That‘s one of the biggest health myths around. Cold weather does NOT weaken your immune system AT ALL (except if you‘re actually hypothermic, which is very different from just feeling uncomfortable). It’s the CONDITIONS that RESULT from cold weather that actually cause those infections to ramp up in winter (think more people staying inside in enclosed spaces).
Yeah, using NetNewsWire. The original author bought it back somewhat recently and afaik it's a complete rewrite now and open source, go ahead and check it out https://ranchero.com/netnewswire/