Sealcoat interval
Severe-tier lots need sealcoat every 2 years. Stretching to 4 in a 110-cycle market is how a lot ends up needing an overlay a decade early.
See sealcoating program Free Dataset · Updated 2026
The Freeze–Thaw Index for Northern Pavement
Annual snowfall does not destroy asphalt — crossing 32°F over and over does. This index models how many freeze–thaw cycles hit 25 markets across Montana, Idaho, Washington, North Dakota and South Dakota each year, and what that means for your sealcoat window and service interval. Free to use and cite.
The Data
Freeze–Thaw Cycles by Market
Sort by cycle load or elevation. Severe markets (100+ cycles) degrade roughly twice as fast as moderate ones under identical traffic.
| Sealcoat window | First hard freeze | Recommended interval | Tier | |||
|---|---|---|---|---|---|---|
| West Yellowstone, MT | 135 | 6,667 ft | Jun 15 – Aug 31 | Sep 5 – Sep 20 | Every 2 years | Severe |
| Butte, MT | 125 | 5,538 ft | Jun 1 – Sep 10 | Sep 15 – Sep 30 | Every 2 years | Severe |
| Bozeman, MT | 115 | 4,820 ft | May 20 – Sep 20 | Sep 25 – Oct 10 | Every 2 years | Severe |
| Helena, MT | 110 | 3,875 ft | May 15 – Sep 25 | Sep 30 – Oct 12 | Every 2 years | Severe |
| Great Falls, MT | 110 | 3,330 ft | May 15 – Sep 25 | Sep 28 – Oct 10 | Every 2 years | Severe |
| Whitefish, MT | 105 | 3,033 ft | May 25 – Sep 15 | Sep 25 – Oct 8 | Every 2 years | Severe |
| Rapid City, SD | 105 | 3,202 ft | May 10 – Oct 1 | Oct 1 – Oct 15 | Every 2 years | Severe |
| Columbia Falls, MT | 100 | 3,081 ft | May 25 – Sep 15 | Sep 25 – Oct 8 | Every 2 years | Severe |
| Kalispell, MT | 100 | 2,956 ft | May 20 – Sep 20 | Sep 28 – Oct 12 | Every 2 years | Severe |
| Hamilton, MT | 100 | 3,572 ft | May 15 – Sep 25 | Sep 25 – Oct 10 | Every 2 years | Severe |
| Bismarck, ND | 95 | 1,686 ft | May 10 – Sep 25 | Sep 30 – Oct 12 | Every 2–3 years | High |
| Billings, MT | 95 | 3,123 ft | May 5 – Oct 5 | Oct 5 – Oct 18 | Every 2–3 years | High |
| Bigfork, MT | 95 | 2,903 ft | May 25 – Sep 15 | Sep 30 – Oct 12 | Every 2–3 years | High |
| Polson, MT | 90 | 2,933 ft | May 20 – Sep 20 | Oct 1 – Oct 15 | Every 2–3 years | High |
| Somers, MT | 90 | 2,926 ft | May 25 – Sep 15 | Sep 30 – Oct 12 | Every 2–3 years | High |
| Lakeside, MT | 90 | 2,946 ft | May 25 – Sep 15 | Sep 30 – Oct 12 | Every 2–3 years | High |
| Missoula, MT | 90 | 3,209 ft | May 10 – Sep 30 | Oct 5 – Oct 18 | Every 2–3 years | High |
| Fargo, ND | 90 | 902 ft | May 10 – Sep 30 | Oct 1 – Oct 12 | Every 2–3 years | High |
| Sandpoint, ID | 85 | 2,100 ft | May 20 – Sep 20 | Oct 5 – Oct 20 | Every 2–3 years | High |
| Sioux Falls, SD | 85 | 1,450 ft | May 5 – Oct 1 | Oct 5 – Oct 18 | Every 2–3 years | High |
| Coeur d'Alene, ID | 75 | 2,188 ft | May 15 – Sep 30 | Oct 10 – Oct 25 | Every 3 years | Moderate |
| Post Falls, ID | 75 | 2,172 ft | May 15 – Sep 30 | Oct 10 – Oct 25 | Every 3 years | Moderate |
| Hayden, ID | 75 | 2,251 ft | May 15 – Sep 30 | Oct 8 – Oct 22 | Every 3 years | Moderate |
| Boise, ID | 70 | 2,704 ft | Apr 25 – Oct 10 | Oct 20 – Nov 5 | Every 3 years | Moderate |
| Spokane, WA | 70 | 1,843 ft | May 10 – Oct 5 | Oct 10 – Oct 25 | Every 3 years | Moderate |
Methodology
- Cycle definition. A freeze–thaw cycle is a 24-hour period where the daily minimum falls below 32°F and the daily maximum rises above it. Counts are modeled from NOAA 1991–2020 daily climate normals at the nearest first-order station to each market.
- Rounding. Values are rounded to the nearest 5 cycles. Treat them as planning estimates for maintenance budgeting, not as measured station output for any single year.
- Sealcoat windows. Based on the application rule our crews run: surface temperature 50°F and rising, no precipitation forecast for 24 hours, and 8+ hours of daylight cure before overnight lows fall back under 50°F.
- Tiers. Severe = 100+ cycles · High = 80–99 · Moderate = 60–79. Deferring crack sealing effectively moves a market up one tier, because open cracks let water reach the base course where each cycle does the most damage.
Cite this dataset
The Freeze–Thaw Index is free to quote, reproduce, and build on for editorial, academic, municipal, and property-management use — with attribution and a link back.
Summit Surface Partners. “The Freeze–Thaw Index for Northern Pavement.” 2026. https://www.summit-surface.com/resources/freeze-thaw-index
Writing about pavement, winter operations, or municipal infrastructure in our territory and want the underlying breakdown by market? Contact our team and we will send it over.
Put It To Work
What the Cycle Count Should Change
Three decisions the index answers for a property manager or public works director.
Crack sealing priority
Every open crack multiplies the damage each cycle does. In severe markets, hot-pour crack sealing is the highest-return line item on the budget.
See crack sealingWinter treatment plan
High cycle counts mean repeated melt-refreeze on the surface. Anti-icing with brine before the event beats reactive salting after it.
See snow & ice managementFAQ
Freeze–Thaw Questions
Want your own lot scored against its market's cycle load?
Request a pavement assessment