Be Your Own Surf Forecaster

Ocean swell and wind reports and surf forecasting resources for the weather savvy surfer

wave image
Apologies to Hokusai
This site is for ocean people, surfers generally and me in particular. It's a collection of gadgets that help us visualize marine weather. I started building these tools in 1998 when I wanted to graphically see buoy data in ways that weren't available anywhere else. I've been improving and adding to the tool set ever since.

I've started a parallel site for people who want to build something like this for themselves. I'll be slowly posting papers that explain the techniques and code I use. If you're a programmer check out The Open BuoyTools Project here.

If you have any comments or suggestions about this site let me know at


Tides at the Golden Gate in feet for yesterday, today, and tomorrow

tide image

Predicted Golden Gate tides. The time of tides for all our breaks outside the Gate are earlier then Golden Gate times by about 40 - 80 minutes. See the table below for more details.

Data generated by WXTide32, image created by my Buoy_tool tool kit.

Swell heights and periods with wind and spectrum images

Blue bars height in feet, red bars period in seconds, horizontal lines 5 units apart, "wind birds" red beak points into the wind and the number in the circle is wind speed in knots. Grayed bars indicate hours of missing data that are filled in by the Buoy_tool software. See below for a discussion of the spectrum images.


Graph 4

spectrum graph 4

graph 5

spectrum graph 5

graph 5

spectrum graph 5

GIFF images created with, written by me in 100% pure Perl

About the Tide Reports

The predicted Golden Gate tides are given for yesterday, today and tomorrow. Yesterday so if you went out and it got better of worse at some point, you can look back -- could have been a tide thing but check the buoy too. Tomorrow so we can plan.

Data generated by WXTide32, image created by my Buoy_tool tool kit.

Time Differences for Nearby Tides


High Tide

Low Tide

Point Arena



Fort Ross



Point Reyes



Ocean Beach



Half Moon Bay



Santa Cruz, Monterey Bay



Use this table to correct Golden Gate tide times for nearby locations. The time of tides for all breaks outside the Gate are earlier then Golden Gate times (i.e. all the correction factors in this table are negative). As a rule of thumb, if you surf Ocean Beach or north of the bay remember that the tides are about 40 minutes earlier then the Golden Gate and you'll be close. If you go south of Half Moon Bay think an hour.

About the Wind Reports

The wind reports are extracted from the excellent wind model "SAN FRANCISCO BAY WIND PATTERNS" at Note that these are modeled winds based on current observations at about 20 weather stations scattered around the greater Bay Area. None of these breaks (other than Fort Point) have networked wind sensors. Also, at the time this page is updated these wind observations can be 15 to 45 or more minutes old. This is about the best that can be done on an automated page like this. (Of course, we could put in our own network of wind sensors like the windsurfing guys do -- Funding anyone?). Enjoy.

About the Swell Height and Period Images

This is my winter buoy pattern.

The SE Papa Buoy 46006 is about 24 hours out for a 20 second North Pacific swell heading towards the Northern California beaches. Shorter period swell components will take longer with 13 second swells taking about 40 hours. The California Buoy 46059 is about 12 hours out and San Francisco 46026 is just an hour or so out.

Drop me an e-mail and let me know what you think at

About the Swell Spectrum Images

In the swell spectrum images, the bar height for each hour is the sum of swell height in feet and dominant period in seconds just like the the images above them. The colors show the mix of wave lengths in the swell with the size of each color proportional to the energy in that band. A powerful, clean ground swell will have most of its energy at the red, long period end of the spectrum. The faster moving long waves will be the first to arrive from a distant storm with shorter waves coming later as the swell tapers off. Local wind swell will add cooler colors to the mix.

This version of the software uses 33 colors to display the 33 bands in the the raw buoy data. This makes a pretty picture but as surfers we're more interested in periods above about 12 seconds. When I revisit this part of the project I want to try to re map the data to favor the longer end of the spectrum and use fewer colors so the changes in the bands will be clearer. For now I'll be interested to see what this display will do as different swells roll through.

Buoy locations in the Eastern Pacific

Pacific map The map to the right is a detail from the blue rectangle in the map above. Red indicates buoys used in the above graphs inside map

Development notes (mostly geek speak and safe to ignore...):

The information on this page is gathered from sources beyond my control but the representations of the data are generated by programs created by me for my use and our enjoyment. Everything on this site is copyright protected © by Frank Cox and Practical Wizardry. I'll be as careful as I can be to publish accurate reports but I can't guarantee them. Ocean sports contain an element of risk and it's up to you to surf safe.

In other words, you can't sue me if you get hurt, no matter what you see here.
(Not that I think you would, but it's a weird world out there!)

And, you can't use my images or other works without asking me. Enjoy them here. (But do ask, I usually say yes.)

Thanks, -- Frank Cox

Comments and questions: