Is it good to coat in St. Louis, MO this week?
A live 7-day go/no-go calendar for epoxy & resin floors in St. Louis, built from the local forecast against the 5°F-above-dew-point rule. We lead with the signal a weather app misses: overnight condensation risk.
- Dew margin
- 3.6°F
- Overnight dew
- Watch
- Rain
- 0%
- Window
- 9am–5pm
Watch overnight dew — surface comes within 3.6°F of the dew point (margin is 5°F). Time the coat to dry well before evening.
- Dew margin
- 18.3°F
- Overnight dew
- Low
- Rain
- 3%
- Window
- 8am–5pm
Clear to coat: temps 58–85°F, RH under 64%, surface stays 18.3°F+ above the dew point, no rain in the cure window.
- Dew margin
- 13.9°F
- Overnight dew
- Low
- Rain
- 5%
- Window
- —
Too hot — high of 92°F is well over the 86°F ceiling; the film skins over before it can level or adhere.
- Dew margin
- -8.3°F
- Overnight dew
- High
- Rain
- 65%
- Window
- —
High condensation risk overnight — surface dips to within -8.3°F of the 67°F dew point (low 58°F, 100% cloud, 2 mph wind). A fresh coat can blush/blister. Stop 4h before dew falls.
- Dew margin
- -9°F
- Overnight dew
- High
- Rain
- 61%
- Window
- —
High condensation risk overnight — surface dips to within -9°F of the 59°F dew point (low 50°F, 100% cloud, 5 mph wind). A fresh coat can blush/blister. Stop 4h before dew falls.
- Dew margin
- -26.3°F
- Overnight dew
- High
- Rain
- 31%
- Window
- —
High condensation risk overnight — surface dips to within -26.3°F of the 67°F dew point (low 41°F, 100% cloud, 4 mph wind). A fresh coat can blush/blister. Stop 4h before dew falls.
- Dew margin
- 13.8°F
- Overnight dew
- Low
- Rain
- 4%
- Window
- 11am–5pm
High humidity (93%, over the 85% mark) slows drying — keep an eye on the cure window.
- Watch overnight dew — surface comes within 3.6°F of the dew point (margin is 5°F). Time the coat to dry well before evening.
Caution. These are forecast numbers — confirm the surface temperature on-site before you start.
Why these thresholds
Installing within 5°F of the dew point causes amine blush / carbamation — a cloudy, greasy, hazed floor. The slab surface temp, not the air, is what counts.
- • Surface temp must stay 5°F above the dew point through application and cure (ASTM D3276 / ISO 8502-42).
- • Air + surface in the 50–86°F band (low-temp lines to 50°F).
- • Humidity under 85%; ideally under 80%.
- • No rain for 24h after application.
- • We use the forecast ground-surface temperature as a surface-temp proxy — confirm on-site with an IR thermometer.
Free in the beta
Watch this job site 24/7
Get an email the moment overnight dew, rain, or an out-of-range stretch threatens a fresh coat — and a morning digest with the best window ahead. No app to check; we watch the forecast for you.