Dry, cool and breezy at times with below normal temperatures through Monday due to onshore flow. A significant warming trend next week with hot weather returning. Abnormally warm temperatures are likely to persist into the following week.
Discussion
The weak trough that has been sitting just off shore over the Eastern Pacific the past several days will move through NorCal today and weaken as it lifts northwest into Idaho Monday. This will give the area one more day of well below normal temperatures before a significant warming trend begins Monday lasting through the end of the week.
Onshore flow will strengthen briefly today with marine layer stratus possible this morning over the Delta and Southern Sacramento Valley. Valley high temperatures will be in the upper 70’s/low 80’s Delta/srn sac Valley and near 90 nrn sac Valley.
Strong upper high pressure over the Desert SW will amplify north Monday through Wednesday with progressively higher heights. Monday highs are expected to climb into the upper 80s to mid 90s in the Valley, still near to slightly below normal.
Moderate heat risk is likely over portions of the Sacramento Valley Tuesday and Wednesday as Valley high temperatures climb into the mid 90s to around 100 degrees.
The National Blend of Models advertises a 40-75% probability of reaching 100 degrees for the northern Sacramento Valley both Tuesday and Wednesday. Be prepared to practice heat safety next week, especially heat sensitive groups. Dry conditions will prevail through the forecast period.
Extended Discussion (Thursday through Sunday)
An upper level ridge over the Desert Southwest will continue to expand over California, causing temperatures to rise throughout the extended forecast period. Ensembles continue to trend higher with temperatures Friday through Sunday.
High temperatures will likely pass the century mark in the Valley over the weekend (60-85% probabilities in the southern Sacramento Valley and northern San Joaquin Valley, and 85-100% probabilities in the northern Sacramento Valley) and there will be an associated widespread Moderate to High Heat Risk across the area.
Be sure to practice both heat safety and cold water safety, as rivers are still running fast and cold.