In the off season, whenever that happens to be for Switzerland. Little things such as whether or not it's school holidays can also effect the price of the ticket/s.
Either of the "off-seasons" (fall and spring). Towns are filled with tourists in the summer and mountain skiers in the winter.
The cheapest time of the year to fly to El salvador is from February to March and then again in May, and then from August to October.
about February =)
spring break
when the kids are at school
March
during Ausgust or October
ALL YEAR LONG
There is no such cheapest time of the year. You just has to book well in advance for your flights and you get a best deal. Say almost one or two months in advance and try to fly on Saturday you will get chap air deals.
I think... November
January and February are considered out of season and are generally the lowest cost.
If you want to fly cheap book your seats 6 months earlyer
in august, September, January or march or by may