In this Wednesday Jan. 3, 2018 file photo, Grant Davis, director of the Dept. of Water Resources, center, discusses the results of the first snow survey of the season at the nearly snow barren Phillips Station snow course, near Echo Summit, Calif. California's water managers are carrying out their mid-winter snowpack survey Thursday, Feb. 1, 2018, as the winter's dry spell persists. (AP Photo/Rich Pedroncelli, File)

Amid record-setting heat in the state's south, California's water managers will measure the Sierra Nevada snowpack, which supplies water to millions.

Department of Water Resources officials will trek to the mountains Thursday to check the snow depth, one gauge of the state's water supply. Electronic sensors show snow levels are about one-third of normal.

At the peak of California's recently ended five-year drought, Gov. Jerry Brown ordered 25 percent water conservation in cities and towns and declared a drought emergency.

Heavy rains in Northern California last year finally snapped the drought, and Brown declared the emergency over in April.

But the drought never really seemed to end in some Southern California areas, said Daniel Swain, a climate scientist with the University of California, Los Angeles.

Los Angeles received only one significant rain in almost the last 12 months.

In Ventura and Santa Barbara counties, which are about 100 miles (161 kilometers) north of Los Angeles, the lack of rain and dry vegetation were perfect fuel for a December wildfire that grew to be the largest recorded in state history. When it finally rained, the scorched earth turned into deadly mudslides.

In this Dec. 14, 2017 file photo, Los Angeles skyline is seen through burned trees after a brush fire erupted in the hills in Elysian Park in Los Angeles. California's water managers are carrying out their mid-winter snowpack survey as the winter's dry spell persists. The Department of Water Resources on Thursday, Feb. 1, 2018, will carry out manual measurements of the Sierra Nevada snowpack. (AP Photo/Damian Dovarganes, File)

The most recent weekly U.S. drought monitor, a product of the federal government and others, shows only small patches of the state, in Southern California, in the mildest form of drought. That compares to 2014 and 2015, some of the driest years in history in California, when much of the state was rated as in the most severe categories of drought.

In the middle of the state's winter rain and snow season, no rain is in the forecast. In Southern California, "it really is pretty grim," said Swain, who has tracked the stubborn weather patterns blocking rain from the state's south for years.

Doug Carlson, spokesman for the state's Department of Water Resources, which carries out the snowpack surveys, said the dry weather is a growing concern, although reservoirs are still fuller than usual thanks to last year's rain in Northern California.

Considerations of what constitutes a drought vary, and include: rainfall, the state of waterways, soil dryness, and other measures. Any decision to declare a new drought emergency if the winter remains dry, or later, would be up to Brown.

In this Jan. 16, 2018 file photo, Mark Waissar, 49, is silhouetted against sunset as he walks on an overpass above the Pacific Coast Highway in Santa Monica, Calif. California's water managers are carrying out their mid-winter snowpack survey Thursday, Feb. 1, 2018, as the winter's dry spell persists. Some Southern California areas including Los Angeles have received only one significant rain in months, and that rain, in January, caused deadly mudslides. (AP Photo/Jae C. Hong, File)

In this April 10, 2017 file photo, boxes of bottled drinking water are seen in Hardwick, a small community in the San Joaquin Valley, where drought has yet to loosen its grip on some residents near Hanford, Calif. Rural residents whose wells went dry in California's record dry spell were still trucking in water this week as if the drought never ended. California's water managers are carrying out their mid-winter snowpack survey Thursday, Feb. 1, 2018, as the winter's dry spell persists. (AP Photo/Scott Smith, File)

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