California’s drought conditions have gone from bad to worse in scarcely a month.

In the weeks following April 1, the traditional end of the rainy season, warm temperatures have burned off most of the Sierra Nevada snowpack and left the state’s water network gasping. Instead of delivering a generous volume of melted snow into California’s rivers and reservoirs, the snowpack has largely evaporated into the air or trickled into the ground.

“We got unlucky. A lot of it didn’t make it into the reservoirs,” said Jeffrey Mount, a geologist and water expert at the Public Policy Institute of California.