Wildfire — North Bay Mountains, California

2020-09-27 to 2020-09-30 · North Bay Mountains, California

Event narrative

Dry gusty offshore winds as well as strengthening high pressure enabled the generation and rapid spread of the Glass Fire across Napa and Sonoma counties at the end of September https://www.fire.ca.gov/incidents/2020/9/27/glass-fire/. Tens of thousands of residents were ordered to evacuate including the entire city of Calistoga. Over 50,000 acres burned by the end of the month along with nearly 80 residential structures and numerous additional structures. Strong and dry offshore winds enabled the Glass Fire to grow nearly fourfold in just one day https://www.latimes.com/california/story/2020-09-29/glass-fire-quadruples-in-size-burning-80-homes-in-napa-valley. The fire was still burning well into October.

Wider weather episode

Dry gusty offshore winds as well as strengthening high pressure enabled the generation and rapid spread of the Glass Fire across Napa and Sonoma counties at the end of September. The mountains of the North Bay saw wind gusts of 40 to 65 mph into the morning of the 28th with 30 to 40 mph gusts across the East Bay Hills. These gusty winds along with dry conditions enabled the Glass Fire to spread almost fourfold in one day. Tens of thousands of residents were evacuated and nearly 80 homes were destroyed along with numerous additional structures including a famous Napa winery. Offshore flow and strong high pressure also broke several daily temperature records across the SF Bay Area. High temperatures were in the mid/upper 90s to low 100s inland and mid 80s to low 90s along the coast.

Source: NOAA Storm Events Database, event_id 917313. Narrative written by the NWS forecast office that issued the report.