California Just Recorded Its Warmest December in State History

December 2025 rewrote the record books in California, officially becoming the warmest December ever recorded in the state, according to data from the National Centers for Environmental Information.

California’s average temperature for the month reached 49.8 degrees, nearly seven degrees above normal and warmer than the previous record set just one year earlier. The milestone capped off an already hot year, with 2025 ranking as the state’s fifth-warmest year on record. Notably, California’s 10 warmest years have all occurred since 2014.

The December heat was especially surprising because a La Niña pattern developed in the fall, a climate cycle that typically brings cooler, snowier winters to the West. This time, however, the La Niña was weak and largely overshadowed by unusually warm ocean temperatures in the North Pacific and off the West Coast. Climate scientists say those warm seas helped funnel mild, moisture-rich air into the region.

Experts point to a combination of short-term weather patterns layered on top of long-term climate warming. While individual storms and atmospheric setups drove the month-to-month conditions, the broader trend is unmistakable: baseline temperatures continue to rise.

Despite the warmth, California’s snowpack sat at exactly 100% of average in mid-January, a contrast to below-average snow levels in much of the Pacific Northwest and Idaho. Still, forecasters say the current La Niña is expected to fade soon, offering limited cooling relief.

Nationwide, the U.S. experienced its fourth-warmest year on record, with the western third of the country, including California, marking its hottest year ever as a region.