Climate Change & Heat

As the Earth's climate warms, hotter-than-usual days are becoming more common.
A persistent period of unusually hot days is referred to as an extreme heat event or a heat wave.

Heat waves are occurring more often,
lasting longer, and getting hotter.

Frequency

The average number of heat waves per year
across major cities.

MORE OFTEN

Increased from
2 heat waves in 1960s to ^ ^
6 heat waves in 2020s 21'^

Season

The average time span between the first and last
heat wave of the year across major cities.

STARTING EARLIER
ENDING LATER

46 days longer

in 2020s compared to

1960s

61

4—t

46

Duration

The average length of heat waves
across major cities.

LONGER

Increased from

3	days in 1960s to

4	days in 2020s



:.3

Intensity

The average temperature above a
city-specific temperature threshold.

GETTING HOTTER

Increased from
1.9°F in the 1960s to
2.5°F in the 2020s



::4

Heat waves are more than just uncomfortable:
they can lead to illness and death.

HEAT-RELATED
DEATHS

14,000+ Americans

have died from heat-related
causes since 1979, according to
death certificates.

Taking action: the best defense against extreme
heat is to be prepared, and remember...

GET READY.

Stay up to date on your local
weather forecast and be
aware of extreme heat events.

GET SET.

Know the symptoms of
heat-related illnesses and
what to do in an emergency.

GO.

Stay cool during heat waves.
Avoid being outside during
the hottest part of the day.

x>EPA epa.gov/climate-indicators

December 2024
EPA 430-F-24-009

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