Additional Coverage:
- Extraordinary, climate change-fueled heat wave envelops the West with mounting consequences (cnn.com)
Unprecedented Heatwave Scorches Western US, Threatening Records and Public Health
The Western United States is bracing for an extraordinary and potentially record-shattering heatwave, with meteorologists using “superlatives” to describe its intensity and unseasonable timing. This extreme weather event, significantly amplified by human-caused climate change, is poised to bring summer-like temperatures to a vast area stretching from California to Texas and as far north as Montana, before the month of April even begins.
Millions are already under extreme heat warnings and alerts, from San Francisco to Phoenix, with further expansions anticipated. The heatwave, which is just commencing, is expected to impact nearly the entire Western US and parts of the Plains states by late next week, obliterating dozens of daily and monthly temperature records by considerable margins.
Phoenix, for instance, is projected to see temperatures reach at least 106 degrees Fahrenheit, staying above the century mark for several days. This far exceeds the city’s all-time March high of 100 degrees. The National Weather Service warns that “many locations are likely to set both all-time high temperatures for the month of March and their earliest 100-degree temperature on record,” with some areas experiencing temperatures up to 30 degrees above average for this time of year.
This unprecedented heat event draws parallels in its intensity and rarity to the devastating 2021 Pacific Northwest heatwave, which resulted in hundreds of fatalities and saw temperatures soar into the 120s Fahrenheit in Oregon and Washington State that June. While temperatures over the next two weeks will not reach those extremes (given it is still March), both events are rooted in the same phenomenon: record-strong “heat domes”-sprawling areas of high pressure-persisting over a specific region for extended periods, exacerbated by climate change.
A heat dome compresses and heats the air beneath it, suppressing storm activity and rerouting weather systems. The current heat dome is expected to set records for its strength relative to the time of year and could even rival or surpass the intensity of previous summer heat domes, including the 2021 event.
Such measurements are vital for meteorologists to compare historical heatwaves and analyze the influence of climate change. Studies have already indicated that the 2021 heatwave would have been virtually impossible without human-caused climate change from the burning of fossil fuels, underscoring how heatwaves are becoming more frequent, longer-lasting, and more severe as the planet warms.
Russ Schumacher, a meteorologist and Colorado’s state climatologist, described the heat dome as “astonishing” for its intensity in March, a sentiment echoed by other meteorologists who have used terms like “genuinely startling” and “mind-boggling.” Schumacher emphasized that while warming makes such conditions more likely, it also requires “a really unusual weather pattern to set something like this up.”
Beyond the record-breaking temperatures, the heatwave poses a significant public health threat. Extreme heat is the leading weather-related killer in the US annually.
An early-season heatwave presents particular dangers as residents in affected areas are not yet acclimated to temperatures in the upper 80s to low 100s. The lack of air conditioning in some regions further compounds this risk.
The multifaceted health threat extends to water safety. While summer heatwaves often prompt people to seek relief in rivers and lakes, the current March temperatures mean many waterways will still be too cold for safe swimming, carrying a serious risk of hypothermia for those attempting to cool down.
The long-term consequences of this early heat could reverberate for months. Experts fear it could cause the region’s already low snowpack to melt out at least a month ahead of schedule, raising critical concerns for water supply and increasing wildfire risks during the upcoming dry season. The West is entering this heatwave directly after experiencing its hottest winter on record, with Colorado seeing its thinnest snowpack since 1981.
In California’s Sierra Nevada Mountains, despite closer-to-average snowfall this winter, the heatwave is expected to cause the remaining snowpack to vanish rapidly, potentially completely, approximately five weeks earlier than normal. Schumacher stressed the importance of understanding the causes of this warm winter and studying the heatwave to better anticipate future conditions in the West, as “these kinds of warm months and seasons are probably going to become more likely with future warming.”