Four seasons in one day: weather, wind and staying warm

People often say New Zealand can have four seasons in one day. It's true. Our islands sit in the middle of a huge ocean, with long mountain ranges that push moving air upwards. When air rises it cools, and clouds and rain can form quickly. A sunny morning at the car park can become a cold, wet, windy afternoon on the tops.

Signs the weather is changing

How your body loses heat

Your body makes heat all the time, and it is always losing some. Wind blows warm air away from your skin, which is why a windy day feels colder than the thermometer says. This is called wind chill. Water is even worse: wet clothes pull heat from your body many times faster than dry clothes do.

Hypothermia

Hypothermia happens when your body loses heat faster than it can make it, and your core temperature drops. It can happen on a cool summer day if you are wet, tired, hungry and in the wind. Watch for the 'umbles': - Stumbles: tripping and clumsy walking. - Mumbles: slurred or confused talking. - Fumbles: fingers that can't do up a zip. - Grumbles: grumpy, quiet or not acting like themselves.

What to do

Stop early. Get the person into shelter and out of the wind, change them into dry layers, add a hat, share food and a warm drink, and get help. Don't wait for it to get worse.

Layers: the best defence