Meteo can cause problem ?

In my experience IC engines always run better on a humid day. The air holds more moisture which makes it more dense which effectively raises your compression ratio which makes your engine run stronger. Also "4 stroking" is an ignition problem. Could be a fouled plug or a faulty plug wire or connection in your wiring, orrrrrr your CDI is dying... RIP

4 stroking is not just an ignition problem. It also occurs when you're jetted too rich or your fuel mix is too heavy.

I found RT carbs do not like high heat/humidity, with a lack of adjustability, and will cause motor to 4 stroke.
Drag racers get better times as the night cools the atmosphere,
Cooler air is more dense, as hotter air is thinner leading to over rich.
I do wonder if high humidity helps to act a little like water injection, which has been used to help pinging?
But I agree 4 stroking is unlikely an ignition problem,