The National Weather Service’s Extreme Heat Warning for the Las Vegas Valley is still active as you read this — it runs through 8 p.m. PDT Monday, and it covers Moapa Valley, Pahrump, the Colorado River Valley, and Death Valley right along with the city itself. Harry Reid International Airport hit 115°F on Saturday. That’s the hottest day Las Vegas has logged all year, and it landed one degree short of the all-time record set back in 1979 and 1938.

Two states over, the same heat dome put 72 people in medical tents at a Colorado Springs festival the same afternoon. This isn’t a “summer’s hot, be careful” post. It’s a live event, it’s sitting directly on top of the terrain a lot of you hike, and if you’re deciding whether to load the dog up this week, the answer depends on numbers that are changing day to day.

Quick Verdict: What’s Happening and What to Do

Detail	What You Need to Know
Warning active now	NWS Extreme Heat Warning for the Las Vegas Valley, Moapa Valley, Pahrump, Colorado River Valley, and Death Valley — through 8 p.m. PDT Monday, Aug. 10
Las Vegas heat	Harry Reid Airport hit 115°F Saturday, Aug. 8 — hottest day of 2026, one degree off the all-time record (1979 and 1938)
Colorado Springs incident	72 people treated for heat illness, about 10 hospitalized, at the Tacos and Tequila Festival at UCHealth Park Saturday, as the high hit 97°F, tying the 2025 daily record
People under warning	Roughly 12 million under Level 4 “Extreme” HeatRisk, another 12 million under Level 3 “Major” — Southwest, Mountain West, and northern Great Plains
What’s coming	Denver, Albuquerque, and possibly Oklahoma City near or above 100°F this week as the dome pushes into the Southern Plains and mid-Mississippi Valley
Your dog, today	Check HeatRisk for your specific trailhead zip code. Under an active Warning, this is an indoor day or a pre-dawn-only day — not a normal hike with an earlier start.

Las Vegas: 115°F and Still Climbing Toward the Record

Saturday’s 115°F reading at Harry Reid didn’t come out of nowhere. The Las Vegas Review-Journal has been tracking this heat dome for over a week, and it’s the kind of stubborn, parked ridge of high pressure that doesn’t move fast. The NWS Las Vegas office has issued and re-issued Extreme Heat Warnings almost daily since — the current one runs through Monday evening, and it puts the Las Vegas Valley, Pahrump, and Moapa Valley at 110 to 115°F, with the Colorado River Valley in the same range and Death Valley pushing toward 120°F.

One degree off an all-time record is close enough that it’s worth sitting with for a second. Vegas has been keeping temperature records since 1937. Saturday landed second on that list, in a single afternoon.

Overnight lows aren’t giving anyone a break, either. They’ve been sitting in the high 80s to low 90s — which matters more than it sounds like it should. A dog (or a human) who’s spent the day heat-stressed needs the overnight hours to actually recover. When it doesn’t drop below 90°F until sunrise, that recovery mostly doesn’t happen. Heat stress stacks, day over day, instead of resetting.

If you’re anywhere in this warning zone with a dog, the short version is: this isn’t a “walk before 9 AM” situation. It’s a stay-inside situation until the Warning lifts.

The Festival That Sent 72 People to the Medical Tent

Saturday’s other data point came from 750 miles northeast, in Colorado Springs. The Tacos and Tequila Festival at UCHealth Park started at 1:30 p.m. with the high already climbing toward 97°F — tying the city’s 2025 record for the date. By the time the day wound down, Colorado Springs Fire Department and American Medical Response crews had treated 72 people for heat-related illness, with about 10 sent to hospitals for serious dehydration symptoms. The department pulled in extra units mid-event because the volume of patients outpaced what was originally staffed.

That’s people. Adults, standing on turf and asphalt in direct sun for hours, with water available and shade options nearby if they wanted them. A dog on a hot trail has none of those advantages — no shade options it can choose for itself, no ability to say “I need water now,” and a cooling system that runs entirely through panting and paw pads instead of sweat. If a heat advisory day put 72 healthy adults into medical tents at a stationary outdoor event, that same air isn’t something to test out on a hiking trail with a dog that can’t tap out.

How Do I Know If It’s Too Hot to Hike My Dog Today?

The fastest way to answer that question for your specific location:

1. Check NOAA’s HeatRisk map for your trailhead’s zip code, not your home zip code — mountain valleys and exposed ridgelines can run several degrees off the nearest city forecast.
2. Treat Level 4 (“Extreme”) as a hard cancel. No hike, no exceptions, regardless of what time you’d start.
3. Treat Level 3 (“Major”) as dawn-only, following the timing math in our summer hiking dawn-rule guide — and only if you’re back at the car before the day’s heat actually builds.
4. Check whether an NWS Extreme Heat Warning (not just a Heat Advisory) is active for your county — a Warning is the higher tier, reserved for conditions expected to cause widespread heat illness even in healthy people.
5. If in doubt, don’t. A missed hike costs you a Saturday. A heat emergency on trail costs a lot more, and rescue access in remote terrain is slower than you want it to be.

Who’s Actually Under This Dome Right Now

This isn’t a two-city story. Roughly 12 million people across the Southwest, Mountain West, and northern Great Plains are currently under Level 4 “Extreme” HeatRisk, with another 12 million or so sitting under Level 3 “Major” — put together, that’s north of 24 million people, and a good chunk of that footprint is exactly where this site’s readers hike. ABC News has been tracking the warnings spreading county by county as the ridge holds its position.

The pattern that’s easy to miss: elevation isn’t buying anyone protection here. We wrote about the same false assumption during last week’s Colorado wildfire smoke event — mountain towns aren’t automatically above a regional weather event just because they’re higher up. A heat dome works the same way. High-altitude trailheads warm slower in the morning, sure, but a dome this strong pushes triple digits into elevations that don’t usually see them, and the intense high-altitude sun does the rest.

Where This Goes Next

The forecast trend isn’t “this breaks in a day or two and everyone forgets about it.” Meteorologists are watching the dome push east into the Southern Plains and mid-Mississippi Valley through the week, with Denver, Albuquerque, and possibly Oklahoma City all forecast near or above 100°F. If your usual trail is in any of those metro areas, plan on this being a multi-day problem, not a weekend blip.

For Las Vegas specifically, some relief is finally on the forecast — a more meaningful cooldown is expected by midweek, bringing temperatures back toward normal mid-August levels. Until then, the Warning stands, and “normal” isn’t the word for what’s happening outside right now.

What to Actually Do With Your Dog This Week

If you’re anywhere inside this footprint, here’s the practical rundown:

• Check HeatRisk before you check the trail map, every single day this event runs — conditions are shifting fast enough that yesterday’s read doesn’t apply to today.
• Know your dog’s early warning signs before you need them. Our overheating warning signs guide covers the treat test and gum-color check that flag trouble before it becomes an emergency.
• If you do go out at dawn on a Level 3 day, check surface temperature, not just air temperature. Rock and pavement can run 30 to 50°F hotter than the air above them — our paw burn guide has the specifics on what that does to pads.
• Over-pack water, not under. Our summer hydration guide has the ounces-per-pound math, and heat-dome days are exactly when you want to round up, not down.
• Never leave the dog in the car “for a minute” at the trailhead. A parked car in this heat turns into an oven faster than most people expect — the specifics are in our car heat guide.
• If your dog does show heat stress, know the protocol before you’re standing there panicking. Our heatstroke emergency guide walks through field cooling steps that make the difference between a scare and a tragedy.

None of this is exotic advice. It’s the same heat-safety fundamentals we cover every summer. The difference this week is that the numbers backing it up aren’t theoretical — they’re 115°F at Harry Reid and 72 people in medical tents in Colorado Springs, both from the same Saturday.

Bottom Line

An Extreme Heat Warning is running for the Las Vegas Valley and the surrounding desert through Monday night, Harry Reid hit 115°F Saturday — a degree off the all-time record — and a Colorado Springs festival sent 72 people, roughly 10 of them to the hospital, into heat treatment the same afternoon. Around 24 million people across the Southwest, Mountain West, and northern Great Plains are under Major to Extreme heat risk right now, and the dome is pushing into the Southern Plains and mid-Mississippi Valley next.

If your trailhead sits anywhere in that footprint this week, check HeatRisk before you check anything else. Under a Warning, there isn’t a smart way to hike your dog around it — the smart move is not hiking, full stop, until the numbers actually change.

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Heat warning and temperature details sourced from the National Weather Service Las Vegas office and the Las Vegas Review-Journal. Colorado Springs festival details from the Colorado Springs Gazette. National heat risk footprint reporting from ABC News. Check current HeatRisk levels for your location at NOAA’s HeatRisk map before any hike — this is an active, evolving heat event, and conditions can shift within a single day.