Christchurch weather:  the only certainty is change...

 

Rule number one for visitors to Christchurch:  pack for all weather and temperatures.

The weather's changeability shouldn't take visitors by surprise - just look at New Zealand on a world map to see why.  The islands are smack in the path of an endless procession of anticyclones, depressions and fronts that march across the south Pacific Ocean, usually from the west. 

Don't let this put you off.  New Zealand has an equable, temperate climate.  Christchurch itself is the driest of New Zealand's main cities.  Just don't be surprised if you get all four seasons in a day.

 

The nor'wester:  Christchurch's signature wind. 

 

You can tell that a nor’wester is coming by a glance at the weather map.  Look for a depression approaching the South Island from the west (as they normally do).  The leading edge is a very humid airflow from the north-west, moving from the Tasman Sea on to the West Coast of the South Island. 

The rising, cooling air dumps its moisture as rain - an awful lot of rain - on the West Coast and the Southern Alps.  With all of its moisture depleted, the wind continues eastwards across the Canterbury plains and roars into Christchurch as the warm, dry nor'wester.  This is the New Zealand version of the dry Fohn wind of Norway and the Chinook of North America.

The 'rain shadow' effect in Canterbury is one of the most pronounced in the world.

In a single 24-hour period in November 2006, over 300mm (12 inches) of rain fell in the Cropp valley on the western side of the Southern Alps (by comparison, Christchurch and London both get around 650mm of rain per year).  In that 24 hours, the same wind brought a dry, mild spring day to Christchurch, with not a drop of rain. 

 

The southerly wind:  have your jacket handy

 

When a depression and cold front moves across the South Island, the weather in Canterbury can change abruptly from a warm nor'wester to a cold southerly, bringing frigid air and rain straight up from the Antarctic Ocean.  If you see ominous clouds massing over the Port Hills, have your jacket handy!

At times like this, the 'rain shadow' works in reverse:  while it is cold and wet in Christchurch, the West Coast is enjoying a clear, sunny day.

 

Christchurch  temperatures - monthly

 

  Average Daily Minimum Average Daily Maximum
  C F C F
January 12 54 22 72
February 12 53 22 71
March 10 50 20 68
April 7 44 17 63
May 4 39 14 57
June 1 34 11 52
July 1 33 11 51
August 36  12  54 
September 40  14  58 
October 44  17  63 
November 47 19  66 
December 11  51  21  70 

 

Current weather forecast for Christchurch

 

 

 

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