During El Niño years, why is is Christchurch, New Zealand’s air temperature cooler than usual?

Claim 1
Christchurch’s air temperature changed because
the ocean current near Christchurch changed.

Claim 2
Christchurch’s air temperature changed because
the prevailing winds near the equator changed.

Claim 2

Explanation:

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.