Weather

Important note

Whilst racing, weather data or services such as routing that are not free of charge or easily available to all boats are not allowed by Rule 41(c) (outside help) of the RRS. See Case 120 in the Case book. However, Case 120 clarifies that rule 41c may be changed for any particular race by the notice of race and sailing instructions.

Weather maps and observations

Weather maps, satellite images and observations are available from many sources, including MyImage and observations in Expedition or Squid. Another very good service is SailFlow.

Windy may be the best of the online weather viewers, with GFS, ICON, ECMWF, Arôme & NAM data. It is also available as Android and Apple apps.

Grib data

Most data is available from Saildocs, Squid/Great Circle or Expedition.

Squid is a complete weather service.

Saildocs is free, designed to satisfy Rule 41(c).

The Expedition grib server is designed as a backup to Squid and Saildocs.

Data and sources we have found useful over many years of use:

Global models

From experience, 0.25° is a good compromise for global model data.

0.5° is usually too coarse, but is an option for slow connections.

1/8°-1/10° data may be more useful, but file sizes will be larger. Doubling the resolution will increase file size by about a factor of 4.

GFS

Available from Saildocs, Squid or Expedition 4x daily at 1/4° resolution.

ICON

Available from Saildocs or Expedition 4x daily at 1/4° or 1/8° hourly data.
ICON data is generally available earlier than GFS.

GDPS

Available from Expedition and Squid at 0.24° & 0.15° resolution.
Data Source: Environment and Climate Change Canada, licence terms.

Arpège

Available from Squid at 1/2° resolution.

Navgem

Available from Saildocs.

Regional models

Sources noted in [ ].

Australia

Access, often the best model for Australia [BOM]

Expedition WRF

Canada

RDPS [Squid]

Cape Town

Expedition WRF

Caribbean

NOAA HRRR & NAM [Saildocs, Squid]

Expedition WRF

Arôme [Squid, Meteo France]

Europe

Arôme, often the best model for French waters [Squid, Meteo France]

Expedition WRF, some areas are on demand for regattas

ICON EU & CosmoDE [Saildocs, Squid, Expedition]

HIRLAM & Harmonie, FMI, KNMI & YR.no [Squid, Expedition]

SMHI Sweden

Japan, Hong Kong, Philippines

Expedition WRF, on demand

NZ

Expedition WRF

USA

NOAA HRRR & NAM [Saildocs, Squid]

GLERL - Great Lakes winds & currents [Expedition]

SailFlow

Oceanographic models

RTOFS - Global currents and sea temperature. [Saildocs, Squid, Tidetech]

WW3 - Global waves [Saildocs, Squid]

MyOcean - Europe [Squid, Tidetech]

BSH Baltic & North Sea tidal currents [Expedition]

Hong Kong tidal current data

Tidetech [Expedition, Tidetech]

Expedition has integrated current models for various areas, including:

Proudman European tidal currents
SHOM tidal currents for France

Reanalysis

Copernicus
ECMWF