CHICAGO (AP) — Chicago hasn’t logged any snow on the ground in January or February for the first time in the 146 years that the National Weather Service has been keeping track.

Traces have fallen, but not enough to record. The weather service takes measurements at 6 a.m. at O’Hare International Airport, which means small amounts that may have fallen later in the day and melted weren’t recorded. The Chicago Tribune reports that’s what happened when trace amounts fell on Jan. 30 and Feb. 25.

Jim Angel is state climatologist at the University of Illinois’ Illinois State Water Survey. He says January and February are usually the snowiest months of the year.

He says warm air and ground temperatures contribute to the lack of snow accumulation, which affects animals, trees and insects.