Frequent heavy showers and thunderstorms are expected, potentially bringing 10-15 mm of rain in less than an hour, and 30-40 mm over several hours in some areas.
The storms may also bring lightning, hail, and strong winds, causing potential disruptions to public transport and hazardous driving conditions.
The Met Office warns of possible damage to buildings from lightning strikes and short-term power loss.
Despite the stormy weekend and dropping temperatures, the Met Office's three-month outlook suggests a higher chance of a hot summer with an increased risk of heatwaves.