Most of Hertfordshire falls within a heavy wind alert zone which includes potential tornadoes today.

“Isolated tornadoes” could hit parts of Hertfordshire, according to a warning issued by the Tornado and Storm Research Organisation (TORRO) this afternoon (March 28).

It also said that a large area of southern England may see wind gusts of 50 to 70mph, occasional lightning, and hail until 8pm. In Hertfordshire, the warning area extends from the west of the county to around the A10.

The TORRO alert said: “Whilst the overall tornado threat is low, given the linear nature of much of the activity, there is a low-end chance of one or two developing.”

A Met Office weather warning for wind is also in place across the south coast of England all day today, but this does not extend north of Surrey.

It comes as drivers are being warned over long delays on roads as more than 14 million Easter getaway trips are expected to take place.

From 4pm on Thursday, the RAC expects the M25 to be the busiest route in both directions between the M23 for Gatwick and the M1 in Hertfordshire-with journeys taking more than two hours – over double the usual time.