Today is a mostly sunny day across New Zealand but that southerly has a sting to it.
So what makes a sunny, dry, winter’s day so bitterly cold sometimes? It’s because of the wind.
The “Feels Like” temperature measures air temperature + humidity in summer and air temperature + wind in winter…to calculate what the air actually ‘feels like’ on your skin when you’re outdoors in the elements.
Here are some examples:
Many places across New Zealand today will at least reach the 10 degree mark. Add a gentle southerly breeze (say walking speed) and it will feel more like 8. Add a slightly stronger southerly wind (say jogging speed) and it will feel more like 5 or 6. That’s a typical set up for Auckland.
However most places that use wind chill calculators really only use them for temperatures 4 or 5 degrees and lower.
Lets say Wellington has a strong cold southerly change arrive. The air temperature is 4 degrees and the southerly is blowing at 10km/h. The wind chill is now 1.5 degrees. Quite often in winter Wellington can have a bitterly cold southerly change with winds around 50km/h. So if it was 4 degrees with a 50km/h wind the wind chill (what the air/wind feels like on your skin) is -3.
Quite often in Christchurch when a southerly has arrived and it’s borderline snowing the wind chill can be extreme. Lets say it’s 1 degree with a gale southerly (62km/h). The wind chill factor is -8.
And the other day in exposed parts of northern Southland it was -8 (the air temperature, not the wind chill). Add a fairly breezy southerly to that (20km/h) and the wind chill is -15. Add a strong southerly (40km/h) and it’s -18. Add a gale southerly and it’s minus 20.
These sorts of temperatures, -20 for example, are frequent wind chill temperatures in places like Toronto and Chicago each winter. Some parts of Canada can reach -30 degrees and that’s withOUT the wind. So, even in winter, we really are sub-tropical to some degree!
Story by WeatherWatch.co.nz