In general, when looking for the cheapest flight to Basel, try to choose a flight departing in November for the best deal.
From most locations, booking your flights to Basel around 60 days prior to your departure date finds the best deals.
On average, the cheapest flights to Basel are found when departing on a Wednesday. Try to avoid departing on a Sunday, as this is usually the most expensive day.
On average you can find the best deals on plane tickets to Basel when looking for flights with midday departure times.