A record snow drought is plaguing the western US, leaving some of the thirstiest states bracing for less water and elevated fire risks through the drier months to come.

Snow cover is roughly a third of what it typically is for this time of year across the west, according to measurements from the National Snow and Ice Data Center, prompting widespread concern among experts and water managers that several key basins will be severely impacted through the rest of the year.

Oregon, Colorado and Utah have all reported their lowest statewide snowpack since the early 1980s, as far back as records go.

“The snowpack is essentially as bad as it’s ever been in recorded history for the time of year in at least some portion of every single western US state,” climate scientist Daniel Swain said in a weather and conditions discussion shared to his website last week, calling the record-breaking warmth that preceded it “astonishing”.

The dire conditions are fueled by an extremely warm winter, according to federal forecasters, with unseasonable weather breaking records across the region.

“I have not seen a winter like this before,” said Mark Serreze, the director of the the National Snow and Ice Data Center, who has been in Colorado almost 40 years. “This pattern that we’re in is so darned persistent.”

The snowpack is an essential source of water that feeds basins relied on by millions of people, sprawling agricultural centers, and ecosystems already under strain. Water content within the snow, an important measurement that offers a sense of how much melt will be available for use, was measured below the median at 91% of weather stations across the west on 1 February.

The strikingly low levels have added pressure to the urgent negotiations under way over the future of the Colorado River, the 1,450-mile (2,300km) waterway that snakes through the western US and supplies roughly 40 million people in seven states, 5.5m acres (2.23m hectares) of farmland, dozens of tribes and parts of Mexico.

Roughly 80% of the river’s supply goes to agriculture, growing water–intensive crops such as alfalfa and hay, which are used as feed for livestock.

Representatives from states that depend on its flows have remained at an impasse about how to manage the imperiled basin as the resources grow increasingly scarce. Long-term overuse and rising pressures from the climate crisis have served as a one-two punch that has left the system in crisis.

Negotiators are facing an end-of-week deadline before the US Bureau of Reclamation inflicts its own plan, an outcome that is expected to lead to litigation and even more uncertainty. But the challenging conditions serve as their own deadline, according to experts, who said the devastatingly low flows require urgent action.

February’s water supply outlook for the Colorado River Basin was the worst in more than three decades. More than two thirds of the river’s water is fed by mountain snow.

“The river isn’t going to wait for process or politics,” said Matt Rice, south-west regional director for the conservation organization American Rivers.

Experts said the snow drought could also kick-start an early wildfire season. Snow disappearing earlier than average leaves the ground exposed to warmer weather in the spring and summer that dries out soils and vegetation quicker, said Daniel McEvoy, a researcher with the Western Regional Climate Center.

Warm temperatures have resulted in an elevational gradient to the snowpack. Snow is present at higher elevations but has melted or is not present at lower elevations. A lack of snow cover may lead to early drying of the landscape, which could result in a longer fire season or reduce runoff efficiency as snow melts.

“It was so warm, especially in December, that the snow was only falling at the highest parts of the mountains,” McEvoy said. “And then we moved into January and it got really dry almost everywhere for the last three to four weeks and stayed warm.”

Meteorologists expect wetter, cooler weather across the west this week with some snow, so this may be the peak of the snow drought. But it will still be warmer than usual in many areas, and scientists aren’t optimistic the snow will be enough.

“I don’t think there’s any way we’re going to go back up to, you know, average or anywhere close to that,” said Russ Schumacher, professor of atmospheric science at Colorado State University and Colorado State Climatologist. “But at least we can chip away at those deficits a little bit if it does get more active.”

Associated Press contributed reporting