Methodology

Two independent networks supply air temperature. METAR is the aviation network: airports worldwide, reporting continuously, roughly every 30 to 60 minutes. SYNOP is the national weather service network, reporting at the main synoptic hours of 00, 06, 12 and 18 UTC.

Both are needed, and the reason is specific. METAR is an airport network, and the coldest places on Earth have no airport. Measured on 22 September 2026, the coldest METAR station on the planet was McMurdo at −20.1 °C, with positions three to ten filled by ordinary airports between −3 and −4 °C. SYNOP for the same moment carried Vostok at −70.4 °C. Without SYNOP the cold half of this site would be wrong by roughly 50 degrees while still looking entirely plausible.

Where a station appears in both networks, both readings are kept. That is useful rather than redundant: it gives two independent measurements of the same place in two different formats, which is one of the ways a reading gets confirmed.

A reading cannot be shown, ranked or recorded unless it passes every rule:

• Not older than its network allows: 2 hours for METAR, 9 hours for SYNOP.
• Within the absolute range of -95 to 56.8 °C. The upper figure sits just above the highest reading the WMO accepts, so a genuine new world record would be set aside here as well: a record needs adjudicating, not a live tile.
• Not more than 15 °C different from the same station an hour earlier. That limit comes from measured data rather than judgement: real weather reaches about 12 °C in an hour at desert sunrise or under a thunderstorm outflow, and the sensor faults found in our own readings were 20 °C and more.
• Not more than 12 °C from the median of stations within 150 km, when at least 3 such stations exist.
• Has a real position. These feeds use placeholder coordinates for unknown locations, and a reading with no location is discarded rather than placed in the ocean.
• Not manually suppressed.

The staleness rule differs by network because their cadences differ. A single 2 hour rule applied to SYNOP would discard the entire network, including every Antarctic station. The observation time is shown beside every reading instead, so a six hour old report is visibly a six hour old report.

Passing quality control is not enough to be called the hottest or coldest place on Earth. A headline reading also needs a second, independent signal: either another reading from the same station agreeing within 1.5 °C, or a station within 150 km agreeing within 5 °C.

A reading that passes quality control but has nothing to corroborate it is marked unconfirmed. It stays in the table, because removing it would mean the table no longer shows the most extreme reading we actually have, but it cannot be the headline figure, set a record or be posted. A station reporting for the very first time is always held for one further cycle.

This is why the headline number is sometimes not the number at the top of the table. When that happens the page says so and shows both.

Station readings are air temperature, measured about 1.5 to 2 m above the ground. Satellite readings are land surface temperature, the temperature of the ground itself, which in a daytime desert runs far hotter than the air above it.

These are different quantities. They are shown together, because that is what readers want, but they are never ranked against each other, never combined into one list and never share a record. Satellite values are pinned above the table without a rank number and always carry a ground label.

Some otherwise useful sources are excluded on licence or terms. They are listed so the decision is visible rather than implied.

• Open-Meteo free APITerms permit the free API for non-commercial purposes only and name ad-supported sites as commercial. This site carries ads.
• JAXA Himawari Monitor (P-Tree)Non-commercial terms and redistribution prohibited.
• Ogimetrobots.txt is "User-agent: * / Disallow: /", a blanket ban on automated fetching.
• Crowd-sourced personal weather stationsRooftop and sun-exposed siting produces false extremes.
• MODIS Terra and Aqua, live useTerra and Aqua have drifted from their original orbits and NASA is transitioning to VIIRS. Historical context only.

• NOAA Aviation Weather Center (US Government work, public domain)
• NOAA National Weather Service, and the reporting national meteorological services (US Government work, public domain)
• WMO WIS2, and the reporting national meteorological services (WMO Unified Data Policy core data, free and unrestricted, attribution requested)
• NASA LANCE VIIRS (NASA, public domain)
• NOAA GOES-R (US Government work, public domain)
• NOAA NCEI GHCN-Daily (US Government work, public domain)
• NOAA NCEI Global Summary of the Day (US Government work, public domain)
• NOAA NCEI GHCNh (CC0-1.0 public domain dedication)
• Source: Meteostat and its data providers (CC BY 4.0, commercial use permitted)
• NOAA NCEI OISST v2.1 (US Government work, public domain)