Staunton Star - Times - Published in the Interest of the Staunton Community for Over 143 Years

Most of Oct. in Ill. had above average temperatures, until a weather shift in the last few days of the month brought a shockingly cold Halloween and even snow in some areas, according to Illinois State Climatologist Trent Ford at the Illinois State Water Survey.

A few days in the final week of the month were 15 to 20 degrees above normal. Oct.'s average temperatures ranged from the low 50s in northern Ill. to the low 60s in southern Ill., between one and two degrees above normal in most places.

The brief taste of winter in the last few days of the month brought widespread low temperatures in the low 20s, including 21 degrees in Mt. Vernon and 23 in Bloomington. Halloween nighttime temperatures dipped into the low 20s and high teens across much of the state. The daytime high temperatures on Halloween were the coldest on record in several spots across the state, including Chicago’s Midway airport with 37 degrees.

The preliminary statewide average Oct. temperature was 56.7 degrees, 1.9 degrees above the 1991–2020 average.

Rainfall

The first two-thirds of the month were somewhat to very dry across the state, as most places were one to two inches drier than normal through Oct. 24.

More active weather brought multiple rounds of rain and some snow to Ill., raising month-end totals near or above the 30-year normal. The dry start to the month was ideal for fall harvest, while the wetter end of the month helped improve dry conditions that prevailed in Aug. and Sept.

Oct. precipitation ranged from nearly six inches in northeast Ill. to less than 2.5 inches in the St. Louis Metro East. Most of the state north of Interstate 70 was one to two inches wetter than normal, while areas farther south were up to two inches drier than normal.

Overall, the preliminary statewide total Oct. precipitation was 3.46 inches, 0.20 inches above the 1991–2020 average.

Halloween snow in northern and central Ill. is not necessarily a rarity but happens once every four to six years. Measurable snow, with totals exceeding 0.1 inches, was recorded in much of the state north of Interstate 74, with totals as high as 1.5 inches in Mundelein and 0.9 inches at O’Hare. The average first measurable snow comes in the third or fourth week of Nov. for most of northern and central Ill., so this year’s event came about two to three weeks early.

Outlooks

The latest Climate Prediction Center outlooks lean into El Niño with higher chances of below normal Nov. precipitation. Nov. temperature outlooks are more mixed, with equal chances of warmer and colder weather this month.