Northern Lights in California: Tonight's Aurora Forecast

Check the live panel on this page: it compares tonight's NOAA forecast Kp with the Kp 8 that California's darkest northern areas need, then folds in tonight's cloud cover and the moon. As a rule, a forecast Kp of 8 or higher with under 40% cloud and a dark northern horizon is worth going out for; below Kp 7 it is not.

About Kp 8 for a display low on the northern horizon from California's darkest northern spots, and roughly Kp 9 for it to climb overhead. California sits near 43° geomagnetic latitude; every ~2° further south adds about one Kp step to what you need.

Lava Beds National Monument; Lassen Volcanic National Park; Lake Siskiyou, Mount Shasta. Far northeast corner near Tule Lake — high desert within 20 miles of the Oregon line, and about as dark as California gets. The common thread is a dark, unobstructed view to the north — a lakeshore, open prairie, or a summit — well away from city glow.

September, October, March, April. Geomagnetic storms cluster around the equinoxes (the Russell–McPherron effect), and the autumn and spring windows combine that with long, dark nights. Outside those windows, any G3+ storm forecast is worth watching regardless of month.

Usually between 10 pm and 2 am local time, with the most intense substorms often near local magnetic midnight (roughly 11 pm–1 am). Give your eyes 15–20 minutes to adapt, and stay out — displays come in waves separated by quiet half-hours.

At California's latitude the aurora is usually faint and low, and the eye's night vision cannot see color in dim light. A phone in night mode or a camera with a 5–15 second exposure collects far more light and shows the true green (oxygen at ~100 km) and red (oxygen higher up). If you can see a pale, moving arc that is not a cloud, photograph it.

Use night mode (iPhone) or Night Sight / Pro mode (Android), set exposure to 3–10 seconds, brace the phone on something or use a small tripod, turn the flash off, and point at the darkest part of the northern sky. Tap to focus on a distant light or a star first. Shoot wide and keep shooting — the best frames come during brightenings that last only a minute or two.

Rarely — a few times per solar cycle, and only in a severe storm. The most recent one to put aurora over much of the lower 48 was 10–11 May 2024, which NOAA rated G5 (extreme) — the top of its scale. Solar cycle 25 is still active, so another G4–G5 storm is plausible; treat any sighting from California as exceptional.