up of quartzite and also make up the Sajahat Formation . At a glance Afternoon thunderstorms are a frequent occurrence in Singapore, which has a tropical rainforest climate. Geographic coordinates: 1°18′N 103°51′E﻿ / ﻿1.3°N 103.85°E﻿ / 1.3; 103.85 (most of the maps are not very up-to-date, they do not show the 1997