Early risers were greeted by curious cloud formations splattered across the sky in various parts of Singapore yesterday morning.

As rays of sunshine peaked through the sieve of clouds, social media lit up with photos of the formation - known as cirrocumulus clouds - from Toa Payoh to HarbourFront.

Cirrocumulus clouds, a relatively rare type of formation, are made up of many cloudlets, or small white clouds, which are usually grouped together at altitudes between 5km and 10km.

The clouds are often made up of both ice and supercooled water, which is water that remains a liquid even at temperatures well below 0 deg C.

While the clouds are usually associated with fair weather, they can also often prelude stormy weather.

Predictably, it did yesterday, as playful puffs of clouds slowly turned heavy and foreboding, bringing thundery showers in the afternoon and evening over many areas.