Humidity suppresses brix but encourages mildew, so moderate is best.
Can you elaborate on why humidity suppresses brix or point me to a source of more information? Growing grapes in Maryland, this interests me but has never been a topic of discussion among any of the growers/winemakers I know. Only discussion that takes place wrt humidity is the impact on mildew and options to protect against mildew.
The book you want is Wine, Terroir and Climate Change by the celebrated Australian viticulturalist John Gladstones, possibly the best book on viticulture in the English language. Gladstones is an inveterate academic, and does not seem to fully comprehend the implications of his work, and the lengthy two-part review of it by Brian Croser is an essential guide. This was published behind the pay wall of Jancis Robinson’s Purple Pages, but it’s definitely worth a subscription to that wonderful site.
The premise is idiotically obvious. High humidity inhibits evaporation. Dry climes have higher brixes at maturity. Duh.
I suddenly realized to my horror that you might have thought I just called you an idiot. Just in case, that’s not what I meant. It seems we have ALL been idiots for several decades not to have realized this obvious element. Me, UCD, all the pros in the game. It’s embarrassing.