Practising open burning to clear land for agricultural uses is common in certain areas in the region. The vastness of the land makes it difficult for local authorities to police this practice.
A combination of dry season, wind direction, cloud formation and poor precipitation formation creates haze. Thus haze could potentially occur at any time of the year.
Prevailing winds sometimes carry smoke produced by the forest fires across to Singapore. Such instances are particularly likely during the Southwest Monsoon Season.