Excessive heat warnings will remain in effect on the coast as the state closes in on a new record of 4m acres burned

Smoke from nearly two dozen wildfires burning across California will continue to darken skies across the west this weekend, as residents prepare for more heat, toxic air and conditions that are expected to keep fueling the flames.

The National Weather Service reports that both excessive heat warnings and heat advisories will remain in effect along California’s coast, while the Bay Area Air Quality Management District has extended its Spare the Air Alert through Tuesday, with air quality deemed “unhealthy”. Meanwhile the state is closing in on a devastating new record, with close to 4m acres now consumed by wildfires this season.

Fueled by a heatwave, the Glass fire left a trail of smoldering remains along Mountain Hawk Drive in Santa Rosa

Smoke mixed with morning mist on Mountain Hawk Drive in Santa Rosa, California, on Wednesday morning, creating a thick layer of gray that hung over the smoldering remains of family homes that had been charred by the Glass fire days before.

The fast-moving fire had arrived in the neighborhood on Monday night, consuming roughly an acre every five seconds and leveling many of the hillside homes. Now, remnants of lives lived lined the street. Melted squirt guns left on burned patio tables. A charred piano underneath askew picture frames. Homegrown apples on a singed tree were cooked on the vine.

All 55 patients who were being treated at the Napa Valley hospital were safely evacuated

A wind-driven wildfire has forced the evacuation of several hundred homes and a hospital in the heart of northern California’s wine country.

The blaze, dubbed the Glass Fire, broke out before dawn on Sunday near in Calistoga in Napa Valley, and raced toward the adjacent towns of Deer Park and St Helena. The fire spread across more than 1,000 acres (400 hectares) and flames advanced within a mile of the Adventist Health St Helena hospital.