PHILADELPHIA - A heat wave is well underway in Philadelphia with the past four days reaching the 90s, but we haven't seen the worst of it yet.
Following a high of 91 degrees Monday, 93 degrees Tuesday, 95 degrees Wednesday and 96 degrees Thursday, it's possible that Friday could peak in the upper 90s, according to the FOX 29 Weather Authority.
The hottest day of the year so far in Philadelphia was June 30, when a 97-degree high was recorded at Philadelphia International Airport. This temperature will be challenged on Friday, but it will feel much hotter with the oppressive humidity.
The National Weather Service has issued an excessive heat warning for much of the Delaware Valley through 8 p.m. Friday, as the heat index will exceed 105 degrees in most areas during the afternoon.
Record highs are likely out of reach (99 degrees on Friday in Philadelphia), but that doesn't mean it won't be dangerously hot and humid.
Friday morning's low only dropped to 79 degrees in Philadelphia, so temperatures were already off to a very warm start at sunrise. Although this was not a record-warm low for the date (82 degrees, set back in 2016), it was the warmest low so far this summer.
Through Thursday, Philadelphia had tallied 27 days at or above 90 degrees so far this year. The average number of 90-degree days in a year is 30, based on the 30-year average from 1991 to 2020, so we are right on pace to reach that mark.
Much needed relief from the heat and humidity will arrive by next week. The FOX 29 Weather Authority says highs will hold in the lower to mid-80s from Sunday through the first half of the week. That's a couple of degrees below the mid-August average high of 86 degrees.