STR Owner Resource

Summit County Colorado Weather: The Pre-Arrival Guide Every STR Host Should Share

The weather questions your guests will ask before, during, and after arrival, answered in one place, ready to share.

Timberline Properties
Summit County, Colorado
6 min read

Summit County sits between 9,000 and 13,000 feet and has some of the most variable weather in Colorado. Guests who have never stayed at altitude arrive expecting a mountain vacation and are often surprised by how differently the weather behaves. Snow in June. Thunderstorms that build over the Ten Mile Range and arrive by 2pm. Mornings cold enough for a coat, afternoons warm enough for a t-shirt.

None of this is dangerous if guests know what to expect. Most weather-related issues in STR stays, the panicked texts, the early checkouts, the reviews that mention "the weather was unpredictable," come from guests who were not prepared. This guide changes that.

A note for hosts

Drop the link to this page in your pre-arrival message, or download the printable version below and add it to your welcome book. Guests who know what Summit County weather does arrive better prepared, stay more comfortable, and review more favorably.

☀️
Summer
Jun · Jul · Aug
Days: 65–75°F
Nights: 35–50°F
Storms: most afternoons
🍂
Fall
Sep · Oct
Days: 40–60°F
Nights: 15–35°F
Snow: possible Sep 1
❄️
Winter
Nov · Feb · Mar
Days: 20–40°F
Nights: -5–15°F
Heavy snow typical
🌱
Spring
Apr · May
Days: 40–60°F
Nights: 20–35°F
Mud season, variable
🌡

General Weather at Altitude in Summit County, Colorado

How high is Summit County and why does it matter for weather?

Breckenridge sits at 9,600 feet above sea level. Frisco, Dillon, and Silverthorne sit at approximately 9,000 feet, and Keystone is around 9,300 feet. Properties on the hillsides above town can be significantly higher. At this elevation, weather behaves differently than guests are used to. Air is thinner, UV is stronger, temperatures swing dramatically between morning and afternoon, and storms form and move faster than at lower elevations. The weather is not dangerous if you know what to expect, but it will surprise anyone who comes unprepared.
Check the forecast the morning of any outdoor activity. What starts as a clear summit day can change by noon.

Can it snow any time of year?

Yes. Snow has been recorded in Summit County in every month of the year. July and August snowfall is rare in town but occurs above 12,000 feet with some regularity. September is when snow becomes a realistic possibility at any elevation for any given week. By October, significant snowfall is common and the ski season often begins. Guests visiting in spring or fall should be prepared for winter conditions regardless of what the forecast shows when they leave home.

How much can the temperature change in a single day?

Temperature swings of 30 to 40 degrees between morning low and afternoon high are common in Summit County, especially in spring and fall. A morning that starts at 30°F can reach 65°F by 2pm. A warm afternoon can drop sharply when a storm moves in from the west. Guests should dress in layers and never assume the morning weather represents the rest of the day.
Layers, not just a jacket. The difference between 9am and 3pm in Summit County can be significant enough to need a different outfit entirely.
⛈

Summer Thunderstorms in Summit County

Are afternoon thunderstorms common in summer?

Very. Summer thunderstorms are the single most predictable weather pattern in Summit County. Most afternoons between late June and mid-August, storms build over the Ten Mile Range and the Gore Range and move through the area, typically arriving between 1pm and 4pm. They can bring heavy rain, hail, lightning, and rapid temperature drops, then clear within an hour. Guests planning hikes or time above treeline should plan to be back at the trailhead before noon if storms are in the forecast.
Lightning above treeline is a serious hazard. Get off ridges, peaks, and open terrain immediately when clouds begin building, even if the storm looks distant.

Can it hail in summer?

Yes. Hail is a regular part of Summit County summer storms. Most hailstones are small, but larger hail is possible during more intense cells. Guests with rental cars or convertibles should be aware and can check storm forecasts at weather.gov. Hail during a storm is typically short-lived but can be intense at elevation.

Where can we check the forecast for real-time storm tracking?

The National Weather Service (weather.gov) provides detailed forecasts for Summit County. For real-time radar, apps like RadarScope or the Weather Channel app are reliable. Mountain forecasts change quickly — checking the morning of is more useful than checking the night before for any outdoor planning above 11,000 feet.
🌨

Winter Conditions in Summit County, Colorado

How cold does it get in winter?

Very cold. Overnight temperatures in January and February in Breckenridge regularly fall to -5°F or colder. Properties at higher elevations, on exposed ridges, or in valley locations sheltered from sun can be even colder. Daytime highs in midwinter typically reach the 20s and 30s on a sunny day. Wind chill on the mountain or above treeline can make temperatures feel extreme. Guests should pack true winter gear: insulated base layers, heavy coats, gloves, hats, and warm socks. Casual winter clothing appropriate for Denver or the Front Range is not sufficient.
Pipes in some mountain properties can freeze if the heat is turned too low. Never set the thermostat below 60°F, even overnight.

How much snow does Summit County get?

Breckenridge town receives approximately 100 to 120 inches of snow annually. Ski resort terrain above town receives over 300 inches in a good season. Winter storms can deposit a foot or more of snow in a single day. Streets, driveways, and walkways require regular plowing throughout the winter season. Hosts should communicate clearly whether plowing is included and what the turnaround time is after a significant storm.

Do we need four-wheel drive in winter?

Yes, for most Summit County property locations. Colorado's traction law is regularly in effect on I-70 through the mountains and requires traction tires or chains on all vehicles. County roads and driveways outside of town require four-wheel drive or all-wheel drive. Even with 4WD, guests should drive slowly on snow-packed and icy roads, particularly on side streets and private driveways. Check current traction requirements at cotrip.org before driving in.
Front-wheel drive is not adequate for most Summit County winter road conditions. If guests have FWD, check with your host about driveway and road access before arrival.

What should we do if we get snowed in?

Stay at the property and let main roads improve rather than attempting to drive on unplowed side streets and driveways. Most significant storms in Summit County clear within 12 to 24 hours, and I-70 is plowed as a high priority. If plowing is needed at the property, contact your host. Keep emergency supplies in your vehicle: a blanket, jumper cables, water, and a small bag of sand or kitty litter for traction.
🛣

Summit County Road Conditions and Mountain Driving

Where do we check road conditions before driving in?

Colorado Department of Transportation provides real-time road and pass conditions at cotrip.org and via the COTRIP app. Always check I-70 corridor conditions and the status of the Eisenhower-Johnson Tunnel before leaving. For county road conditions, call Summit County Public Works at 970-668-4210.

Can I-70 and mountain roads close during storms?

Yes. I-70 can close temporarily during severe winter storms, and the Eisenhower-Johnson Tunnel, the primary route between Denver and Summit County, can have traction requirements or brief closures during extreme conditions. Closure and delay information is updated in real time at cotrip.org. If roads close, the safest course of action is to wait at your current location rather than attempting to drive. Closures are typically lifted within a few hours once CDOT clears the corridor.

What about spring road conditions?

April and May bring variable conditions in Summit County. I-70 and main roads in Breckenridge, Frisco, and Silverthorne remain accessible, but unpaved roads to properties off the main corridors can be soft, muddy, and difficult even for 4WD vehicles. Guests visiting in spring should check specifically with their host about road access to the property and whether conditions could affect arrival or departure.
🏔

Altitude Sickness in Summit County, Colorado

Can you get altitude sickness in Summit County?

Yes. Summit County sits between 9,000 and 11,000 feet in the valley communities, with ski terrain climbing to 13,000 feet and above. Altitude sickness is common, especially for guests arriving from sea level or low-elevation cities. Symptoms include headache, fatigue, shortness of breath, dizziness, and nausea. Guests driving up I-70 from Denver gain nearly 4,000 feet of elevation in roughly an hour. Most guests feel some effect in the first 24 to 48 hours, and symptoms usually resolve as your body adjusts.
Start hydrating the day before you arrive, not when you get there. Dehydration significantly worsens altitude symptoms at elevation.

How do you prevent altitude sickness at 9,000 to 10,000 feet?

Arrive a day early if possible to allow your body to adjust before strenuous activity. Drink more water than you think you need, at least 3 to 4 liters per day. Avoid alcohol for the first 24 hours, it accelerates dehydration and worsens symptoms considerably at altitude. Take it easy on arrival day and avoid intense hiking or exercise until you have had at least one full night at elevation. Ibuprofen or Tylenol can help with altitude headaches. If symptoms are severe or do not improve within 48 hours, descend to lower elevation.

What elevation is Breckenridge, Colorado?

Breckenridge sits at 9,600 feet above sea level. Frisco, Dillon, and Silverthorne are approximately 9,000 feet. Keystone is around 9,300 feet. Properties on the hillsides above town can be at 10,000 feet or higher. Ski resort terrain at Breckenridge reaches 12,998 feet at the highest lift-served area, making it one of the highest ski areas in North America.
☀️

Sun, UV, and Dry Air at High Altitude

Is the sun stronger at altitude?

Significantly. UV radiation increases roughly 10% for every 1,000 feet of elevation. At 9,600 feet in Breckenridge, you are receiving approximately 20 to 25% more UV exposure than at sea level. On the ski mountain at 12,000 feet, that increases to roughly 35% more. Snow and water reflect UV back up from below, compounding the exposure. Sunburn happens faster than guests expect, even on cloudy days and even in winter. SPF 50 or higher is recommended for any time spent outdoors at any season.
Apply sunscreen before going outside. At altitude you often will not feel the burn building until it is already done.

Why do we feel so dried out at altitude?

The air at high altitude holds significantly less moisture than at lower elevations. Guests commonly experience dry skin, chapped lips, dry nasal passages, and increased thirst within the first day or two. Drinking more water than usual helps, as does bringing or buying a good lip balm and hand lotion. Nosebleeds are more common at altitude, particularly in winter when indoor heat removes additional moisture from the air.
🎒

What to Pack for Summit County by Season

Summer (Jun–Aug)
  • Layers, mornings and evenings are cool
  • Rain jacket or packable poncho
  • SPF 50+ sunscreen
  • Sunglasses with UV protection
  • Light fleece or hoodie
  • Water bottle, hydrate more than usual
  • Closed-toe shoes for hiking
Fall (Sep–Oct)
  • Winter coat, temperatures drop quickly
  • Gloves, hat, and scarf
  • Waterproof boots
  • Snow scraper for the car
  • Extra layers for unexpected cold snaps
  • Lip balm and hand lotion for dry air
Winter (Nov–Mar)
  • Heavy insulated coat
  • Thermal or wool base layers
  • Insulated waterproof boots
  • Heavy gloves and warm hat
  • Snow chains or cables (check traction law)
  • Ice scraper and snow brush
  • Emergency kit in the car
Spring (Apr–May)
  • Waterproof or mud-resistant boots
  • Layers for variable conditions
  • Rain jacket
  • Expect snow and mud, plan accordingly
  • Check road conditions before arrival
Free Printable
Summit County Weather Reference Card
One-page printable version, perfect for your welcome book or guest packet.
Download Printable
Timberline Properties

We Keep Summit County Properties Guest-Ready Year-Round.

Turnover cleaning, hot tub maintenance, snow removal, and property services for STR owners across Breckenridge, Frisco, Dillon, Silverthorne, and Keystone.

Learn More