Is it good to stain in Philadelphia, PA this week?
A live 7-day go/no-go calendar for deck & fence stain in Philadelphia, 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
- 0.9°F
- Overnight dew
- High
- Rain
- 13%
- Window
- —
High condensation risk overnight — surface dips to within 0.9°F of the 66°F dew point (low 66°F, 33% cloud, 4 mph wind). A fresh stain can blush/blister. Stop 4h before dew falls.
- Dew margin
- 2.1°F
- Overnight dew
- High
- Rain
- 9%
- Window
- —
High condensation risk overnight — surface dips to within 2.1°F of the 64°F dew point (low 67°F, 11% cloud, 3 mph wind). A fresh stain can blush/blister. Stop 4h before dew falls.
- Dew margin
- 3.4°F
- Overnight dew
- Watch
- Rain
- 7%
- Window
- —
Rain likely in the 24h cure window (7% chance, ~3.4mm) — it can wash out or mar an uncured stain.
- Dew margin
- 9.1°F
- Overnight dew
- Low
- Rain
- 5%
- Window
- —
Too hot — high of 101°F is well over the 90°F ceiling; the film skins over before it can level or adhere.
- Dew margin
- 12.4°F
- Overnight dew
- Low
- Rain
- 3%
- Window
- —
Too hot — high of 105°F is well over the 90°F ceiling; the film skins over before it can level or adhere.
- Dew margin
- 11°F
- Overnight dew
- Low
- Rain
- 21%
- Window
- —
Too hot — high of 104°F is well over the 90°F ceiling; the film skins over before it can level or adhere.
- Dew margin
- 4.9°F
- Overnight dew
- Watch
- Rain
- 36%
- Window
- —
Too hot — high of 104°F is well over the 90°F ceiling; the film skins over before it can level or adhere.
- High condensation risk overnight — surface dips to within 0.9°F of the 66°F dew point (low 66°F, 33% cloud, 4 mph wind). A fresh stain can blush/blister. Stop 4h before dew falls.
- High humidity (95%, 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
Stain applied to a damp or dew-wet board can't penetrate — it beads, stays tacky and flakes. Wood must be dry and stay above the dew point while it sets.
- • Surface temp must stay 5°F above the dew point through application and cure (ASTM D3276 / ISO 8502-42).
- • Air + surface in the 50–90°F band (low-temp lines to 45°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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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.