Northern California typically experiences a wet season, October through May, and a dry season May through September. This water year, starting October 2019 through September 2020, was one of the driest on records.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS STO wrote it up.
Northern California typically experiences a wet season, October through May, and a dry season May through September. This water year, starting October 2019 through September 2020, was one of the driest on records. This likely contributed to the U.S. Drought Monitor's decision to place portions of interior northern California into extreme drought on September 29, 2020. Portions of Shasta, Tehama, Butte, Glenn, Colusa, Yolo, Solano, Yuba, Nevada, and Sacramento counties were placed extreme drought; however, the state of California has not announced that these locations are in drought.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Sacramento, CA wrote its last area forecast discussion before the first event at Sep 29, 2:20 AM PST, 1 hour 40 minutes earlier.
Area Forecast Discussion National Weather Service Sacramento CA 320 AM PDT Tue Sep 29 2020 .SYNOPSIS... Above normal temperatures and very dry conditions will continue through much of the week. Areas of wildfire smoke will drift over interior Norcal for the next couple of days. && .DISCUSSION... A strong and highly amplified 2+ height anomaly ridge with a 5 to 10 year return interval will remain stationary over the W coastal states into Old Mexico through the short-term forecast period. This will result in well above normal temps with max temps some 10 to 18 degrees above normal and widespread areas of moderate heat risk for this time of year. In fact, the Solano Co area may encounter high heat risk Wed/Thu as winds turn down valley and adiabatic warming effects from the Vaca Mtns result in the potential for triple digit temps there, and in the Nrn Sac Vly in the afternoons. The strong ridge and periods of downslope winds will result in a dry air mass, but fortunately the Ely winds will weakening today with relatively a light wind regime through the rest of the forecast period. Humidity recovery will remain poor to moderate over the higher terrain due to a strong subsidence inversion. Experimental smoke forecast indicates the areal coverage of smoke from area wildfires will spread over most of the CWA during the next couple of days. Not only will this suppress max temps in the areas of dense smoke, it will also negatively impact air quality generally over the coastal range and into the Valley over the next day or two. As the Ely gradients weaken, upslope flow may transport some smoke over the W Slope Sierra at times as well. JHM && .EXTENDED DISCUSSION (Saturday THROUGH Tuesday)... Upper ridging over the area Saturday, weakens and shifts into the Great Basin Sunday as upper low approaches California then lingers along the coast early next week. This will result in dry weather with a minor cooling trend. High temperatures remain slightly above normal, but could locally be impacted by smoke from wild fires. && .AVIATION... VFR conds ovr intr NorCal exc lcl MVFR conds poss in HZ/FU vcnty of wild fires. Lcl ely sfc wnd gsts up to 30 kts poss in ern fthls til abt 18z. Swly sfc wnd gsts to 20 kts poss vcnty of Delta aft 00z, otrw sfc wnd genly blo 12 kts nxt 24 hrs. && .STO WATCHES/WARNINGS/ADVISORIES... None. &&
5 drought. Local standard time, as filed.
On September 29, the U.S. Drought Monitor placed the western most side of Shasta County in extreme drought (D3).
On September 29, the U.S. Drought Monitor placed most of Tehama County in extreme drought (D3).
On September 29, the U.S. Drought Monitor placed most of Glenn and Colusa, and Sutter counties along with the western portions of Butte and Yuba counties in extreme drought (D3).
On September 29, the U.S. Drought Monitor placed all of zone 63, which covers western Tehama, Glenn, and Colusa counties in extreme drought (D3).
On September 29, the U.S. Drought Monitor placed all of Yolo County, and portions of Sacramento, Sutter, Solano counties in extreme drought (D3).
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2020Every state in 2020This day in weather historyWarnings in California, September 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 922628, 922629, 922630, 922631, 922632.