Thursday, September 07, 2006

Fog's back!...again...

Fog's back...and again, and again....

Generally we see a 6-day fog cycle during the summer: 3 days of heat where the fog doesn't enter Wine Country, followed by 3 days of progressively thicker which point the fog has cooled the area enough to stop the cycle, and we wait another 3 days for it to start again. Temps usually drop ~10°F on the foggy days from the otherwise highs, with extreme thick fog maybe plunging temps 20°F lower than normal.

August saw so much fog that the hot (100°F+) weather we had in June & July seems like only bad dreams. And the usual fog cycle is a thing of the past...with weeks straight of fog in August...

Looking at the data for Santa Rosa, June had an avg high temp of 83.2°F (102°F max temp, with 5 days above 90°F, and a minimum of 45°F which occurred on one of the foggiest days), and 13 days had fog, with 3 of those days fog so thick visibility was just 1/4 mile.

July produced an avg high temp of 89.4°F (108°F max temp, with 13 days above 90°F, again a minimum of 45°F ), 11 foggy days, but only 1 of those days had that really thick wet fog.

August saw an avg high temp of 89.4°F (97°F max temp, with just 2 days above 90°F, a minimum of 44°F ), and a whopping 22 days with fog, 5 of those days with thick fog and reduced visibility to a 1/4 mile.

September has started with fog every day so far, and that crisp golden glow in the warm afternoons that signals the arrival of harvest and "Indian summer" as it's locally called - cool gray mornings with sunny afternoons and highs peaking in the mid 80' to 90's.
Perfect for sneaking up on those perfect combinations of acids, sugars, and ripe flavor.

Now the last time I remember a string of foggy days that lasted this long it was back in th eearly 90's, and the fog was so thick & wet it brought some "bunch rot" ("cluster rot") to the Carneros area white grapes - especially the Chard. I haven't seen anything like that yet, so the conclusion I'll draw is that it hasn't been as thick & wet, and that the daytime temps & winds have kept the clusters from being wet too long into the morning & promoting mold or rot.

What effect will it have?
It delays harvest slightly, but produces wines with crisper acidity and more pronounced flavors (all other things being equal). Another bit of good news is that it tends to stretch the harvest out a bit and keep everthing coming into the wineries at a regular, methodical pace...
So while harvest has certainly started, it doesn't look to be one of those massive-everybody-picking-everything-at-once type of years, and will allow everyone to take full care of the vintage without getting too bogged down.


Post a Comment

<< Home