SINGAPORE - Singapore has been hit by the haze again, with the three-hour Pollutant Standards Index (PSI) entering the "unhealthy" range on Monday morning.

The haze originates from the annual burning of land and forests during the June-September dry season. Indonesian authorities are making plans for cloud seeding operations to extinguish forest and plantation fires in South Sumatra and Riau.

Last year, Singapore was hit by its worst spell of haze on record, with the three-hour PSI hitting 401, in the "hazardous" range.

Using information compiled from Nasa's EODIS database, we have created an interactive map showing the monthly distribution of hotspots in Sumatra, Peninsular Malaysia and Borneo since November 2000.

You may watch the playback or drag the slider to see the distribution for a specific month.

Regional hotspots from Nov 2000 to June 2014

Source: NASA EODIS | Straits Times Graphic: Lin Zhaowei