Rainfall in the Dry Tropics
May 3, 2022
Although the Blue Weber Agave we are growing at our Eden Lassie Farm has a low water requirement relevant to other crops, the wet season is still a very important factor in our agave farming.
We are starting to build our own weather dataset at Eden Lassie thanks to our own weather station which was installed in January 2020. This data has shown us that our peak rainfall occurs during the summer/autumn wet season but there is still considerable variation from year to year with this year being one of the driest in recent years.
We can measure our rainfall against other local weather stations at Bowen (25kms to the north) and Proserpine (35km to the south). Average rainfall for both Bowen and Proserpine has been below average for the past two years despite being classified as La Nina years.
The rainfall we receive at Eden Lassie has been very similar to Proserpine in the past few years but this year it is closer to Bowen given the dry wet season we have had. We envisage that as we continue to collect our rainfall data our mean annual rainfall will sit somewhere between Bowen and Proserpine.
Another factor influencing our rainfall is Eden Lassie’s location in Queensland's dry tropics.
Outside of the periods of monsoonal rainfall, the dominant trade winds come from the south-east and these carry moisture from the sea onto the coast.
The reason for this stretch of coastline being drier than other locations both north and south of it is primarily due to the angle of the coastline.
The angle of the coast in the dry tropics zone is about 45 degrees, meaning the warm, moisture laden SE trade winds go straight past this section of coast and instead hit the coast much further north - the Wet Tropics. Similarly, the angle of the coastline from Airlie Beach southwards means the moist trade windsare 'on-shore' and this region receives significantly more rainfall throughout the year than the Dry Tropics.
The absence of mountain ranges is the final piece of the equation that creates the unique conditions at Eden Lassie and the wider region. This lack of mountainous topography means the warm, moist air carried by the SE winds does not rise and condense before falling from the sky as rain.