In an example of a modern highly rain fade resistant ptp microwave system in the 18GHz band, standard fcc part 101 fdd band plan. The radios might be talking to each other in both H and V polarities, 80MHz wide channel in both, at 2048QAM 5/6 during a normal sunny day. In an extreme rain fade event they may go all the way down to QPSK 1/2 and the link's capacity in Mbps could be as poor as 40Mbps (from what is nominally a 900Mbps+ link), but the end to end latency will remain pretty much the same.

Latency as experienced by users might be much worse, however, if suddenly 300Mbps of traffic is trying to be shoved through a 40-75Mbps link, for a period of several minutes or more.