#Cycling: Hot Humid Days = Faster Than Cool Dry Days

Added: 2026-05-22

[00:00:00]Assuming you can put out enough power to go fast, a hot humid day is much faster than a cold dry day. And that is because of the air viscosity. So, air that is lighter is less viscous, it gets out of your way easier, and it creates less of a low pressure behind you than cold air. So, cold dry air is slow, and hot moist air is fast. That's just the way it works. And it has to do with the molecular mass of water versus nitrogen.

[00:00:37]And it has to do with the mass of the air itself with respect to temperature.

[00:00:41]So, the chemical composition, in terms of how moist it is, makes the I know it seems counterintuitive, right? A dry day features high pressure. That's because the air is more massive, and because it's more massive, it's pressing down more through gravity.

[00:00:56]So, that's a little bit about how air works.