Here are the monthly temperature and precipitation departures for 2014. September joins January, February, March, and July as much cooler than average months. For precipitation, we noted last month that we were regularly alternating between wetter- and drier-than-average months in 2014. That changed in September with two months in a row of wetter-than-average conditions.
The statewide temperature in Illinois for the January-July period this year stands at 47.5 degrees, 3.9 degrees below average and the 5th coldest January-July on record for the state. It is no surprise why this would be the case. The bar graph below shows the monthly temperature departures from average (1981-2010) for 2014 in Illinois. The much-below-average temperatures of January, February, and March standout as well as for July.
This graph is for monthly precipitation departures from average for 2014 in Illinois. Precipitation seems to be doing a good job of alternating between above and below-average months. In fact, the statewide precipitation departure to date is very close to zero.
Here are the precipitation departures from average across Illinois. The areas in the lightest shade of green are 0 to 2 inches above average. The areas in the lightest tan are 0 to 2 inches below average. There is a band of wetter conditions in the northeast and a band of drier conditions close to Interstate 70.
The preliminary data for October indicates that Illinois received an average of 3.2 inches of precipitation across the state. That is close to the long-term average of 3.26 inches.
The first map shows the distribution of the precipitation across the state. Most of this precipitation fell in the last few days of the month. The heaviest amounts were in Cook, Will, and Kankakee counties along with some areas in far southern Illinois. The largest monthly total so far is 6.79 inches at Bourbonnais.
Below the first map are two more lower-resolution maps showing the precipitation totals and percent of average maps. While the first map is based on both radar and surface observations, the remaining maps are based on surface observations only.
Finally, we have the snowfall map for October that shows the measurable snowfall across northwest Illinois. Many places across northern and central Illinois saw snow flurries in October.
The highest monthly snowfall total was at Mendota with 3.5 inches. [I am going to strike this from the posting because of some inconsistencies in their report]. Several sites in the northwest part of the state reported 1 to 2.5 inches of snow for October.
The statewide average temperature in Illinois for January to November this year was 57.3 degrees, based on preliminary data. That is 3.1 degrees above normal and the second warmest on record back to 1895. Only 1921 was warmer with 57.6 degrees. This was in spite of a fall where the statewide average temperature was 52.7 degrees and 1.5 degrees below normal. Most of the above-normal warmth occurred in the January to July time frame. See graph below.
As mentioned earlier, the statewide average precipitation in Illinois for January to November this year was 27.6 inches and the 12th driest on record. This was in spite of a fall where the statewide average precipitation was 10.13 inches, 0.16 inches above normal. The graph below illustrates the beginning of a drought recovery in September and October before the dry November.