Exterior Painting Weather in St. Augustine, FL: 10-Day Windows & Best Months

Q: What temperature can you paint outside?

50–90°F for standard formulas, 35°F+ for low-temp lines, and the wall itself must stay 5°F above the dew point. In St. Augustine the practical range is set by nights: the 40°F overnight floor arrives around January and leaves after December.

Q: How many dry hours does exterior paint need before rain?

Plan 24 rain-free hours after the last coat; the engine fails any day that can't deliver them. With St. Augustine's rain odds swinging from 24% of days in April to 46% in August, the strip above is mostly a search for that dry pair.

Q: Why does dew ruin fresh paint?

Fresh latex needs hours before it can take standing water; evening condensation gets there first on cooling siding. The check: air minus dew point from 6–11 p.m., 5°F or better. Humid August evenings in St. Augustine are when GOOD afternoons hide failing nights.

Q: Can you paint in high humidity?

Up to about 80% daytime RH — above that, dry times stretch until the film meets the evening dew. 80–83% reads MARGINAL on the engine; more is a fail. Pair humidity with St. Augustine's dew-point spread rule and paint mornings-into-early-afternoons in the humid months.

Q: What is surface temperature vs air temperature?

Two different numbers: air (what the app shows) and the wall (what the paint feels). Sun adds 20°F or more; evening radiational cooling subtracts. That's why the engine checks the 90°F top on St. Augustine's hot afternoons and the dew-point spread after sunset — both are surface problems the air forecast hides.

Q: When does painting season end in St. Augustine?

When nights stop clearing 40°F — in St. Augustine that's typically after June, when average lows hit 72°F and falling. Low-temp formulas (35°F rated) buy a few extra weeks; the engine shows them as MARGINAL days before the hard close.

By NOAA 1991–2020 normals, St. Augustine keeps a exterior painting window open in all 12 months — a year-round season few US cities match. The single best month is May, averaging 23 days that clear every check — highs of 85°F, lows near 67°F, and a 25% daily rain chance. Below: today through day 10 against the label rules, then the year at a glance.

GOOD — every label check passes MARGINAL — one soft fail NO — hard fail or several soft

The rules this check uses

These rows are what the St. Augustine strip checks hour by hour: consensus paint-can requirements, plus the low-temp-formula band the engine marks MARGINAL.

Typical label thresholds for exterior painting — the ruleset behind every St. Augustine verdict above.
Check	Threshold	Why it matters
Air temperature	50–90°F (low-temp formulas from 35°F)	The film (or mix) chemistry runs on temperature — both while you work and for the first hours after.
Overnight low	≥35°F during the first 24 h (≥40°F preferred)	Curing continues after dark; the first night can undo a perfect afternoon.
Dry before	≤0.05" rain in the prior 12 h; watch back to 24 h	Checked backward from your start hour using the two look-back days in the forecast data.
Dry after	<0.05" rain for 24 h after	The engine sums forecast rain hour by hour through the cure window for St. Augustine.
Evening dew-point spread	≥5°F from 6–11 pm	When air temperature meets the dew point, water condenses on your fresh work first.
Daytime humidity	≤80%	Read as the daytime maximum, 10 a.m.–5 p.m.; within 3 points of the limit counts as marginal.
Wind	≤15 mph (brush only up to 20 mph)	Wind dries the leading edge too fast and carries overspray.

Always follow your product label — formulas vary. The table above is the typical range across major manufacturers, not a promise about your can.

Best months for exterior painting in St. Augustine

St. Augustine's calendar, scored: each month's days passing the temperature rules, discounted by that day's historical rain odds (NOAA 1991–2020). Not a forecast.
Month	Avg high	Avg low	Rain odds/day	Workable days
January	68°F	48°F	29%	22
February	70°F	50°F	28%	21
March	74°F	55°F	27%	23
April	80°F	61°F	24%	23
May	85°F	67°F	25%	23
June	89°F	72°F	39%	18
July	91°F	74°F	41%	0
August	90°F	74°F	46%	10
September	87°F	73°F	44%	17
October	82°F	66°F	31%	21
November	75°F	58°F	27%	22
December	69°F	51°F	28%	22

St. Augustine's calendar never really closes: even January, the leanest month, averages 22 workable days against the 50–90°F rules. The 10-day strip above matters more here than any season chart. The Florida table ranks every listed city by the same math.

July here fails on heat, not rain: the average high of 91°F sits over the 90°F label ceiling, and 31 of 31 days typically top 90°F. Midsummer work moves to dawn or waits for May.

The rain odds swing hard across the year — 24% of days in April up to 46% in August. Season the plan accordingly: prep in the wet months, apply in the dry ones.

If the walls pass, the roof might too: roof coating in St. Augustine uses the same film chemistry with tighter dew and wind limits.

Source honesty: every monthly figure on this page is the 1991–2020 normal at St Augustine Lighthouse, Fl Us, 2.4 km from St. Augustine's center — your block's shade lines and wind exposure sit on top of that baseline. Scoring details are on the methodology page.

St. Augustine by the numbers

Hottest month: July — 91°F average high, 31 days topping 90°F.
The cold floor is January at 68°F afternoons and 48°F overnight.
Measurable rain: August leads at 46% of days; April is the quiet end at 24%.
Bottom line for St. Augustine: roughly 222 workable exterior painting days a year.

Prep checklist

Find application day plus 24 dry hours with nights at 40°F+; St. Augustine offers that pairing most often in May (23 workable days).
Scrape, then wash: loose paint and chalk go first, because latex only grips solid substrate.
Give washed siding 24 hours — north walls in St. Augustine can need double after a August-grade soak.
An ir surface thermometer settles arguments: label limits bind the wall surface, which outruns St. Augustine's air by 20°F+ in sun.
Bare wood gets primer, stains get stain-blocker, gaps get caulk — in that order, on dry substrate.
Sequence walls so you always paint in shade; midday sun skins latex before it levels.
Cut in with an angled brush set, roll a wet edge, and drop the sprayer plan over 15 mph.
Stop 2 hours before sunset: with May lows near 67°F, St. Augustine's siding meets the dew point before the late news.

Gear that saves a window

Transparency note: gear links here become affiliate links only when the program is enabled — today they are plain references. See the affiliate disclosure.

Exterior paint + primer
One-coat hide on sound, prepped siding.
Canvas drop cloths
Grips ladders and won't shred like plastic.
Extension pole
Second-story reach without moving the ladder every pass.
Angled brush set
Control at trim, corners, and cut-in lines.
IR surface thermometer
Reads the wall, not the air — sun-baked siding runs hotter.

FAQ

What temperature can you paint outside?

50–90°F for standard formulas, 35°F+ for low-temp lines, and the wall itself must stay 5°F above the dew point. In St. Augustine the practical range is set by nights: the 40°F overnight floor arrives around January and leaves after December.

How many dry hours does exterior paint need before rain?

Plan 24 rain-free hours after the last coat; the engine fails any day that can't deliver them. With St. Augustine's rain odds swinging from 24% of days in April to 46% in August, the strip above is mostly a search for that dry pair.

Why does dew ruin fresh paint?