Forecast, each 12 hours
Thunder
For
The chance of a thunderstorm in each 12 hours for seven days: where storms are likely, before any radar sees them.
080%
Forecast map / Forecast, hour by hour
Forecast sky cover map
Over Glenaire, Missouri, where the map opens. The whole country
How much of the sky cloud will cover, hour by hour: clear sky is the map itself, the brighter the thicker the cloud. How to read it.
The rings are the storms the radars detect, the larger ring a severe one; each line runs to where its storm will be in an hour if it keeps its present speed and heading. Rotation and hail are what the radars detect and the analysis measures, not warnings: the official watches and warnings in force are drawn on the map in their own colours and set out in full under Alerts.
What the sky cover map shows
How much of the sky cloud will cover, in percent, hour by hour. Clear sky is the map itself; the thicker the cloud, the brighter it is drawn. Played, the cloud decks drift across the country.
How to read it
- 0 to 10%
- Clear.
- 10 to 30%
- Mostly clear.
- 30 to 60%
- Partly cloudy.
- 60 to 90%
- Mostly cloudy.
- Over 90%
- Overcast.
What it is for
- Find a clear night for the stars, a meteor shower or an eclipse.
- See where the sun will warm the day, and where cloud will hold it back.
- Plan solar power and photography by the hour.
How it is made
The forecast maps are drawn from the national blend of the forecast models: the models joined into one forecast and corrected against what each place has measured, on a grid 1.6 miles across, the forecast the country’s forecasters start from. Each of its main runs, four a day, is read whole, laid onto the same grid of latitude and longitude as the radar at 2.8 miles a cell, and played forward from now.
A frame every 3 hours to 3 days, then every 6 hours to 7 days, played from now as a loop of 1 to 7 days. As data: /radar/now.json?show=fsky, the times of its frames.
In the Field Book
- Cloud classificationFB-SKY-001
Over a state
AlabamaAlaskaArizonaArkansasCaliforniaColoradoConnecticutDelawareDistrict of ColumbiaFloridaGeorgiaHawaiiIdahoIllinoisIndianaIowaKansasKentuckyLouisianaMaineMarylandMassachusettsMichiganMinnesotaMississippiMissouriMontanaNebraskaNevadaNew HampshireNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaOhioOklahomaOregonPennsylvaniaRhode IslandSouth CarolinaSouth DakotaTennesseeTexasUtahVermontVirginiaWashingtonWest VirginiaWisconsinWyoming
With it
Severe AlertsWeather by stateForecast accuracyInstrument atlas
Beside it
Forecast, each 12 hours
Chance of rain
For
The chance of rain or snow in each 12 hours, day and night, for seven days: when to expect it, and how surely.
0100%
Forecast, hour by hour
Temperature
For
The temperature ahead across the lower 48, Alaska, Hawaii and Puerto Rico, hour by hour, for seven days: warm and cold air on the move.
-20110 F