Climate / Weather / Cyclones
Derby has a tropical climate which is pleasant for most of the year. With warm Winters and hot, humid Summers, the temperature is hardly ever cold. The town is subject to cyclones between December and February, however the warm, torrential rain is a great feature of the wet season. In Summer (December to February), the average maximum temperature is 36°C with an average minimum temperature of 25°C. In Winter (June to August), the average maximum temperature is 32°C with an average minimum temperature of 18°C.
Derby is located between the Tropic of Capricorn and the Equator. It has two main seasons offering very different experiences for visitors.
THE DRY SEASON - May to October
These are comfortable months with warm dry days (28-34°C). Nights are cool on the coast (18-20°C) but colder in the ranges. Very little rain falls in these months but showers may occur.
Most tours take place from Derby at this time of year as these are the most comfortable months and access to remote locations by road, sea and air is generally possible.
Loose comfortable cotton clothing is recommended for day wear - shorts / cotton trousers with a light windproof jacket and pullover for evenings. A good quality sleeping bag or swag bed and track suit clothing is needed for night time comfort. A mosquito net or dome and insect repellent is recommended for those camping out.
May - July : The countryside still has a green tinge after the wet and waterholes and water falls are often still flowing. The humidity level is dropping and conditions are very pleasant.
August - September: Streams are confined to waterholes and many smaller waterfalls cease to flow. The countryside is drying out and bird life is collecting around the billabongs. Temperatures increase towards the end of September and can be in the vicinity of 40°C during the day.
THE TROPICAL SUMMER - November to April
This is the season when the humidity is high to very high and an average of 600mm of rain falls in tropical downpours from thunderstorms and cyclones. The boab trees are clothed in leaves and flowers. The barramundi start to bite as the waters warm up. Estuarine and river fishing is usually very rewarding at this time both prior to the rains, and later as river levels drop and the waters clear.
Access to many remote locations and gorges is restricted as flooding of rivers and streams occur. The unsealed roads become impassable and are closed by authorities.
Loose comfortable cotton clothing is recommended. Long sleeved shirts and long trousers plus a good tropical mosquito repellent should be worn.
The coming of the rains can be unpredictable. Some years they come early and others not at all.
October - December. This is usually the build up time for the heavy rains. Temperatures can be very hot (35-42°C) and humidity is increasing. If rains have not fallen the countryside will be dry and the watercourses low. Birds congregate at billabongs and the migratory waders from the northern hemisphere are moving south through the area. (Sep-Nov)
January- April. The rains transform the countryside, the billabongs fill and the birds disperse. Rivers and streams may flood and spectacular waterfalls appear. Temperatures are less extreme as cloud cover is common. Flying in light aircraft is one of the best ways to see the countryside at this time of the year. Access by road off the main highway may be difficult. The migratory waders are returning north during April. As river levels drop fishing for barramundi resumes.
The Bureau of Meteorology provides climate information (observations, warnings and forecasts) for the Kimberley District and local towns.
Should you require assistance at any stage, please contact your DFES State Emergency Service District Office or your local SES unit.
For all life threatening emergencies, call 000
State Emergency Service (For Emergency Only) 13 3337
How Cyclones Threaten
Cyclones threaten life and property in three ways:
|1||FLUCTUATING WIND PRESSURE can weaken and possibly collapse buildings and other structures.|
|2||LOOSE OBJECTS ie patio furniture, rubbish bins, dog kennels or building material, become lethal
wind-borne projectiles that can cause severe damage to homes, and kill or injure people in their path.
|3||FLOODING, due to an abnormal rising of the ocean or as a result of heavy rainfall in river catchments.|
During a cyclone, the WATCH and WARNING messages are broadcast on the ABC Regional Radio network at quarter past the hour - 6DB 873AM. The Bureau of Meteorology issues messages at 1am, 7am, 1pm & 7pm during the WATCH PHASE, and at 1am. 4am, 7am, 10am, 1pm, 4pm, 7pm, and 10pm during the WARNING PHASE. Both messages inform of the cyclone’s position, movement, severity and current coastal areas under threat.
Australian Tropical Cyclone Severity Categories
The severity of a cyclone ranges from 1 - 5; 5 being the most severe.
Average Wind Speed
|1||63-88 km/h||985 + hPa|
|2||89-117 km/h||985 - 970 hPa|
|3||118-159 km/h||970 - 955 hPa|
|4||160-199 km/h||955 - 930 hPa|
|5||200+ km/h||Less than 930 hPa|
Be Prepared For Cyclones
The Cyclone season extends from November 1 to April 30, but before the season begins a number of precautions should be undertaken.
- Clean up loose materials and rubbish from yard.
- Trim trees of excess height to withstand high winds.
- Clear drains of rubbish or obstructions.
- Have on hand emergency supplies; eg first aid kit, candles, tinned food, water containers, etc.
- Decide where best to shelter your pets.
- Determine location and establish cyclone tie-down areas for caravans, boats, trailers, etc.
- Be familiar with the 3 stages of the cyclone alert.
|Blue Alert||Get Ready for a cyclone. You need to start preparing for cyclonic weather.|
|Yellow Alert||Take action and get ready to shelter from a cyclone. You need to prepare for the arrival of a cyclone.|
|Red Alert||Take shelter from the cyclone. You need to go shelter immediatley.|
|All Clear||The cyclone danger has passed but take care. Wind and storm surge dangers have passed but you need to take care to avoid the dangers caused by the damage.
|DO NOT DRIVE ON RED ALERT - IT IS DANGEROUS|
The following information is available for download to help you prepare for cyclones:
Cyclone Smart - Community Alert Card
Fact Sheet 6 - Travelling During the Wet Season
(Information supplied by the Bureau of Meteorology and the Department of Fire & Emergency Services Authority of Western Australia)
The following websites provide current information on cyclones and cyclone tracking: