The warnings are in place from Wednesday evening into Thursday, following the fourth heatwave of the summer which saw temperatures reach 33C in some places.
Forecasters anticipate heavy showers, with up to 50mm of rainfall possible, alongside hail and gusty winds.
Potential disruptions include difficult driving conditions, road closures, and a slight chance of power cuts.
There is also a warning of a small risk to life from fast-flowing or deep floodwater in affected areas.