Yellow Thunderstorm Warning in Effect

The Met Office has issued a yellow thunderstorm warning covering the vast majority of Wales, arriving on the heels of an exceptional heat event. [1] The warning covers all counties apart from Flintshire, and lasts from 15:00 BST until 23:59 on Wednesday. [1]

What Prompted the Warning

The alert follows an official heatwave declaration in Wales, with a new record set for the hottest May day on Tuesday. [1] The dramatic shift from record heat to storm threat is the defining feature of this weather episode.

Risks and Hazards

The Met Office has warned of a chance of power cuts, flooding, difficult driving conditions and delays, with the potential of some cancellations to bus and train services. [1] Authorities warned that spray and sudden flooding could lead to difficult driving conditions and some road closures. [1]

There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds. [1]

Power Outages Already Reported

The storms did not wait for warnings to take effect — at one point, a total of 1,530 customers were left without power due to high voltage faults during thunderstorms in Pembrokeshire and Carmarthenshire earlier on Wednesday afternoon. [1]

What to Watch Next

With the warning running until midnight Wednesday and storms already causing disruption across parts of Wales, residents and travellers should monitor conditions closely throughout the evening. The rapid turnaround from heatwave to severe thunderstorm activity underlines how quickly Welsh weather can shift in late spring. Check the forecast for your city at PrestoWeather to stay ahead of the next development.