Please be aware that Paris has multiple airports and that these results are for all airports serving the city.
The best month to fly between Paris and Madrid is June and the most expensive month to fly is May. (Average prices, based on 349 datapoints.)
The best day to arrive at Paris is Friday and it would be best to avoid Sunday, as prices are on average 58.97% higher than on Friday. (Average prices, based on 364 datapoints.)
The cheapest airline flying from Paris to Madrid is Air Europa. They are 43% cheaper than Air France. (Average prices, based on 357 datapoints.)