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Humidity to ease…for a few days

If you’re finding the humidity unbearable – you’re not alone.  Humidity levels across the nation have lifted in recent days due to an air flow coming out of the sub-tropics.  Coupled with daytime heating the ‘feels like’ temperature is jumping several degrees above the predicted high in some areas.

“The feels like or humidex reading takes into account humidity plus heat.  It’s subjective, not everyone agrees with the readings, but the vast majority identify with the fact it’s felt more like the low 30s than the mid 20s in a number of places in recent days” says head weather analyst Philip Duncan.

But a south west change at the weekend should reset things.

Dunedin will go from 23 degrees Friday to 18 on Saturday and just 15 degrees by Sunday.

Christchurch will slide from 28 degrees Friday to 26 Saturday, but 18 on Sunday.

Hamilton in the north will go from 27 degrees on Friday to 24 Saturday and 22 by Monday with lower humidity and therefore a the feels like temperature will be closer to the predicted high.

Humidity levels will drop as the drier southerly air moves in.

A large high will roll in behind this change on Sunday and Monday bringing settled, dry and hot weather to many places – but with slightly lower humidity levels than this week.

But humidity and easterlies will both increase again in the upper North Island as we go through next week.



Derek on 20/02/2014 11:22pm

Hi WW, I have often wondered how the daily temperatures are derived several days in advance and that they are mostly very accurate. 

Any chance of an explanation by your weather guru Phil. Thank you.

WW Forecast Team on 23/02/2014 7:01pm

Hi there – so sorry for the late reply, only just saw this!

We use a combination of raw computer data and then gut instinct.  Same as most weather forecasters.  So you get the raw data – lets say for Auckland it says 22, 24, 24, 25, 19 for the 5 days ahead.  We look at WHY it goes up, then why it suddenly drops.  We then factor in other things – wind, cloud, rain, time of year, and general air flow.  Humidity plays a part, especially in summer – just like wind plays a bigger part in winter.  Then it comes down to the forecast that best interprets the set up on that day – AND works out local geography too.  We got our highs for Chch wrong on Friday, expecting it to be much hotter – that was because the wind failed to be as strong and that is often why Chch temps can be swing and miss some times.  Overall – it comes down to the best gut instinct along with an accurate forecast and the best understanding of the geography locally.

 – Phil

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