I dont think they are referring to weather. They are referring...

I dont think they are referring to weather. They are referring to economic cycles affecting industries, typically in commodities, building materials, shipping, etc. The common feature in cyclical industries is that supply and demand are mismatched due to capital investment cycles, for example, it takes time to build a mine or a ship, and when they are build, demand and prices are going down, hence oversupply, which leads to underinvestment leading to undersupply when demand picks up again.

How this applies to metal detectors sold to consumer hobbyists is far from clear in the case of CDA. and judging by the lack of response, i wager that the original poster who made this assertion is still trying to figure it out.