The tempers and tantrums of spring


Just as we were ready to dust of our Jandals, you may be wondering why suddenly it feels as though we have been hit with a second winter! NIWA forecaster Chris Brandolino explains the mysteries and miseries of spring.

Spring Equinox

The spring or Vernal Equinox will occur on 23 September at 8:20 pm NZT. This is when the sun passes directly over the equator and is the astronomical beginning of spring (the meteorological start of spring occurred on the first day of September).

What does this mean?

This means the sun is, and will continue to become, more intense through the summer solstice as it climbs higher in the sky. It also means we will have longer days (more hours of day versus hours of night).

So why then aren’t temperatures warmer? Why is the weather seemingly more like winter than spring?

A couple of explanations. Spring is a transition season between the cold season and warm season. This doesn’t happen in a straight line. It’s not a revolution, rather it is an evolution. Spring is a very changeable season (it’s also very challenging as a meteorological forecaster!). It is a season that likes to have temper tantrums or fits – not too dissimilar to how a three year old may act at times.

Thus, cold outbreaks are not uncommon in spring, in particular in September and October as we are closer to winter than we are summer. However, as the season unfolds and we are closer to summer, cold outbreaks will become less numerous, a reflection of annual rise of average temperatures and moreover a result of the longer days and stronger sun.

The other reason, and this is more apropos to this spring, is El Niño. El Nino is one of New Zealand’s climate drivers. Typically it can bring more frequent and/or more intense southwesterly winds. In fact, cooler-than-usual temperatures have been indicated as a distinct possibility for much of New Zealand in NIWA’s most recent Seasonal Climate Outlook.

In summary, be patient for the warm weather. It will arrive. However, you may need to be especially patient this spring thanks to our friend El Niño.