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SunnyDays

ERA5 almanac — 8 years of real data

Sydney in October

Sydney in October: 39% of days see measurable rain, 74°F average high, 27% of days historically clear (n=248, ERA5 2018–2025).

Sydney in October is historically a poor month for sun: only 27% of days clear across 8 years (n=248, avg high 74°F). December is the clearest month for Sydney historically. 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 Sydney 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 October

Clear-sky percentage for Sydney in October, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early October
1st–15th		 28% n=120 74°F
Late October
16th–end		 26% n=128 74°F
Full month average 27% n=248 74°F

Sunshine & warmth in October

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 Sydney in October. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early October
1st–15th		 45% n=120
Late October
16th–end		 52% n=128
Full month average 49% n=248
11.7 h median sunshine per day 81% of days exceed 8 h sunshine 39% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 27%. Sunshine-based “warm & sunny”: 49%. The 22-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

Sydney is mostly overcast in October historically: only 27% of days are clear across 8 years (n=248), avg high 74°F. If you want sun in Sydney, December is historically much better. Most visitors this month will see more clouds than sun.

→ See all destinations in December — historically the best month for sun in Sydney.

Every month in Sydney

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

Historical clear-sky % for Sydney, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 31% n=248 All destinations →
February 22% n=226 All destinations →
March 21% n=248 All destinations →
April 24% n=240 All destinations →
May 8% n=248 All destinations →
June 0% n=240 All destinations →
July 2% n=248 All destinations →
August 5% n=248 All destinations →
September 23% n=240 All destinations →
October ← this page 27% n=248 All destinations →
November 26% n=240 All destinations →
December 33% n=248 All destinations →

Frequently asked

Does it rain in Sydney in October?

Sometimes. Sydney sees measurable rain on 39% of days in October historically (n=248 days, ERA5 2018–2025) — not frequent enough to plan around, but not negligible either.

Is Sydney good for sun in October?

Not usually. Sydney is historically overcast in October: only 27% of days are clear (avg high 74°F, n=248 days, ERA5 2018–2025). December is historically far better for sun here.

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.