SAN FRANCISCO (AP) — Deadly wildfires in California have burned more than 4 million acres (6,250 square miles) this year — more than double the previous record for the most land burned in a single year in the state.

California fire officials said the state hit the astonishing milestone Sunday with about two months remaining in the fire season. The previous record was set two years ago when wildfires destroyed 1.67 million acres (2,609 square miles).

“The 4 million mark is unfathomable. It boggles the mind, and it takes your breath away,” said Scott McLean, a spokesman for the California Department of Forestry and Fire Protection, known as Cal Fire.

Cal Fire said in a statement Sunday that there have been more than 8,200 wildfires since the start of the year that have burned “well over 4 million acres in California.”

The flames have scorched an area larger than Connecticut. About 17,000 firefighters are still battling nearly two dozen major blazes throughout the state.

Despite the grim milestone, there were signs for optimism this weekend.

Powerful winds that had been expected to drive flames in recent days hadn’t materialized, and warnings of extreme fire danger for hot, dry and gusty weather expired Saturday morning as a layer of fog rolled in. Clearer skies in some areas allowed large air tankers to drop retardant after being sidelined by smoky conditions several days earlier.

“In certain areas, we were able to get quite a bit of aircraft in. So we really pounded, a couple different areas hard with aircraft,” Mclean said. “If the weather does what is predicted, we’re on that glide path I hope. But that doesn’t diminish the amount of work that still needs to be done.”

Virtually all the damage has occurred since mid-August, when five of the six largest fires in state history erupted. Lightning strikes caused some of the most devastating blazes. The wildfires have incinerated hundreds of homes and killed 31 people but large parts of them are burning in largely unpopulated land.

Many of the most destructive fires sparked in Northern California, where hills and mountains dotted with many dead trees have provided plenty of fuel for fires igniting amid high temperatures and strong winds fanning the flames. Thick, gray smoke from the blazes has fouled the air in many hill communities and major cities in the San Francisco Bay Area and beyond.

Numerous studies have linked bigger wildfires in America to climate change from the burning of coal, oil and gas. Scientists say climate change has made California much drier, meaning trees and other plants are more flammable.

Fire officials said the Glass Fire burning in wine country for the past week was their top priority.

Three fires, driven by strong winds and high temperatures, merged into one tearing into vineyards and forested mountain areas, including part of the city of Santa Rosa. Thousands of people were under evacuation orders, including the entire population of Calistoga, a town of 5,000.