Do you have a yard to set up a sprinkler? My day care kids were entertained for hours with that and bubbles.
http://www.creativekidsathome.com/ac...tivity_5a.html
"Camping" under the dinning room table, maybe a picnic! Vinyl tablecloths are handy here. Maybe even spend the night in the "tent".
Treasure hunts, inside or out. Prize at the end.
Some malls have kids areas if you are close to one, good way to get in some playtime and in the AC.