SINGAPORE: A rare optical event known as a sun halo appeared in the skies over Singapore on 25 August 2025, drawing attention from observers and prompting documentation by photography enthusiasts across the island.
The phenomenon, which takes the form of a luminous ring encircling the sun, was visible in several areas around midday and early afternoon.
This marks the second sighting in the year, following a similar appearance on 15 March.Sun halos form when sunlight interacts with ice crystals suspended in high-altitude cirrus clouds.
These crystals refract light at a specific angle, commonly 22 degrees, resulting in the halo’s circular appearance.
The 22-degree halo is the most frequently observed type.
Its formation depends on the consistent shape and orientation of ice crystals found in upper-level clouds.Such conditions are rarely met in Singapore.
The country’s typical cloud cover is dominated by low to mid-level clouds, and its warm, humid climate does not favour the formation of the high, ice-filled cirrus clouds necessary for halos.
The National Environment Agency (NEA) has previously noted that the presence and position of these cirrus clouds are difficult to predict, making accurate forecasting of halo appearances challenging.
On 15 March, a sun halo was observed from areas including Chinese Garden, Serangoon Gardens, Bedok, and Woodlands, with sightings recorded between 11am and 3pm.
The August occurrence followed a similar pattern in terms of time and distribution across the island.
Other documented sightings in recent years include 22 September 2020 and an event in 2021, suggesting that sun halos occur in Singapore only once every few years.
Despite their eye-catching appearance, experts continue to remind the public that while the halo itself is safe to observe with the naked eye, looking directly at the sun can be hazardous and should be avoided without proper protection.
The post Rare sun halo sighting in Singapore marks second appearance of the year on 25 August 2025 appeared first on The Online Citizen.
