Weather Temperature Converter: Celsius and Fahrenheit
Reading a forecast from another country? Convert any weather temperature between Celsius and Fahrenheit, then see what that temperature feels like and what to wear. Press ⇄ Swap units to go the other way.
Results and worked steps are rounded to at most 2 decimal places; calculations and unit swaps use unrounded values. How calculations work.
Weather temperature bands and what to wear
The bands below are a practical guide for still air and moderate humidity. Wind, sun, rain and humidity can shift how a temperature feels by several degrees, and people who are used to a climate feel it differently, so treat these as a starting point.
| Band | Celsius | Fahrenheit | What to wear |
|---|---|---|---|
| Freezing | below 0 °C | below 32 °F | Heavy coat, hat, gloves and scarf; waterproof boots with grip for ice |
| Cold | 0 °C to 10 °C | 32 °F to 50 °F | Warm coat over layers; a hat and gloves on windy days |
| Cool | 10 °C to 15 °C | 50 °F to 59 °F | Light jacket or sweater; long trousers |
| Mild | 15 °C to 20 °C | 59 °F to 68 °F | Long sleeves or a light layer to add in the evening |
| Warm | 20 °C to 25 °C | 68 °F to 77 °F | T-shirt, light trousers, skirt or shorts |
| Hot | 25 °C to 35 °C | 77 °F to 95 °F | Loose, light-coloured breathable clothes, sunglasses, a hat and water |
| Extreme heat | 35 °C and above | 95 °F and above | Very light loose clothing; stay in the shade, avoid midday exertion, drink regularly |
Two quick anchors help when switching between scales. 0 °C is 32 °F, the freezing point, and the moment to watch for ice. 20 °C is 68 °F, a pleasant mild day. Each 5 °C step on a Celsius forecast is exactly 9 °F.
Common forecast temperatures
Use these tables to translate a forecast quickly. The first runs through Celsius forecasts in 5° steps; the second covers the round Fahrenheit numbers common in US weather reports.
| Forecast (°C) | Forecast (°F) |
|---|---|
| −10 °C | 14 °F |
| −5 °C | 23 °F |
| 0 °C | 32 °F |
| 5 °C | 41 °F |
| 10 °C | 50 °F |
| 15 °C | 59 °F |
| 20 °C | 68 °F |
| 25 °C | 77 °F |
| 30 °C | 86 °F |
| 35 °C | 95 °F |
| 40 °C | 104 °F |
| 45 °C | 113 °F |
| Forecast (°F) | Forecast (°C) |
|---|---|
| 0 °F | −17.78 °C |
| 10 °F | −12.22 °C |
| 20 °F | −6.67 °C |
| 30 °F | −1.11 °C |
| 40 °F | 4.44 °C |
| 50 °F | 10 °C |
| 60 °F | 15.56 °C |
| 70 °F | 21.11 °C |
| 80 °F | 26.67 °C |
| 90 °F | 32.22 °C |
| 100 °F | 37.78 °C |
| 110 °F | 43.33 °C |
Need a value that is not listed? Type it into the converter above, or use the Celsius to Fahrenheit chart and the Fahrenheit to Celsius chart, both of which you can print.
Feels-like temperatures: wind chill and heat index
Many forecasts show a second “feels like” number. It is not a different air temperature; it estimates how cold or hot conditions feel on exposed skin.
Wind chill
Wind carries heat away from the body faster, so cold air feels colder when it is windy. The US National Weather Service (NWS) wind-chill formula (PDF) uses the following expression, with temperature T in °F and wind speed V in mph:
Wind chill = 35.74 + 0.6215T − 35.75V0.16 + 0.4275TV0.16
It is defined only for air temperatures of 50 °F (10 °C) or below and wind speeds of 3 mph or more. For example, 30 °F air with a 20 mph wind feels like 17 °F. At very low wind chill values, exposed skin can get frostbite in under 30 minutes. In the table, wind speeds of 10, 20 and 30 mph are about 16, 32 and 48 km/h.
| Air temp | Wind 10 mph | Wind 20 mph | Wind 30 mph |
|---|---|---|---|
| 40 °F / 4 °C | 34 °F / 1 °C | 30 °F / −1 °C | 28 °F / −2 °C |
| 30 °F / −1 °C | 21 °F / −6 °C | 17 °F / −8 °C | 15 °F / −9 °C |
| 20 °F / −7 °C | 9 °F / −13 °C | 4 °F / −16 °C | 1 °F / −17 °C |
| 10 °F / −12 °C | −4 °F / −20 °C | −9 °F / −23 °C | −12 °F / −24 °C |
| 0 °F / −18 °C | −16 °F / −27 °C | −22 °F / −30 °C | −26 °F / −32 °C |
| −10 °F / −23 °C | −28 °F / −33 °C | −35 °F / −37 °C | −39 °F / −39 °C |
Heat index
In hot weather, humidity slows the evaporation of sweat, so the body cools less efficiently and the air feels hotter. The NWS heat index combines air temperature and relative humidity using a published NWS regression equation (PDF); NWS heat-index guidance specifies shade and light wind; direct sunshine can increase the apparent temperature. At 90 °F (32 °C) and 60% humidity, the heat index is about 100 °F.
| Air temp | Humidity 40% | Humidity 60% | Humidity 80% |
|---|---|---|---|
| 80 °F / 27 °C | 80 °F / 27 °C | 82 °F / 28 °C | 84 °F / 29 °C |
| 85 °F / 29 °C | 84 °F / 29 °C | 89 °F / 32 °C | 97 °F / 36 °C |
| 90 °F / 32 °C | 91 °F / 33 °C | 100 °F / 38 °C | 113 °F / 45 °C |
| 95 °F / 35 °C | 99 °F / 37 °C | 113 °F / 45 °C | 134 °F / 57 °C |
| 100 °F / 38 °C | 109 °F / 43 °C | 129 °F / 54 °C | 158 °F / 70 °C |
Wind-chill cells use the published NWS wind-chill formula. Heat-index cells use the published NWS regression equation; operational weather products may apply additional adjustments. Results are rounded to whole degrees, and Celsius values convert those rounded figures. Follow official local heat and cold warnings.
Sources and calculation notes
Source links checked on .
- NWS: wind-chill calculation (PDF) — formula and required Fahrenheit/mph units.
- NWS: wind-chill questions and cold safety — effects of wind chill and cold-exposure risks.
- NWS: heat-index calculation (PDF) — regression equation using Fahrenheit and relative humidity.
- NWS: heat forecast tools — shade/light-wind assumptions and limits of heat-index guidance.
The tables are rounded reference examples, not a live forecast. Clothing suggestions are general comfort tips; use official local warnings for safety decisions.
Why the same number feels different
A thermometer measures the air, but your body reacts to the whole environment. Bright sun can make a 15 °C (59 °F) afternoon feel pleasantly warm, while the same temperature under cloud with a breeze feels chilly. Dry heat is easier to tolerate than humid heat because sweat evaporates faster. Altitude, clothing, activity and what you are used to all play a part, so locals and visitors often dress very differently for the same forecast.
Tips for travellers
- Most countries forecast in Celsius; the United States and a few others use Fahrenheit. Phone weather apps can usually switch units in their settings.
- A summer “high of 30” means hot weather in Celsius (86 °F), but a cold day in Fahrenheit (−1.11 °C). Always check the unit.
- Indoors, a comfortable room is about 20–22 °C, or 68–71.6 °F.
- For a rough conversion on the go, double the Celsius number and add 30. The formula guide shows how accurate that is.
Frequently asked questions
What is a comfortable outdoor temperature in Celsius and Fahrenheit?
Most people find about 18–24 °C (64.4–75.2 °F) comfortable outdoors in still air, though humidity, sun and wind all make a difference.
Is 25 °C hot?
25 °C is 77 °F: a warm day, ideal for T-shirts. Above about 30 °C (86 °F) most people call it hot.
What is 0 °C in Fahrenheit?
0 °C is 32 °F, the freezing point of water. Roads and paths can be icy around this temperature.
What does “feels like” mean in a forecast?
It is an estimate of how the air feels on exposed skin. In cold weather it usually reflects wind chill, and in hot weather the heat index, which accounts for humidity.
How is wind chill calculated?
The NWS formula is 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16, with T in °F and wind speed V in mph. It applies at 50 °F or below with wind of at least 3 mph.
What should I wear at 10 °C?
10 °C is 50 °F, cool weather. A warm jacket or a sweater with a light coat works for most people.