Well, technically that's correct on a whole for these types of viruses!

In general, these viruses indeed, don't care about the weather!

Instead, they spread primarily and simply by the amount and frequency of people congregated closer together.

As such winter months bring a huge and drastic spike in the number of people hunkering down close to each other indoors, rather than outdoors.

For example, the cold/flu season in Jamaica is towards the rainy season in July, not winter.

So while humans care about the weather, the virus does not.

All that said, there are some additional ideas and hypothesis, that certain such viruses don't survive well on surfaces in certain temperatures. But I don't think that's an area that's been researched all that much, overall?

So the knowledge on that is rather fuzzy?

As well, in general: many a human living space in Western Civilization maintains a fairly consistent room temperature, no matter the season, thanks to air conditioning and heating.