NOAA data, computed here
How long does a storm sit? Episode length by state and weather type
Weather pages count how many days a storm touches a state. This one measures how long each system lasts: five years of National Weather Service episodes, from the first warning to the last, by state and type, with a calculator for the hours your trucks might be stopped.
Five yearsNOAA NCEI Storm Events Database, 2021 to 2025Events started from January 1, 2021 to December 31, 2025Retrieved Oct 10, 2026, 06:22 UTCretrieved Oct 10, 2026
Read this first
An episode length is the span of National Weather Service warnings and advisories in one state, not the time roads were closed or your trucks were stopped. Counts depend on how closely each office logs events. This is history, not a forecast, and it says nothing about your lane on a given day. The stopped-share and cost in the calculator are your own estimates.
What a storm costs your parked trucks
Pick a state and a type of weather. The charts show how long such episodes last and when they start.
California, winter weather: episodes by length
Episodes by length in whole hours.
California, winter weather: episodes by start month
Month the episode started, 2021 to 2025.
Pre-filled values are Example data. Replace them with your own.
Cost of a typical episode, all trucks
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- Episodes a year in the state
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- Median length
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- Length reached 9 times in 10
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- Cost of a long episode (90th percentile)
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- Episodes a year that reach you
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- Expected cost a year
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Enter your trucks.
Formula: cost of an episode = trucks x episode hours x share stopped x cost per stopped hour. Episodes that reach you a year = episodes a year x share that reach you. Expected cost = reached episodes x cost at the median length. Integer cents, rounded once. Nothing you type leaves this page.
Winter weather by state
Click a heading to sort. States with at least 10 episodes in 5 years. Lengths are whole hours; shares are of that state's episodes.
| State | Episodes | Per year | Median length | 90th percentile | A day or more | Two days or more | Busiest start month |
|---|---|---|---|---|---|---|---|
| Alabama | 32 | 6.4 | 12 h | 34 h | 21.9% | 3.1% | Jan (16) |
| Alaska | 360 | 72.0 | 29 h | 68 h | 61.9% | 23.9% | Dec (72) |
| Arizona | 72 | 14.4 | 24 h | 50 h | 55.6% | 15.3% | Jan (21) |
| Arkansas | 93 | 18.6 | 19 h | 39 h | 39.8% | 5.4% | Jan (42) |
| California | 447 | 89.4 | 26 h | 64 h | 68.9% | 24.2% | Mar (104) |
| Colorado | 424 | 84.8 | 30 h | 60 h | 66.3% | 22.4% | Mar (80) |
| Connecticut | 72 | 14.4 | 14 h | 26 h | 20.8% | 1.4% | Feb (27) |
| Delaware | 27 | 5.4 | 10 h | 22 h | 7.4% | 0.0% | Jan (11) |
| District of Columbia | 18 | 3.6 | 11 h | 30 h | 27.8% | 0.0% | Jan (11) |
| Georgia | 24 | 4.8 | 16 h | 24 h | 16.7% | 4.2% | Jan (20) |
| Hawaii | 11 | 2.2 | 33 h | 58 h | 63.6% | 36.4% | Apr (3) |
| Idaho | 217 | 43.4 | 26 h | 77 h | 59.0% | 24.0% | Dec (54) |
| Illinois | 125 | 25.0 | 14 h | 30 h | 28.0% | 2.4% | Jan (48) |
| Indiana | 140 | 28.0 | 14 h | 32 h | 21.4% | 2.9% | Jan (48) |
| Iowa | 126 | 25.2 | 16 h | 36 h | 30.2% | 5.6% | Jan (45) |
| Kansas | 133 | 26.6 | 14 h | 35 h | 27.1% | 3.8% | Jan (49) |
| Kentucky | 101 | 20.2 | 17 h | 35 h | 33.7% | 1.0% | Jan (39) |
| Louisiana | 24 | 4.8 | 18 h | 38 h | 33.3% | 4.2% | Jan (11) |
| Maine | 140 | 28.0 | 15 h | 28 h | 17.9% | 0.7% | Jan (35) |
| Maryland | 162 | 32.4 | 15 h | 29 h | 21.0% | 0.6% | Jan (60) |
| Massachusetts | 75 | 15.0 | 18 h | 32 h | 30.7% | 0.0% | Jan (24) |
| Michigan | 251 | 50.2 | 23 h | 53 h | 49.4% | 19.1% | Feb (60) |
| Minnesota | 283 | 56.6 | 17 h | 45 h | 33.9% | 9.2% | Dec (76) |
| Mississippi | 35 | 7.0 | 13 h | 29 h | 17.1% | 0.0% | Feb (17) |
| Missouri | 113 | 22.6 | 16 h | 33 h | 29.2% | 1.8% | Jan (54) |
| Montana | 300 | 60.0 | 26 h | 62 h | 58.0% | 20.3% | Dec (69) |
| Nebraska | 156 | 31.2 | 18 h | 42 h | 35.9% | 9.0% | Jan (49) |
| Nevada | 191 | 38.2 | 25 h | 57 h | 75.4% | 17.8% | Mar (47) |
| New Hampshire | 42 | 8.4 | 16 h | 29 h | 28.6% | 0.0% | Jan (14) |
| New Jersey | 83 | 16.6 | 12 h | 23 h | 8.4% | 1.2% | Feb (30) |
| New Mexico | 88 | 17.6 | 21 h | 42 h | 45.5% | 6.8% | Jan (25) |
| New York | 302 | 60.4 | 20 h | 44 h | 42.7% | 8.6% | Feb (76) |
| North Carolina | 111 | 22.2 | 16 h | 33 h | 18.0% | 1.8% | Jan (69) |
| North Dakota | 92 | 18.4 | 18 h | 51 h | 39.1% | 13.0% | Feb (23) |
| Ohio | 132 | 26.4 | 17 h | 36 h | 28.8% | 0.8% | Jan (47) |
| Oklahoma | 64 | 12.8 | 16 h | 34 h | 29.7% | 1.6% | Feb (31) |
| Oregon | 142 | 28.4 | 33 h | 65 h | 79.6% | 25.4% | Feb (42) |
| Pennsylvania | 268 | 53.6 | 14 h | 34 h | 23.5% | 3.0% | Jan (82) |
| South Carolina | 27 | 5.4 | 14 h | 20 h | 0.0% | 0.0% | Jan (21) |
| South Dakota | 190 | 38.0 | 19 h | 45 h | 36.8% | 8.9% | Mar (45) |
| Tennessee | 94 | 18.8 | 14 h | 35 h | 27.7% | 1.1% | Jan (42) |
| Texas | 130 | 26.0 | 17 h | 39 h | 34.6% | 6.2% | Feb (64) |
| Utah | 163 | 32.6 | 36 h | 69 h | 76.7% | 28.2% | Mar (40) |
| Vermont | 102 | 20.4 | 17 h | 36 h | 35.3% | 2.0% | Jan (28) |
| Virginia | 174 | 34.8 | 17 h | 34 h | 30.5% | 2.3% | Jan (72) |
| Washington | 211 | 42.2 | 29 h | 71 h | 67.3% | 28.0% | Dec (61) |
| West Virginia | 242 | 48.4 | 18 h | 36 h | 31.0% | 4.1% | Jan (89) |
| Wisconsin | 246 | 49.2 | 16 h | 34 h | 24.8% | 3.7% | Dec (62) |
| Wyoming | 318 | 63.6 | 26 h | 55 h | 60.1% | 17.3% | Feb (61) |
Source: NOAA NCEI Storm Events Database, retrieved Oct 10, 2026. Episodes per state, not per storm: a system over two states is in both rows. Nearest-rank percentiles. Busiest month shows the number of episodes that started in it.
All five weather types, all states pooled
The same measures for each type of weather, with every state's episodes in one list.
| Weather type | Episodes | Median length | 90th percentile | A day or more | Two days or more | Busiest start month |
|---|---|---|---|---|---|---|
| Winter weather (snow, ice, blizzard, sleet, freezing fog) | 7,385 | 20 h | 49 h | 44.1% | 11.9% | Jan (1951) |
| High wind (high wind, strong wind) | 5,765 | 6 h | 25 h | 12.1% | 3.0% | Mar (917) |
| Flooding (flash flood, flood, coastal and lakeshore flood) | 8,005 | 4 h | 52 h | 18.3% | 11.1% | Jul (1665) |
| Dense fog | 682 | 8 h | 17 h | 5.7% | 2.6% | Dec (160) |
| Heat (excessive heat, heat) | 1,978 | 34 h | 128 h | 63.5% | 45.7% | Jul (737) |
Source: NOAA NCEI Storm Events Database, retrieved Oct 10, 2026. Groups: Winter weather: winter storm, heavy snow, blizzard, ice storm, lake-effect snow, winter weather, sleet, freezing fog; High wind: high wind, strong wind; Flooding: flash flood, flood, coastal flood, lakeshore flood; Dense fog: dense fog; Heat: excessive heat, heat.
What this number means
- The median says what a typical system looks like; the 90th percentile is the one to plan a cash buffer around.
- A short median with a long tail means most storms pass quickly and a few sit: budget for the few.
- These are warnings logged in a state. The real stop for a truck on a pass or a bridge can be longer or shorter.
What to do about it
- Run the calculator with your own cost per stopped hour, then keep the long-episode figure in the cash plan for the season.
- Check your rate confirmations for weather and layover language before the season, not during a storm.
- Pair this with the month calendar of how often systems arrive: this page tells you how long they stay.
Questions
What is an episode?
NOAA groups the National Weather Service reports of one weather system into an episode. We take the reports of one type group in one state, and measure from the earliest start to the latest end. A snow episode that crosses three states counts once in each.
Is the length of an episode the time roads were closed?
No. It is the span of the National Weather Service warnings and advisories logged in the state, in local clock hours. Roads can reopen sooner, or stay bad longer. It is a planning scale for how long a system can sit over a state.
Why nearest-rank percentiles?
Nearest rank picks an actual episode from the list: the one that is 50th or 90th when you sort them. It needs no assumption about the shape of the data and gives whole hours.
Why 5 years?
NOAA files are published a year at a time. 2021 to 2025 is the most recent five complete years in the files retrieved. A single bad winter moves the numbers of a small state.
Why are some states missing from the winter table?
States with fewer than 10 winter episodes in 5 years are not shown. A median from a handful of events says little. They are still in the selector when there is at least one episode.
Related guides and tools
- Weather calendar: how many event days each month brings
- Corridor weather planner: snow, freeze and heat by month
- Layover calculator: what a night stopped costs
- Layover pay: what you can ask for
- Weather risk: active alerts by state
- All intelligence pages: official data in plain English
See what your last 20 loads show.
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