Napa, CA — Northern California is gearing up for its first major heat wave of 2025, with temperatures predicted to climb significantly by the end of this week. The National Weather Service (NWS) has warned that some areas may approach—or even surpass—calendar record highs, marking the hottest conditions ever recorded for this time of year.

A strong ridge of high pressure is set to settle over the region, bringing widespread hot and dry weather conditions. The heat wave is expected to peak on Friday and Saturday, with the most intense temperatures occurring in inland locations.

The NWS has issued an Extreme Heat Watch for parts of Northern California, including the Sacramento Valley, where daytime highs could reach between 97 and 107 degrees Fahrenheit.

Projected peak temperatures for Friday across Northern California include:

  • San Francisco: 78°F

  • Alameda: 86°F

  • Fremont: 94°F

  • San Ramon: 96°F

  • Pleasanton: 98°F

  • Healdsburg: 100°F

  • Napa: 97°F

  • Sacramento: 104°F

Meteorologists highlight that this early-season heat surge is unusual. “This is a little early to be experiencing these kinds of temperatures,” said Fox40 meteorologist Dennis Shanahan.

The heat wave is anticipated to be the first widespread heat outbreak of 2025 across California, potentially marking the hottest day of the year so far. Temperatures are expected to moderate by the weekend, with widespread cooling predicted by Sunday and Monday, providing relief to both Northern and Southern California.

Authorities are urging residents to prepare for the extreme heat by taking precautions such as staying hydrated, limiting outdoor activities during peak heat hours, wearing light-colored and loose-fitting clothing, and checking on vulnerable populations including children, the elderly, and those with health conditions.

The National Weather Service also stresses the importance of never leaving children or pets unattended in vehicles, where temperatures can rapidly rise to dangerous levels.

Californians are advised to remain vigilant and take the necessary steps to stay safe as this heat wave unfolds.