Malawians have been warned of an extreme heatwave that could see temperatures rise up to 44C.
People have been urged to avoid alcohol and caffeine as the drinks could cause dehydration.
The weather bureau says high temperatures are usual for October but are likely to become more frequent and severe because of climate change.
Intense heatwaves also hit parts of North Africa, Europe, the US and Mexico in July.
Experts say 2023 is likely to be the warmest year on record due to ongoing emissions of warming gases and El Niño weather events.
In an advisory, Malawi’s Department of Climate Change and Meteorological Services said a “prolonged period” of hot and uncomfortable weather was expected to persist until Saturday.
The projected maximum temperature in the southern Shire Valley is 44C and 40C in northern areas along Lake Malawi, it added.
Malawi’s chief meteorologist Yobu Kachiwanda told the BBC that a daily continuous rise in temperatures had culminated in a heatwave.
“The high temperatures are due to direct heat energy from the sun which is apparently overhead Malawi,” Mr Kachiwanda said.
The elderly, children and those with pre-existing health conditions are at risk of suffering serious health risks if exposed to extreme heat for a long period.
“Heat-related illnesses like heat exhaustion and heatstroke are a significant concern,” the weather bureau said.
Locals are advised to drink plenty of water throughout the day, even if they do not feel thirsty.
They are also urged to wear light clothing, avoid intensive physical activities and use sunscreen to protect their skin from harmful sunlight.
However, the high temperatures are essential to attract weather systems that generate the first rains in the country, the chief meteorologist said.
Malawi is still recovering from a devastating tropical storm in March that killed more than 500 people.
Tropical Storm Freddy saw mudslides sweep through neighbourhoods and bury people in mud.
The storm also struck neighbouring Mozambique and Madagascar earlier that month, destroying scores of homes and triggering widespread floods.
A study by World Weather Attribution group showed that global warming has exacerbated extreme weather in southern Africa.