The July 2026 Western Heat Wave Smashed the Northern Rockies — Montana Hit 115°F and 350 Records Fell in Three Days

The July 11–13, 2026 heat wave broke roughly 350 daily high-temperature records across the northern Rockies and Plains — and it did most of the damage in a single day. On July 12 alone, 217 stations set new daily heat records in our NOAA data. Miles City, Montana hit 115°F, twelve degrees above its old mark. Billings reached 111°F, Salt Lake City and Sheridan, Wyoming both touched 109°F, and the tiny badlands town of Medora, North Dakota hit 110°F.

Here's the number that tells the real story: of those 217 records, 109 replaced marks set in 2002 — the northern Rockies' last great mid-July heat event, and the year that had held the record book across Montana and Wyoming for a generation. This heat wave dethroned it at more than a hundred stations at once. We measured it the way we measure every heat event: by pulling each station's daily high from our NOAA records database and stacking July 2026 against every prior year on the same calendar day.

And it wasn't finished. This was the second major US heat wave in two weeks — the same dome that had already delivered a record-breaking July 4th heat wave on the East Coast rebuilt over the West, then began sliding toward the Midwest and Eastern Seaboard for July 14–16.

For most of the summer, the northern Rockies and high Plains are the country's relief valve — the place that stays merciful while the Southwest bakes. Not this week. A powerful upper-level ridge, the same kind of “heat dome” that torched the East Coast over the Fourth of July, rebuilt directly over Montana, Wyoming and the Dakotas. Air sinking under a ridge warms as it compresses, clears out the clouds, and lets the July sun cook the surface day after day. In a region built for 85–90°F summer afternoons, the thermometer ran 15 to 25 degrees hotter.

What makes an event like this stand out isn't one freak number — it's how many places broke records at the same time. When one town sets a daily record, that's weather. When Montana and Wyoming combine for more than 200 broken records inside 72 hours, the ridge was doing the same thing to an entire region. The peak landed on July 12, when 217 of our stations set new daily highs in a single day.

A record by one degree is a footnote. A record by nine, eleven, or thirteen degrees is a different animal — it means the day wasn't just hot for the date, it was hot for the place. These are the ones worth remembering:

• Miles City, MT — 115°F (July 12). Twelve degrees above the old July 12 record of 103°F, which had stood since 2002. This is one of the hottest readings ever logged in eastern Montana, and it ran the town past most of the Desert Southwest for the day.
• Big Sheep Mountain, MT — 111°F. A remote southeastern Montana site that broke its date record by a staggering 13°F— the single largest margin we found anywhere in the event.
• Billings, MT — 111°F (July 12). Montana's largest city cleared its old July 12 record (107°F, 2002) by four degrees after already hitting 104°F the day before.
• Salt Lake City, UT — 109°F (July 12). The city's hottest reading of 2026 and a new daily record, four degrees above the 105°F it hit in 2024. See how it fits Utah's longer history on our Utah records page.
• Medora, ND — 110°F (July 12), then 109°F (July 13). A Theodore-Roosevelt-country badlands town that beat a record set in 1985 by nine degrees — and then did it again the next day, one of the few northern-Plains sites to break records on back-to-back days.

Wyoming quietly led the whole event: 106 broken records over three days, more than any other state, including 109°F at Sheridan and triple digits across the Powder River and Bighorn basins. It was the epicenter, even if Montana produced the loudest single number.

Dig into the previous records and a single year keeps appearing: 2002. Of the 217 daily records that fell on July 12, 109 — slightly over half — had been set in July 2002, the northern Rockies' benchmark heat event of the last quarter century. For 24 years, if you looked up the hottest July 12 in Miles City, Billings, or a hundred ranch stations across Montana and Wyoming, the answer was “2002.” This week, at all of them at once, the answer became “2026.”

That's the tell that separates a hot day from a climatologically significant one. Beating a record set last year is noise. Beating a record that has survived every summer since 2002 — simultaneously, across an entire mountain region — is signal.

The immediate consequence is fire. Weeks of heat on top of a dry spring have turned the northern Rockies into tinder: NIFC counted more than 3.6 million acres burned nationwide by mid-July with 46 uncontained large fires and the country at Preparedness Level 4. Utah alone had burned more acreage by early July than it did in the previous five years combined. You can watch the fires burning right now on our live wildfire tracker, and see how this season fits the pattern in our 2026 wildfire season analysis.

The heat itself didn't dissipate — it moved. The same ridge was forecast to expand east for July 14–16, pushing into the Midwest and up the Eastern Seaboard. The National Weather Service warned the heat would be “exceptionally rare for mid-July,” with widespread 95–105°F highs and the potential to approach monthly and all-time records; forecasters flagged readings near 103°F in New York and up to 107°F in Philadelphia. Phoenix and Tempe, meanwhile, kept doing what they do — 110°F and up.

Zoom out and the frequency is the story. This was the second coast-to-coast heat wave in two weeks, on the heels of a summer that's tracking toward the hottest year on record. Our Summer 2026 outlook flagged above-normal heat for most of the country, and a developing El Niño nudges the dial further. A warmer baseline means the same weather pattern that produced a 103°F day in Miles City in 2002 now produces 115°F. You don't need the pattern to be more extreme; you just need to start it from a hotter floor. For the all-time context, our hottest temperatures ever recorded page shows how far even 115°F sits below Death Valley's ceiling — but for eastern Montana, it was historic.

Curious what your own city did on any date? Our historical weather lookup pulls the daily high and low for any US location going back decades — type in a date and see how July 2026 stacks up where you live.