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SunnyDays

ERA5 almanac — 8 years of real data

Cape Cod in July

Cape Cod in July: 33% of days see measurable rain, 80°F average high, 42% of days historically clear (n=248, ERA5 2018–2025).

Cape Cod in July is a mixed month for sun: 42% of days historically clear (n=248, avg high 80°F). The outcome varies year to year — check the early/late split below. Historical average, not a forecast.

What you are reading: 8-year historical averages from the ERA5 reanalysis, not a forecast. A month that is historically 90% clear can still be overcast on your specific trip. For this week’s actual forecast, see the live Cape Cod page. Both can be true at once: “historically strong in this month; this particular week is not.” We label which is which.

Early vs. Late July

Clear-sky percentage for Cape Cod in July, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early July
1st–15th		 44% n=120 80°F
Late July
16th–end		 41% n=128 80°F
Full month average 42% n=248 80°F

Sunshine & warmth in July

A second measure using actual sunshine hours (ERA5 sunshine_duration), not the daily weather code. A Lowcountry day with 12 hours of sun and a 25-minute afternoon storm is counted below as a warm, sunny day — because it was. How we define this.

Sunshine-based metrics for Cape Cod in July. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early July
1st–15th		 82% n=120
Late July
16th–end		 91% n=128
Full month average 87% n=248
12.9 h median sunshine per day 83% of days exceed 8 h sunshine 33% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 42%. Sunshine-based “warm & sunny”: 87%. The 45-point gap is from brief afternoon convective storms that stamp the whole day as “rain” in the WMO code but leave the bulk of the sunshine untouched.

Bottom line

Cape Cod in July is genuinely mixed: 42% of days historically clear (n=248), avg high 80°F — more cloudy than clear. The outcome varies year to year; don't book if you need guaranteed sun.

Every month in Cape Cod

Compare across all months with data. Numbers are historical clear-sky %.

Historical clear-sky % for Cape Cod, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 0% n=248 All destinations →
February 0% n=226 All destinations →
March 0% n=248 All destinations →
April 2% n=240 All destinations →
May 6% n=248 All destinations →
June 32% n=240 All destinations →
July ← this page 42% n=248 All destinations →
August 41% n=248 All destinations →
September 27% n=240 All destinations →
October 5% n=248 All destinations →
November 1% n=240 All destinations →
December 0% n=248 All destinations →

Frequently asked

Does it rain in Cape Cod in July?

Sometimes. Cape Cod sees measurable rain on 33% of days in July historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Cape Cod good for sun in July?

It's mixed. Cape Cod in July is clear on 42% of days historically (avg high 80°F, n=248 days, ERA5 2018–2025) — the outcome varies year to year.

How Cape Cod compares in July

Head-to-head clear-sky comparisons against destinations travelers plausibly weigh against Cape Cod this month — same passport tier, similar flight distance, both sides from the same 8-year ERA5 record.

All percentages are historical averages from the ERA5 reanalysis via Open-Meteo, 8 full years (2018–2025). “Clear” means avg high ≥ 72 °F, precipitation < 1 mm, and a non-precipitation weather code. This is history, not a forecast. The live 7-day outlook for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.