Clear skies over Napa, CA tonight

Napa ranks 142nd out of 500 US cities for night-sky darkness, with a darkness index of 79 out of 100. That estimate comes from the population of every community within 150 km, weighted by distance — so what matters is the glow of the whole metro area, not just the city's own size.

That is middling — the brighter constellations and planets come through, but the Milky Way stays faint from inside town. A 30–60 minute drive away from the glow changes what you can see dramatically.

Head away from major roads and shopping districts, and give your eyes about 20 minutes to fully adapt to the dark — most of what people call "bad seeing" is really just eyes that never adjusted.

Light pollution is the part that does not change night to night. Cloud cover and moonlight do, which is what the forecast above tracks.