NZ Weather Forum

Thanks for your replies New and spwill. This morning (Sunday 19th Aug) was a good illustration of the range of temperatures in and around Dunedin. The airport had a minimum of -4.8*C (from the synop), but the lowest two hourly minimum temperature at the City site was +1*C. I cannot find a figure for the Musselburgh site.

According to a MetService tweet, the temperature fell to -7.2*C at Pukaki Airport.

PS, thanks for editing Churchill to Christchurch. Not sure what I was thinking about at the time!

There is another site in Dunedin at the University of Otago campus, which is in northern Dunedin. it recorded a minimum of +0.1*C on Sunday morning. Not sure of the exposure for this site.

http://www.physics.otago.ac.nz/eman/wea ... urrent.php

Simon Culling wrote: ↑Sun 19/08/2018 21:49 There is another site in Dunedin at the University of Otago campus, which is in northern Dunedin. it recorded a minimum of +0.1*C on Sunday morning. Not sure of the exposure for this site.

http://www.physics.otago.ac.nz/eman/wea ... urrent.php

The university area is getting into a valley so a bit of a frost trap there. The terrain around Dunedin region is very steep which enhances the frost effects in low lying areas.

And I think the climate of Pukaki could just about be described as a sub alpine climate.

Getting cold here again tonight, down to minus 0.7C at 10pm.

No frost here since June. We had 4 or 5 frosts late May/June but nothing more than ground frost. Pukas and Kentia Palms looking undamaged this year.

Frost again here overnight with it getting down to minus 2.2C but clouded up from early this morning but still white at 8am. It rained a bit later on.

Slight frosting this morning still on the ground around 8:30am. Minus 1.1C 0vernight.

Another frost this morning. Down to minus 1.1C again. Lovely fine clear day again.Where's this nasty weather?

I know! FB talking up for the last week a return to winter but is stunning

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Another good white frost this morning, hanging around in sheltered areas from the sun to about 11am.
Down to minus 1.2C.

Colder at the house than MS this morning, +0.3C. Further inland, more sheltered from SW flow. Thought had messed up as Bananna plant has pushed out its first new leaf and wasn't expecting any risk till the weekend. Lucky nothing including dew on grass had actually frozen.

A low of -1.4deg this morning

Frosty here,yet, again this morning. Down to minus 1.1C.

Another frost this morning, down to minus 1C.

John, I have counted up the air frost references in this thread for your site in Geraldine this year (I hope you do not mind) and this gives the monthly totals for 2018 up to 27th August as:

April 4
May 8
June 10
July 19
August 15

This gives a running total of 56 for 2018 (so far) if my maths are correct. As it appears that this winter has been on the mild side in NZ, does this suggest an annual average of air frosts of 60-70+ for your area?

Simon Culling wrote: ↑Tue 28/08/2018 01:07 John, I have counted up the air frost references in this thread for your site in Geraldine this year (I hope you do not mind) and this gives the monthly totals for 2018 up to 27th August as:

April 4
May 8
June 10
July 19
August 15

This gives a running total of 56 for 2018 (so far) if my maths are correct. As it appears that this winter has been on the mild side in NZ, does this suggest an annual average of air frosts of 60-70+ for your area?

I'm not too sure on this as I have only been taking readings at this site since May, last year.
Talking to locals, they say the Raukapuka area ( on the NE side of the Geraldine township) tends to get more frosts than other parts of the town, probably because of it's sheltered but exposed location.
Up, on the Downs (sounds Irish), the hilly area just to the west of the township, tend to have much less frosts than down here.

Thanks John. Local geography has a similar effect on the occurrence of frost here in the UK. As the average minimum temperature in the winter and spring is only a few degrees above zero (in both countries), these local differences can double the air frost numbers at some sites compared to more exposed areas, although I would suggest that ground frost numbers would be much closer.

I did have a ground frost thermometer back in West Melton but sadly I broke it as was shakening it down and it flew out of my hand, as I had a bit of gout in my wrist at the time

Frosty this morning with it dropping down to minus 1.1C again.

got as low as zero this morning

+1.1°C here at present, lawn looks white, not sure if that's frost or dew...

-1.2°C here now.

Frost this morning, first for a while. Down to minus 1.6C.

Slight frost this morning with -0.1deg

-1.5°C at 7am, lawn still white.