Fargo Weather, Frost and Flood Numbers for Pavement Owners

Last reviewed 2026-07-25. Journalists, researchers, and community groups are welcome to cite any figure on this page with attribution and a link.

Each number used across this site comes from a public source, and this page gathers the ones that matter most for asphalt in one place. Climate values come from NOAA's 1991-2020 normals for Hector International Airport, station USW00014914, which sits roughly three miles northwest of the downtown core. NOAA publishes most of these values in tenths of a unit, and they are converted here. The river figures come from the National Weather Service gauge on the Red River at Fargo.

To count freeze-thaw days, the table takes the days with a low of 32 degrees or less and subtracts the days whose high never rose above 32, leaving the days the pavement crossed the freezing line. Normals are 30-year averages, so any single year can run warmer, colder, wetter or drier than these tables. The sources at the bottom of the page list the exact fields used.

Month by month at Hector International Airport

The freeze-thaw column is the one that explains most asphalt damage here. Deep winter contributes few crossings because the pavement stays frozen: January averages 25.3 days when the high never passes 32. The crossings pile up in March and April, about 31 combined, and again in October and November, about 27. June through August have none.

Freeze-thaw days: nights reaching 32 F or lower, less the days when the high stayed at 32 F or lower. The monthly figures add up to 83.8 because of rounding; the annual value is taken from NOAA's annual file.

Frost dates and season length

NOAA publishes freeze dates as probabilities. The median is the date with even odds; the one-in-ten columns show how late the last spring freeze or how early the first fall freeze can come in a less typical year. For sealing, the 32 and 36 degree rows matter most, because a water-based coat needs to stay well above freezing while it cures.

Sealing-weather counts, April through October

Manufacturers' labels call for 50 degrees and climbing, sustained through the day after application. These counts show how often the afternoon clears that bar and how often the night falls below it. June, July and August are the only months with both a warm afternoon almost every day and very few nights at or below 40 degrees.

The Red River at Fargo: ten highest crests

The National Weather Service sets flood stages at the Fargo gauge of 17 feet for action, 18 for minor flooding, 25 for moderate and 30 for major. The city begins road closures at 18 feet and starts building earth and sandbag levees at 36. Every one of the ten highest crests came between March 21 and April 18, the same weeks that carry the thaw's worst pavement damage, and seven of the ten have come since 1997. Since that year the city has bought and removed more than 200 flood-prone properties.

Frost depth, deep cold and snow cover

Two building rules show how far the cold reaches. The City of Fargo's deck handout, revised in October 2019, gives the frost line as 52 inches, and Minnesota's footing rule puts Clay County, home to Moorhead and Dilworth, in its Zone I, with a five-foot minimum footing depth. No residential driveway base comes close to either, which is why drainage, not depth, is the defense against heave.

Deep cold is routine rather than rare. The airport averages 41.7 nights a year at or below zero, most of them from December through February, and 88.3 days whose high never climbs past freezing. Snow cover is long-lived as well, and the city runs storm sewer lift stations to move storm water because the valley floor is so flat.

• Nights at or below 0 F: 15.5 in January, 10.5 in February, 11.1 in December
• Snow cover an inch deep or more: about 99 days a year
• Normal snowfall: 50.1 inches a year, with 38.4 days of 0.1 inch or more
• Storm sewer lift stations operated by the City of Fargo: 81

Sources & Methodology

Every figure above was taken from the primary sources below (accessed 2026-07-25). Where a number is derived (arithmetic on published figures) or covers a broader period or area, the text says so.

1. NOAA NCEI normals (annual and seasonal, 1991-2020), Fargo Hector International Airport (USW00014914) — Values in tenths: ANN-TMIN-AVGNDS-LSTH032 1720 and ANN-TMAX-AVGNDS-LSTH032 883 give 83.7 freeze-thaw days; ANN-TMIN-AVGNDS-LSTH000 417 (41.7 nights at or below 0 F); ANN-SNOW-NORMAL 501 (50.1 in); ANN-SNOW-AVGNDS-GE001TI 384; ANN-PRCP-AVGNDS-GE010HI 486; PRBLST, PRBFST and PRBGSL fields for 36, 32, 28 and 24 F.
2. NOAA NCEI, 1991-2020 monthly normals, Fargo Hector International Airport — Monthly normal highs and lows, snowfall, wet-day counts (0.10 in or more), counts of days with highs of 50 F and 60 F or more, nights at or below 50, 40 and 0 F, and snow-depth days of 1 in or more.
3. NOAA NCEI, monthly counts of days at or below 32 F, Hector — Fields MLY-TMAX-AVGNDS-LSTH032 (highs at or below 32 F) and MLY-TMIN-AVGNDS-LSTH032 (lows at or below 32 F), used for the freeze-thaw column.
4. NOAA National Water Prediction Service, Red River of the North at Fargo (FGON8) — Flood categories (17, 18, 25 and 30 ft) and the ten highest historic crests with dates.
5. City of Fargo, Spring Flooding — Road closures begin at 18 ft; earth and sandbag levee building begins at 36 ft.
6. City of Fargo, Flooding — More than 200 flood-prone properties purchased and removed since 1997.
7. City of Fargo Inspections, Patio Decks handout (rev. 10/2/19) — Recommends foundations extend below the frost line of 52 inches.
8. Minnesota Rules part 1303.1600, frost-protection footing depths — Zone I, which includes Clay County, has a five-foot minimum footing depth.
9. City of Fargo, Storm Sewer Utilities — 81 storm sewer lift stations, operated because of the Red River Valley's extremely flat terrain.