Thermometer Emoji

A red-tipped glass thermometer tilted on its side, with mercury risen partway up the scale. 🌡️ is Unicode's official icon for temperature itself: the number, the reading, the fact that something is hot or cold. It doesn't carry an emotion the way 🥵 or 🥶 do. It's the measuring instrument, not the feeling.

That neutrality is why 🌡️ has two lives. Half the time it's a weather post ("103°F by Thursday 🌡️"), and half the time it's a health update ("kid's at 102, canceling 🌡️"). Both uses trace back to the same object, just pointed at different surfaces. The Unicode Consortium files it under the "weather-ti" subcategory (weather indicators), but real-world usage splits cleanly down the middle, and platforms like Apple render it with a medical-looking bulb rather than an outdoor air thermometer.

One quiet irony: the emoji shows a mercury thermometer, even though mercury medical thermometers have been banned or phased out across most of the world under the Minamata Convention on Mercury since 2013. The WHO called for the phase-out by 2020. The icon is a museum piece that nobody notices is a museum piece.

On Twitter/X, 🌡️ spikes hard during heatwaves. When a city breaks a record, it shows up next to the number: "Phoenix just hit 117°F 🌡️." Phoenix in 2023 logged 14 straight days at or above 110°F, the third-longest such streak on record, and 🌡️ rode every one of them. Same pattern for "feels like -40" posts in January. The emoji is shorthand for "this number is worth posting about."

On Instagram and TikTok, it's more often captioning a fever story or a sick day. "Mom life 🌡️🧸" or "POV: your thermometer reads 101.4 🌡️." Parents use it as a compact way to say I'm not coming in without typing out why. A fever in adults is clinically defined as 100.4°F or higher, and that's roughly the line where people feel justified reaching for the emoji.

There's a third, smaller usage: climate discourse. News accounts and activists pair 🌡️ with 🌎 and 🔥 to signal global warming, and the emoji started showing up regularly in posts about 2024 becoming the hottest year on record. It never became the climate emoji, but it's a reliable supporting cast member when the headline involves a number.

The thermometer emoji came out of the same 2011 Unicode push that added most of today's weather icons. It was included in proposal L2/11-052, the Emoji Ad-Hoc Committee's recommendation for expanded symbol sets, alongside ⛈️, 🌫️, 🌪️, and the rest of the weather group. Unicode approved it as part of Unicode 7.0 in June 2014 and rolled it into Emoji 1.0 in 2015.

The design spec called for a "liquid-in-glass thermometer" at an angle, with red liquid risen from the bulb. Vendors were free to pick the angle and the level of mercury, which is why Apple's sits nearly horizontal while Samsung's and Google's tilt more dramatically. The red liquid is technically not mercury on most modern renders: platforms use red to signal warmth without implying a specific chemical, though the silhouette still echoes the classic mercury-in-glass design that Daniel Gabriel Fahrenheit perfected in 1714.

Thermometer's journey from Galileo's thermoscope (1592) to Santorio's scaled version (1612) to Fahrenheit's mercury bulb (1714) to the emoji version (2014) took roughly 400 years. The icon preserves an object that's been obsolete in hospitals for a decade.

1. 1592Galileo builds the first thermoscope, a thermometer without a scale.
2. 1612Santorio Santorio applies a numbered scale to the thermoscope, inventing the thermometer as we know it.
3. 1714Daniel Gabriel Fahrenheit produces the first accurate mercury-in-glass thermometer. Scale arrives in 1724.
4. 1742Anders Celsius introduces the centigrade scale, fixing freezing and boiling points of water at sea level.
5. 1848William Thomson (Lord Kelvin) proposes the absolute scale that starts at -273.15°C.
6. 2011Unicode's Emoji Ad-Hoc Committee proposes the thermometer in L2/11-052.↗
7. 2014Unicode 7.0 approves U+1F321 THERMOMETER in the Weather Symbols subblock.↗
8. 2015Added to Emoji 1.0; first rendered by Apple on iOS 9.1 and Google on Android 6.0.1.
9. 2020WHO's target date for global phase-out of mercury medical thermometers under the Minamata Convention. Emoji keeps the old design anyway.↗
10. 2020COVID-19 pandemic drives a spike in 🌡️ usage as temperature checks become a daily routine at every airport, office, and school entrance.

• •The thermometer emoji's codepoint is U+1F321, placing it in Unicode's "Miscellaneous Symbols and Pictographs" block, right next to ☁️ cloud variations and ⛈️ thunderstorms.
• •Galileo built a thermoscope in 1592, but he never added a scale, so he invented the device without inventing the measurement. Santorio Santorio's 1612 scaled version is what actually turned it into a thermometer.
• •The world's highest reliably recorded air temperature is 134°F (56.7°C) at Furnace Creek, Death Valley, on July 10, 1913. A 2024 analysis, though, argued it was probably observer error and the real value was closer to 120°F.
• •Fahrenheit chose 100°F as a rough estimate of human body temperature. He was off: the real average is closer to 97.5°F based on modern data, and 98.6°F comes from an 1851 German study that used different thermometers and measurement sites.
• •2024 was the hottest year on record, beating 2023, which had beaten every prior year. The thermometer emoji has gotten measurably more relevant each year since its 2014 release.
• •The Minamata Convention, signed in 2013 and named after the Japanese city where thousands were poisoned by industrial mercury dumping, targeted the end of mercury thermometers by 2020. The emoji still depicts one.
• •China banned the manufacture of mercury thermometers starting in 2026, triggering a buying rush from traditionalists who preferred them to digital.
• •Thermometer is filed under Unicode's "weather-ti" subcategory, alongside 🌬️ wind face and 🌀 cyclone, not under medical icons. The health association is purely emergent from how people use it.