I"m not sure of the resource you are looking at, but you can use the san francisco forecast information as a general guideline for northern california diving, as long as you are not using san francisco bay information, as the bay is obviosly not effected by offshore weather the same way as the open ocean. I use the two resources that I explain below, I can get much mor localized information from there. To answer your question I would not use the SF as a guidline unless that is the forecast area you will be in.
Not to split hairs, but instead of his link
http://www.wrh.noaa.gov/mtr/ i use
http://www.wrh.noaa.gov/ just taking off the mtr, this allows me to pan out for all of california, the mtr narrows it down to a smaller area of the coast which still satisfies most Nor-Cal diving. Actually, I came on scubaboard today to give the forecast for the people who have trouble with the forecast or don't know about all of the resources. I use two resources, which the second is actually a compilation of other resources. the NOAA resource as listed above is nice, as well as Chuck's site which is a blessing to have as otherwise I doubt I would have found those sources of information.
My sources
http://www.wrh.noaa.gov/
http://www.garlic.com/~triblet/swell/wamglance.html monterey
http://www.garlic.com/~triblet/swell/abglance.html north coast
I was out yesterday with the NOAA prediction of 4-6 NW swell by NOAA and 79 degrees from weather.com, both were wrong with the temp never getting to 70 degrees, no sun at all and seas that didn't seem to be 4-6 x8 seconds. So the forecasts are just that, and are not always accurate. Use them as a guide and as a guide only. The swell forecast models on Chuck's site are quite conservative, often giving you a forecast that is rougher than it will actually be and NOAA is often quite accurate although keep in mind that they change their predictions 2-4 times a day, so go with the most up to date forecast you can get.
As for weather, Yesterday off the Sonoma coast it was greasy flat, probably the smoothest
I have seen it all year. The weekend looks promising
Here are the NOAA forecasts as of this posting.
PZZ455-475-272200-
CAPE MENDOCINO TO PT ARENA OUT 20 NM-
CAPE MENDOCINO TO PT ARENA 20 TO 60 NM-
900 AM PDT FRI MAY 27 2005
.TODAY...NW WIND 5 TO 10 KT. WIND WAVES 2 FT OR LESS. NW SWELL 2 TO
4 FT AT 13 SECONDS. PATCHY FOG.
.TONIGHT...NW WIND 10 TO 15 KT. WIND WAVES 2 TO 3 FT. NW SWELL 3 TO
4 FT AT 13 SECONDS. PATCHY FOG.
.SAT...NW WIND 5 TO 10 KT. WIND WAVES 2 FT OR LESS. NW SWELL 3 FT
AT 8 SECONDS.
.SAT NIGHT...NW WIND 10 TO 15 KT. WIND WAVES 2 TO 3 FT. NW
SWELL 4 TO 5 FT.
.SUN...NW WIND 15 TO 25 KT...BECOMING N 20 TO 25 KT. WIND WAVES
4 TO 6 FT. NW SWELL 4 TO 6 FT. SLIGHT CHANCE OF SHOWERS.
.MON...N WIND 20 TO 30 KT. WIND WAVES 5 TO 7 FT. NW SWELL 8 FT.
.TUE...N WIND 20 TO 30 KT. WIND WAVES 6 TO 8 FT. NW SWELL 8 FT.
PZZ535-272200-
MONTEREY BAY-
900 AM PDT FRI MAY 27 2005
.TODAY...W WINDS 5 TO 15 KT. WIND WAVES 1 TO 2 FT.
W SWELL 1 TO 2 FT AT 8 SECONDS. AREAS OF MORNING FOG.
.TONIGHT...W WINDS 5 KT IN THE EVENING...BECOMING LIGHT. WIND
WAVES SLIGHT. NW SWELL 1 TO 3 FT AT 8 SECONDS. AREAS OF FOG.
.SAT...LIGHT WINDS...BECOMING W 5 TO 15 KT BY THE AFTERNOON.
WIND WAVES 1 TO 2 FT. W SWELL 1 TO 3 FT AT 8 SECONDS.
AREAS OF MORNING FOG.
.SAT NIGHT...W WINDS 10 KT OR LESS. WIND WAVES 1 FT OR LESS.
NW SWELL 1 TO 3 FT. PATCHY FOG.
.SUN...W WINDS 5 TO 15 KT. WIND WAVES 1 TO 3 FT.
NW SWELL 1 TO 3 FT. PATCHY NIGHT AND MORNING FOG.
.MON...W TO SW WINDS 5 TO 15 KT. WIND WAVES 1 TO 3 FT.
NW SWELL 2 TO 5 FT. PATCHY NIGHT AND MORNING FOG.
.TUE...W WINDS 5 TO 15 KT. WIND WAVES 1 TO 3 FT.
NW SWELL 2 TO 6 FT. PATCHY NIGHT AND MORNING FOG.
Looks like we are going to have fine diving. Sonoma showed surface temps of 57-58 degrees while dropping to 52 5-7 miles offshore
