Saturday morning leaving the big cities and Monday afternoon returning to them will also have some traffic jams but Sunday should be an easier day to travel on.
In particular, journeys between the biggest cities and holiday destinations will be the busiest, especially on the coasts. This will even be the case on Sunday as people go for day trips.
On Monday most holidayers will be returning home in the afternoon, with 17:00 being the busiest time. This is likely to be the case on all the major roads leading into the big cities.