This web site gives access to up-to-date meteorological forecasts in order to provide astronomers with information to plan their sky observation activities. The forecasts cover North America and are produced by the numerical weather prediction models that execute at the Canadian Meteorological Centre.The following forecast parameters are available in real time: forecasts of cloud, surface winds, temperatures and humidity as well as more specific parameters such as seeing forecasts and sky transparency.

Cloud forecast

Cloud forecasts at hourly intervals up to 48 hours.These forecasts can be interpreted in the same way as satellite pictures in the visible spectrum.

Seeing forecast

Seeing forecasts at 3-hourly intervals up to 48 hours. The "seeing" is the term used in astronomy to quantify the steadiness or the turbulence of the atmosphere. The detailed observation of planets, planetary nebulae or any celestial object requires excellent seeing conditions.

Sky transparency forecast

Sky transparency forecast at hourly intervals up to 48 hours.Observing deep sky objects such as faint galaxies and nebulae requires excellent sky transparency. Astronomers evaluate sky transparency based on the magnitude of the faintest star visible to the unaided eye. Sky transparency varies with airmass type.

Weather forecast near the ground

Wind, temperature and humidity forecasts near the ground surface for the next 48 hours.