WHERE IS IT BLOWING? - Article courtesy TWC member Jeff MacIntosh

  • iWindsurf gives you current wind data for all of their sensor stations (and they have lots): this is the quickest way to find out where it’s blowing at any given time
  • you can also see what wind their computers are predicting
  • they use several different types of models, and you can easily view all of them
  • if you have paid for it, you can also get a meteorologist’s forecast

But even if you subscribe to iWindsurf, it is wise to consult other services to see if there is consistency in the forecasts emanating from different sources.   If there is a strong consensus, it is very likely that you won’t be disappointed.  On the other hand, if there are material differences in the various forecasts, you might want to hang back a bit and see if and where it actually blows.

Here are some of the sites that I regularly check:

Our Own Club Website www.torontowindsurfingclub.com

  • The smart folks who run our website have put a link on the right side of the main page headed “TWC Weather Station”, which links you directly to the Weather Underground weather data right at our club. Wow, you can’t get much better than that.
  • If you want to go straight to this website, it can be found at www.wunderground.com/personal-weather-station/dashboard?ID=IONTARIO783
  • The coordinates of the weather station are 43°38 '21''N, 79°20'12''W
  • If you want to see where it is located, just copy the above coordinates into Google Earth and it will take you there
  • You can also look at the “TWC BEACHCAM” on the TWC website, which will give you more information about the wind (and whether anyone you know is at the beach!)

Weather Underground www.wunderground.com/global/stations/71265.html

  • The Weather Underground website will also give you a forecast for pretty much anywhere you want to sail. For some reason, their wind forecasts tend to be lower than many other stations. If they are forecasting a lot of wind, chances are there will indeed be wind.
  • Weather Underground gives you hourly forecasts for the current day plus ten days into the future
  • Look at the “10 Day Weather Forecast”: you can get the info that you want from either the “graph” presentation or the “table” presentation
  • Again, the further you go into the future, the lower the accuracy

If you want to get the report for a particular sensor station (like, say, Wasaga Beach)

  • Go to the Weather Underground address noted above
  • In the “Search Locations” box enter the general location (e.g. “Wasaga”)
  • You’ll get a drop-down menu of various locations with “Wasaga” in them including “Wasaga Beach, Canada”
  • Click on that
  • On the left side of the page, you’ll get weather data for Wasaga Beach
  • Click on the name of the actual weather station, which is the first thing you’ll see under “Wasaga Beach”
  • In the case of Wasaga Beach, the name of the weather station is “APRSWXNET”
  • When you click on that, it will bring up a map that shows you a map with
    • the location of the weather station
    • the direction of the wind (from the direction of the little stick)
    • the strength of the wind (see Appendix entitled “How to Read Wind Barbs”)
    • the local temperature (the number in the middle of the circle)

Farmzone www.farmzone.com/next_twentyfourhours/SO088

  • Farmzone is a free service for farmers, who need to know stuff like what temperature it’s going to be, how hard it’s going to blow and from what direction, and how wet it will be. All of this stuff is really important for planting, watering, maintenance, harvesting, etc. I find Farmzone to be one of the most reliable websites when it comes to wind speed and direction (not to mention other stuff like temperature and precipitation).
  • Farmzone has a 24-hour forecast (www.farmzone.com/next_twentyfourhours/SO088) and a 7-day forecast (www.farmzone.com/sevenday_forecast/so088)
  • You can get the forecast for a wide variety of different spots in Ontario.

The Weather Network www.theweathernetwork.com/weather/canada/ontario/toronto

  • The Weather Network gives you forecasts for just about anywhere
  • Click on the “hourly” tab, and then “table” (instead of “graph”, the default presentation) to get a weather forecast by the hour, which can be extremely useful if you want to know exactly when you should go sailing
  • They have hourly forecasts for the current day plus 3 days into the future, although of course the longer into the future you go, the lower the degree of reliability

Windfinder www.windfinder.com/forecast/upper_beaches_toronto

  • Windfinder used to bill themselves as “Windsurf Canada”
  • They give you a nice 3-hour visual presentation that stretches over 4 days

Unisys weather.unisys.com/nam/nam.php?plot=surf&inv=1&t=18

  • Unisys gets its raw data from NOAA (the U.S. National Oceanic and Atmospheric Administration)
  • It tends to be one of the most reliable sites re wind
  • There is a wealth of data and forecasts here, and what you need to start with is the NAM/wrf surface model 18 hour forecast, which can be found at weather.unisys.com/nam/nam.php?plot=surf&inv=1&t=18
  • The forecast times are all delivered in Universal Time (formerly Greenwich Mean Time), which is denoted by the letter “Z” on the website Here is how you read the forecast tagline on the top of the forecast diagram:
  • Suppose the tag line reads “NAM 30 hour valid 18Z Tue 15 Mar 16”
  • “valid 18Z Tue 15 Mar 16” tells you the exact hour to which the forecast refers: in this case, 18Z on Tuesday March 15, 2016
  • “18Z” means 18:00 Universal Time
  • To convert to Toronto time:
    • Since daylight saving time is not on, you subtract 5 hours to get the equivalent Toronto time – here 13:00, or 1 pm.
    • When daylight saving time is on, you subtract 4 hours. Thus, “18Z” would mean 14:00 Toronto time, or 2 pm.
  • What about the “NAM 30 hour” part? This means that the forecast uses the NAM computer model, and that it was made 30 hours prior to 1 pm on Tuesday, March 15

Unisys makes simultaneous forecasts for 6, 12, 18, 24, 30, 36, 42, 48, 54, and 60 hours into the future

  • You can switch between them by clicking on the different forecasts in the “TIME” line just above the forecast map
  • Let’s say the tagline that you’re at is “NAM 30 hour valid 18Z Tue 15 Mar 16”, and you want to see if it will be blowing on Wednesday afternoon
  • If you switch to the 54 hour forecast (or NAM 54 hour valid 18Z Wed 16 Mar 16”) you’ll get the forecast for 1 pm on Wednesday

Generally speaking, the longer the forecast is into the future, the less reliable it will be.

Environment Canada weather.gc.ca/city/pages/on-143_metric_e.html

  • Environment Canada has forecasts for pretty much anywhere in the country. They used to be horrible when it came to wind, but seem to have improved somewhat in recent years
  • You can check not only the general forecast, but the marine forecast for the different Great Lakes: see weather.gc.ca/marine/region_e.html?mapID=11
  • They seem to have a tendency to over-predict the wind, and, personally, I never rely on the accuracy of these forecasts; I always seek confirmation from other sites.

Ice Conditions

If you want to find if the ice is off your favourite sailing spot, check

For reasons I can’t fathom, Environment Canada does not have any ice report for Lake Simcoe. For that, you’ll have to check out sites like www.fishinglakesimcoe.ca/ice-watch and www.lakesimcoeoutdoors.com/forums/ (or phone Crate Marine, which is near the Keswick sailing site)

Lightning Danger

Needless to say, it’s not a good idea to sail when there is a risk of lightning. Environment Canada has a lightning warning site:


One method that I use to get all of this information quickly and without a lot of hassle is to set up buttons on my Bookmarks Bar with various locations where I think I might want to sail. Thus, for example, I have a “T” folder for Toronto.  In that folder I have all of the URLs for each of the above websites, all set to point to Toronto.  I also have folders for Wasaga Beach, Barrie, Keswick, Beaverton, and Fort Erie (for Lake Erie).  Once again, these are set up so that each of the above sites points to that location.  This is a very quick way to find out if it’s blowing anywhere that you might want to go.


Springtime presents special problems with respect to forecasts for Lake Ontario and Lake Erie.   There is often an effect referred to as “doming” that occurs at Cherry Beach and other Lake Ontario and Lake Erie sailing spots. 

Doming means that the wind stays aloft and does not come down to the surface. It can be blowing like crazy a quarter of a mile up (or even 25 meters up) but dead calm on the surface.

Doming generally only occurs when the wind is coming from a southerly direction. This is true for a number of reasons:

  1. Air coming from the south originates in warm regions, and so the air mass is warm compared to the air that it is displacing. Since colder air is denser, it tends to force the warmer airflow from the south to rise – and keep on rising (in the lexicon of the meteorologist, the southerly air mass is “unstable” air).
  2. The tendency of the warm southerly air mass to rise is exacerbated by the fact that the lake water is still very cool in the spring. The cool lake water creates a semi-impenetrable blanket of cool, dense air that won’t allow the warmer winds to mix down to the surface.
  3. Toronto’s skyline, with all its tall buildings, forces southerly breezes to rise. In the spring, when the southerly winds are unstable, this creates an inert layer of immobile air at the beach, accentuating the doming effect. The result is that it can be blowing like hell out beyond the Leslie Street Spit, but be dead calm in at TWC. Shucks.

I have gone down to Fort Erie on numerous occasions on the basis of great forecasts from just about everyone, and been treated to the sight of tree branches dancing in the wind inland, only to find that Lake Erie was pretty much glassy (or at least sub-planning winds). The annoying thing is that on some of these days, the iWindsurf wind sensors were registering great wind.  These sensors are on land, and even though they are only meters above the water level, there can be solid wind at the sensors and nothing on the lake itself.

Doming is a problem with any wind from the south. Note, however, that doming does not seem to occur on a northeast or even an east wind.  It occurs mostly when the wind is actually crossing the lake from the south.

When doming is likely, I sail at Lake Simcoe. Lake Simcoe is much smaller than Lake Ontario and does not have the same thermal mass to keep the winds from mixing down to the surface.  Also, Lake Simcoe is at a higher altitude than Lake Ontario, and the winds seem to be less unstable at that altitude (i.e. they don’t skip upwards and then keep rising when they go over obstacles).  Added to this, there are just plain fewer obstacles to drive them upwards.


I hope that’s helpful. If anyone has any suggestions about other wind resources, I’d be glad to hear about them.  You can contact me at jeff.macintosh@sympatico.ca.   Happy sailing!


(SOURCE: www.xcskies.com/community/faq/reading_barbs)

Reading Wind Barbs

Reading wind barbs is not complicated. The use of wind barbs shows both wind direction and speed. Think of them as arrows in terms of direction, with each barb (or pennant) at the tail representing speed. These speeds are as follows:

  • A full blacked pennant or triangle is 50 knots
  • A full line on the wind barb is 10 knots
  • A half line is 5 knotsOf course, if you are viewing plots with wind speed units other than knots, the wind barbs have been adjusted automatically for you. An example below illustrates how to read the wind direction based on the angle of the barb. North is always up, just as a map is typically drawn.

wind barbs

TWC Weather Station



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