This afternoon will be mostly sunny, hot and a little humid before a cold front approaches the Miami Valley early this evening.

Highs across the area are expected to be around 90 degrees today, according to Storm Center 7 Meteorologist Rich Wirdzek. An approaching cold front may trigger a shower or thunderstorm by early evening in the far northwest, and the thunderstorms will become more scattered in the area into the late evening hours, he said.

Once the front passes, cooler and less humid conditions will arrive. The low Friday morning will be in the mid-60s, and the high will be in the mid-80s, he said.

Today marks the second heat wave of 2012 after three consecutive days of temperatures of at least 90 degrees.