Whiteside Co. here ...
I say it year after year ... Watch for Dandelions to begin blooming in middle of yards .
NOT along buildings or sidewalks , as this is a false indicator due to this area holding more heat .
I've studied this for years now , and from what I've learned , In this area of the state , is that the morel season is typically from the time the Dandelions bloom , until the time they go to seed .
Depending on how quickly it heats up , usually about a 3 - 5 week time frame .
Feel free to look back on my previous postings from years back on the Northwestern illinois forum .