Thunderstorms are expected to move into northern Iowa by mid to late morning as a cold front approaches from the northwest. Strong to severe storms are possible across this afternoon and evening as additional storms develop ahead of the boundary and move southeast through central and southern Iowa. Another very warm day is forecast with high temperatures in the upper 80s to lower 90s. Heat index values will approach 100 degrees by this afternoon. Much cooler conditions are forecast for Tuesday with highs in the 70s to lower 80s. The seasonably cool weather will continue through much of the week. Chances for thunderstorms will return late in the week and next weekend as another cold front arrives.