Hazards, warnings and safety

Rough water image

Each year marine rescue organisations respond to thousands of calls for assistance from boaters operating in Australian coastal waters, and a large number of these are caused by the weather. Understanding the impact of weather hazards can help boaters be better prepared or change their plans for safer conditions.

 

Before you go

Before heading out, use the Bureau’s marine forecasts and warnings and run through the five vital checks to be prepared.

Going boating?  Do the five vital weather safety checks

Check your local maritime authority and also the Australia New Zealand Safe Boating Education Group website for boating safety information.

The Australia New Zealand Safe Boating Education Group recommends that boaters change their plans, delay their journey, or cancel their trip if weather or wave conditions exceed the limits of their vessels capability or risk the safety of crew and passengers.

Weather hazards that influence conditions at sea include winds, tropical cyclones, thunderstorms & lightning, squalls, winds, sea fog and waterspouts.

Marine warnings

1The Bureau of Meteorology issues warnings for marine areas when dangerous winds are expected. Wind warnings are updated every six hours.

The Six things you need to know about wind warnings can help you to understand the key information about the dangerous conditions.

Definitions of wind strength used in coastal and high seas warnings

Wind warning Wind range
Strong wind 26 to 33 knots
Gale 34 to 47 knots
Storm force 48 to 63 knots
Hurricane force 64 knots or more

*Note: These wind speeds are 10-minute averages

For activities on the coast or in ports, warnings for hazardous storm tides, dangerous surf, severe weather and thunderstorms can be relevant and useful for preparing and reacting to these hazards.

For more information about each warning service, see:

Changing weather

2Take note of forecasts indicating reduced visibility from fog or rain, or risks to safety and comfort from thunderstorms, lightning or squall conditions.

Some forecasts will also include information on UV levels and the times of day to use sun protection.

Tropical cyclones pose a significant danger to mariners due to huge waves, extreme winds, thunderstorms and torrential rain with poor visibility.

  • Warning services for tropical cyclones
    Information about the types of warnings that are issued, when and where they are issued and provides samples of the individual warnings
  • Frequently asked questions
    Information about tropical cyclone development, impacts and warnings should help you better understand these dangerous weather systems.

Thunderstorms can generate strong, squally winds, heavy rain with reduced visibility, hail, waterspouts and lightning. They are common across the Australian region and can pose a threat to mariners. Warnings for thunderstorms or severe thunderstorms are not provided for Coastal Waters areas. Mariners should refer to the Coastal Waters forecast for the likelihood of thunderstorms.

Thunderstorms may be associated with the passage of a frontal system, a tropical depression, or they may form over land and move out to sea.

Find information about severe thunderstorm warnings:

  • About Severe Thunderstorm warnings
    When thunderstorms are forecast for capital city Local Waters areas, it is important to check whether Severe Thunderstorm Warnings have been issued for the capital city area. Severe Thunderstorm Warnings are issued when wind gusts exceeding 48 knots, or large hail, or heavy rainfall, or tornadoes are expected. 
  • Cooking up a storm - how thunderstorms form
    Read about how thunderstorms develop

East Coast Lows are intense low-pressure systems which occur on average several times each year off the eastern coast of Australia, in particular southern Queensland, NSW and eastern Victoria. These storms can produce heavy rainfall, gale to storm force winds, powerful waves and storm surges.

Cold Fronts can cause strong to gale force winds, gusty conditions around the front, thunderstorms, hail and heavy rain and showers. Cold fronts are boundaries between a warm and cold air mass. Winds are usually northerly before the front then westerly or southerly behind the front.

The Monsoon is a large scale rain and wind event experienced in the tropics during the wet season. It can persist for multiple days and is associated with the inflow of moist west to northwesterly winds into the monsoon trough, producing convective cloud and heavy rainfall over northern Australia.

Sea Fog can be extensive and long-lasting, presenting a significant hazard to mariners. Visibility can reduce to less than 100 metres in sea fog, making navigation difficult and greatly increasing the risk of collision with obstacles or other vessels.

Waterspouts are spinning columns of air and water. They can be very dangerous, much like the hazardous tornadoes seen over land.

Wind conditions

3Marine wind warnings are issued whenever strong winds, gales, storm force or hurricane force winds are expected. You can access warnings for all states from our Marine & Ocean web page.

The Six things you need to know about wind warnings help you understand the key information about the dangerous conditions.

Local wind regimes can make conditions rough in certain areas. One example is the Southerly Buster along Australia's east coast.

A squall is an abrupt and large increase in wind speed that usually only lasts for minutes then diminishes rather suddenly. The gusts in a squall may exceed 40 or 50 knots and boaters should avoid these situations.

Wind gusts are typically 40% stronger than the average wind speeds provided in marine forecasts. However, thunderstorms and squalls may produce much higher gusts.

Wave conditions

4Large waves originate from intense weather systems. These waves can be higher, steeper and more chaotic than usual, making conditions dangerous and uncomfortable for boating, especially close to the coast where the waves enter shallower water. Wave recording buoys provide near real-time wave information in most states, and the Bureau's marine forecasts include information about expected wave heights.

Long period swells are typically generated by low-pressure weather systems. These swells can travel for days and many hundreds of kilometres from where they were formed. While they're in deep water, these long, low swells are not a problem, but as they approach shallow water they break powerfully. Because the systems that generate these waves can be far off the coast, these waves can come as a surprise since it could be sunny with little wind when they arrive.

Tide times

5Knowing when high and low tide will occur is important for boats entering and exiting river entrances and crossing bars. The combination of an outgoing tidal flow or low tide can cause waves to become steeper than usual, making your boat difficult to navigate.

The changing tide over the day can cover rock platforms or reefs at high tide, whilst exposing them and creating a hazard at low tide.

Fishing on rock platforms may become dangerous at high tide as waves start to wash over or break onto the rock platform.

 
 

Reference

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