Scorching summer weather gave way to a thunder and lightning storm over St Albans district overnight.
This photo was taken by Rob Ellingham over the M1 near Redbourn in the thick of the downpour.
Despite a seemingly crisper morning after the storm, Met Office forecasters are not predicting any break in the heatwave and temperatures are expected to rise to the late 20°Cs today.
Tomorrow, the Met Office experts believe it will reach 36°C by 4pm - although they say it will only feel like a marginally milder 35°C.
Over the next few days, the UK might beat its record temperature of 38.5°C from August 2003. The all-time July record of 36.7°C, from 2015, is also likely to be overturned.
The NHS Herts Valleys Clinical Commissioning Group has issued safety advice in the sweltering weather, which includes using suncream, carrying water, and looking out for others - especially older people, young children and babies.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here