.5	54.4	1921	1871
Indianapolis	IN	57.0	56.5	1921	1871
South Bend	IN	53.3	53.0	1998	1893
Des Moines	IA	56.0	54.5	1931	1880
Louisville	KY	60.8	60.4	2007	1872
Detroit	MI	53.8	52.4	1998	1874
Grand Rapids	MI	52.9	52.4	1921	1896
Lansing	MI	51.7	50.6	1921	1863
Muskegon	MI	52.6	50.9	1998	1896
Sault Ste Marie	MI	45.7	45.5	1998	1888
Minneapolis-St. Paul	MN	50.8	50.8	1931	1873
Rochester	MN	50.2	49.8	1931	1887
Columbia	MO	59.4	58.3	1938	1890
St. Louis	MO	61.2	60.1	1921	1874
Cleveland	OH	54.1	53.6	1998	1871
Columbus	OH	56.5	56.3	1998	1878
Green Bay	WI	49.4	49.4	1931	1887
Madison	WI	51.3	51.0	1931	1869
Milwaukee	WI	51.9	51.9	1931	1871

Snow Spreads South in December

Following a fall with relatively low snow totals, December brought some significant snows (Figure 5). Early in the month on the 9th and 10th, heavy snows fell in southern Minnesota and west central Wisconsin (Figure 6). Totals ranged from 6" to 13" across those areas. December 19th and 20th saw blizzard conditions extend from Iowa to northern Michigan. Snowfall totals ranged up to 15" in parts of southern Wisconsin (Figure 7). On the 26th, another round of blizzard conditions extended from southeast Missouri to Lake Erie. Another storm followed a similar path just days later pushing snowfall totals over a foot in many locations along the path of the storms (Figure 8).

December precipitation (Figure 9) totals ranged from well below normal (less than 50% of normal) in northwest Minnesota, western Missouri, and a small area in Upper Michigan. Areas with twice their normal precipitation for the month were located in southwest Minnesota and southeast Ohio.

Annual precipitation values were mostly below normal in 2012 across the region (Figure 10). Some areas along the northern and eastern edges of the Midwest were slightly above normal but large areas of Missouri, Iowa, and Illinois received between 50% and 75% of normal precipitation for the year. Drought conditions were widespread in summer but the eastern parts of the region improved in the fall while conditions deteriorated to the north and west as the year progressed (Figure 11).
 

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The Indiana State Climate Office also contributed to this report.
The Iowa Climatology Bureau also contributed to this report.
The Kentucky Climate Center also contributed to this report.
The Minnesota State Climatology Office also contributed to this report.
The Missouri Climate Center also contributed to this report.
The State Climatology Office for Ohio also contributed to this report.
The Wisconsin State Climatology Office also contributed to this report.