Please be aware that Kuala Lumpur has multiple airports and that these results are for all airports serving the city.
The best month to fly between Kuala Lumpur and Chiang Mai is September and the most expensive month to fly is April. (Average prices, based on 388 datapoints.)
The best day to arrive at Kuala Lumpur is Monday and it would be best to avoid Saturday, as prices are on average 68.66% higher than on Monday. (Average prices, based on 388 datapoints.)