It's hot, but not a heat wave, officially speaking

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Stephanie and Solomon Fulton look at theIr large oak that winds toppled onto a neighbor's house on Pennypacker Drive in Willingboro during the storms on July 29, 2009.

The stretch of hot, humid, volatile weather is expected to continue through the weekend - but we missed marking the first official "heat wave" of the summer by a couple degrees today.

After two days of 90 or plus temperatures, the mercury at the Philadelphia International Airport topped out at 88 degress this afternoon. It takes three days of 90-degree or higher temperatures to meet the definition of a heat wave.

In the Poconos, meanwhile, clean up operations were under way a day after a tornado in Monroe County caused major damage, destroying several farm buildings and blowing the roofs off two houses.

 "Ping pong size hail" - about 1.5 inches in diameter - was reported around noon yesterday in Upper Providence Township.

Last evening, trees and wires were downed in several parts of South Jersey, including Chesilhurst in Camden County, Willingboro and Tabernacle in Burlington County, Vineland in Cumberland County, and Buena in Atlantic County.

In Willingboro, a pin oak from a neighbor's yard slammed into the Scott famuily's home, which has been condemned.

Irving Scott, who was home at the time, said there was a "high pitch sound" when the tree toppled.

"Pictures fell off the wall, the doors started opening and closing," he said. "It was an unusual sight, then the power went out."

More thunderstorms are in the forecast for every day through Tuesday. Tomorrow appears to be the biggest threat, with a 60 chance of boomers tomorrow afternoon or evening.

Meanwhile, the heat keeps coming. Temperatures are expected to be in the high 80s through Wednesday, with overnight lows around 70.

Yesterday's high of 92 tied it for second hottest day of the year, matching April 25. Only April 26's 93 was higher.

Tuesday hit 91.

Add in Sunday's 91 and Monday's 87, and this has been the year's hottest week. April saw cooler days, with highs in the 60s and 70s, before and after its heat wave, and during May and June, the temperature hit 90 only once - on June 26.

This spell of heat has been far more uncomfortable than April's, when nighttime temperatures fell into the 60s and relative humidities were way, way lower. For example, on April 26, at 3 p.m. it was 92 degrees at the airport, but the humidity was down there at 19 percent. The dewpoint – that's the temperature at which water vapor condenses and is a truer measure of moisture in the air – was a comforftable 45. Yesterday, at 3 p.m. it was 91, the humidity was 49 percent, the dewpoint, 69.

Still, the current wave of warmth - we could wind up with a dozen straight days in the high 80s or above - wilts in comparison with other summers.

Last year, July 16 began a stretch of highs that read like this: 92, 95, 96, 95, 95, 91 and 92.

The average temperature last July was 88.

For more on the forecast, go to http://go.philly.com/weather and fill in the town or Zip code for the area you want to check.


Staff photographer Elizabeth Robertson contributed to this article.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.