Warm, muggy Sunday in Philadelphia area before dangerous heat wave arrives. Here's the forecast.

After a wet start to the weekend, we keep the muggy conditions around for Sunday, although the temperatures will be a bit warmer. There is a slight chance of a few scattered showers or a rumble of thunder.

A heat wave with dangerous feels-like temperatures in the triple digits is on the way to the Philadelphia region next week.

NEXT big weather changes

A very dangerous heat wave arrives next week in the Philadelphia area.

A bubble of extreme heat will affect everyone east of the Rockies. Expect many record highs and record warm lows to be challenged and broken.

Monday, we flirt with 90 degrees, and this heatwave could stretch through the 4th of July weekend.

Wednesday, Thursday, and Friday will be the hottest days with highs from 98 to 103. The humidity will make it feel like 105-110 or higher.

The record highs each day next week are 100 or above.

Heat Advisories will likely be necessary and even Extreme Heat Warnings may be needed in response to the potentially dangerous heat.

A NEXT Weather Alert will go in to affect Wednesday and remain in effect through at least Friday.

Pop-up thunderstorms are possible each afternoon due to the heat and humidity. Anywhere that sees rain could keep some locations in the upper 90's rather than 100s.

Plan and prepare for the heat

Have somewhere cool to rest, special care for pets, check on neighbors and family, limit time outdoors, check fluid in cars.

Buildings with no air conditioning will retain the heat. That cumulative effect of the heat after 2-5 days could be deadly for some. Travel delays are possible.

Chasing temperature records in the Philadelphia area

The forecasted high temperatures for this heat wave are close to some of the hottest temperatures Philadelphia has ever felt in the first week of July. 100 degree days are very rare.

• Philadelphia's record high for Wednesday, July 1 is 102 degrees set in 1901.
• The city's record high for Thursday, July 2 is 103 degrees, also set in 1901.
• The hottest ever temperature on July 3 is 104 degrees, set in 1966. This is also the city's record-hottest July day.

FYI: The hottest all-time temperature on record for Philly is 106, set on on Aug. 7, 1918.

Here's your 7-day forecast:

Sunday: Mainly cloudy. High 83, low 69.

Monday: Partly cloudy. High 89, low 68.

Tuesday: Heating up. High 91, low 68.

Wednesday: NEXT Weather Alert: Heat. High 99, low 74.

Thursday: NEXT Weather Alert: Hot and humid. High 101, low 80.

Friday: NEXT Weather Alert: Hot and humid. High 102, low 82.

Saturday: Few storms. High 98, low 80.