Current Drought Conditions 

A lack of precipitation and snow, which persisted from the start of this water year 

through the end of February, drove the development and expansion of drought in 

southern California. According to the U.S. Drought Monitor, moderate to extreme 

(D1-D3) drought expanded in southern California in February while dry conditions 

remained in Northern California and Nevada. By early March, extreme drought 

(D3) drought reached the southern central coast and rangeland conditions had 

begun to deteriorate. Recent March storms have halted this expansion and 

improved drought conditions in California, with the exception of conditions 

worsening in the desert southwest (Fig. 1). As of April 3, 29% of California-Nevada 

was in moderate-extreme drought and 56% was abnormally dry.

CALIFORNIANEVADA 

DROUGHT 

OUTLOOK 

MARCH 2018

National Integrated Drought 

Information System

Drought.gov

Fig 1. U.S. Drought Monitor for April 3. 

Source: droughtmonitor.unl.edu

Regional Climate Update

Winter precipitation leading into March was below 

normal across California-Nevada, with the greatest 

precipitation deficits developing in the south. At the 

end of February, the southern region received <20-

50% of normal water year precipitation to date, while 

the north received 40-85% of normal. Snowpack was 

also low, with snow water equivalents (SWE) in the 

0-69% range over the Sierra Nevadas and eastern 

Nevada ranges, according to the Natural Resources 

Conservation Services (NRCS). Rangeland forage 

conditions were also low in central and southern 

California, where drought strategies were being 

considered along the central coast and ranchers in the 

San Joaquin Valley were feeding hay instead of forage 

in March. 

March brought several storms, including atmospheric 

rivers, to the region with the most notable event 

occurring on or around March 20-22. Precipitation 

for the month was above normal across much of 

the region, especially over the Sierras. Combined 

with below-normal temperatures (1-5oF), snowpack 

conditions improved, but precipitation and SWE 

remain below normal for the water year as of April 

1st (Fig. 2). Sierra SWE was at or below 2014-2015 

levels until March, but did not improve as radically 

as in 1990-1991, the most recent “Miracle March”. For 

a full recap of February and March conditions in the 

West, check out the Western Regional Climate Center 

Monthly Summary. 

The Sierra Nevada Snow Drought of 2018

This year the Sierra Nevada snow drought was both 

warm and dry, dependent on elevation and region. 

Winter snowpack at lower elevations began as a warm 

snow drought (lack of snow accumulation despite 

near-normal precipitation) and evolved into dry snow 

drought (below-normal cold-season precipitation) 

through mid-winter at all elevations (Fig. 3). 

For more information about NIDIS, visit www.drought.gov

Fig. 2. (left) Percent of normal precipitation (%) (https://wrcc.dri.edu/

wwdt/), October 2017 - March 2018. (right) Percent (%) of 1981-2010 

median snow water equivalent (https://www.wcc.nrcs.usda.gov/cgibin/

grtbsnow.pl?state=great_basin)
For more information about NIDIS, visit www.drought.gov

About this Outlook

On March 26, 2018, NIDIS and its partners held this 

webinar as part of a series of drought and climate 

outlook webinars designed to provide stakeholders 

in the region with timely information on current 

drought status and impacts, as well as a preview of 

current and developing climatic events.

A recording this webinar can be found at: https://www.

drought.gov/drought/calendar

Fig. 4. A = chances of above-normal; EC= equal chances of above, below, 

normal; B = chances of below-normal. Source: cpc.ncep.noaa.gov/

Precipitation Outlook Temperature Outlook

MAR-APR-MAY APR-MAY-JUN MAR-APR-MAY APR-MAY-JUN

Exploring the temporal winter evolution of snow 

drought is the preferred method for characterizing 

the origin, termination, and potential impacts of snow 

drought. Using April 1 alone as a defining time for 

snow drought may miss important aspects of impacts, 

such as this winter’s westwide tourism and recreation 

impacts. In response to the need for snow drought 

resources, NIDIS has launched a new snow drought 

page in a multi-agency collaborative effort to increase 

awareness of snow drought and its impacts. There 

you can find relevant data and tools and report snow 

drought impacts to the Drought Impact Reporter in an 

effort to improve understanding of how snow drought 

impacts citizens and economies.

Drought & Climate Outlook

The March 2018 Seasonal Outlooks produced by 

NOAA’s Climate Prediction Center (CPC) favor belownormal precipitation across California and Nevada 

for April-May-June (AMJ) (Fig. 4). There is a 33-60% 

chance of above-normal temperatures over much of 

the region through early summer, with the greatest 

chances over the more southeastern portion of the 

region. Spring and summer streamflow forecasts are 

70-100% of the 1981-2010 average in the Sierras and 

25-89% in the Nevada ranges as snowpack is generally 

below-normal (Fig. 5). Through April, current U.S. 

Drought Monitor conditions are likely to persist as the 

region enters its climatological dry season.

During FebruaryMarch 2018, La Niña 

conditions weakened 

but were still reflected 

by below-average sea 

surface temperatures 

(SSTs) in the east-central 

equatorial Pacific Ocean. 

The NOAA’s ENSO alert 

system status is currently 

a La Niña advisory with 

a transition from La Niña 

to ENSO-neutral most 

likely (~55% chance) 

during the March-May 

season, with neutral 

conditions likely to 

continue into the second 

half of the year.

Contributors:

Amanda Sheffield, NOAA/NIDIS

Ben Hatchett, DRI

Jennifer Balachowski, USDA California Climate Hub

Leslie Roche, UC Davis

Kathryn Dyer, Bureau of Land Management

Fig. 3. Time series of SWE at Fallen Leaf (6,242 ft), a low elevation Sierra 

Nevada station. Source: NRCS

Fig. 5.Spring & Summer Streamflow 

Forecast Maps for the Great Basin and 

California as of April 1, 2018. Source: 

https://www.wcc.nrcs.usda.gov/cgibin

/grtb_strmflow.pl?state=great_basin