A significant and unusually early heatwave is building across the south-western US this week, bringing temperatures more typical of early summer than mid-March. In Phoenix, Arizona, the National Weather Service (NWS) forecasts temperatures could exceed 100F (38C) as soon as Wednesday, marking the earliest arrival of triple-digit heat to the city in nearly four decades.
A strong, slow-moving high-pressure system — often called a heat dome — is trapping hot air over the region, pushing temperatures 20–30F above normal in parts of California, Nevada, and Arizona. The heat is expected to persist for several days, with limited overnight cooling aggravating the situation. Millions are likely to be affected.
Highs are anticipated to reach well above 90F in many areas, including typically cooler coastal regions, while inland and desert locations could exceed 100F, threatening long-standing March records. The NWS has issued heat advisories for parts of California, including the Bay Area and central coast.
Residents in affected areas are advised to check on the elderly and other at-risk groups, and to schedule events around peak heat. ‘Extreme early-season heat coupled with high tourism rates will make this heat very dangerous, particularly for those not acclimated to the heat and/or traveling from cooler climates,’ warned the Las Vegas, Nevada NWS office.
This developing heatwave follows recent severe weather conditions across other parts of the US, raising concerns about health risks and environmental impacts, including a possible prolonged event that could affect water supplies due to early snowmelt.
A strong, slow-moving high-pressure system — often called a heat dome — is trapping hot air over the region, pushing temperatures 20–30F above normal in parts of California, Nevada, and Arizona. The heat is expected to persist for several days, with limited overnight cooling aggravating the situation. Millions are likely to be affected.
Highs are anticipated to reach well above 90F in many areas, including typically cooler coastal regions, while inland and desert locations could exceed 100F, threatening long-standing March records. The NWS has issued heat advisories for parts of California, including the Bay Area and central coast.
Residents in affected areas are advised to check on the elderly and other at-risk groups, and to schedule events around peak heat. ‘Extreme early-season heat coupled with high tourism rates will make this heat very dangerous, particularly for those not acclimated to the heat and/or traveling from cooler climates,’ warned the Las Vegas, Nevada NWS office.
This developing heatwave follows recent severe weather conditions across other parts of the US, raising concerns about health risks and environmental impacts, including a possible prolonged event that could affect water supplies due to early snowmelt.
