Why Friday the 13th is considered unlucky and the superstitions surrounding it

It's Friday the 13^th today, and for many of us that means one thing: it's the weekend tomorrow.

These days the average Australian doesn't put much stock into fears of the number 13, black cats or opening umbrellas inside, but that doesn't mean these superstitions have stopped existing.

Even if the only tradition you'll be observing today is knocking off five minutes early and heading straight for the pub, there are a few old wives' tales you might want to keep in mind.

There's a reason so many horror films involve the spooky day. (Paramount Pictures)

What is Friday the 13th?

Friday the 13^th has been considered unlucky for centuries, with some claims the tradition was started in Biblical times when Jesus' last supper saw 13 people join for a meal on a Friday.

Others insist the tradition began later, during the Middle Ages, and some people now insist it's the unluckiest day of the year.

The day usually comes around 20 times each decade, and we have only one Friday the 13ths this year: today, May 13.

Though the day can come and go without many people even realising, some individuals are so afraid of the 'unlucky day' that they actually develop a phobia of it called paraskevidekatriaphobia.

What are the biggest superstitions on Friday the 13^th?

There are plenty of superstitions that exist all year round, but for some reason they seem just a little more ominous on Friday the 13^th.

So what should you be looking out for today if you want to avoid bad luck? According to superstitions, all of the following can bring you bad luck.

Don't walk under a ladder
Avoid smashing any mirrors
Steer clear of black cats
Never open an umbrella inside
Avoid the number 666
Don't cut both ends off a loaf of bread
Never put new shoes on a table

Black cats are a sign of bad luck on any day, but even moreso on a Friday the 13th. (Getty Images/iStockphoto)

Is there any proof?

You'd have a hard time proving Friday the 13^th is more dangerous or unlucky than other days of the year, but there have been a few strange coincidences surrounding the date.

The Buckingham Palace bombing during the Blitz of 1940 occurred on Friday the 13^th of September, making it 79 years since the palace was attacked.

On August 13, 2010, a 13-year-old boy was struck by lightning in Suffolk, UK, at 1:13pm and survived, though the recurring number 13 left plenty of people spooked.

Tupac was shot dead on September 13 in 1996, exactly 23 years ago today, and a number of planes have crashed on Fridays that fell on the 13^th throughout the last few decades.

The King and Queen stand amid the bomb damage at Buckingham Palace. (PA/AAP)

In fact, the plane that crashed into the Andes in 1972 carrying a South American rugby team went down on a Friday the 13^th.

The 16 survivors of the crash later ate the bodies of the dead victims in order to survive.

While none of these events individually prove Friday the 13^th is an unlucky day, they're just a few of a whole range of terrible events that have occurred on these Fridays throughout the years.

Could they all be coincidences, or is this day genuinely cursed?