Storm Emma is set to arrive in Ireland this afternoon, merging with the Beast from the East to make the weather even worse.
There'll be heavy snow, sub-zero temperatures, gale force winds, and a risk of thunderstorms with hail tonight.
Met Eireann has issued a Status Red weather warning for the whole country - which means you need to take action to protect yourself and your property.
But whatever you do, don't do any of these things...
1. Don't make unnecessary journeys
This is an obvious one. The government has advised the public to stay indoors between 4pm today and midday tomorrow, so don't hit the road without an important reason.
2. Don't forget about supplies
If you're disorganised enough to have nothing to eat in the house, bear in mind that most shops will close early today (if they've opened at all). Smaller local shops are a better bet than large stores, and make sure you have boots with a good grip if you have to leave the house.
You should also have a torch, batteries and candles in case you lose power.
3. Don't wear regular pyjamas to bed
It might seem weird to go to bed wearing a hat, but you'll need a lot more warmth tonight. Wear several layers, put on some thick socks and add some extra blankets.
4. Don't let your home get too cold
It's important to keep your house warm - especially if you have babies or elderly people living with you.
Babies should sleep in rooms heated to between 16 and 20 degrees, while the elderly need temperatures of at least 18 degrees to stave off illness.
5. Don't pour boiling water on your windscreen
It might seem like a handy way to defrost it, but it could actually cause the glass to contract and crack.
Turn on the engine and let the car gradually heat up from the inside instead.
6. Don't leave pets outdoors
At least two dogs have been found frozen to death in Ireland over the past few days.
Bring your pets indoors and make sure they have somewhere warm to sleep.
7. Don't leave your taps running
You might think leaving your taps running will stop them freezing, but according to the Heating and Plumbing Association of Ireland, that's a myth. In fact, if the water is left running continuously it risks freezing the drain as it's leaving the sink.