Is it good to paint in Lowell, MA this week?
A live 7-day go/no-go calendar for exterior paint in Lowell, 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
- 4°F
- Overnight dew
- High
- Rain
- 23%
- Window
- —
High condensation risk overnight — surface dips to within 4°F of the 57°F dew point (low 61°F, 0% cloud, 4 mph wind). A fresh paint can blush/blister. Stop 4h before dew falls.
- Dew margin
- 9.4°F
- Overnight dew
- Low
- Rain
- 3%
- Window
- 8am–5pm
Clear to paint: temps 68–81°F, RH under 71%, surface stays 9.4°F+ above the dew point, no rain in the cure window.
- Dew margin
- 7.5°F
- Overnight dew
- Low
- Rain
- 1%
- Window
- 8am–5pm
Clear to paint: temps 64–81°F, RH under 54%, surface stays 7.5°F+ above the dew point, no rain in the cure window.
- Dew margin
- 0.1°F
- Overnight dew
- High
- Rain
- 56%
- Window
- —
High condensation risk overnight — surface dips to within 0.1°F of the 64°F dew point (low 64°F, 100% cloud, 4 mph wind). A fresh paint can blush/blister. Stop 4h before dew falls.
- Dew margin
- 0.1°F
- Overnight dew
- High
- Rain
- 52%
- Window
- —
High condensation risk overnight — surface dips to within 0.1°F of the 63°F dew point (low 62°F, 100% cloud, 5 mph wind). A fresh paint can blush/blister. Stop 4h before dew falls.
- Dew margin
- -6.4°F
- Overnight dew
- High
- Rain
- 1%
- Window
- —
High condensation risk overnight — surface dips to within -6.4°F of the 63°F dew point (low 56°F, 36% cloud, 1 mph wind). A fresh paint can blush/blister. Stop 4h before dew falls.
- Dew margin
- 11.4°F
- Overnight dew
- Low
- Rain
- 6%
- Window
- 9am–5pm
Hot afternoon (89°F, ceiling 85°F) — paint early and follow the shade.
- High condensation risk overnight — surface dips to within 4°F of the 57°F dew point (low 61°F, 0% cloud, 4 mph wind). A fresh paint can blush/blister. Stop 4h before dew falls.
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.