The highest recorded temperature is on 17 April 1983. The lowest recorded temperature was in 14 February 1989 at Paya Lebar. Temperature often goes above and can reach at times. Relative humidity has a diurnal range in the high 90s in the early morning to around 60% in the mid-afternoon, but does go below 50% at times. During prolonged heavy rain, relative humidity often reaches 100%. Generally, there is much more rainfall on the western side of the island than on the eastern portion of Singapore, owing to a rain shadow effect. Thus, the eastern side of Singapore is much drier and slightly hotter than western Singapore. This can cause slight weather disparities from one side of the island to the other. This is significant to note because even a small hill such as Bukit Timah Hill can cause this phenomenon. Despite Singapore's small size, there may be sunshine on one side while there is rain on the other. Further contrasts that prevent true all-year uniformity are the monsoon seasons which happen twice each year. The first one is the Northeast Monsoon which occurs from mid-November to early March. The second is the Southwest Monsoon season which occurs from June to September. Periods between monsoon seasons receive less rain and wind. During the Northeast Monsoon, northeast winds prevail, sometimes reach . There are cloudy conditions in December and January with frequent afternoon showers. Spells of widespread moderate to heavy rain occur lasting from 1 to 3 days at a stretch. It is relatively dry in February till early March although rainfall still exceeds 120mm. It is also generally windy with wind speeds sometimes reaching in the months of January and February. During the Southwest Monsoon season, southeast winds prevail. Isolated to scattered showers occur in the late morning and early afternoon. Early morning "Sumatras" – squall lines that originate over nearby Sumatra – are common. Climate change initiatives Singapore recognises that climate change in the decades ahead will have major implications for the island-nation. It has taken a three-prong approach to the issue - researching how the nation will be affected in specific details, implementing mitigation measures and adapting to the coming changes. For the research, a Centre for Climate Research Singapore (CCRS) has been established. The government estimates that $100 billion will need to be spent over a 100-year time frame to address the issue. In the 2020 budget,