Drought in California, April 1 to 30, 2021

Name: Drought in California, April 1 to 30, 2021
Start: 2021-04-01T00:00
End: 2021-04-30T23:59
Location: California

April 1 to 30, 2021 · NWS STO · 7 events in 7 counties and zones

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 7

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.

What happened

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. Last year's water year, 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 remain in extreme drought. The rest of interior northern California was placed into severe drought (D2) on December 8; however, the state of California has not announced that these locations are in drought.

What forecasters said that day

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 Mar 31, 12:46 PM PST, 11 hours 14 minutes earlier.

Area forecast discussion, Mar 31, 12:46 PM PST, 11 hours 14 minutes before

Area Forecast Discussion
National Weather Service Sacramento CA
146 PM PDT Wed Mar 31 2021

.SYNOPSIS...

Dry conditions with much above-normal temperatures through
Friday. Cooler, but still mild this weekend. Light precipitation
may return early next week.

&&

.DISCUSSION...

Visible satellite imagery is effectively a Ctrl+C, Ctrl+V from
yesterday: sunny skies again dominate the Golden State this
afternoon. You'll have to look very carefully to find any clouds
over land in the State; the only ones we could find were over a
few of the Channel Islands associated with marine stratus.

Surface temperatures are responding to the full-solar across the
region. As of noon PDT, temperatures in Redding are running 10
deg F warmer compared to 24 hours ago, 9 deg F warmer at Red
Bluff, and 3 deg F warmer at Sac Exec Airport. The sunny skies
combined with increasing 500 mb heights and synoptic-scale
subsidence (i.e., sinking air) under a upper level ridge will
allow temperatures to warm to well-above normal values. Highs
today will land in the low/mid 80s across the Valley this
afternoon, or about 12 to 17 deg F above March 31 climatology.

Upper level ridge axis will position itself right over California
tonight and into Thursday, resulting in further day-to-day
warming. European ensemble mean brings 500 mb geopotential heights
to around 5890 meters, or right around climatological maximum at
the nearest Oakland upper-air site. After collaboration with NWS
Bay Area, have nudged high temperatures to around the National
Blend of Models (NBM) 75th percentile, resulting in widespread
middle 80s Valley-wide. Valley locations from Sacramento southward
-- including the Delta region -- will have a run for the upper
80s. An isolated 90 deg F reading is not out of the question. The
latest NBM probabilities of hitting/exceeding 85 deg F include: 68
percent at Sac Exec Airport, 75 percent at Stockton, and 87
percent at Modesto.

With this early season warm spell bringing relatively low heat risk,
it will be a good opportunity to test out air conditioners --
both home and commercial. Always best to find and resolve air
conditioner issues early before the true summer heat arrives.

Temperatures will moderate on Friday as the ridge flattens with
highs ranging from the upper 70s to low 80s for most Valley
communities. Additional cooling will occur over the weekend with
highs within 5 deg F of normal.

Record highs for selected cities in the Sacramento and northern San
Joaquin Valley:

-------------------------------------------------------------------
|            Monthly Record   | Wed       | Thu       | Fri       |
| Site       March            | Mar 31    | Apr 01    | Apr 02    |
-------------------------------------------------------------------
| Redding     93 / 1914-03-17 | 92 / 1966 | 91 / 2002 | 91 / 1961 |
|-----------------------------------------------------------------|
| Red Bluff   92 / 1960-03-23 | 87 / 2011 | 90 / 2002 | 91 / 2000 |
|                             |    / 1966 |           |           |
|-----------------------------------------------------------------|
| Sac Exec    88 / 1988-03-26 | 86 / 1966 | 86 / 1966 | 87 / 1966 |
|-----------------------------------------------------------------|
| Sac         90 / 1988-03-26 | 90 / 1966 | 90 / 1966 | 88 / 2000 |
| Downtown       / 1966-03-31 |           |           |    / 1985 |
|                             |           |           |    / 1966 |
|-----------------------------------------------------------------|
| Stockton    87 / 2007-03-16 | 87 / 1966 | 87 / 1966 | 86 / 2000 |
|                  1988-03-26 |           |           |      1966 |
|                  1966-03-31 |           |           |           |
|-----------------------------------------------------------------|
| Modesto     89 / 1960-03-20 | 86 / 1966 | 88 / 1966 | 87 / 1985 |
-------------------------------------------------------------------

// Rowe

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...

Dry weather expected Sunday as upper ridging moves into the Great
Basin and upstream Pacific storm approaches. Models continue to
differ with handling of this system both in strength and
progression. Given the uncertainty with respect to precipitation
amounts and timing this far out, decided not to differ from the
NBM. One near certainty this far out, though, is that temperatures
will be drastically cooler next week compared to this week. In
fact, many locations will be below their early April normal highs.

&&

.AVIATION...

VFR conditions are forecast to prevail over northern interior
California over the next 24 hours with surface winds generally
at/below 12 kt.

&&

.STO WATCHES/WARNINGS/ADVISORIES...

None.

&&

Event by event

7 drought. Local standard time, as filed.

Drought, Shasta Lake/North Shasta County

When: April 1, 12:00 AM PST to April 30, 11:59 PM PST
Where: Shasta Lake/North Shasta County forecast zone
Reported by: Drought Monitor

For the month of April, the U.S. Drought Monitor kept the majority of zone 13, which covers Shasta County, in extreme drought (D3). They also started mentioning that they expect to see drought impacts expand into the summer, including but not limited too: agriculture, water supplies, recreation, and ecosystems. The California Department of Water Resources decreased the water allocation to 5% on March 26th for the State Water Project.

Drought, Northern Sacramento Valley

When: April 1, 12:00 AM PST to April 30, 11:59 PM PST
Where: Northern Sacramento Valley forecast zone
Reported by: Drought Monitor

For the month of April, the U.S. Drought Monitor kept all of zone 15, portions of Shasta and Tehama counties, into extreme drought (D3).They also noted on this month's call the following impacts for the Sacramento Valley: low groundwater levels, dry stock pond, and poor range-land and pasture conditions. Some ranchers have even stated they've started selling livestock. The Drought Monitor also started mentioning that they expect to see drought impacts expand into the summer, including but not limited too: agriculture, water supplies, recreation, and ecosystems. Additionally, the California Department of Water Resources decreased the water allocation to 5% on March 26th for the State Water Project.

Drought, Central Sacramento Valley

When: April 1, 12:00 AM PST to April 30, 11:59 PM PST
Where: Central Sacramento Valley forecast zone
Reported by: Drought Monitor

For the month of April, the U.S. Drought Monitor put all of zone 16 in extreme drought (D3). They also noted on this month's call the following impacts for the Sacramento Valley: low groundwater levels, dry stock pond, and poor range-land and pasture conditions. Some ranchers have even stated they've started selling livestock. The Drought Monitor also started mentioning that they expect to see drought impacts expand into the summer, including but not limited too: agriculture, water supplies, recreation, and ecosystems. Additionally, the California Department of Water Resources decreased the water allocation to 5% on March 26th for the State Water Project.

Drought, Southern Sacramento Valley

When: April 1, 12:00 AM PST to April 30, 11:59 PM PST
Where: Southern Sacramento Valley forecast zone
Reported by: Drought Monitor

For the month of April, the U.S. Drought Monitor kept all of Yolo, Solano, and Sutter counties, and portions of Sacramento County in extreme drought (D3). They also noted on this month's call the following impacts for the Sacramento Valley: low groundwater levels, dry stock pond, and poor range-land and pasture conditions. Some ranchers have even stated they've started selling livestock. The Drought Monitor also started mentioning that they expect to see drought impacts expand into the summer, including but not limited too: agriculture, water supplies, recreation, and ecosystems. Additionally, the California Department of Water Resources decreased the water allocation to 5% on March 26th for the State Water Project.

Drought, Carquinez Strait and Delta

When: April 1, 12:00 AM PST to April 30, 11:59 PM PST
Where: Carquinez Strait and Delta forecast zone
Reported by: Drought Monitor

For the month of April, the U.S. Drought Monitor put all of zone 18 in extreme drought (D3). They also noted on this month's call the following impacts for the Sacramento Valley: low groundwater levels, dry stock pond, and poor range-land and pasture conditions. Some ranchers have even stated they've started selling or moving livestock. The Drought Monitor also started mentioning that they expect to see drought impacts expand into the summer, including but not limited too: agriculture, water supplies, recreation, and ecosystems. Additionally, the California Department of Water Resources decreased the water allocation to 5% on March 26th for the State Water Project.

Drought, Northern San Joaquin Valley

When: April 1, 12:00 AM PST to April 30, 11:59 PM PST
Where: Northern San Joaquin Valley forecast zone
Reported by: Drought Monitor

For the month of April, the U.S. Drought Monitor put part of San Joaquin County in extreme drought (D3). They also noted on this month's call the following impacts for the Sacramento Valley: low groundwater levels, dry stock pond, and poor range-land and pasture conditions. The Drought Monitor also started mentioning that they expect to see drought impacts expand into the summer, including but not limited too: agriculture, water supplies, recreation, and ecosystems. Additionally, the California Department of Water Resources decreased the water allocation to 5% on March 26th for the State Water Project.

Drought, Mountains Southwestern Shasta County to Western Colusa County

When: April 1, 12:00 AM PST to April 30, 11:59 PM PST
Where: Mountains Southwestern Shasta County to Western Colusa County forecast zone
Reported by: Drought Monitor

For the month of April, the U.S. Drought Monitor kept all of zone 63, which covers western Tehama, Glenn, and Colusa counties in extreme drought (D3). They also noted on this month's call the following impacts for the Sacramento Valley: low groundwater levels, dry stock pond, and poor range-land and pasture conditions. Some ranchers have even stated they've started selling livestock. The Drought Monitor also started mentioning that they expect to see drought impacts expand into the summer, including but not limited too: agriculture, water supplies, recreation, and ecosystems. Additionally, the California Department of Water Resources decreased the water allocation to 5% on March 26th for the State Water Project.

What these are

Drought: A drought reaching severe (D2) or worse on the US Drought Monitor, or with notable impacts.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in California in 2021 Every state in 2021 This day in weather history Warnings in California, April 2021

Sources

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: 955157, 955158, 955160, 955161, 955162, 955163, 955164.