A sprawling heat dome that has already shattered temperature records across the western United States is expected to expand eastward in the coming days, bringing unseasonably warm conditions to much of the country and potentially marking one of the largest early-season heat waves on record.
Forecasters at the National Weather Service say the system, driven by a strong high-pressure ridge trapping hot air near the surface, has already produced record-breaking March temperatures in at least 14 states. In parts of Arizona and California, temperatures have reached as high as 112 degrees, setting a new benchmark for the hottest March conditions ever recorded in the continental U.S.
Meteorologists warn the scale of the event is unusual. As the heat dome shifts east, large portions of the southern and central Plains are expected to see temperatures climb into the 90s by midweek, with as much as one-third of the Lower 48 approaching or exceeding daily or monthly records.
Climatologists say the geographic reach of the current heat wave could rival or exceed notable modern events, including widespread heat episodes in 2012 and 2021. While not expected to match the intensity of mid-summer extremes, the early timing makes the event particularly notable.
Across Pennsylvania and the Mid-Atlantic, the warming trend will arrive after a chilly weekend. In the Gettysburg area and surrounding Adams County, temperatures are forecast to rebound sharply beginning Monday, with highs climbing into the upper 70s and potentially reaching the 80s by Tuesday and Wednesday. The shift will mark a dramatic change from recent cool conditions and bring a taste of early summer to the region.
The heat dome is expected to persist through much of the week before gradually weakening and moving out by late next week. Despite the high temperatures, forecasters note that humidity levels are likely to remain lower than typical summer heat waves, reducing some of the potential for dangerous heat stress.
Scientists say the event also underscores broader climate trends. A recent analysis by the World Weather Attribution found the extreme March heat would have been highly unlikely without the influence of human-driven climate change, which has significantly increased the probability and intensity of such events.
The unusual weather pattern is also tied to a stalled jet stream, which has allowed heat to build over the western U.S. while keeping storm systems locked farther west.
Source: NPR