Can I see the northern lights tonight in Denver?
Unlikely tonight.
NOAA's forecast peaks at Kp 3 during Denver's dark hours tonight (6:00 pm to 5:40 am), strongest from about 11:00 pm. From Denver the aurora usually needs about Kp 7 to show low on the northern horizon and Kp 9 to be overhead. The Moon is 16% lit and up for 23% of the dark hours.
The next three nights
Peak Kp 3 in the dark, 6:00 pm–5:40 am. Moon 16% lit.
Peak Kp 2.33 in the dark, 6:00 pm–5:40 am. Moon 9% lit.
Peak Kp 5 (G1) in the dark, 6:00 pm–5:40 am. Moon 4% lit.
Kp forecast for Denver
NOAA planetary K-index: the past day observed, the next three days forecast, in Denver local time. Lines: the Kp at which the aurora usually reaches Denver's northern horizon, and overhead. The peak value is NOAA's estimated Kp for the 3-hour block starting 11:00 pm.
It is dark in Denver now. Little aurora activity near you right now.
Seeing the aurora from Denver
Denver is at 39.7°N, which is magnetic latitude 48.1°: the aurora follows the magnetic pole, not the geographic one, which is why it reaches further south over North America than over Europe. In a quiet night the auroral oval stays far to the north. When a solar storm arrives the oval widens and slides south; at about Kp 7 it usually reaches low over Denver's northern horizon, and at Kp 9 it can be overhead.
Kp forecasts more than a day ahead are uncertain: the timing and strength of a solar storm are often only clear an hour or so before it hits, when it passes the spacecraft upstream of Earth. So a "possible" night can fizzle, and a quiet forecast can surprise. This page updates every 30 minutes. The full week's aurora forecast · What the Kp index means.
Questions
Can I see the northern lights tonight in Denver?
Unlikely. NOAA's forecast peaks at Kp 3 during Denver's dark hours tonight (6:00 pm to 5:40 am), strongest from about 11:00 pm. From Denver the aurora usually needs about Kp 7 to show low on the northern horizon and Kp 9 to be overhead. The Moon is 16% lit and up for 23% of the dark hours. You also need clear skies to the north, which we do not forecast.
What Kp do you need to see the northern lights in Denver?
About Kp 7 to see the aurora low on the northern horizon, and Kp 9 for it to be overhead. Denver is at magnetic latitude 48.1°; the southern edge of the auroral oval sits near 66.5° at Kp 0 and moves about 2° south per Kp step.
What time is best to see the aurora?
Usually within a couple of hours of midnight local time, when your part of the Earth faces the night side of the auroral oval. During a storm it can show any time it is dark, so watch the live Kp and go out when it jumps.
Where should I look?
North. From Denver the aurora usually appears as a green or grey glow low over the northern horizon, rising higher only in strong storms. Get away from street lights and let your eyes adjust for 15 minutes. A phone camera on night mode often shows colour the eye cannot.
Northern lights nearby
All of Colorado →Also over Denver
Data: NOAA Space Weather Prediction Center (planetary K-index forecast, 3-day forecast, 27-day outlook, OVATION aurora model). Magnetic latitudes: AACGM-v2. Darkness and Moon computed with Skyfield and JPL DE440. We do not forecast clouds: you need a clear view to the north. How the verdict is made.