Today's high in the upper 80s might seem pleasant after the upper 90s forecast for Wednesday and Thursday.

Especially with heaps of humidity expected.

In Philadelphia, the record high of 95 seems likely to fall Wednesday, and Thursday's mark of 98 is vulnerable as well.

Mugginess could make it feel as if it's 100 degrees, according to an excessive heat watch from the National Weather Service in effect until Thursday evening for Philadelphia and its surrounding Pennsylvania counties.

Even at the Shore, temperatures could top 90 Wednesday and Thursday.

According to an air quality alert, ozone levels are also a concern today and Wednesday for older adults, children, and people with respiratory problems in Southeastern Pennsylvania, all of New Jersey and all of Delaware. If thunderstorms materialize on Wednesday, they could reduce the threat, however.

Temperatures should decline into the weekend, from the upper 80s on Friday to mid 80s Saturday and about 80 on Sunday and Monday, with about a 30 percent chance of rain for each period from Friday night into Monday.

For more on the forecast, go to http://go.philly.com/weather.