Dry and breezy weather with slightly below normal temperatures prevail today. Then, a significant warming trend is anticipated from the middle of the week through the upcoming weekend, with widespread moderate to major heat risk forecast for Saturday and Sunday.
Discussion
An upper level trough will continue to progress east-northeastward through the Pacific Northwest throughout the day today while a building ridge over the desert southwest begins to back build westward. This will result in warming temperatures today, with highs in the low to mid 90s throughout the Valley and highs in the mid 70s to 80s moving toward the foothills and mountains.
Dry onshore flow will continue to see breezy conditions across the region, with strongest winds expected through the Delta. Otherwise, quiet weather is expected to prevail.
With ridging aloft becoming the predominant feature over the region through the middle portions of the week ahead, quiet weather is expected to persist into the middle of the week.
Temperatures will respond in kind, as highs warm up to near to slightly above normal values Tuesday through Thursday. Some minor to moderate heat risk is becoming evident throughout the Valley during this time frame, primarily driven by warming overnight low temperatures.
Extended Discussion (Friday through Monday)
Latest cluster analysis indicates that the upper level ridge will continue to strengthen over the region through the end of the week and into the weekend. While this will work to keep the weather quiet and dry, a significant warming trend is anticipated during this time frame.
Widespread moderate (Friday) to major (Saturday and Sunday) heat risk is forecast throughout much of interior NorCal. This will be the result of very high probabilities (85-95% chance) of high temperatures exceeding 100F within the Valley, as well as high probabilities (75-85% chance) of overnight minimum temperatures exceeding 70F in the northern Sacramento Valley and similar probabilities of exceeding 65F through the remainder of the Valley.
With the overall warming trend that has been ongoing over the past few months, mountain snowmelt continues to occur.
As a result, area rivers and creeks are still running fast and cold. Those planning to seek relief from the upcoming hot temperatures should properly prepare for cold water temperatures and always wear a life jacket if participating in water recreation.