May 22, 2024 - News

Philadelphia may see an unusually hot summer

A map showing the summer 2024 temperature outlook for the continental U.S. Most of the country is predicted to have a warmer-than-average summer, with the highest chances in the southwest, mountain west, and New England.
Data: NCEP; Map: Axios Visuals

Philadelphia is bracing for what could be one of the nation's hottest summers on record.

Why it matters: Heat is the top weather-related killer in the U.S. in a typical year. A combination of factors is coming together to make this summer particularly hazardous for the Lower 48.

State of play: Last month, Philadelphia hit 90 for the first time in April in 15 years.

  • Forecasters said the warmer trend would continue this week with above-normal temperatures for the eastern half of the country, per the Inquirer.

The latest: Philadelphians can expect a reprieve from this week's near 90 temps as thunderstorms approach ahead of Memorial Day weekend.

  • Temperatures are expected to drop to anywhere from the mid-to-high 60s to the 80s.

The big picture: Unusually hot ocean waters are already playing a role in elevating temps and increasing humidity, particularly in South Florida and southeastern Texas.

Stunning stat: Key West, Florida, recorded a record warm heat index on Wednesday of 114.4, for example, and high temps this week have been in the upper 90s in much of South Florida.

  • According to a Climate Central index, human-caused atmospheric change likely quintupled the odds of stifling overnight minimum temps from Tampa southward to the Florida Keys Wednesday night.

Meanwhile, events in the tropical Pacific Ocean also factor into NOAA's summer outlook.

  • An El Niño event is transitioning into a likely La Niña, featuring cooler than average ocean waters in the equatorial Pacific.
  • Summer weather patterns typically linked with La Niña include heat and drought in the Southwest, which NOAA forecasts for this summer.
  • However, forecasters said on a press call that Southwestern heat and dryness also signals long-term climate change.

Threat level: Due to sizzling ocean temps in the Atlantic and Pacific, record global warmth persisting the past 11 months straight, and the transition from El Niño to La Niña, it's not out of the question that the summer will be among the hottest across the Lower 48 states.

Go deeper: Sizzling oceans tee up record-shattering summer.

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