A Frost Advisory is in place for West Central and NW Iowa tonight. Areas west of Highway 169 should cover any sensitive vegetation still outside. Clear skies will allow temps to dip to around 40 in Des Moines, with some patchy frost even possible in Central Iowa.
Sunday will be mostly sunny with highs in the upper 60s. Sunday night shouldn't be quite as chilly as slightly warmer air pushes into the state before rain takes over Monday afternoon.
The best chance of rain arrives overnight Monday through early Tuesday morning. This rain is along another cold front which will drop temperatures even lower to the 50s for daytime highs.