# Bandar Seri Begawan in September: weather

Bandar Seri Begawan, Brunei (Southeast Asia). Ten-year climatology (2015-2024), not a forecast. Page: https://beaufixe.net/en/weather/bandar-seri-begawan/september

## Key figures

| Indicator | Value |
|---|---|
| Afternoon (mean daily max) | 30.2 °C |
| Night (mean daily min) | 24.2 °C |
| Sea (surface) | 29.9 °C |
| Rainy days (≥ 1 mm) | 23 / month |
| Relative humidity | 87 % |
| Probability of a 25 °C+ afternoon | 100 % |

## Month by month

| Month | Afternoon | Night | Sea | Rain (d) |
|---|---|---|---|---|
| January | 29.1 °C | 23.9 °C | 28.5 °C | 27 |
| February | 29.2 °C | 24 °C | 27.7 °C | 21 |
| March | 30 °C | 24.2 °C | 28 °C | 25 |
| April | 30.6 °C | 24.5 °C | 29.4 °C | 26 |
| May | 30.7 °C | 24.8 °C | 30.4 °C | 26 |
| June | 30.2 °C | 24.5 °C | 30.3 °C | 23 |
| July | 30.3 °C | 24.2 °C | 30 °C | 21 |
| August | 30.4 °C | 24.2 °C | 30.1 °C | 23 |
| September | 30.2 °C | 24.2 °C | 29.9 °C | 23 |
| October | 29.8 °C | 24 °C | 29.7 °C | 27 |
| November | 29.8 °C | 24 °C | 29.9 °C | 28 |
| December | 29.4 °C | 23.9 °C | 29.4 °C | 28 |

Best months : July, August, February.

## Before you go

- **Safety** : No specific restrictions. Usual precautions apply. (official advice updated 19 March 2026 — https://www.gov.uk/foreign-travel-advice/brunei)
- **Entry** (British passport) : No visa needed for stays of up to 90 days. Passport valid for at least 6 months. Submit the e-arrival declaration form before you travel (may be requested at check-in); get your passport stamped on entry. (per the UK Foreign Office, 19 March 2026)
- **Vaccines** : hepatitis B if you are not already vaccinated; hepatitis A and Japanese encephalitis depending on activities and areas visited. Routine vaccines up to date (measles in particular).
- **Yellow fever** : No yellow fever locally, vaccine not recommended. Certificate required only if you arrive from a country with yellow fever risk.
- **Malaria** : None.
- **Mosquitoes** : dengue reported: protect yourself from bites.
  (per the CDC, page reviewed 25 August 2026 — https://wwwnc.cdc.gov/travel/destinations/traveler/none/brunei)

## Sources

Air, rain, humidity: ERA5-Land reanalysis (Copernicus) served by Open-Meteo (CC BY 4.0). Sea: NOAA OISST. Safety: FCDO (OGL v3), zones reviewed by Beau Fixe. Entry: France Diplomatie (Licence Ouverte 2.0) / FCDO. Health: CDC (public domain). Details: https://beaufixe.net/en/legal#sources

Beau Fixe — https://beaufixe.net — not a forecast; only the authorities are authoritative for safety, entry rules and health.