A rare winter heat wave is bringing record-breaking temperatures to the western United States, with San Francisco experiencing its hottest March weather in at least two decades. The unseasonably warm conditions are affecting cities from California to Arizona, creating stark contrasts with winter storms battering the Midwest and eastern regions.

Temperature records fell across the San Francisco Bay Area on Monday, with San Francisco International Airport reaching 83°F and Silicon Valley's Redwood City hitting 90°F, breaking a record set in 2004. San Jose tied a 1914 record at 85°F. The National Weather Service reported that Tuesday's temperatures were projected to climb even higher, with the Bay Area approaching 90-degree highs.

The extreme heat is extending beyond California. Phoenix is expected to exceed 100°F this week, which typically doesn't occur until early May and has never happened before March 26. Las Vegas could see temperatures between 94-98°F over the coming days, with a possibility of reaching 100°F on Saturday, which would mark the earliest triple-digit temperature on record for the city. The current March record for Las Vegas is 93°F, set in 2022.

Weather forecasters issued extreme heat warnings for Grand Canyon National Park from Wednesday through Sunday, with temperatures expected to range from 96-104°F in lower elevations. Park officials advised visitors to avoid strenuous hiking between 10 a.m. and 4 p.m. Similar warnings were issued for White Sands National Park in New Mexico, where temperatures could reach the mid-90s.

The heat wave is particularly concerning for Colorado, which experienced an unusually warm winter with minimal mountain snowpack. Water providers in the Denver area have enacted or are considering lawn watering restrictions, urging residents not to turn on sprinkler systems early despite temperatures climbing into the 80s this week. The reduced snowpack threatens water supplies that millions depend on throughout the summer months.

Residents across the affected areas are adapting to the unexpected conditions. In San Francisco, where many homes lack air conditioning, people are relying on fans and spending time outdoors. The warm weather has drawn crowds to beaches and parks, with dog walkers and sunbathers taking advantage of the unusual March heat.