Mexico City has a 'pleasant climate' all year because of its high elevation.
Explanation:
The Mexico City is located at a height of about 2250 meters above the sea level.
This orientation of the city allows it to experience a pleasant climate unlike the low-lying areas in the rest of Mexico.
The Mexico City, owing to its elevation, receives optimum rainfall. Its high altitudinal location helps in keeping the weather cooler compared to neighboring low-lying cities.