Marine Weather

Many fatal boating accidents occur in bad weather.

If in doubt, don’t go out!

Always check the weather before you go out boating. Weather conditions can make the difference between an enjoyable day out and a dangerous, perhaps tragic trip.

Remember that the weather can change suddenly and without warning. At the first sight of worsening weather head for shelter.

Marine forecasts are almost always accurate when predicting major weather events, such  as gales. They can be less accurate when predicting local changes of conditions, so you should always be prepared for the unexpected.

Make sure you always use a marine weather forecast. Land and general forecasts do not take in to account wind speed over water, which is double that over the land, or the size of waves. If you are planning ahead or intend to be away for a day or two, obtain a long range weather forecast.

Coastal and local marine weather forecasts consist of the following parts:

Warnings

These are issued for gales or storms anywhere on the New Zealand coast. A wind warning may be included in local area forecasts if wind gusts are expected to reach 33 knots (about 60 km/hr).

Situation

A description of the position and movements of highs, lows and frontal systems expected to affect the New Zealand coast within the next 36 hours. It also names those areas affected by warnings.

Areas

Most boating areas are covered by the Recreational Marine Forecast. Details of the current wind strength can be heard on VHF Radio.

Forecast Details

A description, covering the next 24 hours of expected average conditions over open water.

Wind – direction, such as northwest, is the direction the wind is expected to come from. Speed is given in knots, and one knot is approximately 2 kilometres an hour. This is an average speed so always expect that gusts may be 50% higher. Also allow for funnelling between headlands causing the wind speed to double.

Sea – a description of the waves formed by the local wind.

Swell – caused by longer waves that come from the ocean. Swells increase in height when they reach shallow water.

Visibility – given when visibility is expected to be less than six miles (10 kilometres).

Outlook – all marine forecasts are for up to 48 hours with the outlook for a further 3 days.

Wind and Tide

When the wind is opposing the tide, expect a much rougher sea.

When the wind is with the tide, expect a calmer sea.