What an Oshkosh Winter Actually Puts on Your Pavement

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

Oshkosh is not a heavy snow town by Wisconsin standards. The 1991-2020 normals put the city at about 36 inches of snow in an average year, which is modest for this state. That fact leads a lot of property owners to assume their pavement has an easier winter than pavement further north, and to stretch their sealing intervals accordingly. The data says otherwise, and the reason is that snowfall is not what wears out asphalt here.

What wears it out is chloride and freeze-thaw, and Oshkosh gets a full measure of both. The numbers on this page come from WisDOT's county-level winter maintenance reporting for Winnebago County, from the USDA's soil series records, from the city's own snow and ice policy, and from the published climate normals. Where a figure appears in a table below, its source appears at the bottom with a working link.

What Winnebago County put on the road last winter

WisDOT publishes winter maintenance data county by county, which makes it possible to say precisely what happened on the roads around Oshkosh rather than guessing from a state average. Winnebago County maintains 689.08 lane miles under the state highway maintenance agreement, split across 18 winter patrol sections at about 38.3 lane miles each, and in the 2024-25 season it recorded 43.8 inches of snowfall on those routes.

The material totals are the striking part. Over that season the county applied 6,132 tons of solid road salt and 1,004,628 gallons of salt brine, the latter split between prewetting, anti-icing and direct liquid application. Prewetting accounts for the large majority of it: brine sprayed onto solid salt as it leaves the spreader so it starts working immediately instead of bouncing off the road.

A milder than average winter, salted almost as heavily

WisDOT scores each winter with a severity index in which 100 represents a normal season. In 2024-25 the statewide figure came in at 54.4, and Winnebago County came in below that at 47.05. By the state's own measure, this was a milder winter around Oshkosh than it was across Wisconsin as a whole.

The salt figures did not follow. Winnebago County used 8.9 tons of salt per lane mile against a statewide average of 9.6, which is roughly 93 percent of the state average dose delivered into a winter the state rated as easier than average. That is the single most useful number on this page for a property owner. A mild Oshkosh winter is not a low-chloride winter, and the sealing interval should be set on salt exposure rather than on how much snow came down.

The reason is that ice control is triggered by conditions rather than by accumulation. The city of Oshkosh's own policy puts it in those terms: ice control commences when, in the judgment of the on-call supervisor, an unsafe condition for travel exists. Freezing drizzle, a refreeze after a thaw, or frost on a bridge deck all call out trucks without producing a single inch of measurable snow.

The Oshkosh normals that set the working calendar

The 1991-2020 normals for Oshkosh give an annual snowfall of about 36 inches and an annual precipitation total of 31.59 inches. December is the heaviest snow month at 11 inches, followed by February at 9 and January at 7. January is the coldest month, with an average high of 26 degrees and an average low of 10.

For sealcoating, the low temperatures matter more than the highs, because sealer requires 50 degrees and rising sustained across a 24 hour period. April's average low of 37 degrees is what makes April unreliable here, and October's average low of 40 does the same at the other end. May through September is the dependable window, which is five months of working season against seven months of frost, salt and thaw.

The freeze and thaw calendar the state works to

WisDOT declares roads frozen only once frost has reached at least 18 inches below the pavement surface, and it lifts the declaration when the thawing depth reaches the subsoils beneath. Those two dates bracket the period when the ground under Oshkosh pavement is a solid, load-bearing block, and the long-run averages put them at December 22 and March 4.

The weeks after that are the destructive ones. The surface thaws while deeper ground remains frozen, so meltwater is trapped with no downward path, and the pavement rides on saturated material with no bearing strength. The state responds by posting spring weight restrictions, on average from March 9 to May 9. Two further details from the same guidance are worth carrying: daytime air in the twenties and thirties, with sun on asphalt, can push pavement temperatures into the fifties, and the city notes that salt is only 20 percent as effective at 20 degrees as it is at 30, so the coldest days call for the heaviest applications.

The week in July that shapes every commercial lot in town

Oshkosh has one pavement loading event that no other Wisconsin city has to plan around. EAA AirVenture drew approximately 704,000 people in 2025, its highest total on record. More than 10,000 aircraft arrived at Wittman Regional and other east-central Wisconsin airports, and Wittman alone logged 16,246 aircraft operations across July 17 to 28.

The ground side is what affects pavement. More than 15,000 camping sites accommodated over 40,000 visitors, and 962 commercial exhibitors set up on site. Every hotel, restaurant, retail and church lot in the city runs at capacity for that week, in the hottest stretch of the year, when asphalt is at its softest and most vulnerable to scuffing and power steering marks.

The scheduling conclusion follows directly. A commercial lot that serves any part of this should be sealed in late May or June so the coating has a month to harden fully before the load arrives. Putting fresh sealer down in early July means asking a still-curing surface to take the heaviest week it will see all year. See [parking lot sealcoating](/parking-lot-sealcoating) for how phasing usually works around it.

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. WisDOT Annual Winter Maintenance Data 2024/2025 — County-by-county winter maintenance reporting. Source of Winnebago County's 6,132 tons of salt, 8.9 tons per lane mile, 689.08 lane miles, 18 patrol sections, 43.8 inches of snowfall, 47.05 severity index and the 1,004,628 gallon brine total, plus the statewide comparison figures of 332,458 tons, 9.6 tons per lane mile and a 54.4 severity index.
2. USDA NRCS Official Series Description, OSHKOSH series — The soil series named for this city. Source of the 60 to 85 percent clay control section, the less than 10 percent fine sand or coarser figure, the very-fine taxonomic class, the slow to very slow permeability rating, the clayey lacustrine parent material and the slickensides in the subsoil.
3. USDA NRCS Official Series Description, POYGAN series — The poorly drained clayey soil mapped widely across the low ground of the Lake Winnebago basin. Source of the perched high water table within one foot of the surface for long periods in most years, the 35 to 60 percent clay control section and the slow permeability rating.
4. WisDOT Frozen Road Declaration and spring thaw guidance — Source of the 18 inch frost depth threshold, the December 22 and March 4 average frozen road dates, the March 9 to May 9 average spring weight restriction dates, the description of meltwater unable to drain downward through frozen soil, and the note that sun on asphalt can lift pavement temperatures into the fifties while air sits in the twenties and thirties.
5. City of Oshkosh Snow and Ice Removal Policy — The city's own winter operations policy. Source of the statement that salt is only 20 percent as effective at 20 degrees as at 30 degrees, the three-tier priority routing of arterials, collectors and residential streets, the trigger for ice control operations, and the ordinance language on snow and ice from a sidewalk or driveway apron.
6. U.S. Climate Data, Oshkosh Wisconsin normals — 1991-2020 climate normals for Oshkosh. Source of the monthly average high, low and snowfall table, the 36 inch annual snowfall figure and the 31.59 inch annual precipitation figure.
7. EAA AirVenture Oshkosh 2025 by the numbers — EAA's official post-event figures. Source of the approximately 704,000 attendance, the more than 10,000 aircraft, the 16,246 Wittman Regional operations across July 17-28, the 2,543 showplanes, the more than 15,000 camping sites and 40,000 campers, and the 962 commercial exhibitors.