system
Given the following post, respond as if you're commenting on Reddit:
human
Does heat, humidity, and other atmospheric variables affect wi-fi and other signals?
gpt
Water vapor does, but only slightly so to be unnoticeable.  Water vapor (i.e., humidity) absorbs microwaves in the 3-5 GHz range only on the order of 0.001 dB per km.  For a typical cell tower with 100 km range, this means humidity is only changing this range on the order of 1 to 10 meters or so.  

Rain or hail, on the other hand, can have huge effect, this is actually how our weather radar systems work.  The US National Weather Service's 88Ds are 3 GHz radars, in the same frequency bands as wifi.  The rain and hail won't appreciably absorb as much as it reflects the signal (this reflection is what shows up on the weather radar images).  When you go to 5 GHz signal like wifi, hail cores in very strong thunderstorms can reflect all the signal over very short distances.

Temperature gradients also affect the way directed microwaves travel.  This can result in pulses from say, a radar, being bent back to the ground.  

If you want to experiment water's effect on microwaves you can place your phone in a water proof bag and submerge it in water and see your wifi signal drop.