It was claimed the fire brigade was being asked to rescue people in "life-threatening situations" with all roads into the town, many on steep cliff inclines, deluged with water.
Dozens of lightning strikes were captured on camera as hail and torrential rain battered parts of the West country late on Tuesday as summer was rudely interrupted.
At Nare on the south Cornwall coast, 50mm of rain fell in an hour and there were 32 knots of gusting winds.
Reports suggested some people were trapped in flooded homes and vehicles may have been swept off the road by the torrential rain.
Police appealed to people not to approach the area.
A Met Office spokesman said that by 7.30pm, the worst of the weather had already passed over Cornwall and moved over the Irish Sea.
Hampshire was also experiencing some heavy storms on Tuesday evening, some of which were likely to affect parts of Wales.
The spokesman said the storms would pass over quite quickly.
"In Cornwall, the steepness of the area and the hills has enhanced the impact," he added.
The Met Office issued a yellow, severe weather alert that was due to last from 4pm until just before midnight, warning there could be localised flooding.
The thundery conditions are expected to move north overnight and the weather warning transfers to large swathes of the country north of the M4 on Wednesday.
The Met Office said "Thundery showers are expected to push north across southern parts of the UK through Tuesday evening, perhaps turning more widespread towards midnight.
"Although many places won't see these showers, there is a chance of localised flooding of homes, businesses and susceptible roads."
This article originally appeared on the Daily Telegraph.
