Cooler but high fire danger remains

A massive weather transition begins tonight as the current interior heat wave is replaced by an expanding, 1,500-foot marine layer by the weekend. This shift brings relief from hot temperatures, but introduces a brand-new wildfire lightning watch for early next week. Thursday Forecast  • The Big Drop: The extreme heat wave officially ends tomorrow. A deep Pacific Northwest storm trough is moving toward the coast, forcing a surge of cooler ocean air inland.. • The Numbers: Temperatures across the interior will drop significantly, falling right back to comfortable, mid-July seasonal averages. Thursday's span from 63 at the Coast to 90 Inland..  Critical Fire Danger & Weekend Wind • Tonight's Threat: Elevated fire weather conditions remain critical across the interior and higher terrain through Thursday night. Mountain ridges are enduring roasting heat up to 20 degrees above normal, paired with bone-dry humidity.. • The Wind: Strong, punchy afternoon and evening onshore winds will remain breezy through Friday, howling through mountain passes like the Altamont Pass and Salinas Valley. Avoid any outdoor activity that could spark a flame. Winds 10-20 mph with occasional gusts to 30 mph.. Long-Range Outlook: Renewed Lightning Watch Next Week: A strong onshore wind pattern will lock in through the weekend, deepening the marine fog layer to a steady 1,500 feet. Expect near-to-below-normal temperatures and gray morning overcast that retreats to the beaches by lunchtime. • The Tropical Shift: We are monitoring a heavy pulse of tropical monsoon moisture surging north around a high-pressure system. • Dry Lightning Threat: While the heaviest threat of severe thunderstorms has shifted slightly eastward over the Sierra Nevada for Sunday and Monday, a thick deck of mid-to-high level tropical clouds will stream over the Bay Area. Any high-based storm that develops over the parched local hills will trigger dangerous dry lightning strikes capable of sparking sudden wildfires