ERA5 almanac — 8 years of real data

Cape Cod in June

Cape Cod in June: 34% of days see measurable rain, 73°F average high, 32% of days historically clear (n=240, ERA5 2018–2025).

Cape Cod in June is historically a poor month for sun: only 32% of days clear across 8 years (n=240, avg high 73°F). 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 June

Clear-sky percentage for Cape Cod in June, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period	% Clear days	Sample (n)	Avg high
Early June 1st–15th	27%	n=120	73°F
Late June 16th–end	37%	n=120	73°F
Full month average	32%	n=240	73°F

Sunshine & warmth in June

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 June. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period	Warm & sunny (≥72°F, >6 h sun)	Sample (n)
Early June 1st–15th	38%	n=120
Late June 16th–end	68%	n=120
Full month average	53%	n=240

13.0 h median sunshine per day 82% of days exceed 8 h sunshine 34% of days see ≥ 1 mm rain — rain is not hidden

Comparison (old vs new): WMO-code “clear” bar: 32%. Sunshine-based “warm & sunny”: 53%. The 21-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 is mostly overcast in June historically: only 32% of days are clear across 8 years (n=240), avg high 73°F. Most visitors this month will see more clouds than 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 ← this page	32%	n=240	All destinations →
July	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 June?

Sometimes. Cape Cod sees measurable rain on 34% of days in June historically (n=240 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Cape Cod good for sun in June?

It's mixed. Cape Cod in June is clear on 32% of days historically (avg high 73°F, n=240 days, ERA5 2018–2025) — the outcome varies year to year.

How Cape Cod compares in June

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.

→ Cape Cod vs Austin in June — Austin is 32% clear historically
→ Cape Cod vs Park City in June — Park City is 32% clear historically
→ Cape Cod vs Traverse City in June — Traverse City is 32% clear historically

→ Cape Cod live forecast — this week’s actual 7-day weather, not historical
→ Best destinations in June — all destinations ranked by June clear-sky %
→ All destinations
→ Raw data (JSON) — buckets, n, source

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.