Automatic sensors spread across the massive mountain range show that snowpack levels are about 39 percent of normal levels. Dozens of California communities risked running out of water last fall due to drought conditions.

According to reports, the April 1 Sierra snow reading is traditionally considered to be the most important of the year from a water supply standpoint. Since very little snow falls after this date, whatever measurements are gathered tend to be an accurate indicator for what farmers, city planners and wildlife agencies can expect.

Last year on April 1, snowpack levels measured at around 62 percent of normal. That has since dropped by more than a third.

Going back to 1950, there have only been five other times that snow levels were less on April 1 than they currently are. All of them occurred during major droughts: in 2015 (five percent of normal), 2014 (25 percent), 1977 (25 percent), 1988 (29 percent), and 1976 (37 percent).