Plymouth saw 10mm of rain in an hour during the yellow thunderstorm warning which ran from 6am to 10pm on Sunday.
The Met Office – which said it is the first such advisory since the service was introduced – has also extended the regions where the thunderstoms may hit and moved it further eastwards from Bristol to Portland towards Reading and Worthing.
Forecasters said storms may develop and bring torrential rain, hail and lightning to places in south-west England and Wales.
The warning suggested that heavy showers and thunderstorms affecting parts of south-west England during Sunday morning could spread into south Wales and further east across southern England with “30 to 40mm of rain in an hour possible, though the scattered nature of the showers means it is not certain where these higher totals and any impacts may occur”.
With dry, sunny weather and temperatures in the mid-20Cs for much of this week, tennis lovers should be in line for plenty of action as the Wimbledon championships begin.
Met Office forecaster Simon Partridge said that apart from a low risk of a shower first thing in the morning before play starts on Monday “there should not be too much risk of stoppage of play, certainly not because of the weather anyway”.
There is also a chance temperatures may soar higher a week later.
Wimbledon’s head groundsman Neil Stubley has denied the grass is longer at the All England Club this year and is confident the courts can handle the heat.
Rafael Nadal said on Saturday he thought the grass was longer than in previous years but Stubley, the head of courts and horticulture, said: “Still 8mm, that’s the height we’ve played for many years now and it’s exactly the same this year.”
Last year the state of the courts during a hot first week of play was criticised by a number of players, with France’s Kristina Mladenovic branding them dangerous.
Stubley said: “This year compared to last year we’re about three or four degrees lower. With perennial rye grass, the upper ceiling is 28, 29 degrees, once you go above that the plant naturally will start to stress because it’s a living surface.
“At the moment we’re at that top level but because we can afford to get the irrigation on in the evenings because we’ve got nice weather, at the moment we’re nicely in control.
“We’re constantly monitoring the forecasts and the forecasts are looking like this for next week. We’re very happy with where we are.”