Train tracks are buckling, dogs are being kept out of cars and shops have sold out of fans. The heatwave is here.

The Met Office says today (Wednesday) is the hottest day on record with 36.7C recorded so far at Heathrow.

We know the common advice for coping with the warm weather - stay out of the sun during the hottest part of the day, drink plenty of water, use sunscreen when you're outside.

But what about all those other tips and tricks to help you stay cool? How reliable are they?

Newsbeat is here to sort out the myth from the truth.

I don't have to be in the office if it's over 30C, right?

Unfortunately, if you were hoping to get a day off, this isn't quite the case.

The Health and Safety Executive (HSE) says employers have a legal obligation to make sure that working environments are a "reasonable" temperature - but it doesn't specify an actual maximum.

Unions such as the TUC are telling managers to relax dress codes wherever possible, but if you wear a uniform for example, you don't have the right to put on your own outfit.

Cotton is the only fabric that keeps me cool

A white cotton top and shorts is obviously the best thing to wear, right? Sort of.

Natural fabrics like linen and cotton absorb sweat and allow it to breathe. They're much better than man-made fibres like polyester, which can trap the moisture against your skin, leaving you hot and uncomfortable.

But when it comes to colour, things get a little more complicated.

White is good if you're out in direct sunlight a lot - it will reflect the heat better than any other colour. But if you're spending time in the shade, black is a more effective colour to wear as it radiates out heat into your environment, cooling you down.

Drinking hot drinks actually lowers your body temperature

Staying hydrated is key. According to the NHS, if you don't drink lots of water and beverages like fruit juice, you can start to become unwell, with symptoms of headache and tiredness. It can lead to heat exhaustion and heatstroke, which in the worst cases can be fatal.

But what about hot drinks? Can they help cool you down? Well, it comes back to sweat again.

The thinking is, drinking a hot drink raises your body temperature, causing you to sweat. Sweating cools you down because as the moisture evaporates it takes away some of the heat of your body.

But sweating also means that you are losing liquid from your body, meaning you need to take on more to stay hydrated.

Keep the curtains closed - block out the sun

This is another one where there is no precise answer.

If you have thick dark curtains then keep them open, otherwise the fabric can keep the heat trapped in the room.

Lighter curtains can help reflect the sun's rays back out of the room, so keep them closed.

Putting something reflective on the outside of the glass can bounce the heat away, keeping the room cool - like the screens that go on the windshield of your car.

I never shut the windows during summer - you need to circulate the air

Sorry - this is another one where there is no hard and fast rule. And you should always consider home security and safety when it comes to leaving windows and doors open.

If the room you are in is actually cooler than the temperature outside then keep the windows closed, otherwise all you are doing is letting hot air in.

But if the room is warmer - and this is much more likely to be the case at night - then opening the windows will help cool your home down.

The NHS has advice designed to help you prepare for and manage a heatwave.

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