Emergency road works in Birdham are being blamed for queuing traffic for four miles along the A286 as people looking to make the most of the heatwave and head for the beaches.
Traffic is slow and queuing all along the A27 between Fishbourne and Oving.
Weather sources are recording temperatures of 30 degrees Celsius in Chichester this afternoon.
Resident Annie Farwell wrote in to the Observer and said: "I felt compelled to write to you with regard to the appalling traffic conditions today. We know all back routes to get from town to Birdham and they are all gridlocked. Every road leading to the so called by pass are gridlocked. It can only get worse."
A post on the West Wittering Beach Facebook page reads: "There are emergency road works being undertaken on the way to us. Highways are looking in to it, please expect long delays. We will update you when we can."
Chichester Police added: "Please see the below information from West Wittering Beach. Emergency road works in Birdham are causing significant delays in the area.
"Traffic is currently very busy in Chichester and surrounding roads.#Chichester #A27"