State Fair time usually means sweltering heat time — but not for thisfirst weekend. An unseasonable cool front has swept across Iowa, that’llkeep high temperatures down in the upper 60s and lower 70s today.Jeff Johnson, a meteorologist at the National Weather Service office inmetro Des Moines, says this fall-like forecast with lows in the 40s and 50sis NOT Iowa’s usual weather for the second week in August.Johnson says fans of fall will have to soak up the cool breezes thisweekend, as a warm wave will move back in soon.The forecast lows in the 40s and 50s tonight are in sharp contrast to theheat indices of last month that topped out near 130 degrees.