Frizz forecast: will my curls frizz today?
Humidity is the wrong number. Curls react to the dew point. Type your city and see today’s frizz risk, the next three days, and what to use.
No city? Work it out from temperature and humidity
Why dew point, not humidity
Relative humidity depends on temperature. 60% on a cold morning and 60% on a hot afternoon are very different amounts of water in the air. The dew point measures the water itself, so it is the number your curls actually respond to.
| Dew point | What curls do | What to use |
|---|---|---|
| Below −1°C (30°F) | Air pulls water out of the hair. Dry, static frizz | Creams and oils, little or no glycerin |
| −1 to 4°C (30 to 40°F) | A little dry | Moisturising leave-in, humectants low on the list |
| 4 to 15°C (40 to 60°F) | The sweet spot | Anything. Humectants help |
| 15 to 21°C (60 to 70°F) | Water swells the strand. Frizz starts | Strong-hold gel, film formers, seal with oil |
| Above 21°C (70°F) | Big frizz and lost definition | Strong gel, no glycerin, or a protective style |
How the forecast works
It looks up your city with Open-Meteo, a free open weather service, and checks the dew point for every hour of today. Your style has to survive the whole day, so the rating uses whichever hour is furthest from comfortable, not just the reading right now. Your porosity changes the advice, because high-porosity hair swells most in humid air and loses water fastest in dry air.
Read next
- How to stop frizzy curly hair: the 7 causes, ranked by how often they’re the problem
- How to refresh curls on day 2, 3 and 4 (without re-washing)
- Why does my curly hair look great one day and terrible the next?
Questions people ask
What dew point is best for curly hair?
Roughly 4 to 15°C (40 to 60°F). In that range humectants work well, and curls hold their shape without swelling or drying out.
Why does my hair frizz when it is humid?
Hair absorbs water from humid air. The water swells the strand unevenly, which breaks up curl clumps and lifts the cuticle. A strong-hold gel or a film-forming styler slows the water down.
Should I avoid glycerin in winter?
When the dew point is below about −1°C (30°F), yes. Glycerin pulls water from wherever there is more of it, and in very dry air that is your hair.
How is the frizz risk number calculated?
It is how far the day’s most extreme dew point is from a comfortable 10°C (50°F), scaled from 0 to 100. Higher means more frizz from either humidity or dryness.