Why all the hot weather for chch???

[gopolks]

Okay, this summer has to be a record, have we ever had a summer like this?? and what is the reason, and will it continue into March?

[RWood]

Haven't got monthly temp means for Ch'ch sites to hand, so can't help with that one. The sunniest summer was 2002/3 (802 hours), but temps. were barely average, from memory. For warmth alone I suspect that 1934/5 would be well up the list (hottest ever summer for NZ overall), with 1961/2, 1977/8, 1984/5 and 1997/8 probably prominent.

[NZstorm]

Hot weather is Canterbury comes via the fohn effect. Why such a persistent fohn effect I'm not sure. Next weekend looks hot for Canterbury and much of NZ.

[Manukau heads obs]

I think you missed RWood that gopolks was refering to CHCH having a hot summer

[TonyT]

Hot weather is Canterbury comes via the fohn effect. Why such a persistent fohn effect I'm not sure. Next weekend looks hot for Canterbury and much of NZ.

Whilst thats true, this summer has not seen the "wall to wall" nor'westers which some summers bring - I think it has more to do with persistent northerly flow over the region, and in fact pretty much all of the country. We have had a lot of anticyclones lying over or just east of the country, and relatively few over the Tasman Sea. This has meant less oomph in the SW changes and pretty rapid transition from cool SW to warm N'ly quarter airflow, with the N'ly side of the systems seeming to last for many days in a row.

We certainly havent had a predominance of NW winds over the last two months, there have been if anything more days with NE than usual, but they have been warm, and often light till the afternoons, and that has meant quite a few days with maximums reached early in the day in pretty light wind conditions, and thats whats probably unusual for this summer.

[CHCH Weather Chaser]

Thats a very good point made Tony and i agree with you. Several days this summer (since xmas especially) have seen plenty of clear skies and very little wind in the morning with temps peaking quite often between 29-32 degrees before the late morning or early afternoon northeasterly kicks in and freshens things up dropping the temperature a good 5-7 degrees to around that 25 degree mark.

[gopolks]

Thanks for the info. Im not complaining its great going to the beach, not so great being stuck in a office.

[Myself]

It's worth noting also that the northwesterly has been reaching the surface despite the fronts usually becoming stationary, or very weak, over the Otago/Southland region. This has kept bands of high and mid level cloud away from Christchurch in general, allowing the sun to push up the already hot nor'wester influenced temperatures.

[RWood]

I think you missed RWood that gopolks was refering to CHCH having a hot summer

I hadn't missed it - the numbers I was quoting were for Ch'ch, but I don't have detailed seasonal temps for there on hand, as I said.

If the reference had been to NZ mean temps, a comparison could already be made. Dec & Jan were both reasonably warm, but far from record-breaking. The warmest summer in relatively recent times was 1998/9 (4th highest in the temperature series).

[RWood]

It would be useful to see pressure anomaly charts in NIWA websites somewhere, then (say) the differences between this January and Jan 2008 would be more obvious. Jan 2008 was 0.7C warmer than this one, for the country as a whole. In the south, Otago and Southland were much cloudier this time (record sun in 2008) with above normal rainfall in Southland. Around Wellington there more more NNW/NW flows this time as opposed to N/NNE/NE in 2008.