As we move through the week, residents of the Central Coast interior can expect steadily rising temperatures, culminating in a significant heatwave by the weekend. High-pressure building overhead is driving this upward trend, resulting in above-normal temperatures starting Friday and into early next week.
Short-Term Forecast (Through Saturday)
Today marks the Summer Solstice, bringing the longest daylight hours of the year. This abundance of sunshine contributed to warmer conditions, especially in areas unaffected by marine layer clouds or sea breezes. Interior temperatures were 5 degrees warmer than normal, with an increase of 4 to 8 degrees compared to yesterday due to reduced cloud cover and onshore flow.
By Friday, upper-level heights will rise quickly as high pressure moves in from the east. The decreasing onshore pressure gradients will limit the development of marine layer clouds inland and in coastal valleys, leading to clear skies and higher daytime temperatures. Inland areas, such as Paso Robles, can expect highs reaching the upper 90s, while Central Coast valleys will be in the 70s and 80s. While clearing away from beaches looks good, due to a temperature inversion some beach clouds could be stubborn. Beaches likely remain in the 60s (not all beaches, Avila should be in the 70s).
Saturday will be the peak of the heatwave for the interior. High pressure will settle over the region, causing temperatures to soar. Coastal areas may see marine layer clouds persist due to a strong temperature inversion, but inland areas will feel the brunt of the heat. Our modeling likes better beach cloud clearing on Saturday compared to Friday. Paso Robles and similar inland locations can anticipate highs in the upper 90s and some places hitting or surpassing 100.
A heat advisory is in effect from 10 AM Saturday to 8 PM Sunday for areas including the Cuyama Valley, San Luis Obispo County interior valleys and mountains, and the Southern Salinas Valley with temperatures expected to reach up to 101 degrees.
Additionally, an excessive heat watch remains in effect from Saturday morning through Sunday evening for regions such as the Santa Barbara County interior mountains where dangerously hot conditions with temperatures up to 98 degrees are possible.
Long-Term Forecast (Sunday through Wednesday)
As we move into the extended period, the Central Coast will remain under the influence of strong high pressure centered over Arizona and New Mexico. This pattern will result in consistently warm-to-hot temperatures inland, while coastal areas will stay cooler.
By Sunday and Monday, a slight decrease in interior temperatures is expected due to increasing moisture in the atmosphere, which will dampen daytime heating. The flow from the southeast will bring in monsoonal moisture, raising humidity levels and potentially leading to some afternoon convection. Although the chance of thunderstorms remains low, it is not entirely ruled out.
Looking ahead to Wednesday, the center of high pressure will shift westward, altering the flow and reducing the influx of moisture. This change will help stabilize temperatures and limit the chance of precipitation.
Overall, residents of the Central Coast interior should prepare for a hot and dry weekend. Stay hydrated and take necessary precautions to avoid heat-related illnesses.
