An unusual early season heat wave brought dangerous temperatures to parts of the United States, raising concerns for health, wildfire risk and record-breaking weather.
The heat started in the Southwest and expanded to other parts of the country. Temperatures were far above the March average in California, Nevada, Arizona, Texas and many central states.
For many, it felt less like spring and more like the height of summer.
Weather experts called the pattern a heat dome. That happens when a strong area of high pressure traps hot air near the ground. The system acts as a lid, holding in the heat, and preventing clouds and rain. Temperatures can rise quickly and remain high for several days under the unrelenting sun.
In some locations, temperatures soared 20 to 30 degrees above normal during the event. The March heatwave in western North America was caused by a strong, slow-moving high pressure system that brought temperatures 20 to 30 degrees above average in parts of California, Nevada and Arizona, the World Weather Attribution said.
Early in the year, that sort of heat can be especially dangerous.
Extreme temperatures in March are often more surprising than those in July or August. Homes could be unprepared for heavy cooling. Outdoor workers may not be heat-acclimatized. Older adults, children, and people with health conditions may be at higher risk.
Extreme heat can lead to dehydration, heat exhaustion and heat stroke. High heat can quickly become dangerous, particularly when people stay outside too long or lack access to cooling, the National Weather Service says.
The heat also raised concerns about fire danger. Dry air, warm temperatures and gusty winds can make it easier for fires to ignite and spread. Officials warned that outdoor burning, sparks or careless activity could be hazardous in parts of the Southwest and Plains in those conditions.
March heat wave breaks temperature records in several cities. The Weather Channel said the event broke monthly records in more than 180 cities from the Southwest to the Plains and parts of the East. Some places challenged long-standing heat records for March.
In places like Phoenix and southern California, temperatures were hitting levels more typical of late spring or summer. Texas also had record high heat in some places while parts of the Midwest and Great Plains were well above normal for the season.
The message for residents was simple: take the heat seriously.
People were advised to stay indoors during the hottest part of the day if possible, drink plenty of water, avoid strenuous outdoor activity and check on elderly relatives or neighbours. People working outside were advised to take breaks, seek out shade, and be alert for signs of heat illness.
Never leave children or pets in a parked car, not even for a short period of time. Car temperatures can increase dangerously quickly.
The phrase “stay indoors” is alarming, but the main idea is to limit exposure during peak heat. If you have to go outside, wear light clothing, drink plenty of fluids and avoid strenuous work or exercise.
The March heat wave also prompted broader questions about changing weather patterns. Extreme heat events are happening more often and with greater intensity in many areas. The heat early in the season can be particularly disruptive given it strikes before people and systems are fully prepared.
For now, the lesson from this is simple.
Heat doesn’t have to arrive in mid-summer to be dangerous. If temperatures get substantially higher than normal, especially for several days, people should treat it seriously.
Check local weather forecast.
Listen for National Weather Service alerts.
Hydrate.
Avoid outdoor activity during the hottest parts of the day.
And watch out for the ones who may not be able to protect themselves.
Heat waves may not seem as dramatic as a storm, but they can be just as dangerous. Sometimes the greatest danger is not what you see outside, but how quickly the body can become overwhelmed if the heat does not abate.