Extreme heat warning goes into effect Wednesday in Philadelphia region. Here's how high temperatures will get.

With a high temperature of 91 degrees on Tuesday, the heat wave in the Philadelphia region is now on Day 2. It will continue and ramp up on Wednesday, peaking on Friday. This one looks likely to be historic and unprecedented.

If our current forecast high temps hold, that would give us a four-day stretch of highs above 100, which has never happened on record in Philadelphia. 

Thursday and Friday are likely to break daily heat records, with Thursday's record of 103 dating back to 1901 — 125 years or half the time America has existed (easy mental math this week).

Our forecast high of 100 on the Fourth of July would tie for the second-hottest July Fourth ever. Only twice have we had 100-plus highs on the Fourth of July.

If we hit our forecast high of 105 on Friday, it would be the hottest July temperature ever recorded in the city — the hottest temperature overall is 106 in August 1918.

Wednesday, Thursday, Friday and Saturday are the dangerously hot days. The highs will be from 100-105 degrees with heat index values each afternoon peaking around 110-115.

An extreme heat warning has been issued from noon Wednesday to 8 p.m. Sunday.

Pop-up afternoon and evening thunderstorms are possible each day due to the heat and humidity but no organized weather systems expected over the next few days.

Any rain could keep some locations in the upper 90s, rather than 100s.

We're monitoring the Fourth of July for our next chance of more widespread showers and storms, some of which could potentially be severe.

Sunday brings another chance for scattered showers and storms as the heat begins to break down but temperatures are still expected to be in the mid-90s, making this heat wave a full seven days.

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 and keep hydrated.

Swimming pools, movie theaters and shopping malls are places to stay cool.

Cars become death traps in the heat. No people or pets should ever be left in the car. The heat can reach 125 degrees in minutes and cause death. Check your back seat before leaving a car.

Buildings with no air conditioning will heat up and retain the heat. That cumulative effect of the heat after 3-5 days could be deadly for some.

Our heat records since 1894

• There have only been 64 100-degree days in Philly since 1894 (per the NWS).
• We've had only one 100-plus day in 14 years. That was last June 24, 2025.
• The hottest day on record for Philly is 106 on Aug. 7, 1918.
• The hottest July temperature on record is 104 on July 3, 1966.
• Back-to-back 100-degree days have only occurred 14 times. The last back-to-back 100-degree days were in July 2011.
• Three consecutive 100-degree days have only happened twice in Philly history, during July of 1993 and July of 1966.
• We have never had four consecutive 100-degree days.
• Records we are chasing: July 1 record is 102 from 1901, July 2 is 103 from 1901, July 3 is 104 from 1966.

Here's your 7-day forecast:

Wednesday: NEXT Weather Alert. High 100, low 74.

Thursday: NEXT Weather Alert. High 104, low 79.

Friday: NEXT Weather Alert. High 105, low 82.

Saturday: NEXT Weather Alert. High 100, low 82.

Sunday: NEXT Weather Alert: High 94, low 79.

Monday: Few storms. High 86, low 74.

Tuesday: Partly cloudy. High 85, low 72.