The Touring Club Switzerland (TCS) will do a forecast on a daily and weekly basis and for the summer holiday season.
There is no forecast for summer 2014 yet available, but the figures for 2013 below will give you good guidance already
Link to the daily and weekly (in German):
Link to the summer holiday season forecast:
Days with higher traffic during sommer
Here a graph showing traffic jam lenght by day of the week.
Friday and Saturday are the most busiest.
Color green: Direction south to Italy
Color red: Direction north to Zürich
Traffic jam length during summer holidays per day of the week
Color code of the forecast:
Black: extremely high traffic is expected (peak)
Red: very high traffic
Orange: Medium high traffic
White: normal traffic
The peak traffic times for the direction to Italy during summer holiday season will be on Fridays and Saturdays during the month of July.
Also on Eastern long traffic jams can happen.
The peak traffic times for the North direction, when travelers return from Italy will last from Mid of July till Mid of August and can vary from Friday to Sunday.
Traffic will peak most of the times between 11:00 and 14:00 hrs during such days if there is no accident. Yet this year in July 2013 the pattern has changed. Traffic peaked between 8 and 10 am in the morning and there was always a traffic jam during the night from Fridays to Saturdays averaging at around 3 km length.