CASA GRANDE — When it comes to heat, Arizonans are not easily impressed.
But after an unseasonably cool spring, this week’s oven blast can still be a shock to even the most seasoned natives.
An excessive-heat warning has been issued by the National Weather Service for western Pinal County through Thursday night as temperatures are expected to top 110 degrees before cooling, 8 degrees above normal for this time of year.
The warning covers central and northwest Arizona as well as for southern Nevada, including Las Vegas.
The low temperature Wednesday morning at Sky Harbor International Airport in Phoenix was 80 degrees. The high Wednesday afternoon was 112, breaking a record set in 1974. Lake Havasu City may hit 115 degrees, the NWS said.
Meanwhile, Tucson is outside the warning area but also expected to remain hot.
The warning is scheduled to remain in effect until 8 p.m.
Forecasters warn that overexposure can cause heat cramps and heat exhaustion, and without intervention can lead to heatstroke.
Officials advise drinking plenty of water and say cooling stations are available in the county. Residents also are advised to keep an eye on children, pets and the elderly.
“We are a little more normally acclimated to the heat by this time when we get to this part of mid-June, and a lot of us weren’t because it has been cool,” said Marvin Percha, a meteorologist with the National Weather Service in Phoenix.
“The temperatures in themselves are going to be quite hot — 110 and 112 — but the fact that we are not acclimated, it’s making people even more vulnerable to the hot temperatures.”
Typically the average highs will slowly rise beginning in March from the mid-70s, with an occasional 80, and then reaching the 80s and 90s come April.
Percha said the average first 100-degree day is around the end of May, but it often happens near the first of May.
This year was different, however.
The average high in May was 76 degrees — 19 degrees cooler than last year, when the average May temperature was about 95 degrees. Casa Grande didn’t see its first 100-degree day until May 31, which was nearly a month later than last year, on May 5.
This year, Casa Grande has had seven days with temperatures at or above 100 degrees compared to 21 days by this time last year, with 10 of those days coming in May of last year.
“It does take time for people to get acclimated, especially those that are elderly, people that more handicapped, young children. It will hit them a lot faster,” said Dr. Damon Dell’Aglio, medical director for the emergency department at Banner Casa Grande Medical Center.
Dell’Aglio said that despite the sudden rise in temperatures, he hasn’t seen an uptick in heat-related illness in the emergency room, other than Customs and Border Protection agents bringing in migrants who were found in the desert, which he said is common this time of year.
“Generally for most people, if they go from a climate where it’s cool and they go to someplace that is way hotter, there is somewhat of a hit to the system,” Dell’Aglio said. “What happens when you go to a hotter climate, your cardiac output has to increase.”
The most common signs and symptoms of heat exhaustion include:
- Dark-colored urine
- Pale skin
- Profuse sweating
- Rapid heartbeat
Dell’Aglio recommends that individuals drink plenty of water or energy drinks, which will replenish the electrolytes, while trying to avoid being outside during the peak times from 10 a.m. until 2 p.m.
“It’s very easy to get dehydrated here because the air doesn’t have a lot of moisture,” he said. “Heat kills more people on an average per year than anything else. Fortunately in Arizona we are used to heat. We have air conditioning and people are better able to handle it.”
Dell’Aglio added that the hospital has ways to cool people down such as a cold infusion and putting ice packs under armpits and the groin.
“There is a lot of blood vessels that flow there, so if you put ice there, if you spray someone down with water and blow a fan over them, it will rapidly cool them,” he said.
Percha of the NWS said the reason for the unseasonably cool May was because of a blocking pattern that formed and a low pressure area was set up over the Southwest.
“With that, we had Pacific storms that normally would begin to lift to the north by May, that were still affecting the region through May and were keeping temperatures well below normal in the late spring months,” Percha said.
He added that the pattern has now shifted to a normal one with storm tracks drifting over the Pacific Northwest and the northern Rockies and high pressure building over the Southwest.
The result has been a continued hot pattern, where Thursday’s forecast high is expected to reach 110 before temperatures start to fall back to normal, which is around 106.
“We are in an excessive-heat warning through (Thursday) evening and then we have a Pacific system that is going to knock our temperatures down,” Percha said. “We are looking for noticeably cooler with 105 for a high on Friday and 103 for Saturday and Sunday, but it will definitely take the edge off the heat.”
With June typically being the hottest month of the year, Percha said the odds for the rest of the month and the summer are favoring a warmer than normal summer.
The monsoon season starts officially on Sunday, but Percha said the storms typically don’t start until around July 4.
“Right now (the monsoon is) looking like it might be delayed but there is a good possibility that it could be a little more active in August and September,” Percha said.