
has never been my strong trait
Doc says 2 or 3 months
before my neck heals up
so nows a good time to refine the art.
Understanding the Moon lets you work out where and when to catch the waves. Here are some general guidelines which may be useful to waveriders. The Moon is responsible for wind, weather and tide, and an understanding of the forces involved will help you to know when and where to go.
New and Full moons
Bad weather is associated with New moons in summer and Full moons in winter - they bring storms, especially when other factors are in the picture too. Swells come around perigees (Moon closest to earth for that month), New moons and southern declinations (Moon furthest south for month), also a couple of days after Last Quarter phase.
New moons tend to cause solid wind at water level blowing from the west and Full moons are typically associated with wind from north and east but of lighter force. One of the more common theories/myths that surfers relate to the Moon is that there will be more (bigger) ocean swell during the Full moon period. Some swear by it. Well, it is not just coincidence. Full moon days do bring bigger waves. Also, as a general tendency the wave swell will each day be higher in the hour the Moon is rising. Westerlies are not much help to surfers, and they come typically around New moon.
Every January and February, Full moons coincide with the northern declination (see below), and in every March-April the Full moon occurs as the Moon crosses the equator. These declinations set up turbulence. In June/July/August the Full moon is at the southern declination. At the end of October the Full moon is again crossing the equator, and at end of December Full moon is at the northern declination again. Plus at Full moon times there are king tides, not only in the water but in the air too. It all adds up to increased pulling to and fro of waves.
Air and sea tides
The air has a tide because it is a massive fluid. A person on a board is between two giant tides; that of air and of water. The same rules apply to each and each rolls and flows in response to the Moon. For sea 'wind' read currents and gales are equivalent to swells. There is also a friction effect from the immense surface of the sea interfacing with air, and both directly influence each other. We all know how the wind can suddenly and mysteriously drop just as the tide turns.
Ocean tides are also a factor that surfers consider; some spots work best on high tides, some are better on low tides. This is the most obvious influence of the Moon as far as surfers are concerned. North easterlies affect the eastern side and serve up storm pattern waves, as well as driving a tide further in. The wind often swings around clockwise as the force increases, so after a southern declination and south westerlies have been blowing for a while, in about two weeks there could well be an opposite situation. Full Moons are often preceded by westerlies and bring easterlies almost immediately afterward. In the winter Full moons bring the southerlies to the South Island. As bigger tides happen around Full and New moon it often follows that the west coast is better to surf before a Full moon and the East Coast after one.
Pressure Systems
The best swell for beaches in the west is when low pressure systems pass under the South Island. The swell works north as the low passes under and lasts a few days. Ultimately the best wind is no wind which is hard to get when a system runs under the South Island. Surfers should scout weather maps for low pressure systems or even better, tropical cyclones - the deeper the better. Tropical cyclones mostly form during Full moon to Last Quarter, from about November through to early April, and if they work their way south on a descending Moon(travelling south on the north-south-north declination cycle), generally affect NZ coasts 3 or 4 days later. These systems will generate swell that radiates outwards from their centres, eventually pushing surf onto our shores. Surfers prefer these systems to be far enough offshore so that local winds are light, and surface conditions smooth.
Watch the weather come across from Australia on the isobaric maps. If a high crosses at the top of NZ we can get SW winds, offshore on east coast, good for diving. If the high crosses lower down we can get the SE to NE winds. No good for diving.
Declination
The north-south cycle of the rising Moon takes 27.5 days to complete and is known as declination. It can be seen visibly as the Moon will be seen to rise one day at a certain point on the horizon and the next day rising a little further north or south depending on which part of the declination cycle it is in. When it is at the northernmost point (northern declination) or the southernmost(southern declination), winds start up and swell gets generated as fronts and troughs move across on latitude lines, parallel to the earth's orbit. Southerlies come up from the south a few days after the point of southern declination and they bring cold conditions and wind and rain to the south of NZ. They tend to blow themselves out by the time they get past Raglan.
Conversely northerlies happen after the northern declination and they bring humid air from the tropics which holds much rain for the north but again peters out past Kaikoura as they head south, although they are still potent enough to bring rain and mayhem to the South Island's West Coast. To find out where the Moon is at any one time in the declination cycle, look it up in a book called an 'ephemeris', available from shops that stock books on astrology. Otherwise it is listed in our monthly ezines.
When and where are the low pressure systems going to track? Low pressure systems hang around northern rather than southern declinations and turbulence in the atmosphere is also fairly typical when the Moon is crossing the equator going N or S. Of all declination reference points, if you live in the north the southern declination brings the driest, and the northern declination brings the wettest weather. If you live in the south of NZ this is reversed. The bottom half of Australia is exposed to southerlies but winter anticyclones caused by nortthern declination can drag up cold southerly systems. Lunar equinox can drive winds faster within two days.
Perigee
When the Moon comes closest to Earth each month the situation is called perigee. As well as causing more wind and swell through greater gravitational pull, the Moon is also moving faster due to the elliptical nature of its cycle. Perigee exaggerates the air-tide, especially potent at full moon times and quarter moons, which can generate cyclones and therefore swells.
A faster Moon brings winds of greater force. For instance the 1998 Sydney-to-Hobart yacht race was held right on the December perigee. 67 boats turned back and 6 lives were lost. The race planners clearly knew nothing about the Moon. Other times when the Moon moves faster are New moon and when crossing the equator. These are also times of increased wind speed within a couple of days.
The perigee spends about 3 years in each hemisphere and a year or so around the equator each in-between time, making a return cycle every 8.85 years. When the perigee is in the southern hemisphere, NZ is affected more, and this was the case from April 2003 till 2006. The previous last time the perigee was in the southern part of the world was 1994-7. The following 2-3 years has seen it around the equator and this year the perigees will be in the northern hemisphere
So look out for some less powerful storms in coming years, and less swells on both coasts. In the next few years you will see bigger waves on the east side of NZ in the summer, and on the west side in the following winters.





