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Planet warming, year by year — the backdrop for every local heatwave

Each bar is one calendar year — NOAA global land+ocean temperature vs the 1901–2000 average (1880–present). Blue = cooler years; red = hotter.

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≥3 days above local weekly 95th

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near active stations

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daily maximum (TMAX)

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latest NOAA annual

Active heatwaves at US stations

What does heat do to a body?

A heatwave is not only a high temperature. Humidity, warm nights, age, work, medication, housing, and acclimatization all decide whether the body can shed heat fast enough. The reference thresholds below use wet-bulb temperature — what a thermometer reads when wrapped in a wet cloth in still air, which accounts for how much cooling sweat-evaporation can provide. The higher the humidity, the less the wet-bulb falls below the air temperature, and the harder it is for the body to stay cool.

3+ daysOur active-heatwave rule: daily highs above the local weekly 95th percentile, long enough for heat stress to accumulate in vulnerable people.

32 °C wet-bulbAround this level, healthy adults can no longer safely do physical work outside without cooling, shade, water, and rest. Construction, agriculture, deliveries become dangerous.

35 °C wet-bulbThe theoretical survival ceiling — even a fit, hydrated person sitting in shade overheats within hours, because sweat cannot evaporate fast enough to keep core temperature down.

Your nearest monitored city

Finding your nearest weather station…

40°C+ dangerous 30°C 20°C comfortable

Daily maximum temperature at your nearest station.

Or pick one of 15 cities:

Which US cities are warming fastest?

Summer (Jun–Aug) daily high vs each city’s 1991–2020 average — sorted by warming rate (fastest first).

Deadliest heatwaves on record

Curated

Climate connections

What drives this

Ocean heat →Most excess heat is stored in the ocean, loading the atmosphere with a warmer baseline.
Global temperature →The same warming dial that moves tipping risk raises the floor for extreme heat.

What this drives

Crop stress →Hot spells intensify drought stress and crop water demand.
Wildfire →Heat dries fuels and lengthens fire seasons.
Marine heatwaves →Ocean heatwaves are the saltwater counterpart to land heatwaves.

How we know this

Source: NOAA Climate at a Glance (global annual anomaly CSV) and NOAA NCEI GHCN-Daily station maximum temperatures for 15 US cities.
Update cadence: We download public NOAA files daily; global annual values change when NOAA posts a new year.
Time coverage: Global stripes from 1880; station stripes from 1991 summers; active heatwave rule uses the latest ~7 station days in our snapshot.
Methods: Active heatwave = ≥3 consecutive days at or above the 1991–2020 weekly 95th-percentile TMAX. Not wet-bulb, humidity, or a global gridded heatwave map.
Uncertainty: Fifteen US stations are illustrative, not exhaustive; geolocation picks the nearest station, which may be far from you.
Limitations: International “live” heatwave detection is not wired here — the global stripe is planet-wide context only.
Primary data: NOAA Climate at a Glance · NOAA NCEI Daily Summaries · How this page is built

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