The Severn Bridges were both temporarily closed to all traffic for what is thought to be the "first time" due to high wind speeds caused by Storm Eunice.
The M4 Prince of Wales Bridge and the M48 Severn Bridge are the main routes between south Wales and England.
The Prince of Wales Bridge has subsequently reopened, but the M48 Severn Bridge will remain closed for the time being.
A spokesman for the Severn crossings said earlier on Friday (February 18): “For what we believe is the first time, due to wind speeds both the M4 Prince of Wales Bridge and M48 Severn Bridge are closed to all traffic.
“Traffic management teams are heading to site to initiate the closure of the M4. Please do not travel to the location.”
The Severn Bridges official Twitter account later shared an additional tweet urging motorists to stop abusing staff, describing the decision to close both bridges as "extremely rare."
A spokesperson said: "We understand the effect a dual bridge closure has on people wishing to travel. This is an extremely rare event for us.
"We have staff out in this storm ensuring action is taken to keep roadusers safe and they are being abused for it. Respectfully, stop. Thank you."
A rare red warning - the Met Office's highest alert - was issued across south Wales and the southwest of England between 07:00 and 12:00 on Friday (February 18) due to the combination of high tides, strong winds and storm surges.
An amber warning remains in force across all of Wales and most of England until 21:00.
The UK government will hold an emergency Cobra meeting on Friday afternoon to discuss the response to Storm Eunice.
The public are urged to stay at home and the Army is on standby.