Vehicles broke down, homes were flooded to "waist deep" and roads were closed after flash floods hit Dorset.
The worst-hit areas were Lulworth to Bournemouth, where an air show had been due to begin, and on to Christchurch.
Patients had to be evacuated from a private hospital after a ceiling was damaged because of the water.
Several people were rescued from vehicles stuck in flood water. Bournemouth's Lower and Central Gardens were also submerged.
Police said much of the flood water had now receded and most roads and businesses had reopened.
However the Lower and Central Gardens and Boscombe Gardens remain closed.
At the height of the flooding, residents reported drains lifting up and water rising to almost to the height of their car bonnets.
In Exeter Road, Bournemouth, several buildings were evacuated and the road closed after a gas pipe was ruptured when a wall collapsed on to the pavement.
It has now been repaired, the road has reopened and people have been allowed to return to their homes and businesses.
The Met Office said 53mm (2.1in) of rain was recorded in the Springbourne area of Bournemouth between 04:00 BST and 13:00 BST, and 57.8mm (2.3in) of rain fell in Portland during the same period.
Dorset Fire and Rescue Service said it had responded to more than 100 incidents in two hours from about 10:30 BST.
A spokeswoman said it had been called to homes where water was "up to waist deep" and assistance was brought in from the neighbouring Hampshire service.
Operations were cancelled at the Bournemouth Nuffield Hospital in Lansdowne Road when the ceiling was damaged.
Bournemouth Borough Council said it had reports of flooding in 120 locations and up until 14:00 BST it had taken nearly 1,000 calls at its call centre, with 98% being flood-related.
Police said worried callers reported 2ft to 3ft (0.6m to 0.9m) of water near Castle Point Shopping Centre and one person told officers the road was "caving in".
Buildings and businesses were forced to close because of the downpour, including Poole's Dolphin Shopping Centre, the Russell Coates Museum on Bournemouth seafront and the Sir David English Sports Centre.
Drains and manhole covers lifted in a number of streets, including Magna Road and Coniston Avenue in Bear Cross, Nuffield Road in Poole, Commercial Road in Bournemouth and Burts Hill in Wimborne.
The A338 Wessex Way from the Liverpool Victoria building to St Paul's roundabout was completely blocked for a time, causing traffic gridlock. Traffic was diverted via The Triangle in Bournemouth town centre.
The Met Office said that although the worst of the weather on Thursday had passed by the afternoon, it issued a yellow weather alert for heavy and thundery showers on Sunday, moving across the Channel from France. A spokeswoman said these had the potential to cause similar problems.
Organisers of the four-day Bournemouth Air Festival, which was due to begin earlier on Thursday, said all daytime flying displays would be cancelled to maintain public safety.
A dusk air display was due to go ahead from 19:00 BST but was also cancelled.
Wessex Water said it had drafted in extra staff to help the council and customers affected by flooding after an "unprecedented amount of rainfall".
Bournemouth council said it had suspended its afternoon collection of green waste because crews were out helping to clear the drains. It said if the weather improved later bins would be collected during the evening.