It probably comes as no surprise that December was colder than average. The statewide temperature of 25.5 degrees was 4.4 degrees below average. The puts it at the 20th coldest December on record with statewide records going back to 1895. However, it is far short of the record coldest December of 1983 when the statewide temperature was only 17.1 degrees, 8.4 degrees colder than this December.
The pattern of much-below average temperatures in December persisted throughout the Midwest with the departures strongest in the northern-most states.
Note: the summary for 2013 will be coming out by Friday.
The statewide precipitation was 2.5 inches, which is slightly below average. But the precipitation varied widely across the state. Conditions were very dry across northern and central Illinois, while much wetter in southern Illinois. In fact, the dry conditions in December persisted throughout much of the Midwest except along the Ohio River.
Note: we are having some technical difficulties with the snowfall maps so I will talk about snowfall in a later post. Precipitation is defined as the amount of any rainfall plus the water content of any snow, sleet, freezing rain, etc.
It was disappointing that both November and December were so dry for Illinois. As a result, stream flows and lake levels were below where they should be for this time of year. The last figure shows the stream flows from the USGS. Several gauges across the central part of the state are less than 25 percent of their January 1 stream flow levels.