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SunnyDays

ERA5 almanac — 8 years of real data

Singapore in September

Singapore in September: 81% of days see measurable rain, 86°F average high, 6% of days historically clear (n=240, ERA5 2018–2025).

Singapore in September is historically a poor month for sun: only 6% of days clear across 8 years (n=240, avg high 86°F). February is the clearest month for Singapore 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 Singapore 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 September

Clear-sky percentage for Singapore in September, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period % Clear days Sample (n) Avg high
Early September
1st–15th		 4% n=120 86°F
Late September
16th–end		 7% n=120 86°F
Full month average 6% n=240 86°F

Sunshine & warmth in September

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 Singapore in September. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period Warm & sunny (≥72°F, >6 h sun) Sample (n)
Early September
1st–15th		 84% n=120
Late September
16th–end		 88% n=120
Full month average 86% n=240
10.6 h median sunshine per day 80% of days exceed 8 h sunshine 81% of days see ≥ 1 mm rain — rain is not hidden
Comparison (old vs new): WMO-code “clear” bar: 6%. Sunshine-based “warm & sunny”: 86%. The 80-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

Singapore is a poor choice for sun in September: just 6% of days clear historically (n=240). February is the historically strongest month for sun here. The 8-year record is consistent — this is not a fluke bad stretch.

→ See all destinations in February — historically the best month for sun in Singapore.

Every month in Singapore

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

Historical clear-sky % for Singapore, all months, ERA5 2018–2025.
Month % Clear Sample (n)
January 4% n=248 All destinations →
February 10% n=226 All destinations →
March 6% n=248 All destinations →
April 2% n=240 All destinations →
May 3% n=248 All destinations →
June 4% n=240 All destinations →
July 3% n=248 All destinations →
August 2% n=248 All destinations →
September ← this page 6% n=240 All destinations →
October 3% n=248 All destinations →
November 1% n=240 All destinations →
December 1% n=248 All destinations →

Frequently asked

Does it rain in Singapore in September?

Yes, frequently. In Singapore, 81% of days in September see measurable rain, based on 8 years of ERA5 historical data (n=240 days, 2018–2025). This is a historical average, not a forecast.

Is Singapore good for sun in September?

Not usually. Singapore is historically overcast in September: only 6% of days are clear (avg high 86°F, n=240 days, ERA5 2018–2025). February 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.