Two out of three lanes have been closed in both directions to allow emergency repairs to take place.
National highways revealed that work is being done on the lighting columns after identifying an immediate risk that could cause a collapse.
In a statement, they added: “There are severe delays approaching the M4 Prince Of Wales Bridge in both directions due to emergency roadworks.
“2 lanes of 3 have had to be closed in both directions for safety reasons, awaiting emergency repairs to a number of lamp columns.
“This is due to urgent safety inspections of lighting columns on the bridge, which have identified an immediate risk.
“Testing found several columns in need of immediate removal due to the risk of collapse.
“However, we have to wait for the high winds to subside before work can take place. We appreciate your patience while we complete this vital safety work.”