Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
071 FXUS66 KSTO 292019 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 119 PM PDT Sun Jun 29 2025 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .DISCUSSION... .SYNOPSIS... Warm and dry weather continues this week with periodically breezy onshore winds. Widespread Moderate HeatRisk persists into the middle of next week. Mountain thunderstorm chances return next week. Lightning on dry fuels may lead to easier fire starts early next week. && .KEY MESSAGES... * Today: -Continued warm temperatures across the area, with highs in the upper 90s to around 106; higher temperatures in the northern Sacramento Valley. -Widespread Moderate HeatRisk across interior NorCal -Probability of Valley high temperatures > 100F: Northern Sacramento Valley: 75-100% Elsewhere: around 20-40% -A non-zero (5-10%) chance of an afternoon/evening shower or isolated t-storm along the Sierra crest. Confidence low on development, best forcing mechanisms remain off shore and to the east of Sierra crest. * Early to Mid Week: -Above normal temperatures persist this week with Moderate HeatRisk, although increased onshore flow brings some relief to the Delta vicinity Monday-Tuesday -Slight (10-20%) probability of thunderstorms early to mid next week during the afternoon and early evening hours across the mountains of interior NorCal. Highest thunderstorm probabilities over the northern mountains on Monday-Tuesday. Thunderstorm chances expand farther south into the Sierra by Wednesday. -Lightning on dry fuels may lead to easier fire starts. A Red Flag Warning has been issued for the northern Coast Range, Shasta County mountains and Burney Basin from 11 AM - 8 PM Tuesday. * Later This Week: -Slight cooling trend with Minor HeatRisk returning to interior NorCal -Potential for mountain thunderstorm chances (10-20%) persisting through late week. .Changes from previous forecast... -Fire Weather Watch has been upgraded to a Red Flag Warning for lightning on dry fuels for the northern Coast Range, Shasta County mountains and Burney Basin from 11 AM to 8 PM Tuesday. Slight areal expansion of the warning (fire zones 266 and 268 within Shasta County), along with a temporal extension (now runs through Tuesday, July 1 at 8 PM PDT). && .AVIATION... VFR conditions prevail across interior NorCal next 24 hours. Surface winds 12 kts or less, except in the Delta vicinity where southwest gusts 20 to 25 kts are expected through 06Z Monday. Isolated mountain thunderstorms possible across northern Sacramento Valley and surrounding terrain after 18z Monday. && .STO WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 11 AM Monday to 8 PM PDT Tuesday for Burney Basin and Northeast Plateau in Shasta County Including Northwest Lassen NF north of Lassen NP-Eastern Mendocino NF- Eastern Portion of Shasta/Trinity NF-Northern Sierra Foothills from 1000 to 3000 Ft. Includes portions of Shasta-Trinity and Butte Units-Northern Sierra Including Lassen NP and Plumas and Lassen NF/S West of the Sierra Crest (West of Evans Peak-Grizzly Peak-Beckworth Peak)-Southeast Edge Shasta-Trinity NF and Western Portions of Tehama-Glenn Unit. && $$