Discover real natural events happening around our amazing planet right now!
Real-time heatwave and extreme cold data from NASA EONET thermal monitoring
View on Globe →Temperature extremes happen when the weather gets dangerously hot or cold. During a heatwave, temperatures can soar so high that roads melt and it becomes dangerous to go outside. During extreme cold snaps, temperatures can drop far below freezing, turning even rivers into solid ice.
NASA satellites measure land surface temperatures globally every day, identifying areas where temperatures are far above or below normal. These measurements help scientists track developing heatwaves before they become emergencies and model how climate change is shifting the frequency and intensity of temperature extremes worldwide.
NASA's MODIS instrument measures land surface temperatures globally every day, detecting heat anomalies and unusual cold patterns against long-term baseline averages. When a region's surface temperature significantly exceeds what is normal for that time of year, the anomaly is flagged and tracked as a potential temperature extreme event.
The ECOSTRESS instrument on the International Space Station maps surface temperature at very high resolution — fine enough to distinguish between a sun-drenched car park and a nearby park — making it extremely useful for studying urban heat islands and identifying which parts of a city are most at risk during heatwaves.
NASA's climate reanalysis products, including MERRA-2, combine satellite observations with weather model data to produce a consistent global temperature record stretching back to 1980, enabling scientists to see exactly how today's extremes compare to anything in the historical record.
Earth Explorer displays temperature extreme events tracked by NASA's EONET monitoring network. Significant heatwaves and dangerous cold snap events worldwide appear as glowing dots on the interactive globe.
View Live Temperature Events →A heatwave is a period of unusually hot weather lasting at least two to three days — significantly warmer than normal for that place and time of year. The exact definition varies by region. Heatwaves are the deadliest weather hazard in many developed countries, killing more people than floods, storms, or cold events combined. They are becoming more frequent and intense as the climate warms.
The polar vortex is a belt of very cold, fast-moving air that circulates around the North and South Poles. In winter, when the polar vortex weakens or buckles, blasts of Arctic air can spill far south into normally temperate regions. These events bring dangerously cold temperatures — sometimes 20–30°C below normal — to places like Texas, Central Europe, or South Korea that are not equipped to handle extreme cold.
When you overheat, your body sweats to cool down. But in very hot and humid air, sweat evaporates slowly, and body temperature can rise dangerously. Heat exhaustion causes heavy sweating, weakness, and nausea. Heatstroke — confusion, hot dry skin, and loss of consciousness — is a medical emergency that can be fatal within minutes without immediate cooling and treatment. Always act quickly if someone shows these signs.
Cities experience the "urban heat island" effect: dark buildings, roads, and car parks absorb solar heat during the day and release it slowly at night, keeping temperatures 2–5°C warmer than surrounding rural areas. With less green space, there is less cooling from plant transpiration. During heatwaves, this can make city temperatures dangerously higher than what forecast weather stations — often located outside urban centres — report.
Drink water regularly — do not wait until you feel thirsty. Stay out of direct sunlight between noon and 3 pm. Keep curtains or blinds shut on sunny windows to slow heat build-up indoors. Check on elderly neighbours and young children, who are most vulnerable to heatstroke. Know the signs of heatstroke — confusion, hot and dry skin, no sweating — and call emergency services immediately if you see them.
MODIS measures daily global land surface temperatures, flagging anomalies against historical norms. ECOSTRESS on the ISS maps urban surface temperatures at very high resolution. NASA's MERRA-2 climate reanalysis combines satellite data with weather models to provide a complete global temperature record back to 1980, letting scientists place any current event in full historical context.