Depending on the fire will depend on what you use to put it out. Alpha fires can be put out with water, Bravo fires require a smothering agent, Charlie fires require a chemical powder or CO2, and Delta fires, well..............you push them over the side, or you let them burn out, because they make their own oxygen.
And, while a helo has been shown to put out a small apartment fire on a building, it was only 1/8th to 1/10th the size of the fire in Notre Dame, and they were able to put it out, but only after 2 drops, because the first one missed. I'd like to know how much the collateral damage was from the first drop that missed.
And, the apartment fire that was shown being put out by a helo in the city didn't produce nearly as much smoke as the fire at Notre Dame. Because of the amount of smoke, it would have been very difficult to get accurate drops.
And, did you know that the hotter the air is, the less lift that can be generated by the helo rotors? I'm guessing that the air over the church would have been too hot to safely fly a helo in there.
What effect does cold weather have on helicopter performance?
So in general, the colder it is, the higher the performance. In most helicopters, the difference in performance on a cold, dry winter day is very noticeable and much better than on a humid, hot summer day.
It's also worth understanding the properties of air. The colder the air, the lower the dewpoint so the less moisture it can contain. Moisture in the air also lowers peformance.