Global significance of freshwater swamp forest 
17 
IRE ORCHID 
TZWGAH MET. STATION 
EAYALE&AFIWET STATIOT 
MACRfTCHIE RESEHVi 
J.URONG INDUSTRIAL WATERWORKS 
Fig. 2. Geographical locations of selected meteorological stations in Singapore. 
Historical trends of wind 
The strength and direction of the winds over Singapore are influenced by the monsoon 
(Nieuwolt, 1981; National Environment Agency, 2007). Northeasterly winds prevail 
during the Northeast Monsoon which occurs from December to early March, with 
wind speeds sometimes reaching 30 to 40 km/h in January and February. During the 
Southwest Monsoon (June to September), southeast to southwest winds prevail over 
Singapore (with more consistent southwest winds over the Indian continent). Periods 
between monsoon seasons (Pre-Southwest Monsoon: April and May, Post-Southwest 
Monsoon: October and November) receive less wind. The highest extreme gust speeds 
come from thunderstorms, whereas higher extreme mean wind speeds come from non¬ 
thunderstorm events (Choi, 1999). 
The source of Fig. 3 (monthly mean wind speed (m/s) in Singapore) is the 
National Enviromnent Agency (2012); see also Meterological Services Division 
(2016). Overall, the wind speed at Changi is weaker than at the other three stations. 
The wind speed during the Northeast Monsoon is stronger (by 1-3 m/s, according to 
the site) than in other seasons. Maxima in the monthly mean wind speed tend to occur 
in January and February during the Northeast Monsoon, while minima tend to occur 
in April and May during the pre-Southwest Monsoon. 
