Quick, take a photo so you have proof!
Seriously, I don't remember it being so cold (I think Glasgow was 41F? yesterday) in May. My first memory, though, of Glasgow weather was landing at the Edinburgh airport in June in 2015 to go visit my daughter at Uni and that my teeth were chattering by the time I got to the place I was staying. (She had us walk it from the bus station rather than taking a cab, and it started drizzling.) And then in May when we moved there in 2017 I was wearing jeans and a sweatshirt still. We went out to walk to the Botanics and had a basically clear sky and it started hailing rice-sized hail on us. So, the weather there has always seemed a bit wonky to me!
You guys are having it tough this year. Perhaps that will also mean you don't have any blistering heat that melts the roads or anything later on in the year. (hope, hope?)