If you’re planning a Memorial Day trip to Idaho, you’ll need to be ready for weather that can shift pretty quickly—from spring chill to early summer warmth. Most years, daytime highs land in the 60s to low 70s across much of the state, with nights often dropping into the 40s. Rain showers pop up now and then, and mountain areas sometimes hang onto a bit of snow. Lower valleys? They usually stay dry and mild.
Where you go really shapes your experience. Boise often feels warm and sunny by late May, but places like Idaho Falls and Sandpoint can hang onto cooler temps and a bigger chance of rain. One day you’ll get bluebird skies, and the next, clouds roll in. If you want to hike, camp, or boat, a little flexibility goes a long way.
Typical Memorial Day Weather in Idaho
Late May in Idaho usually brings mild to warm days, cool nights, and less heavy rain than early spring. Valleys tend to be warmer and drier, while mountain areas stay cooler and see more moisture.
Average Temperatures Across the State
By Memorial Day, southern Idaho often sees daytime highs in the 70s to low 80s°F. Boise averages near 72–75°F. Twin Falls and Pocatello usually land in the upper 60s to mid-70s. Nights cool off into the 40s to low 50s°F, so you’ll probably want a jacket after sunset.
In eastern Idaho, including Idaho Falls, highs usually stay in the mid to upper 60s°F. Nights here are colder, often falling into the upper 30s to mid-40s°F.
Northern Idaho, like Coeur d’Alene and Sandpoint, runs a bit cooler. Highs average in the mid to upper 60s°F, with lows in the 40s°F.
So, afternoons are usually comfortable for being outside, but mornings and evenings can feel chilly, especially if you’re up in elevation.
Precipitation Patterns and Rainfall
Late May marks the shift from wetter spring to drier summer. Boise gets about 1.0 inch of rain in May, spread over 5–6 days. Showers tend to be light and don’t last long.
Eastern Idaho, including Idaho Falls, picks up a little more rain—about 1.5 inches for the month. Passing showers happen, but long storms aren’t as common by now.
Northern Idaho is wetter. Sandpoint and Coeur d’Alene average 2.0 inches or more in May, with 8–9 days of rain. Cloudbursts happen more often, though they usually clear out fast.
Valleys don’t really see snow anymore, but mountain passes above 6,000 feet can still have snowpack hanging on.
Sunshine and Cloud Cover
By late May, Idaho enjoys a lot more sunshine. Boise clocks in about 14.8 hours of daylight, and skies are clear or mostly clear over 60% of the time. That makes southern Idaho one of the sunniest spots for the holiday.
Eastern Idaho gets similar daylight, but a bit more cloud cover. Skies are partly cloudy on many afternoons, though sunshine often breaks through by evening.
Northern Idaho stays cloudier. In Sandpoint and Coeur d’Alene, skies are clear or mostly clear only about 45–50% of the time in late May. You’ll probably wake up to overcast mornings, but sun breaks aren’t rare.
With this mix of daylight and clouds, you can plan outdoor stuff but should stay ready for a quick rain shower or two.
Regional Weather Variations
Idaho’s Memorial Day weather varies a lot depending on where you go. Temperatures, precipitation, and daylight hours can all shift between the northern panhandle, southern valleys, and higher mountains. These differences really matter if you’re planning outdoor activities or traveling around the state.
Northern Idaho Conditions
Northern Idaho, including towns like Sandpoint and Coeur d’Alene, usually stays cooler and wetter in late May. Average highs land in the upper 60s to low 70s °F, and nights often drop into the mid-40s °F. Rain is more common here, with about 1 to 1.5 inches falling during May.
Cloud cover is higher, too. Expect a lot of partly to mostly cloudy days, with not as many clear skies as southern Idaho. This keeps things green and lakes full, though.
If you’re heading to Lake Pend Oreille or hiking near the Selkirk Mountains, plan for cooler breezes and possible showers. Light jackets and waterproof gear come in handy up here.
Southern Idaho Conditions
Southern Idaho—think Boise, Twin Falls, and Idaho Falls—usually feels warmer and drier by Memorial Day. Daytime highs often reach 70–80°F, and lows run in the upper 40s to low 50s °F. Rainfall is lighter, averaging 0.5 to 1 inch for May, and storms don’t stick around.
Clear skies show up more in the Snake River Plain. Sunshine levels are higher, making outdoor events and barbecues more comfortable. Winds can still reach 6–9 mph, especially in open valleys, but the weather is generally mild.
If you’re camping, biking, or rafting, you’ll probably get dry weather and longer daylight hours. Light layers work, but evenings cool off after sunset.
Mountain Versus Valley Weather
The higher elevations in Idaho’s central and eastern mountains stay cooler and less predictable in late May. Highs usually range from the 50s to low 60s °F, with lows near freezing. Snow can linger above 7,000 feet, and some passes may still have patchy snow or wet conditions.
Valleys like Boise or Idaho Falls warm up faster and have steadier weather. These spots get longer stretches of clear sky and less rain, so travel and outdoor fun are easier.
If you’re hiking or camping in the mountains, pack extra layers and expect quick weather changes. Nights get cold, even if the valleys feel warm during the day.
Recent Memorial Day Weather Trends
Memorial Day in Idaho often brings a mix of warm valley sunshine and cooler, unsettled mountain weather. Patterns range from dry, sunny stretches to the occasional storm that might mess with your outdoor plans.
Notable Weather Events
In southern Idaho, Memorial Day weekends have often featured dry skies and mild breezes. Boise has had several years with clear, warm weather that made outdoor events and travel easy. Mountain regions like the Sawtooths and central Idaho have been prone to afternoon thunderstorms.
Rainfall events jump around. Some years bring above-average May rain, especially in Boise, where blocking weather patterns lead to wetter conditions. This can cause isolated storm activity during the holiday, even if the valleys stay mostly dry.
Thunderstorms in higher elevations can pop up fast. If you’re camping or hiking in the mountains, you might face brief but strong downpours, gusty winds, and lightning. These storms don’t last long, but they can throw off your afternoon or evening plans.
Valley areas like Boise usually get steadier weather, while mountain regions are more likely to see unsettled Memorial Day conditions.
Temperature Fluctuations in Recent Years
Memorial Day temperatures in Idaho usually stick close to seasonal averages, but swings happen. In Boise, the normal high is around the mid-70s °F, but recent years have often pushed into the low to mid-80s.
Some years, it’s even hotter, with highs hitting the upper 80s. That happens when high pressure builds over the region, bringing days of sunshine and above-average warmth.
Cooler years are less common, but they do pop up. On those, highs might stay in the 60s, especially if late-season systems bring clouds and some showers. Nights stay cool statewide, with lows in the 40s to low 50s in the valleys.
If you’re in the valleys, you’ll usually get comfortable warmth. Mountain visitors should prep for bigger swings between daytime highs and chilly nights.
Weather Impacts on Outdoor Activities
Idaho’s Memorial Day weather bounces between early summer warmth in the valleys and lingering winter in the mountains. These changes affect when and how you can enjoy camping, hiking, and other activities.
Best Times for Outdoor Events
Lower elevations like Boise and the Treasure Valley often reach the 70s or 80s °F during the day. That’s great for barbecues, biking the Greenbelt, or family gatherings in city parks. Clear skies are common, but afternoon winds sometimes pick up.
Mountain areas like McCall, Stanley, and the Sawtooths can still have snow on trails and campgrounds. Nighttime temps often dip near freezing, even if the valleys feel warm. Some higher-elevation campgrounds stay closed until June because of snowpack.
For the most reliable weather, plan events in valley locations or mid-elevation spots. Early afternoons usually offer the warmest and driest window before evening showers or storms show up.
| Location | Typical Highs (°F) | Conditions |
|---|---|---|
| Boise Valley | 70–85 | Warm, sunny, breezy |
| McCall/Stanley | 50–65 | Cool, possible showers, snow at higher trails |
| Eastern Idaho | 60–75 | Variable, chance of thunderstorms |
Precautions for Changing Conditions
You’ll want to prepare for sudden weather changes, especially in the mountains. Rain showers, thunderstorms, and even late snow aren’t out of the question. Waterproof gear, warm layers, and a tarp can save the day.
Always travel with backup plans. Roads to higher elevations might still be snow-covered or muddy, and cell service is spotty. Carry a paper map and compass in case you need to change your route.
Fire danger can rise quickly during warm, dry spells in southern Idaho. If winds pick up, follow fire restrictions and make sure campfires are out cold.
On the trails, practice good etiquette—yield to others, pack out your trash, and avoid muddy paths. If you’re ready for both warm valley weather and cold mountain nights, you’ll have a better time outside.
Comparing Memorial Day Weather to Other Months
Memorial Day in Idaho usually brings mild temps and a mix of sun and clouds, but things really depend on where you are. It helps to compare late May weather with earlier spring and the hotter summer months that follow.
Spring Versus Summer Weather
In southern Idaho cities like Boise, late May highs often reach the low 70s °F. That’s warmer than April, when highs average in the mid-60s °F, but cooler than June, when highs climb into the 80s °F. Nights around Memorial Day are still cool, often near 50 °F.
In eastern Idaho, such as Idaho Falls, May highs average in the upper 60s °F. March and April are still much cooler, with highs in the 40s and 50s °F. Then summer hits fast, with July highs in the mid-80s °F.
Rainfall changes, too. Boise gets about 1.0 inch of rain in May, but July drops to just 0.2 inches. Sandpoint in northern Idaho is wetter, averaging around 2.0 inches in May, though that’s still less than the heavy fall and winter months.
Memorial Day sits right in the transition. You’ll still see some spring showers and cool evenings, but the move toward longer days and drier skies is already starting.
May Weather Compared to June and July
By June, temperatures across much of Idaho really start to climb. In Boise, average highs usually reach around 82 °F, which feels about 10 degrees warmer than late May.
July turns up the heat even more, with highs near 92 °F and barely any rain to speak of.
In Idaho Falls, you’ll see May highs close to 67 °F. By June, those climb to about 77 °F and then hit 86 °F in July.
Nights don’t warm up as quickly, but by midsummer, lows stay in the 50s °F. Back in May, you’re more likely to get chilly nights in the 40s.
Rain keeps dropping off as summer shows up. Boise picks up about 1.0 inch of rain in May, but only 0.6 inch in June. By July, it’s nearly bone dry.
That trend is pretty common throughout Idaho, though the northern part of the state does hang onto a bit more moisture than the south.
If you’re planning outdoor stuff, Memorial Day often feels cooler and a bit unpredictable compared to June or July. You might still want a jacket after dark, but at least you won’t have to deal with the full-on midsummer heat.
Packing and Preparation Tips for Memorial Day in Idaho
Memorial Day in Idaho can bring warm afternoons, cool nights, and sometimes a chance of rain or even a late-season snow flurry if you’re up in the mountains.
You’ll want to pack with flexibility in mind, so you can stay comfortable whether you’re in Boise, Idaho Falls, or one of those mountain towns farther north.
Clothing Recommendations
During the day in southern Idaho cities like Boise, temperatures can reach the low 70s. At night, they might drop into the 40s.
If you’re heading to mountain spots like Sandpoint, expect cooler conditions and more rain than you’d get down south. Layering really helps you handle these ups and downs.
Bring lightweight base layers, a mid-layer fleece or sweater, and a water-resistant jacket. A compact down vest doesn’t take up much space and adds extra warmth.
For bottoms, quick-dry pants or jeans work well during the day, and thermal leggings are great if you’re planning to camp.
Footwear makes a big difference in Idaho’s mixed terrain. Hiking boots with solid traction come in handy for trails, while comfortable walking shoes are perfect for exploring towns.
Don’t forget moisture-wicking socks to keep your feet dry.
Even in spring, the sun can be surprisingly strong, so pack a wide-brimmed hat, sunglasses, and sunscreen.
A spare hat or cap is nice to have in case one gets wet.
Gloves and a beanie might come in handy if you’re heading up to higher elevations.
Gear for Variable Weather
Late May in northern Idaho? Yeah, rain showers sneak up pretty often. Toss a packable rain jacket or poncho in your bag, and if you’re hanging around town, grab a lightweight umbrella too.
If you’re camping, don’t forget a rainfly for your tent—trust me, you’ll need it.
Temperatures sometimes drop below freezing in Idaho Falls or up in the mountain valleys. I’d bring a 20–30°F rated sleeping bag and an insulated sleeping pad to stay cozy at night. Not camping? Just keep a warm blanket in your car for some extra peace of mind.
You’ll want reusable water bottles since the dry air and higher elevations can dry you out fast. If you’re cooking outside or hiking, pack stove fuel, waterproof matches, and a headlamp—better safe than sorry.
Memorial Day kicks off the busy season, so expect crowds. Reserve campsites early and bring backup maps just in case your cell service drops, which happens a lot in Idaho’s remote spots.
A small first-aid kit and insect repellent are pretty much must-haves, too.