Tracking a big change for Labor Day weekend
🌤️ LABOR DAY WEEKEND / EASTERN IDAHO STATE FAIR FORECAST
The fair starts with sunshine, but don't let the blue sky fool you — the second half of the holiday weekend is a different weather animal.
A slow-moving FLO-rida-low-type circulation off Washington is helping draw additional moisture north and east into Idaho. That moisture begins feeding into the central mountains this weekend, and eventually works its way into eastern Idaho and western Wyoming.
So, if you're making plans for the Eastern Idaho State Fair in Blackfoot, here's the cheat sheet:
FRIDAY — FAIR OPENING DAY ☀️
Think sunglasses, sunscreen and layers.
Blackfoot should be sunny with a high around 76–80°, with a noticeable southwest breeze. Winds could run around 10–20 mph with gusts near 20–25 mph, particularly during the afternoon.
Morning: Chilly enough for a light jacket or sweatshirt — temperatures in the 40s.
Late morning/noon: Quickly warming into the 60s and 70s.
Afternoon: The warmest part of the day, near 80°, with the breeze making it feel noticeably cooler in the shade.
Evening at the fair: Comfortable at first, but temperatures slide quickly after sunset. Bring the jacket for FLO-rida show tonight.
What to wear: T-shirt + light jacket. Sunglasses and sunscreen. If you're hauling around a fair hat, hang onto it — the breeze may try to adopt it.
SATURDAY — THE CAMPING & FAIR DAY ☀️🌬️
This may be the best overall weather day of the weekend.
Blackfoot is looking at mostly sunny skies and temperatures around 80°, with southwest winds generally 10–15 mph and gusts potentially around 20 mph.
But Saturday morning is a different story.
If you're camping, expect a brisk start in the 40s.
6–8 AM: Hoodie/jacket weather. Coffee weather. “Why did I bring shorts?” weather.
9–11 AM: Temperatures climb through the 50s and 60s.
Noon–4 PM: Warmest part of the day — around 75–80°, with a breeze.
4–7 PM: Still pleasant for rides, livestock shows and fair food.
After sunset: Jacket time again. Temperatures tumble back toward the 40s overnight.
What to wear: Hoodie in the morning, T-shirt in the afternoon, jacket for the evening.
And secure those tents, canopies and lightweight decorations — the wind is the weekend's sneaky troublemaker.
🌦️ SUNDAY — WEATHER TURNING
This is when the forecast gets interesting.
Sunday may start looking like another beautiful fair day, with sunshine and temperatures potentially reaching the upper 70s or around 80°.
But moisture is increasing.
The National Weather Service currently has a 30% chance of afternoon rain around Idaho Falls/Blackfoot, with the bigger change coming Sunday night.
Sunday timeline
Morning: Mostly sunny and comfortable.
Noon–3 PM: Clouds begin building, especially around higher terrain.
Afternoon: Isolated showers or thunderstorms become possible.
Evening: The odds increase.
Sunday night: This is the big transition.
Showers become likely, with thunderstorms possible, and the chance of precipitation rises to around 70% in the overnight period.
Fair-goer advice: If you're going Sunday, take the rain gear even if the sky looks fine when you leave home.
And if you're camping Sunday night, this is the night I'd be most concerned about having everything secured, covered and waterproofed.
⛈️ LABOR DAY MONDAY — COOLER, WETTER
This is where summer basically gets its eviction notice.
Blackfoot's forecast drops sharply into the upper 60s, with rain chances continuing Monday. The current NWS forecast has a 40% chance of rain before noon, followed by some improvement, although showers and thunderstorms can remain possible.
Early morning: Cloudy, damp and chilly — around the 40s.
Morning: Periods of rain possible.
Late morning/noon: Rain chances decrease somewhat.
Afternoon: Some breaks of sun are possible, but don't completely put the umbrella away.
High: Around 67°.
That's a huge difference from the warm sunshine expected Friday and Saturday.
Monday wardrobe: Jeans, long sleeves, waterproof jacket. This is not your shorts-and-flip-flops fair day.
📍 BLACKFOOT FAIR WEATHER AT A GLANCE
| Day | Weather | High | Wind | Fair Strategy |
|---|---|---|---|---|
| Friday | ☀️ Sunny/breezy | 76–80° | 10–20 mph, gusts 20–25 | Light layers |
| Saturday | ☀️ Sunny/breezy | ~80° | 10–15 mph, gusts ~20 | Hoodie AM, T-shirt PM |
| Sunday | ☀️ → ⛈️ | Upper 70s/around 80° | Variable | Rain gear nearby |
| Sunday Night | 🌧️⛈️ Wet | 40s | Gusty possible | Secure camping gear |
| Labor Day | 🌧️ → 🌤️ | ~67° | Breezy | Jacket/long sleeves |
The current NWS forecast also shows Idaho Falls following essentially the same progression: sunny Friday/Saturday, increasing rain chances Sunday, 70% Sunday night, then a much cooler Monday around 67°.
🌲 EASTERN IDAHO & WESTERN WYOMING
The mountains are going to be the first place that really notices the moisture increase.
Friday and Saturday remain largely favorable for outdoor plans, but you'll see clouds developing around the higher terrain as the weekend progresses. By Sunday, showers and thunderstorms become more widespread, with the greatest concern Sunday afternoon through Sunday night and into Labor Day.
For Jackson, Teton Valley, Island Park, Swan Valley and the higher elevations, remember that temperatures can be 10–20° colder than the valley, especially after sunset and when rain moves through.
If you're heading into the mountains:
Friday/Saturday: Layers, windbreaker, sunglasses.
Sunday: Add rain shell and waterproof footwear.
Sunday night/Monday: Treat it like early fall — warm layer, rain protection and a backup plan
Jeff Roper, First Alert Weather
