The Met Office has issued a yellow thunderstorm alert in Stroud this weekend with warnings of flooding, lightning and power cuts.
Spray and sudden flooding could lead to difficult driving conditions and some road closures.
Following the alert, Highways England are asking drivers to be take extra care on motorways and A roads.
National network manager Amy Shaw said: “It’s really important for people to adapt their driving in rain. “Rain makes it harder for tyres to grip the road and harder for drivers to see ahead – significantly increasing the chances of being involved in a collision.
“Hail showers on higher ground can also create issues. These can happen with very little warning, resulting in short-lived but treacherous driving conditions. “We’re encouraging drivers to be aware and to check the latest weather and travel conditions before setting off on journeys.”
Heavy and thundery showers are expected throughout Saturday, broken by sunny spells before torrential thunderstorms soon develop carrying the risk of hail.
Showers, heavy and possibly thundery, will gradually ease for most by late evening to leave a largely dry but often cloudy night with some clear spells.
On Sunday, the Met Office expect a largely dry day for many with sunny spells and some showers.
In wet weather Highways England advises drivers to:
• Slow down if the rain and spray from vehicles is making it difficult to see and be seen and remember that stopping distances will be at least double in wet weather, because your tyres will have less grip on the road.
• Keep well back from the vehicle in front as this will increase your ability to see and plan ahead
• Ease off the accelerator and slow down gradually if the steering becomes unresponsive as it probably means that water is preventing the tyres from gripping the road
Following the easing of Covid restrictions, and the first weekend of the school holidays, traffic levels are expected to be high and Highways England is also asking people to be prepared for any long journeys.