Does weather/humidity affect your evaporation rate?

[jigidyjim]

I ended up with around 1/2 gallon more wort than normal, causing my OG to be too light today... Though I'm not sure why.

It's much hotter today than it is when I normally brew. Wondering if weather has anything to do with it. (I brew indoor stove top).

Thanks.

 

[LKABrewer]

Humidity will play a huge role in evaporation. The higher the humidity, the less will evaporate. If is is hot and humid, even less will evaporate.

 

[XcoM274]

As humidity increases, it becomes (mathematically) exponentially more difficult to create more water vapor. Barometric pressure also plays a role. Air at high pressure can sustain less water vapor than can air at lower pressure.

 

[Wakadaka]

would less boil off effect DMS production. I live in a very humid environment.

 

[XcoM274]

DMS production? I doubt it. But more DMS might remain in the wort during the boil. Remember, the main reason for DMS flavors comes from leaving the lid on the boil pot, then the condensation (saturated with DMS) falls back into the wort.

Just don't cover your boil pot, and I doubt you'll have a problem.

Cheers

 

[Wakadaka]

DMS production isn't the best way to describe it I guess. I have heard people say to do 90 minute boils when using pilsner (I think) malt, and I didn't know if the extra boil off was what was important or not. I don't know what DMS tastes like or even is, I just know to leave the top off when I am boiling. Didn't know if I should account for less boil off as well.

 

[XcoM274]

DMS is Dimethyl Sulfide. It tastes like corn on the cob. It makes beer taste like vegetables if there is enough of it. You will know as soon as you drink a bottle that has high DMS content.

I very seriously doubt high humidity will lower the evap rate enough to prevent boiling out DMS. The yeast are tough. They will take care of the little bit that does get left in the beer.

 

[jigidyjim]

Sigh. I'm a moron. I went back and looked at my brew logs today, still wondering if humidity could account for the extra 1/2 gallon I ended up with.

Then I realized... the last few batches I did, the ones where I really dialed in my system and everything came out predictably, were 90 min boils. This one, was... a 60 min boil.

So that explains the extra 1/2 gallon! Oh well, now I know...