SoCal Channel Crossing
Catalina · Santa Barbara ChannelChart 001 · San Pedro Channel — pick your run on the chart: any mainland harbor, any island harbor or dive mark. Backside spots route around the island; the reading re-scores for that run.
Ship's log · next 7 days · San Pedro ⇄ Avalon
A passage is only as calm as its roughest stretch, so each hour takes the worse of the two ends — then swell can knock an hour down a level. A run of green is your window.
This week's read
Fri is the day — 15 green hours
On the San Pedro ⇄ Avalon run, the rough hours this week sit mostly on the island end. Swell stays small or long-period all week, so wind alone sets the colors. Santa Ana conditions in the forecast — offshore NE wind flips the usual geometry: the front side gets exposed and the south side becomes the lee. Mornings run calmest before the afternoon breeze fills in.
Across the year
When the season cooperates
Peak flat water: late June through September — warm, light winds, small long-period south swell. Spring brings windy afternoons; winter is roughest, when NW swell events and Santa Ana winds move through. One rule holds year-round: mornings are calmest, afternoons build — early departures win in every season.
Notes to mariners
Light wind
Under ~8 knots the surface stays glassy to gentle. Past 13, whitecaps — hold off.
Long-period swell
Small swell at 12+ seconds rolls gently under a hull and is left alone. A steep set (4 ft at 8 seconds or less) or anything 6 ft and up knocks the hour down a level.
Worst end wins
The crossing is scored by its roughest stretch — pick your two ends on the chart and the reading takes the worse of them, hour by hour.
Summer south swells
Hurricane season off Mexico sends long-period south swell up the line. South-facing shores get sketchy fast, so a sizable swell out of the south knocks hours down at the backside spots and raises a watch flag.
Santa Ana winds
High pressure over the Great Basin circulates clockwise and drives desert air downslope to the coast, heating as it falls. When the source air is cold — snow line low — it arrives merely warm and blows hardest. Hot on the mainland, warm at the island, and the lee flips to Catalina's south side. The watch flag reads wind direction and the freezing level to call it.
About these charts
This site is drawn from a real set of Coast & Geodetic Survey charts of these waters, printed in the 1960s and worked hard ever since. Decades ago, a diver who knew this coast marked his spots on them in pen — Pinnacles with its coordinates, Ramming Rock, Farnsworth Bank on Catalina's backside.
That's what a chart is for: the official survey underneath, and local knowledge written over the top. SoCal Channel Crossing works the same way — live forecast data underneath, a waterman's rules of thumb written over it.
His story is coming to this page.
Notice to Mariners
Free membership — crossing alerts and more SoCal channels, when they publish.
Data: wind from Open-Meteo forecast at both ends of whichever run you select on the chart; waves from Open-Meteo marine at that route's midpoint. The default view refreshes about every 30 minutes. Reliable roughly 7–10 days out; past that, lean on the seasonal pattern. Conditions are a planning aid, not a safety guarantee — check current NOAA marine forecasts and use your own judgment before a crossing.
socalchannelcrossing.com — Catalina is the first crossing; more SoCal channels to come.