Is it good to paint in Chicago, IL this week?
A live 7-day go/no-go calendar for exterior paint in Chicago, 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
- 0.6°F
- Overnight dew
- High
- Rain
- 96%
- Window
- —
High condensation risk overnight — surface dips to within 0.6°F of the 64°F dew point (low 56°F, 100% cloud, 9 mph wind). A fresh paint can blush/blister. Stop 4h before dew falls.
- Dew margin
- 7°F
- Overnight dew
- Low
- Rain
- 1%
- Window
- 8am–5pm
Clear to paint: temps 56–60°F, RH under 75%, surface stays 7°F+ above the dew point, no rain in the cure window.
- Dew margin
- 4.5°F
- Overnight dew
- High
- Rain
- 1%
- Window
- —
High condensation risk overnight — surface dips to within 4.5°F of the 46°F dew point (low 51°F, 6% cloud, 5 mph wind). A fresh paint can blush/blister. Stop 4h before dew falls.
- Dew margin
- 10.1°F
- Overnight dew
- Low
- Rain
- 0%
- Window
- 8am–5pm
Clear to paint: temps 57–73°F, RH under 66%, surface stays 10.1°F+ above the dew point, no rain in the cure window.
- Dew margin
- 8.7°F
- Overnight dew
- Low
- Rain
- 0%
- Window
- 8am–5pm
Clear to paint: temps 58–60°F, RH under 50%, surface stays 8.7°F+ above the dew point, no rain in the cure window.
- Dew margin
- 17.6°F
- Overnight dew
- Low
- Rain
- 3%
- Window
- 8am–5pm
Clear to paint: temps 52–67°F, RH under 50%, surface stays 17.6°F+ above the dew point, no rain in the cure window.
- Dew margin
- 3.1°F
- Overnight dew
- Watch
- Rain
- 3%
- Window
- 8am–5pm
Watch overnight dew — surface comes within 3.1°F of the dew point (margin is 5°F). Time the coat to dry well before evening.
- High condensation risk overnight — surface dips to within 0.6°F of the 64°F dew point (low 56°F, 100% cloud, 9 mph wind). A fresh paint can blush/blister. Stop 4h before dew falls.
- Rain likely in the 24h cure window (96% chance, ~81mm) — it can wash out or mar an uncured paint.
- High humidity (94%, over the 85% mark) slows drying — keep an eye on the cure window.
Hold off. These are forecast numbers — confirm the surface temperature on-site before you start.
Why these thresholds
Overnight dew condensing on a fresh coat causes blistering, surfactant leaching and peeling — the cause of 40%+ of exterior paint failures.
- • Surface temp must stay 5°F above the dew point through application and cure (ASTM D3276 / ISO 8502-42).
- • Air + surface in the 50–85°F band (low-temp lines to 35°F).
- • Humidity under 85%; ideally under 70%.
- • 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.
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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.