THE WEATHER BEAT · OCT 23

Five years ago this week, the Sierra took 10.4 inches of rain in a day at Blue Canyon, one of 25 wettest-day records

On October 24, 2021, 25 gauges from the Bay Area to the Sierra and Nevada recorded their wettest day, led by Blue Canyon at 10.4 inches.

By the Weather Rock October 23, 2026, 10:04 a.m. · 7 min read

GOES satellite view of the event region — Afternoon satellite view of northern California and western Nevada on October 22, 2026, the region where 25 gauges recorded their wettest day on October 24, 2021. Image: NOAA GOES-West GeoColor via NASA GIBS, 2026-10-22 21:00Z.

Key points

Five years ago tomorrow, on October 24, 2021, 25 gauges in northern California and Nevada each recorded their wettest day in our NOAA station archive. The top reading was Blue Canyon in the Sierra, at 10.4 inches.
Santa Rosa measured 7.8 inches and Angwin 7.6 inches. Mt Rose Ski Area above Incline Village, Nevada, measured 7.3 inches, and Sacramento's two airport gauges each measured 5.4 inches.
Every figure here comes from our archive of NOAA daily station records. We do not name a weather system or describe any damage, because the archive records neither.

Five years ago this week, the Blue Canyon gauge in the Sierra Nevada east of Alta, California, caught 10.4 inches of rain in a single day. That was October 24, 2021, and it is the wettest day in the record we keep for that gauge.

Blue Canyon was one of 25 gauges that each set their own wettest day on that date. In the North Bay, Santa Rosa measured 7.8 inches, the Pacific Union College gauge at Angwin measured 7.6 inches and Muir Woods near Mill Valley measured 7.1 inches. Fairfield, Petaluma, Ukiah and the Napa County airport gauge near American Canyon measured between 4.8 and 6.1 inches. Across the Bay, Upper San Leandro Filters near Moraga measured 5.5 inches, Concord's Buchanan Field 4.5 inches and Livermore 3.6 inches.

In the Sacramento Valley, the Sacramento 5 ESE gauge measured 5.4 inches, the Sacramento airport ASOS also measured 5.4 inches and Sacramento Metro measured 4.1 inches. Oroville measured 4.6 inches.

The readings around Lake Tahoe were also high. Mt Rose Ski Area measured 7.3 inches, Tahoe City Cross 7.2, Rubicon near Tahoma 6.4, Truckee 5.4 and the South Lake Tahoe airport 4.9. South of the lake, Poison Flat near Coleville measured 6.1 inches and Carson Pass near Kirkwood 6.0. On the Nevada side, Big Meadow near Mogul measured 5.0 inches and the Reno weather office gauge 1.9 inches. Farther northeast, the Lamance Creek gauge near Paradise Valley, Nevada, measured 4.1 inches.

The gauges stretch from the coast at Muir Woods to the high desert north of Winnemucca. Our archive records how much rain fell and where it was measured, and nothing more. It does not say what brought the rain or what the water did, so this story does not either.

Date	Town	Gauge	Wettest day
Oct 24, 2021	Alta CA	Blue Canyon Nyack Ap	10.4 in
Oct 24, 2021	Santa Rosa CA	Santa Rosa	7.8 in
Oct 24, 2021	Angwin CA	Angwin Pacific Union College	7.6 in
Oct 24, 2021	Incline Village NV	Mt Rose Ski Area	7.3 in
Oct 24, 2021	Sunnyside-Tahoe City CA	Tahoe City Cross	7.2 in
Oct 24, 2021	Mill Valley CA	Muir Woods	7.1 in
Oct 24, 2021	Tahoma CA	Rubicon	6.4 in
Oct 24, 2021	Coleville CA	Poison Flat	6.1 in
Oct 24, 2021	Fairfield CA	Fairfield	6.1 in
Oct 24, 2021	Kirkwood CA	Carson Pass	6.0 in
Oct 24, 2021	Moraga CA	Upper San Leandro Filters	5.5 in
Oct 24, 2021	Sacramento CA	Sacramento 5 ESE	5.4 in
Oct 24, 2021	West Sacramento CA	Sacramento Ap ASOS	5.4 in
Oct 24, 2021	Truckee CA	Truckee	5.4 in
Oct 24, 2021	Petaluma CA	Petaluma Ap	5.2 in
Oct 24, 2021	Mogul NV	Big Meadow	5.0 in
Oct 24, 2021	Ukiah CA	Ukiah Muni Ap	5.0 in
Oct 24, 2021	South Lake Tahoe CA	S Lake Tahoe Ap	4.9 in
Oct 24, 2021	American Canyon CA	Napa Co Ap	4.8 in
Oct 24, 2021	Oroville CA	Oroville Muni Ap	4.6 in
Oct 24, 2021	Concord CA	Concord Buchanan Fld	4.5 in
Oct 24, 2021	Rio Linda CA	Sacramento Metro Ap	4.1 in
Oct 24, 2021	Paradise Valley NV	Lamance Creek	4.1 in
Oct 24, 2021	Pleasanton CA	Livermore Muni Ap	3.6 in
Oct 24, 2021	Reno NV	Reno WFO	1.9 in

*Source: myweatherrock's archive of NOAA daily station records (GHCN-Daily). Each gauge's station ID is listed in this story's source record.*

The Reno gauge's 1.9 inches is the smallest number in the table, and it is still the wettest day that gauge has on record with us. Looking at the table, which do you think tells you more about that day: the biggest number, or the smallest?

This is a look back at a historic weather day, not emergency information. For current conditions and warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story