The Met Office has warned of heavy rain in St Albans on Friday.
The yellow warning was issued today warns of the possibility of localised flooding and disruption to transport.
Frequent lightning could prove to be an additional hazard.
The warning is in place from 6am on Friday until 11.59pm.
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 The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.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