Free · Any US ZIP · From the National Weather Service forecast
Your week outside
Enter a ZIP for tonight’s stargazing score with the reasons behind it, the best night of the week, a frost watch, and a seven-day outlook, all worked out for the forecast that covers that spot.
Forecast data: National Weather Service. Not a safety service. For watches and warnings, see weather.gov.
Never miss the week’s updates!
One Sunday email for your ZIP: the best night to look up and why, any frost in the forecast, and the moon and meteor dates that fall that week.
How the score works
Each night gets a score from 0 to 10. Most of it is cloud cover: the National Weather Service forecast for the hours after full dark, for the forecast cell that holds your ZIP. Then the moon, computed for your location: how much of it is lit and how long it stays above the horizon while the sky is dark. Humid air and a steady wind take a little off. Every score comes with the reasons behind it, so you can weigh them yourself.
The score describes conditions, not how dark your own sky is. Streetlights and the glow of a nearby city are not in it, so a 9 in a downtown backyard and a 9 at a rural overlook are not the same night.
Frost watch
When the National Weather Service forecasts an overnight low of 36°F or below for your forecast cell, that night gets a frost line: frost possible at 36°F, a freeze at 32°F, a hard freeze at 28°F. The low shown is the Service’s own forecast, never an average or a guess of ours.
Official alerts come first
If the National Weather Service has an alert in effect for your area, its title is shown at the top with a link to weather.gov, and our own suggestions are held back for as long as it runs. We do not summarize or interpret alerts. For watches and warnings, weather.gov is the place to look.
The night sky calendar
Add the calendar and every new moon, full moon and major meteor shower peak shows up in your own calendar app, with the dates worked out for your time zone. It updates itself, so there is nothing to download again next year.
Where the numbers come from
- Forecasts and alerts: the National Weather Service, whose data is in the public domain.
- Sunset, darkness and the moon: computed on our side with Astronomy Engine, an open-source astronomy library.
- ZIP locations: U.S. Census Bureau, ZIP Code Tabulation Areas.
- Meteor shower peak dates: the International Meteor Organization’s working list.
What happens to your ZIP
The ZIP you enter is sent to our server to look up the forecast for that area, and is used for nothing else. Forecasts are cached by place, and there is no record of who asked for which one. The calendar link carries your ZIP too, because the calendar is worked out for it. If you sign up for the weekly note, the ZIP you choose is kept with your email address so the note can be written for it, and leaving the note clears it. The privacy page has the rest.