Planning around Singapore's weather is not a matter of choosing a dry month, because there isn't one. It is a matter of knowing which hours of a given day are likely to be spoiled, and having somewhere to be when they are.
The good news is that Singapore publishes more usable weather information than almost anywhere — a two-hour nowcast, a live lightning map, a heat stress index by station — and that the city is engineered for the climate it has.
The shape of a Singapore year
| Month | Rainfall | Rain days | Mean daily max |
|---|---|---|---|
| January | 221.6 mm | 13 | 30.6°C |
| February | 105.1 mm | 9 | 31.5°C |
| April | 164.3 mm | 15 | 32.4°C |
| June | 135.3 mm | 13 | 31.9°C |
| September | 124.9 mm | 13 | 31.6°C |
| November | 252.3 mm | 19 | 31.2°C |
| December | 331.9 mm | 19 | 30.5°C |
Two patterns matter more than the totals. Rainfall is higher over the central and western parts of the island and decreases towards the east, and it falls "more frequently during the daytime, particularly in the afternoons when solar heating is strongest."
The temperature band is remarkably narrow. Minima rarely fall below 23 to 25°C at night and maxima rarely rise above 31 to 33°C by day. May is the warmest month on a 24-hour mean of 28.6°C, December and January the coolest at 26.8°C — a spread of under two degrees across the year.
Humidity does the work that temperature does not, averaging around 82% and swinging from over 90% before sunrise to around 60% on a rainless afternoon.
Two monsoons and two gaps between them
| Period | Months | What it brings |
|---|---|---|
| Northeast Monsoon | December to early March | Monsoon surges with widespread moderate to heavy rain in the first half; windy and relatively dry from late January |
| Inter-monsoon | Late March to May | Afternoon and early evening thunderstorms, at times severe; hot afternoons above 32°C |
| Southwest Monsoon | June to September | Occasional Sumatra squalls with 40 to 80 km/h gusts between predawn and midday; short afternoon showers |
| Inter-monsoon | October to November | Afternoon and evening thunderstorms; generally wetter than the earlier inter-monsoon |
The Sumatra squall is the phenomenon worth knowing by name. It is an organised line of thunderstorms originating over Sumatra or the Strait of Malacca, moving east under southwesterly winds, usually reaching Singapore overnight or in the morning. Onset is sudden — gusts of 40 to 80 km/h with heavy rain for one to two hours, and a maximum recorded gust of 93 km/h.
Monsoon surges are the northeast counterpart: two to four a year, each lasting one to five days of widespread continuous rain, with mean wind speeds up to 10 metres per second or more.
Thunderstorms and lightning, which are not a footnote here
Singapore averages about 167 thunderstorm days and 176 lightning days a year — among the highest rates of lightning activity in the world. The inter-monsoon months account for more than half the year's lightning strokes, with November the peak followed by April and May.
An individual storm cloud takes about an hour to grow and dissipate and produces under thirty minutes of thunder and lightning, so the disruption is short but sharp.
Heat, and the official thresholds for it
Singapore publishes a heat stress advisory using wet-bulb globe temperature, a composite of air temperature, humidity, wind and solar radiation — not the same as the air temperature on your phone. Readings come from about 35 stations island-wide and are averaged over the preceding fifteen minutes.
| Band | Threshold | What it advises |
|---|---|---|
| Low | Below 31°C | Continue normal activities, hydrate normally |
| Moderate | 31 to below 33°C | Reduce outdoor activities, take regular breaks in shade, drink more |
| High | 33°C and above | Minimise outdoor activities, more frequent breaks, cool actively during breaks |
The advisory applies to prolonged outdoor activities under direct sun for the general population, and was developed with the health ministry's heat stress guidelines expert panel.
Its list of vulnerable groups names one that travel writing usually omits: "people who recently travelled from cooler climates." That is most readers of this article in their first 48 hours.
The trend is also documented. Mean surface air temperature has risen by an average of 0.25°C per decade between 1948 and 2025, roughly double the global rate, and the highest temperature recorded in Singapore is 37.0°C — reached at Tengah in April 1983 and again at Ang Mo Kio in May 2023.
Haze, which is seasonal but unpredictable
Transboundary haze affects Singapore mainly during the Southwest Monsoon months of June to September, when regional fire activity increases.
| 24-hour PSI | Band | Advice for healthy people |
|---|---|---|
| 0–50 | Good | Normal activities |
| 51–100 | Moderate | Normal activities |
| 101–200 | Unhealthy | Reduce prolonged or strenuous outdoor exertion |
| 201–300 | Very unhealthy | Avoid prolonged or strenuous outdoor exertion |
| Above 300 | Hazardous | Minimise outdoor activity |
Advice tightens for the elderly, pregnant women, children and people with chronic lung or heart disease at each band. Readings are published as the 24-hour PSI and the 1-hour PM2.5 on the environment agency's site and the myENV app.
The city is built for this
The practical answer to both rain and heat is infrastructure. Since 2018 about 200 kilometres of sheltered walkway have been added under the Walk2Ride programme, covering 400 metres from all MRT stations and 200 metres from bus interchanges, LRT stations and selected high-volume bus stops.
That coverage radius is the useful number. If you are within a few minutes of a station, you are probably within a few minutes of cover — which changes how much a forecast should alter your plans.
Malls, museums and the conservatories at Gardens by the Bay are the obvious wet-afternoon fallbacks, and they are concentrated in exactly the areas the walkway network serves.
What to check, and when
| Tool | What it answers |
|---|---|
| Two-hour nowcast | Whether to leave now or wait |
| Heavy rain warning | 15 to 30 minutes of lead time |
| Lightning information service | Whether outdoor plans are safe |
| Heat stress map | Which band your area is in |
| myENV app | All of the above, plus PSI |
Check the nowcast rather than the daily forecast. In a climate where rain is local, short and afternoon-weighted, a two-hour window is the decision-relevant one.
What to pack
An umbrella rather than a raincoat — a raincoat in 82% humidity is worse than the rain. Light, loose, light-coloured clothing, which is what the heat advisory recommends in the moderate and high bands. And a layer for indoors, since air conditioning is set aggressively.
Then plan mornings outdoors and afternoons flexibly, which is the shape the climate data supports in every month of the year.
What this guide does not cover
No figure is given for Singapore's underground pedestrian network, because no official source could be retrieved for its extent. Nor is a live PSI or heat stress reading quoted — both change hourly and belong on the app rather than in an article.
All climate figures use the 1991 to 2020 reference period published by the Meteorological Service Singapore and were confirmed on 17 September 2026.