Heavy rain is on the way, according to a weather warning issued by the Met Office this morning (Thursday 28 August).
Some areas could see 2in or closer to 3in of rainfall in just a few hours overnight, the official forecaster said.
The warning said: “Heavy showers and longer spells of heavy rain may bring some disruption to transport and infrastructure.”
The Met Office warned passengers that bus and train services would probably be affected, with journey times taking longer.
Spray and flooding on roads could also make journey times longer, with the flooding of some homes and businesses likely.
The forecaster said: “Heavy showers, perhaps merging into longer spells of heavy rain at times, are likely to reach south west England and south Wales on Thursday night before pushing quickly east to affect other parts of southern and south eastern England into Friday morning.
“While not everywhere will see the heavy showers or rain, where they do occur, 10mm to 20mm of rain in less than an hour is possible.
“50mm to 70mm of rain is possible in a few hours where heavy showers become more prolonged, this most likely near coasts.
“Some flooding in these wetter areas is possible. A few showers could be accompanied by the odd rumble of thunder, again this more likely near to coasts.
“Heavy showers and rain should clear into the North Sea by early afternoon.”
The warning takes effect from 10pm tonight until midday tomorrow.
