KUALA LUMPUR: The southwest monsoon may cause lower rainfall in most parts of the country, but the phenomenon is unlikely to trigger drought or heatwaves. Typically occurring between late May and September, it is expected to arrive in Malaysia on Saturday.
Former Malaysian Meteorological Department (MetMalaysia) director-general Jailan Simon said the country would still experience rain occasionally during this period, which reduced the chance of heatwaves.
"Heatwaves generally occur between late January and April. The phenomenon is more likely to occur during the El Nino years, such as 1997-1998 and 2015-2016.
"Normally, this is the time droughts occur in our country. It is quite rare for heatwaves to occur after April in Malaysia.
"The areas that are usually prone to heatwaves are Perlis, Kedah, Seberang Prai, northern Perak and the inland areas of Pahang and Kelantan in the peninsula.
"Heatwaves are more pronounced in certain places in Tawau, Keningau and several areas in interior Sabah, as well as in Miri, Sarawak.
"During strong El Nino cycles, more areas endure heatwaves, including the Klang Valley, northern and eastern parts of Johor, Melaka and several areas in Negri Sembilan.
"In order to reach heatwaves conditions, the temperature must exceed 37°C for three consecutive days. However, the chances for such conditions to occur is very low because the country will still get rainfall occasionally.
"Although urban areas may experience temperatures above 35°C, but it will not result in heat- waves. After all, we have weathered through quite a wet year this year," he told the New Straits Times.
MetMalaysia, on Tuesday, said the squall line phenomenon during the southwest monsoon could lead to heavy rain with strong winds and lightning on the west coast of the peninsula and west Sabah during early mornings.
The department also cautioned that uncontrolled open burning could trigger haze, especially between August and October.
Jailan said the monsoon winds could blow haze, resulting from rampant open burning in Sumatra as well as south and western Borneo, into the country between late July to September. The affected areas, he said, would include the peninsula and Sarawak.
"The chances of having transboundary haze are higher during the El Nino cycle since Indonesia usually experiences severe drought that time.
"Nevertheless, local haze can also occur domestically, if land clearing, forest fires, burning in landfills and agricultural burning, are done here.
"Several peat soil areas often become the sources (hotspots) for local haze, namely Johan Setia in Selangor, Rompin and Pekan in Pahang, as well as Miri in Sarawak," he said.
Jailan said climate change also influenced monsoons, such as the northeast monsoon that was highly dependent on the temperature and pressure difference between the north pole, northern Asia as well as Australia and southern Asia.
"If temperature in the polar region increases, it will alter the pressure difference between the areas and may result in weaker monsoon winds. This will significantly impact the overall weather system and even trigger extreme weather changes," he said.
To endure the dry weather, Professor Dr G. Jayakumar advised people to increase their fluid intake, even though they might not be thirsty, to ensure that they were properly hydrated.
Dr Jayakumar, a community and occupational medicine professor at Manipal University College Malaysia, said extreme temperatures could lead to heat cramps, heat exhaustion and heat stroke.
"Please carry water bottles while going out. People should don loose, lightweight and light-coloured clothing — preferably cotton clothes — during this period.
"Apply sunscreens when you are outdoors. Avoid leaving people in parked vehicles for long durations.
Limit your outdoor activities and cover your head with light-coloured scarves, caps or umbrella when walking under the sun," he said.
Sahabat Alam Malaysia (SAM) president Meenakshi Raman urged the authorities to step up monitoring and surveillance in pollution control, including on open burning, emissions from vehicles and industrial activities.
The authorities, she said, should engage with the public and encourage them to lodge complaints on open burning incidents through hotlines.
She also called on Malaysians to use water prudently and reuse water from their kitchens to wash cars and water plants.