For the purpose of this question,
temperature refers to daily mean temperature in a month (shown as "daily mean" on Wikipedia) of the city/town that an airport primarily serves
passenger flight refers to scheduled flights and public charters with a published schedule
it can be any month of the year
Singapore (SIN) - Moscow (DME) SQ 362 in February, daily mean for Singapore 27.1°C, daily mean for Moscow -6.7°C, difference 33.8°C.