Houses damaged by lightning strikes as storms bring an end to the heatwave.
A lightning strike on a TV aerial set the roof of a house alight in the upmarket hamlet of Murton in Gower, Swansea.
And homes in Barry and Cardiff were also struck, causing damage to the buildings.
Surface water gave motorists problems, and torrential overnight rain led to flood watches being put in place on rivers in South, Mid and West Wales.
Met Officer weatherman Andy Sibly warned of more thunderstorms to come today but he said tomorrow would very warm and sunny with mixed weather next week.
Firefighters were called to the house in Murton, Gower, at 5.15am yesterday after the owner, a mother of two, woken by the sound of the storm, reported she could smell burning.
A fire developed in a roof extension in her house at Long Acre which firefighters took an hour to put out.
Paul and Liz Edwards, who live next door with their two-year-old daughter Caitlin, also suffered smoke damage to their premises.
Swansea fire officer Andy Collis said the lightning probably heated a bracket on the aerial leading to the fire but he said such instances were very rare.
No one was injured in the incident.
Although fire did not break out at the house in Barry, which was struck at 5.49am, the roof was badly damaged.
A property in the Pentwyn area of Cardiff was also struck with damage to the electric fuse box and it split a gas pipe.
Meanwhile, the M4 was severely affected by heavy rain, which led to surface water and spray.
According to experts, thunder and lightning often follows long, sticky summer days because moist air rises rapidly into the sky, causing huge cumulonimbus clouds.
Updraughts of air lead to rapid movement with ice and water particles rubbing against each leading to a massive build-up of static.
The build-up is often discharged from cloud to ground (fork lighting) with bolts travelling at 14,000mph and heating the air around it to an astonishing 30,000C, or the equivalent of five times hotter than the surface of the sun.
Around five people a year are killed by lightning bolts in the UK.