The Met Office has told people to prepare as more heavy rain is expected and more warnings are likely. More heavy rain could cause travel disruption and flooding in southern England and south Wales on Friday.

The Met Office has issued a yellow warning for rain in the area until midnight, following a similar warning on Thursday. Heavy rain could cause some disruption to travel and flooding in places across southern England and south Wales on Friday.

Further warnings are likely to be issued over the weekend, the forecasting agency said. Friday’s rainfall could bring the total amount of rain falling on parts of the affected area to between 50mm and 100mm in 48 hours – Okehampton in Devon will see 44.4mm on Thursday.

Commuters are being warned to expect spray and flash flooding, leading to difficult driving conditions and some road closures. Met Office meteorologist Aidan McGivern said: “The rain we’ve seen in the south and southwest through Thursday is set to continue into Friday and into the weekend.

“There will be ebbs and flows in the rainfall. There will be pulses of heavier rain at times and then pulses of lighter rain at other times.”

After a relatively calm start to Friday, he said the rain would become “heavier and more persistent during the morning”, with the wettest weather likely to be south of the M4. Cloud is expected to move northwards in the evening and the rain will ease.

“Depending on where you are in the UK you will experience completely different weather conditions,” he said, with much of the country expected to see plenty of warm sunshine under clearer skies, except for the North Sea coast, where there will be much cloud.

Temperatures could reach 27C in places, with the potential for the hottest day of the year in parts of western Scotland. The weekend will remain blustery, but will start off mainly dry before cloud and rain return to the south, with showers further north.

It will be cooler from Sunday into Monday with further outbreaks of showery rain. The Environment Agency issued six flood warnings, where flooding is possible, across England on Thursday, including three in Devon and on the River Thames between Putney Bridge and Teddington Weir.

The agency said that while surface water flooding is “possible and not expected” in the warning area on Friday, inland flooding remains possible until Monday. No warnings have been issued by Natural Resources Wales.

The Met Office has issued advice on how to stay safe:

Follow these 6 simple steps to protect your home or business:

1. Check the flood advisory in your area to find out when and where flooding will occur

2. Charging mobile phones

3. Park your car outside the flood zone

4. Prepare a flood kit to help you cope with flooding in your home or business.

5. Store valuables such as electrical appliances, important documents and furniture high up

6. Turn off gas, water and electricity

If you are trapped in a building by flood water, follow these simple instructions to protect yourself and your family:

• Go to the highest level in the building you are in

• Avoid going into attics to avoid being trapped by rising water

• Only go to a roof if necessary

• Call 999 and wait for help