Mid-latitude weather at it’s best! Changeable says it all. New Zealand weather comes from the continual stream of fronts that bombards the innocent-come-tough islands from the Great Southern Ocean. In the winter – King Neptune delivers air straight from the Antarctic freezer. Getting tired of this, he might stir a brew and conjure a typhoon from the north. Watching the New Zealand weather map is more interesting than the stock market, that is for certain.

Kaikoura, especially SurfWatch is directly exposed to the ferocities of the weather. Although the East Coast is technically the “leeward” coast, this does not mean the weather is tamer. What it does mean is we experience more extremes.

Kaikoura is famous for it’s windless “dead calm” days. All day, yes, we can get days at anytime of the year (usually winter though) which are absolutely windless. But wait a day or two, and the wind might blow so hard you will wonder why you came to the place.

The basic frontal weather cycle is:

Calm settled weather follows the passing of a “southerly” front. During the winter or cooler temperatures, this will often mean windless days. In summer or warmer days, an onshore seabreeze may arise. These winds may blow 25 knots, but usually range from a light breeze to 15-18 knots.

Easterly Conditions. Onshore easterlies are usually the product of seabreeze land/sea temperature variation, and therefore die at night and rise in the morning, but rarely an easterly pressure gradient will hold these winds in place for up to a few days.

Nor’west Conditions. Ahead of a cold front the winds blow from the northwest. When the winds “go around” to the nor’west, the temperatures rises significantly and the air dries out. A cloud “ridge” appearing above the mountains indicates this event. Should the pressure gradient be large enough, these exciting Nor’west winds may “hit”. They can come from the mountains to the west, or from the south or southwest, or even from the northeast (called a “nor’west notherly”). Nor’west conditions produce amazing sunsets, warm relief in the winter, but they kill any ocean swells running, faster than you can imagine.

Southerly Conditiions follow the northwest winds. Southerly’s often “slam” in forceful squall lines. The south winds bring cold air and moisture, and can blow like hell for 1-5 days. Southerly rain is known to be horizontal in Kaikoura. Southerlies are weaker and dryer in the summer.

Both Southerlies and Nor’wests mean “batten the hatches” at SurfWatch.

The rain, temperature, wind, and sea swell patterns vary significantly from season to season.

Summer weather starts in early January and an “Indian” summer can last into May. The most settled time of the year, summers can be dry, warm, and sometimes hot with drought conditions. The odd “southerly” delivers cool relief. Cool onshore sea breezes are common in the summer, and can get up to 25 knots. Summer can mean long flat periods for surfers, but it also the time for South Pacific Typhoons, which drift south and east of the country, producing excellent swells. Occasionally one will hit land, mostly on the North Island.

Spring and Autumn really varies. In general, it is unpredictable and changeable from year to year. The normal cycle described above with fronts with varying intensity crossing at the rate of about one per week. Occasionally warm fronts from Northern Australia or the Pacific Islands will wander down, making for overcast drizzly days.

Winter weather is characterized by the cold and intense southerly fronts, and of course cold temperatures. The southerly winds kick up large South swells, making winter the most consistent time for surfing – but only for the hardy souls who can brave the cold water. The mountains are blanketed in snow from about June through September.

Kaikoura produces some amazing and interesting clouds and cloud patterns. “Lenticular”, or “flying saucer” clouds are a sign of the Nor’west weather pattern. Interestingly enough, unlike more common cumulus or rain clouds which drift along with the wind, air flows through lenticulars. This is why they are often called stationary clouds. Often, a long lenticular cloud parallels the mountains. Locals call this cloud the “Nor’west Ridge”; often the only indicator of nor’west air flow conditions, which often warn of an approaching southerly front.

Crepuscular Rays are a fascinating phenomenon. Although occurring at or before sunset, they are visible in the eastern sky radiating towards a point on the horizon. It seems that from a position lower than and west of the mountains, the sun shines upwards over the mountains. The mountain peaks and valleys cast shadows in the light, which then reflects off higher cloud cover back down to the horizon in the east, causing radiating bands of shadow and light.

These photos show the strong onshore “easterly” winds that occur more often in the summer months, caused by the temperature differential between the cool sea and the warm land.

“Southerly fronts” provide Kaikoura with rain and cold air. Ahead of the front, warm northwest winds flow. With the passing of the front, temperatures can drop significantly, and the wind changes to the south or southwest. These changes can be almost unnoticeable, or seriously violent…

The satellite photo below shows a southerly front which has just passed over SurfWatch. Pictures 1 and 2, shot only a few minutes before the satellite shot, catch the front from the ground as it passed over SurfWatch. The leading squall line of this particular front produced a significant wind change, but no moisture. Although the photos don’t show it, the wind in front of the cloud line was whitecapping northwest, and just behind was an even stronger southerly. A band of calm water perhaps 50-100 metres wide between the two winds, is where the warmer northwest air was forced up over the cooler southerly air. As the satellite shot shows, the initial squall line was followed by a period of clear sky, followed by solid rain-producing clouds.

Southerlies are normally associated with winter: strong cold winds and rain, snow on the mountains and highway passes, pumpkin soup, and cosy conversations by the wood burner. They also bring the surf up, but only the brave and the crazy will be surfing it.