Weather

Current Forecast for 3 Anchor Bay


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Reading the Weather Forecast for 3 Anchor Bay

Three Anchor Bay has a very specific micro-climate based on the protection that Table Mountain offers from the prevailing South Easterly wind. In a pure moderate to strong South Easter, the wind shadow extends from the Green Point lighthouse to Clifton Ridge. However, as the wind speed increases, the wind shadow shrinks towards Three Anchor Bay.

Once the wind gusts indicated on Windfinder reach about 17 knots as on Tuesday at 18:00 below, the South Easter starts catching Three Anchor Bay. Obviously this represents a safety risk, as the wind direction is off-shore and already pretty strong.

In this particular example, the average of 16 knots is quite close to the gusts of 17 knots so it would almost certainly be too strong. If the average was much lower than the gusts conditions might be okay. Never take a risk with the South Easter at sunset!

Westerly winds are onshore, have a long fetch over the ocean, and can make the sea very choppy but there is less risk of surprises. Looking at the forecast below, the 9 to 11 knot NW on Sunday at 08:00 will result in the first sign of whitecaps, which are an indication of choppy conditions. As a rule of thumb the first whitecaps will appear at 10 knots and the sea will be covered in whitecaps at 12 knots.

Note that the trend in the conditions above is worsening, so if it looks marginal for you at 08:00, don’t go out because it’s going to get worse.

In the forecast below, Wednesday morning from 05:00 to 14:00 is a good example of improving conditions, so if it looks okay at 05:00 you know it’s only going to get better for at least 9 hours. This example would apply even if the wind direction was Westerly.

Three Anchor Bay also provides some protection from the prevailing South Westerly swell. The swell will break on either side of the bay, leaving a calm passage in between. As the swell size increases the passage becomes narrower and when the swell height reaches about 3.5m (deep sea swell) waves will break right across the bay. The swell period (time in seconds between wave peaks) also has a significant effect on the size of the surf. The longer the period, the more water the swell contains and the bigger the surf. As an example a 3 m swell with a 16 second period will break across the bay. A typical swell period for Three Anchor Bay is about 11 seconds. Another factor influencing surf conditions at the entrance to the bay is the height of the tide. The lower the tide the more likely waves will break across the bay.

When conditions are marginal, it is important to watch the swell for some time to ensure you have seen the big sets as there may be as much as 20 minutes between big sets. When the swell is big paddle far from shore especially rounding the point at Mouille Point lighthouse! Also, be sure to take the right line when returning to the beach. The correct line is shown in the satellite image below. Note that you need to line up the middle of the beach with the left hand carriage way of Helen Suzman boulevard. There is a large green traffic information sign which is on the correct line.

There is always a risk of fog with a light onshore wind. Fog combined with big swell presents a significant risk – take a GPS or paddle another day! Fog is not a great risk on a day with almost no swell since you can paddle close to shore. The sound of the fog horn at Green Point is very directional (achieved by using 2 tones – you will notice safety whistles on PFDs are also 2 tones) and provides an easy way to navigate around to point between Three Anchor Bay and Granger Bay. The best forecast for fog is Yr.no detailed hourly forecast.