6 min read
Inter-monsoon thunderstorms
Light winds plus strong sun. Storms grow over the island in the afternoon, and lightning days peak. May is the hottest month. November is one of the wettest.
Two windows
- Late March to May: first inter-monsoon. Hottest stretch of the year. April and May average 20 and 19 thunder days.
- October to November: second inter-monsoon, generally wetter. November averages 252.3 mm and 22 lightning days, the most of any month.
Why storms fire in the afternoon
With the large-scale monsoon wind slack, land and sea breezes take over. The island heats. Cumulus build from late morning. By mid-afternoon many of those clouds are cumulonimbus with tops at 9-12 km. That is the daily lightning machine.
These storms are local. It can pour in Toa Payoh and stay dry in Bedok. That is why the area nowcast exists.
Planning around them
- Book outdoor events for morning if you can.
- Treat 2pm to 5pm as the default storm window.
- Check the 2-hour nowcast at lunch, not only at breakfast. Cells pop late.
Questions
Is April hotter than May?
April has the highest mean daily maximum (32.4°C). May has the highest 24-hour mean (28.6°C) because nights stay warmer.
Why does November feel wetter than April?
November rainfall is much higher (252 mm vs 164 mm) and humidity is the highest of the year. The storms are more frequent and often heavier.
Independent guide based on publicly described NEA and Meteorological Service Singapore products. Not affiliated with NEA.