Unseasonal snow has fallen in parts of the north-west US, while the east coast prepares for a heatwave that could see temperatures reach 40C (104F) in major cities by the end of the week.
Cold front brings snow and fire risk
A strong cold front from the northern Pacific swept into the western US over the weekend, bringing abrupt changes to a region experiencing high summer temperatures and drought. Temperatures from the Canadian border to California have been 5-10C below normal since Friday, and more than 10C below in some northern areas, according to meteorologists. This pattern is expected to persist for much of the coming week.
The cold front delivered the first significant rainfall in weeks to parts of the north-west. In the Rocky Mountains across Idaho, Montana, and Wyoming, the cold combined with moisture to produce snowfall at unusually low elevations. While the summer snow line typically sits around 3,300 metres (11,000ft), snow fell as low as 1,800 metres on Sunday, with more expected on Monday. Several inches are forecast to accumulate at higher altitudes.
Wildfire danger heightened
Paradoxically, the cold front has increased wildfire danger. Much of the western US is in drought, and lightning strikes from the front's leading edge pose an ignition risk to dry vegetation and plant litter. Heightened winds have also fuelled existing fires. The gustiest conditions over the weekend occurred in Utah, Colorado, and Arizona, where several major fires were already burning. Strong winds are expected to move north into Wyoming on Monday.
The 2026 fire season is shaping up to be one of the worst on record in terms of the number and extent of areas affected, according to officials.
Eastern heatwave on the way
While the north-west cools, the north-east is bracing for a heatwave ahead of the Fourth of July weekend. Temperatures in the midwest and north-east are forecast to reach the high 30s Celsius. Forecast models suggest highs could hit 40C (104F) in New York, Philadelphia, and Washington DC on Thursday and Friday, with night-time lows struggling to drop below the high 20s Celsius. In contrast, the average July daily high ranges from 29C in New York to 32C in Washington. The record temperatures stand at 42C for New York and 41C for Philadelphia and Washington.
