Interesting one. I mainly focus on Bigfoot evidence so shadow figures aren't really my area, but I've been on enough overnight field investigations in woodland to notice that atmospheric conditions do seem to correlate with unusual activity. Storm fronts drop barometric pressure pretty sharply and theres a decent body of fringe research suggesting that affects how certain phenomena manifest, or at least how we perceive them.
Whether thats the figures themselves becoming "more active" or just our senses being heightened by the charged atmosphere, hard to say. Infrasound from storm systems can also cause unease and visual disturbances which muddies the data considerably.
Anyone actually logging timestamps and cross-referencing with weather data? Would be worth doing properly rather than relying on memory. Keen to see if theres a pattern that holds up under scrutiny.