July 17, 2018 – Hot temperatures continue this week. Thunderstorm chances return to mainly the mountain areas later in the week.


Clear skies across the region early this morning. Areas of smoke and haze originating from the Ferguson Fire burning near Yosemite continue to drift north over portions of the northern Sierra Nevada.

Current temperatures are running pretty similar to 24 hours ago and generally range from the upper 40s and 50s in the mountain valleys to the upper 50s to upper 70s across the Central Valley.

High pressure strengthens today and Wednesday suppressing the marine layer and leading to hotter weather across the region. Highest readings across the northern Sacramento Valley will likely exceed 110 degrees today and Wednesday, but enough lingering Delta Breeze is expected to temper readings across the southern Sacramento Valley and northern San Joaquin Valley.

Overnight lows will also be very mild with portions of the valley and foothills only expected to see lows in the upper 70s and lower 80s. The ridge is forecast to be nudged east Thursday and Friday as an upstream trough approaches the PacNW. This will gradually take the edge off the heat, but will also result in an increasing risk that monsoon moisture will move northward late in the week for a chance of mainly mountain thunderstorms.

Extended Discussion (Saturday through Tuesday)

Upper level high pressure system shifts eastward and will bring some slight cooling to the area. Some easterly flow aloft will allow some monsoon moisture to flow back into the Sierra, and in combination with some potential instability, may produce some afternoon showers and thunderstorms for the mountains through this weekend into early next week.