Apr 17 | Climate Review and Weather Update
by Trent Ford, State Climatologist
ISWS PRI University of Illinois
Our warm spring continued this week, as average temperatures ranged from the high 50s in northern Illinois to the mid-60s in southern Illinois, 10 to 15 degrees above normal. The first half of April has been extremely warm, in fact the second warmest start to April on record in Peoria, Springfield, and St. Louis. Our recent warmth has continued a longer trend from March, making this year the warmest start to spring since 2012 statewide. However, as warm as this season has been so far, it is still a full 4 degrees cooler than March and April 2012, illustrating just how warm that year was.
Precipitation this week was again mostly contained to the northern half of the state. 7-day totals ranged from virtually nothing in south-central Illinois to nearly 5 inches in far northern Illinois. The continued wet pattern in the northern part of the state, along with extremely heavy rain on snow in Wisconsin caused several streams to rise above flood stage, including moderate flooding on the Fox and Des Plaines Rivers. The first half of spring has been the wettest on record in Chicago with over 10 inches of precipitation since March 1st. For context, the state’s largest city typically gets around 10 inches of precipitation for the entire spring season. In contrast, southern Illinois remained dry for yet another week, adding to significant rainfall deficits this season. Most of the southern half of the state has been 2 to 5 inches drier than normal since mid-March, which has made for good topsoil conditions for planting, but less so for good flow in streams. The unusual heat in recent weeks has further taxed soil moisture, which could become a concern if the area doesn’t get wetter before the start of real summer.
Looking ahead, temperatures will drop following a cold front early this weekend, and stick around in the 50s and 60s this weekend before steadily increasing next week. Most of the state is expected to pick up at least around an inch of rain over the next few days, with drier conditions toward the end of next week. Farther out, there is increasing confidence on a bit of a cooldown in the final week of April. While that may bring a risk of frost, it remains unlikely we’ll see temperatures approach or dip below freezing. Still, it’s a good idea to hold off on the sensitive garden plants until we get into May.