Identify the surface and follow the current instructions for your exact products. Do not sand or strip uncertain old coatings. Read the safety guide before disturbing materials.
The four conditions
Check four things against the exact product specification: permitted air and surface temperatures during application and drying; the required rain and frost protection window; the surface temperature margin above the dew point; and the substrate moisture limit. Our tools use screening assumptions, including a three degree dew point margin, but these do not replace a technical sheet or a measurement on site.
On the Fife coast the dew point is the one people miss. A bright afternoon can turn to a damp, still evening where every surface is suddenly wet. Paint applied at four in the afternoon in September may not be dry by then. Our Painting Weather tool does this calculation for any postcode, hour by hour.
The calendar
A rough guide for a typical year on the east coast. Every year is different; the tool is for the actual week.
| Month | Exterior painting | Notes |
|---|---|---|
| January to March | No | Cold, wet, short days. Plan, quote, order materials, do interior work |
| April | Possible in the last two weeks | Watch overnight frosts. Good for stripping and repairs ahead of paint |
| May | Yes, often the best month | Long days, low humidity, before the summer haar settles in |
| June | Yes | Sea haar can roll in for days on the coast; inland is fine |
| July | Yes, with care | Hot surfaces in direct sun blister paint. Follow the shade round the house |
| August | Yes, with care | Thunderstorms. Check the afternoon forecast before starting a big elevation |
| September | Yes, second best month | Settled weather but dew point creeps up. Stop painting mid afternoon |
| October | First half only | Drying slows sharply. Only quick recoats on prepared surfaces |
| November and December | No | Too cold and wet for anything but emergency patching with a fast dry primer |
Salt, wind and the East Neuk
Within a mile of the sea, salt settles on every surface overnight. It attracts moisture and it stops paint bonding. Wash exterior surfaces down with clean water the day before painting and let them dry, even if they look clean. Wind is the other coastal problem: it carries dust and sand into wet paint and it dries the surface before it has levelled. On a windy day paint the lee side.
When is render dry enough
New render needs the curing and moisture conditions required by both the render supplier and the coating maker. Elapsed weeks alone cannot establish readiness. Electrical meters on masonry give comparative readings affected by salts and material, not a reliable timber style moisture percentage. A taped sheet may reveal moisture but cannot prove that render is ready or diagnose its source. Limewash and mineral systems need substrate and existing coating checks; do not assume every old wall should be limewashed.
Common mistakes
- Painting a sunlit wall at midday in July
- Starting a top coat after three in September
- Painting the day after heavy rain
- Not washing off salt
- Trusting the air temperature instead of the surface
If a surface is failing badly, do not paint it out of season to stop it getting worse. Stabilise, prime bare patches, and wait for spring. A proper job in May outlasts three rushed ones in October.
Sources & further reading
Original general guidance from Aethos, informed by the resources below. These references cover relevant safety, materials or techniques, not a specification for your property. Product examples are not paid recommendations.
- Zinsser: AllCoat Exterior Satin (opens in a new tab)
A product example covering exterior substrates, preparation and application conditions, not a universal recommendation.