Weather Data Cycles
When wind, current, and wave data updates in FairWinds, and what to expect when it does. All times are UTC.
Overview
Wind, ocean currents, and waves each update on their own schedule. New data goes live at fixed UTC times, so you can plan around the changeovers.
| Data Type | Source | Update frequency | Goes live |
|---|---|---|---|
| Wind (GFS) | NOAA | Every 6 hours | 00Z, 06Z, 12Z, 18Z |
| Ocean Currents | NOAA, Copernicus | 1–2× daily, by region | See below |
| Waves (GFS-Wave) | NOAA | Once daily | 06Z |
1. Wind (GFS)
Wind comes from the NOAA Global Forecast System (GFS), which runs four times a day at 00Z, 06Z, 12Z and 18Z. Each forecast takes several hours to be published, so FairWinds switches to a new cycle about six hours after its nominal run time.
| Current UTC time | Active GFS cycle |
|---|---|
| 00:00–05:59 | Previous day's 18Z |
| 06:00–11:59 | Today's 00Z |
| 12:00–17:59 | Today's 06Z |
| 18:00–23:59 | Today's 12Z |
What to expect: at 00:00, 06:00, 12:00 and 18:00 UTC the wind forecast refreshes. Forecast winds can shift from one cycle to the next, so it's worth re-checking your plan after each changeover. The race viewer can also preview the upcoming cycle before it goes live.
- Resolution: 0.25° (1.00° where finer data isn't available)
- Coverage: up to 240 forecast hours (10 days)
2. Ocean Currents
Currents are regional, and each region updates on its own schedule.
| Region | Source | Goes live |
|---|---|---|
| Western Atlantic | RTOFS | 12Z daily (previous day's run before then) |
| San Francisco Bay | SFBOFS | 06Z (03Z run) and 18Z (15Z run) |
| Strait of Georgia | SSCOFS | Once daily, around 07–08Z |
| English Channel | Copernicus IBI | 12Z daily |
| Agulhas, East Australia, Kuroshio, Tasman | Copernicus Global | 12Z daily |
3. Waves (GFS-Wave)
Waves update once per day. The new daily wave forecast goes live at 06:00 UTC. Until then, the previous day's forecast is in use.
What to expect: at 06:00 UTC, wave heights and directions can shift noticeably, since wave forecasts often change meaningfully from one day to the next.
- Resolution: 0.50°
- Coverage: 240 hours
See Waves and Boat Speed for how waves affect your boat.
4. Summary Timeline (Single UTC Day)
UTC Event
----------------------------------------------------------------------
00:00 Wind: Switches to the previous day's 18Z cycle
06:00 Wind: Switches to today's 00Z cycle
06:00 Waves: New daily run goes live
06:00 Currents: SF Bay switches to the 03Z run
12:00 Wind: Switches to today's 06Z cycle
12:00 Currents: Atlantic, English Channel and global regions switch to today's run
18:00 Wind: Switches to today's 12Z cycle
18:00 Currents: SF Bay switches to the 15Z run