Overview

• As of Tuesday, valley highs reached about 93°F under a retrograding high pressure ridge, marking the first highs above 90°F in nine days
• The Bay Area’s thinning marine layer has allowed sunnier mornings and pushed coastal highs to near 60°F while inland areas climb into the upper 70s
• Lighter delta breezes have reduced afternoon cooling in the Sacramento Valley, contributing to warmer daytime temperatures
• A secondary low tracking south midweek is expected to nudge valley highs back into the low 90s and heighten Sierra thunderstorm chances through Wednesday
• Drying vegetation in the Sierra Nevada elevates fire-weather concerns if afternoon storms produce lightning without significant rainfall