26.5C — by Australian standards it’s a pretty benign temperature.

Along the eastern seaboard, 26.5C would only be the average for a spring day, let alone high summer. After all, even heat stroke often only kicks in around the mid-30s.

Nonetheless, 26.5C is the temperature emergency services fear particularly at this time of year. It could be the harbinger of destruction, injury and even death.

The concern is not so much about the air temperature but the how warm the sea is.

“26.5C is the all-important temperature the seas have to get above to create the perfect conditions for a tropical cyclone,” Andrew Watkins, the head of climate prediction services at the Bureau of Meteorology (BoM) told news.com.au.

Right now, in the seas surrounding northern Australia, the water is cooking nicely.

On cue the first rumblings of the cyclone season are beginning with a monsoon trough forming off Australia’s north west coast.

If a tropical cyclone does form in Australian waters, the first of the season will be named Yvette. The severe rainfall which accompanies cyclones can bring flooding often causing more damage than the storm itself.

Last year, Cyclone Marcia slammed into the coast north of Rockhampton bringing 300km/h winds and destroying 350 homes.

In 2011, Cyclone Yasi saw homes and crops wiped out, caused millions of dollars in damage, and killed a man when it bore down on Far North Queensland.

But it’s 1974’s Cyclone Tracy, which killed 65 people and almost wiped Darwin off the map, that is still the most remembered.

However, the record few cyclones last summer is concerning emergency services, who are worried people living in the tropics could get complacent about the upcoming storm season.

“Residents in Far North Queensland are well-versed in living with cyclones but people can always do better to ensure they are prepared any year, regardless of the weather forecast,” Steve Waddell, a Queensland State Emergency Service (SES) regional manager, told news.com.au.

Mr Waddell warned that one of the most everyday objects could become deadly should a tropical cyclone hit.

“Trampolines are a classic item that becomes a missile in a cyclone. I often see photos of them caught up on fences or smashed into cars.”

Summer is cyclone season but they can occur anytime between November and April. While usually confined to the tropics they have been known to come as far south as Hervey Bay.

If a tropical cyclone was a cake, one of the main ingredients would be the heat of the ocean.

“You need sea surface temperatures that are quite warm, at least 26.5C,” Greg Browning, a senior climatologist at the Bureau’s Darwin office — right in the heart of the cyclone zone — told news.com.au.

“A lower sea temperature can create mid-latitude cyclones, which you often see off the NSW coast, but while they can be quiet strong they are a different beast altogether to a tropical cyclone.

“A mid-latitude cyclone can get winds of 150km/h but that won’t reach the incredibly strong wind gusts of a category 5 tropical cyclone of 300km/h.”

Sea temperatures around northern Australia are rising and are even pushing 30C off the Northern Territory and north Western Australia coasts.

“As we get into summer there’s no problem getting to that temperature.” said Mr Browning.

“Up here in Darwin, putting your feet in the sea is like dipping them in a hot bath. It’s not so refreshing and you probably be eaten by something if you did it anyway.”

But sea temperature alone is not enough to create a cyclone.

“You also need a large area of moisture extending some depth. Another of the ingredients is somewhere to focus on, so a monsoon trough maybe, and what we see is multiple thunderstorms congregate and if the wind conditions are right these storms rotate around the centre,” Mr Browning said.

This rotation gives the cyclone its distinctive look of a clear and calm eye, often with blue skies, but with angry clouds all around it.

“If conditions are right it will intensify and start a positive feedback loop putting more moisture into the atmosphere and building up to tropical cyclone.”

Technically, the storm only becomes a tropical cyclone when winds reach at least 63km/h.

On average, Australia is bombarded by 11 cyclones a year but last summer only three bubbled up.

This was due to the strong El Niño weather system in the Pacific that cooled the waters down and lessened the amount of readily available moisture.

This year, El Niño has scarpered and La Nina never really arrived. Seas are warming, leading meteorologists to believe an average year is in store with more cyclones than last summer.

“While we’ve yet to have our first tropical cyclone of 2016-17, we’re still expecting an average to above-average number of cyclones this season,” Dr Watkins said.

“We expect the peak of the season to be in January and February and that’s the time for people to really be cautious.”

Mr Waddell said SES volunteers were busy preparing for the worst.

“In the Far North, they are preparing with more sandbagging equipment and flood boats. Our volunteers are trained to assist people to recover and we can respond to cyclones from now onwards,” he said.

But residents in the cyclone zone needed to do their bit too, he said.

“Residents should check their roof is in good condition and that roof gutters are clear so rainfall can get away.

“Falling trees are big problem so ensure overhanging trees are trimmed back and that all loose items in back yard are brought in before winds strike.

“It doesn’t matter how prepared you are, if mother nature takes a disliking you may need to call on your insurer so ensure you’re up to date.”

Mr Waddell also urged residents to pull together cyclone kits to help them survive for up to three days. A battery powered radio, drinking water, non-perishable foods, a camp stove and up to date medications should all be included.

“In cyclone season the emergency services can concentrate on the most vulnerable if everyone else looks after themselves,” he said.

benedict.brook@news.com.au