CALIFORNIANEVADA 

DROUGHT 

OUTLOOK 

MAY 2018

Current Drought Conditions 

Although April-May brought wetter-than-normal conditions to northern 

California-Nevada, drought conditions have slowly continued to worsen in the 

southern portion of the region. According to the U.S. Drought Monitor, moderate 

to severe (D1-D2) drought expanded over the past two months. This includes the 

expansion of severe drought into San Diego and Riverside counties of southern 

California, as well as moderate drought throughout southern Nevada. As of May 

29 (Fig. 1), ~35% of California-Nevada was in moderate-extreme drought and 

~41% was abnormally dry.

National Integrated Drought 

Information System

Drought.gov

Fig 1. U.S. Drought Monitor for May 29. 

Source: droughtmonitor.unl.edu

Regional Climate Update

While spring precipitation was above normal in 

some parts of California-Nevada, water year totals 

at the end of May remained well below normal. Most 

of southern California-Nevada received <25%-70% 

of the 1981-2010 normal water year precipitation, 

with just pockets of northern California and Nevada 

receiving above-normal precipitation (Fig. 2). April 

temperatures left California-Nevada warmer than 

normal, counter to the cooler-than-normal coastal 

temperatures in May. Snow water equivalents (SWE) 

are also low for this time of year, with many areas 

across the Sierra Nevada and Nevada mountain 

ranges reporting <25% of median SWE, according to 

the Natural Resources Conservation Service (NRCS). 

California Nevada River Forecast Center (CNRFC) 

water supply seasonal volume forecasts are at- or 

below-normal in the central-northern Sierras and 

extremely-below-normal in the southern Sierras and 

eastern Nevada (Fig. 3). 

Fig. 2. 10/1/2017 - 5/31/2018 Percentile Precipitation. 

Source: WestWide Drought Tracker

Fig. 3. Percent of normal forecast ESP water supply seasonal volume. 

Source: https://www.cnrfc.noaa.gov/

For more information about NIDIS, visit www.drought.gov
Drought & Climate Outlook

The May 2018 Seasonal Outlooks produced by NOAA’s 

Climate Prediction Center (CPC) favor equal chances 

of above, below, and normal precipitation across 

California and Nevada for June-July-August (JJA) and 

July-August-September (JAS) (Fig. 4) with drought 

forecasted to persist throughout the summer. Warm 

temperatures are also favored, with a 33-60% chance 

of above-normal temperatures over the region, with 

the greatest chances over Nevada. The National 

Significant Wildland Fire Potential Outlook (Fig. 5) 

shows above-normal wildfire potential in June-July 

over southern coast and north-central California due 

to current drought severity coupled with the carryover 

of an above-average fine fuel growth from last year. In 

July, as the fuel moisture decline phase is expected to 

be steeper than average, significant portions of CA-NV 

are expected to have above-normal wildfire potential.

Temperature Outlook

JUN-JUL-AUG JUL-AUG-SEP JUN-JUL-AUG JUL-AUG-SEP

Precipitation Outlook

During April 2018, ENSO conditions in the tropical 

pacific returned to neutral as oceanic and atmospheric 

indicators related to La Niña continued to fade. The 

NOAA ENSO alert system status is currently a Final La 

Niña advisory with neutral conditions favored through 

September-November 2018. 

About this Outlook

On May 29, 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 video of and presentations from this webinar can 

be accessed here: 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/

NIDIS & MAPP Launch “Story Map” Telling the 

Story of the Historic California Drought

In April, NIDIS and NOAA’s Modeling, Analysis, 

Predictions and Projections program (MAPP) 

launched a Story Map that takes a look at the 

historic drought that impacted California from 2011 

to 2017. This Story Map is a visual history of the 

drought, using images and graphs to provide an 

interactive and engaging experience. This webinar 

provided a walkthrough of the Story Map, with 

insights from NOAA and MAPP scientists. Check out 

the Story Map!

Fig. 5. National 

Significant Wildland 

Fire Potential 

Outlook issued 

June 1, 2018. Above 

Normal indicates a 

greater than usual 

likelihood that 

significant wildland 

fires will occur. 

Significant wildland 

fires should be 

expected at typical 

times and intervals 

during normal 

significant wildland 

fire potential 

conditions. Source:

https://www.

predictiveservices.

nifc.gov/outlooks/

outlooks.htm

Contributors:

Dan McEvoy, WRCC/DRI

Alison Stevens, NOAA/CPO/MAPP

Amanda Sheffield, NOAA/NIDIS

Michelle L’Heureux, NOAA NWS Climate Prediction 

Center

Dennis Lettenmaier, UCLA/CNAP

Marty Hoerling, NOAA Earth System Research Lab

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