WorkWindow

Roof Coating Weather in Iowa: Best Months by City

Roof Coating season in Iowa, city by city: peak months, season boundaries, and annual workable-day counts from NOAA 1991–2020 normals. Des Moines leads with 129 workable days a year; Sioux City runs the shortest at 114.

Iowa is not one climate: Des Moines banks 129 workable roof coating days a year while Sioux City gets 114 — a spread the table below itemizes month by month. Season boundaries mark the first and last month averaging 8+ workable days against the label rules (50–90°F, nights 40°F+).

If one month anchors the Iowa calendar it's August, the statewide leader in workable days. Use this page to pick the month, then the city page's 10-day strip to pick the days — and the national roof coating guide for the physics behind each rule.

Cities in Iowa

Peak months and season boundaries from NOAA 1991–2020 normals; season = months with at least 8 workable days.
CityPeak monthsSeasonWorkable days/yr
Des Moines Aug, Sep, Jul April–October 129
Davenport Aug, Jul, Sep May–October 125
Cedar Rapids Aug, Sep, Jul May–October 115
Iowa City Jul, Aug, Sep April–October 122
Waterloo Aug, Jul, Sep May–October 119
Sioux City Sep, Aug, Jul May–October 114

The rules behind these numbers

Typical label thresholds for roof coating — the single ruleset used by every check on this page.
CheckThresholdWhy it matters
Air temperature 50–90°F Acrylic and elastomeric coatings want 50°F+ during application and initial cure.
Overnight low ≥40°F during the first 24 h Water-based coatings can be ruined by a cold, damp night before they skin over.
Dry before ≤0.05" rain in the prior 24 h; watch back to 48 h The membrane must be dry — coatings trap moisture that later blisters.
Dry after <0.05" rain for 24 h after (48 h thick coats want 48 h) Rain inside 24 hours washes uncured coating into gutters.
Evening dew-point spread ≥5°F from 6–11 pm Roofs radiate heat at night and hit the dew point before anything else in the yard.
Daytime humidity ≤85% Humid air slows water-based coatings dramatically.
Wind ≤15 mph (roller only, no spray up to 20 mph) Wind on a roof is a safety limit first and an overspray limit second.

Always follow your product label — formulas vary. The table above is the typical range across major manufacturers, not a promise about your can.

Other tasks in Iowa

More