For Business Class flights, the cheapest month to fly this route is October. The most expensive months are February and December.
In terms of precipitation, rainfall in Portugal ranges from 6.0 - 122.0 mm per month. December is typically the wettest month, when rainfall can reach 122.0 mm. July is typically the driest time to visit Portugal when rainfall is around 6.0 mm.
If weather is an important factor for your trip to Portugal, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 23.0 C. Travellers hoping to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 11.0 C).
Booking a Business Class flight 89 days in advance of your planned departure date is, on average, the best time to get cheap flights to Portugal. The general trend is that the closer you book to the departure date, the more expensive your flight will be.