Heat index values, or humidity-driven “feels like” temperatures, in Austin could reach 107 degrees in Austin by 4 p.m. Sunday, according to the National Blend of Models, a composite weather forecast model.
National Blend of Models/Pivotal Weather
Although rain chances for Austin will linger into Sunday morning, the traditional first day of summer will mark the start of drier weather pattern, featuring temperatures close to 100 degrees over the next several days, according to the National Weather Service.
Austin on Sunday, the day of the summer solstice, has a slight 20% chance of showers until midday, as overcast skies in the morning gradually becomr sunnier, forecasters said. Afternoon temperatures are expected to edge a bit higher than the climate-average for June 21, hitting 95 degrees.
Article continues below this ad
However, southerly winds will be keeping plenty of atmospheric moisture in place. All that humidity will be driving heat index values into the triple digits — making that peak temp of 95 feel more like 107 degrees instead.
“Sunday afternoon then looks to start the drying trend regarding the area rain chances, and this continues onward into the long term,” the weather service said in a forecast bulletin posted online Saturday.
Why heat index matters this week
Triple-digit heat index values represent a potential public health danger, according to the weather service.
Article continues below this ad
“We’ll monitor area extent of the heat indices near or above 108 as we get closer in time to evaluate a possible issuance of a heat advisory,” forecasters said in the bulletin. A heat advisory alerts the public that the level of humidity-boosted heat could increase the chances of heat-related illnesses.
We rely on the evaporation of sweat from our skin to cool down on hot days. But too much humidity makes that process less efficient because the air is already filled with water vapor. The heat index, which takes this into account, more accurately describes the heat your body is experiencing, at least better than what actual air temperatures would suggest.
START OF SUMMER EXPLAINED: When is the first day of summer? In Austin, you can get 5 different answers
Article continues below this ad
Because your body’s ability to cool down is compromised, the dangerous combination of excessive humidity and extreme heat can lead to heat exhaustion or heatstroke if you don’t take adequate precautions.
If you must be outside, drink plenty of water, wear loose-fitting and light-colored clothing, and take frequent breaks in air-conditioned spaces. Also, never leave children or pets unattended in a vehicle, not even for a minute or two.
Don’t expect much relief from the heat at night, though. Sunday night temperatures will remain largely in the 80s, bottoming out around 79 before sunrise Monday, forecasters said.
Monday forecast and beyond
Austin on Monday should be mostly sunny with a temperatures reaching 96 degrees. Southerly winds of around 10 mph could include gusts as strong as 25 mph, forecasters said.
Article continues below this ad
Under clear skies all week, peak daytime temperatures slowly increase throughout the week to 97 on Tuesday, then to 98 on Wednesday and Thursday.
Overnight temperatures this week will continue to stay above the upper 70s, bottoming out only as low as 75 Wednesday night into Thursday morning.