.jpg?width=1600)
01 167 days of thunder, 175 of lightning
The cause is geographical. Singapore sits just over one degree from the equator, with intense solar heating all year, no real thermal seasons and an average relative humidity of around 82%. The atmosphere is permanently loaded and unstable.
Add to that the effect of being a small island: every afternoon sea breezes come in from several coasts at once and collide inland. That collision is the trigger for local storms, and it explains why the weather service notes that light and variable winds favour precisely the formation of thunderstorms in the afternoon and evening.
.jpg?width=1200)
02 No, it is not the lightning capital of the world
It is a label that gets repeated a lot and is worth correcting, because it is false. The place with the most lightning on the planet is Lake Maracaibo, in Venezuela, with around 233 flashes per square kilometre per year. Behind it come two towns in the Democratic Republic of the Congo, Kabare and Kampene, with 205 and 177.
In Singapore, ground-flash density varies enormously depending on where on the island you stand: from about 5 flashes per square kilometre per year on the Changi coast to about 36 in Choa Chu Kang, inland. The honest claim is a different one, and it is still striking: on average, Singapore has more electrical activity than almost any other entire country in the world. The absolute records belong to specific spots; what is exceptional here is that the activity covers the whole territory.
03 The most electric month is not the wettest
December leaves the most water. But the month that produces the most lightning is November, and the calmest by far is February.
The numbers make it clear. December is the wettest month, at 331.9 mm, but records 14 thunderstorm days. November, at 252.3 mm, records 19 thunderstorm days and 22 lightning days: the annual maximum. April and May, with only 164.3 mm each, add up to 20 and 19 thunderstorm days and 21 lightning days each.
The explanation lies in the inter-monsoons, the two transition periods between the northeast and southwest monsoons: late March to May, and October to November. In those months the winds are light and variable, which is exactly the condition that favours local convection. Adding up the four inter-monsoon months gives 82 of the year's 175 lightning days: nearly half the electrical activity in a third of the calendar.
At the other end, February is the calendar's exception: it is the driest month of the year, at 105.1 mm, and also the electrically calmest, with just 5 thunderstorm days and 4 lightning days. It is the dry phase of the northeast monsoon, windy and stable.
04 Two different storm clocks
This is the single most useful practical detail here. Singapore has two types of storm with opposite timetables. The local ones, generated by colliding sea breezes, break in the afternoon and at dusk. And then there are the Sumatra squalls, organised lines of thunderstorms that form over Sumatra or the Strait of Malacca and cross Singapore from west to east.
Sumatra squalls occur year-round, though they are far more frequent between April and November, and they arrive between the small hours and midday. They last one or two hours and bring winds of 40 to 80 km/h; the maximum recorded at Changi is 90.7 km/h. Singapore's all-time wind record, 144.4 km/h at Tengah on 25 April 1984, came from one of them. Around 48 are counted a year.
For a traveler, the consequence is direct: if you wake to a storm at five in the morning, the sky will most likely be clear by mid-morning. If instead the storm arrives at four in the afternoon, that is local convection, and it usually breaks hard and clears in under two hours. Neither cancels a whole day.
05 Which month to pick, and what to do when it thunders
The best window is February and March: the dry phase of the northeast monsoon, with the year's lowest rainfall and electrical activity at its minimum. The months to avoid if you want reliable outdoor plans are November and December, which combine the heaviest rain with the lightning peak. The rest of the year is perfectly viable if you accept reshuffling a couple of hours a day.
As for safety, the country has been managing this risk for decades. The lightning protection code has been mandatory for building submissions since May 2019, the national sensor network detects electrical activity with an efficiency of 90-95%, and the official environment app lets you receive alerts when discharges are detected within a 6-kilometre radius. The lightning fatality rate was measured at 0.35 people per million per year over 2000-2003, the last published series.
The practical rule is the usual one, and here it genuinely applies: if you hear thunder, go indoors. With 167 thunder days a year, it is a situation you will run into, and the city is built so that solving it is trivial.
.jpg?width=1600)
Hermesli Humidity never drops below 70% in any month.
Abishek Palraj There are 1.7 degrees between the warmest month and the coolest.
.jpg?width=1600)
Jeon Han — Korea.net / Korean Culture and Information Service