...Hard Freezes are Possible Tonight and Monday night... Very cold and dry surface high pressure will surge through the region bringing sub-freezing temperatures to the entire Quad State tonight and Monday night. Temperatures may drop into the middle 20s resulting in a hard freeze over the northern half of the region tonight, especially over southern Illinois. Temperatures Monday night are expected to drop into the middle and upper 20s throughout the Quad State, potentially leading to another hard freeze. Although the growing season has not officially started, some tender vegetation could be impacted by these cold temperatures. Please take necessary actions to protect any tender vegetation the next two nights.