Where the ocean is warmest: Earth's warm pool, explained

Get the ocean temperature map as a printable poster: https://www.etsy.com/listing/45987823... The warmest and largest body of seawater on Earth averages above 28°C and stretches nearly halfway around the planet. Here's why it sits where it does, and what it does to the sky. Using NOAA's OISST v2.1 sea surface temperature record (monthly means, 1991–2020), we map the warm pool: about 50 million km² of water above 28°C, 13.9% of the ocean surface, spanning 47% of the way around the globe. We follow the equator from about 29.6°C near 150°E to 24.0°C near the Galapagos, compare upwelling coasts with warm coasts at the same latitude, and track the pool from about 48 million km² in January to 74 million in April. Matched with GPCP v2.3 rainfall for the same years, ocean above 28°C averages about 5.4 mm of rain a day versus 2.5 mm over the rest of the ocean. CHAPTERS 0:00 Intro: the warmest water on Earth 0:30 Above 28°C: what counts as the warm pool 1:42 The whole ocean, by temperature 2:53 Why the west is warm 4:12 The cold coasts 5:35 The pool breathes through the year 6:31 Warm water makes rain 8:05 Reading the map SOURCES Sea surface temperature: NOAA OISST v2.1 (NOAA/NCEI 1/4° Daily Optimum Interpolation SST), monthly long-term mean 1991–2020, via NOAA PSL (public domain; data provided by the NOAA PSL, Boulder, Colorado, USA). Retrieved Oct 15, 2026. https://psl.noaa.gov/data/gridded/dat... NOAA NCEI, Optimum Interpolation Sea Surface Temperature (OISST) product page (satellites, ships, buoys and Argo floats). Retrieved Oct 19, 2026. https://www.ncei.noaa.gov/products/op... Rainfall: GPCP v2.3 monthly long-term mean 1991–2020 (Global Precipitation Climatology Project, NOAA Climate Data Record, satellite-gauge), via NOAA PSL (public domain). Retrieved Oct 19, 2026. https://psl.noaa.gov/data/gridded/dat... and https://www.ncei.noaa.gov/products/cl... NOAA Climate Prediction Center, Pacific Ocean Overview (warm pool near Indonesia and the Philippines; trade winds pile up warm water in the west; thermocline deep in the west, lifted in the east; rising air and heavy rain in the west, sinking air in the east; Walker Circulation). Retrieved Oct 15 and re-checked Oct 19, 2026. https://www.cpc.ncep.noaa.gov/product... NOAA PSL, MJO primer (the warm pool is generally defined as sea surface temperatures above 28°C; it extends from the Indian Ocean to the central Pacific). Retrieved Oct 15, 2026. https://psl.noaa.gov/mjo/MJOprimer/ NOAA Climate.gov, The Walker circulation: ENSO's atmospheric buddy (trade winds push water to the west side of most ocean basins; "The ocean water warms the entire way"). Retrieved Oct 19, 2026. https://www.climate.gov/news-features... NOAA National Ocean Service: upwelling, thermocline, Gulf Stream and ocean-freezing facts, plus the Currents tutorial on upwelling. Retrieved Oct 19, 2026. https://oceanservice.noaa.gov/facts/u... https://oceanservice.noaa.gov/educati... https://oceanservice.noaa.gov/facts/t... https://oceanservice.noaa.gov/facts/g... https://oceanservice.noaa.gov/facts/o... NASA Earth Observatory, Sea Surface Temperature global maps (year-round equator-to-pole difference is the most obvious pattern). Retrieved Oct 19, 2026. https://science.nasa.gov/earth/earth-... Basemap: Made with Natural Earth, 1:50m land (public domain). https://www.naturalearthdata.com Method: Areas are area-weighted on the 0.25° grid over the world ocean plus the Black and Marmara seas (Caspian Sea and lakes excluded). Warm pool = 1991–2020 mean above 28°C; the main pool is the largest connected patch. Equator = 2°S–2°N. Coast values: annual means in a 1° band from the first ocean cell, ±0.5° latitude. Rain: SST averaged to the 2.5° GPCP grid, ocean cells only; tropical bins 30°S–30°N. Diagrams are schematic. Fahrenheit conversions are ours. Music: none. Fonts: Montserrat and Inter (SIL Open Font License). Narration: AI-generated voice. Maps, animation and analysis: Restless Planet. More Planet Scale videos:    • Planet Scale   More Earth-science map posters: https://www.etsy.com/shop/RestlessPla... #RestlessPlanet #ocean #oceanography #earthscience New maps every Tuesday and Friday. Subscribe:    / @restlessplanetearth