Opinion Date of the First 30, 35 and 40 degree days (Sydney)

Jac0b

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Jul 5, 2019
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Western Sydney
Each year I like to take a guess of the date when the first 30, 35 and 40 degree days will occur. The winner would be the person who is closest on average.

The date of each threshold would be declared as the first time for any weather station in Greater Sydney to reach that temperature.

My guess is it's likely we'll get a cooler spring due to negative IOD, and hotter days may happen later than average. But all it takes is one hot day to buck the trend, like a 30 in early September.

My wild guesses are:

First date to crack 30: 24th September
First date to crack 35: 1st November
First date to crack 40: 10th January
 

Billy Bob

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Nov 23, 2020
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Bungendore
First 30 in Sydney these days is usually mid September. This year still has plenty of early heat despite the negative IOD it seems, so I will stick with that prediction. The 16th was going to be my guess too but I will have to go for something different, so I will go the 14th. 35C is usually early to mid October; I will go October 9. 40 may not be reached some years at Obs Hill, but more likely with the current hotter site. I'll go Dec 21st (the solstice).

I am doing something similar for Bungendore on my Palerang Weather page, except the guesses are for 25C and 30C (it's a spring competition). Though we have got to 35C plenty of times in November I think.
 

Wavey

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Jul 3, 2019
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Wollongong, NSW
My guesses are:
30, 29th September
35, 23rd October
40, 2nd December

I agree, I think the warm temps will be quite delayed because I reckon after a very dry July and August with lots of westerlies (apart from tomorrow), September could be quite dominated by periods of E/SE winds, so yeah I think 29th Sep will have the first 30. And extreme heat seems to be quite rare in early December so maybe this year there will be some heat then around before the summer turns quite wet (IMO).
 
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Steve777

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Jul 4, 2019
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For the purpose of this question, I am going to take “Greater Sydney” to mean the BOM’s Sydney Metropolitan forecast district. This corresponds closely to the County of Cumberland, an area almost encircled by the Hawkesbury-Nepean Rivers with a line South of Campbelltown to the coast near Otford.

My gut feel is that we get a Summer similar to the last one, cooler, cloudier and wetter than we’ve become accustomed in recent years. That doesn’t rule out hot days, especially early in the season.

So my guesses:

* First 30° in September, let’s say the 15th, including at OH.
* First 35° max: October 31, most of Sydney except the coast.
* First 40° max: November 25, in the Hawkesbury-Nepean valley.

Random Note - Sydney OH. the recent site move will probably increase the number of 30° and 35° days at OH, as what would have been sunny sea-breezy 28-29° days at the old site are bumped over 30° and 33-34° to over 35°.
 

Wavey

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Jul 3, 2019
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Wollongong, NSW
Does anyone here reckon there'll be any 45 degree days this summer in any of Greater Sydney? My gut feel is that will get close 3 or 4 times in places like Penrith but not quite there.

I think the max temp for summer 2021-22 will be 43.7 at Penrith on January 11th.
 

Principal Douglas

Big Fan
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Mar 21, 2002
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First date to crack 30: 20th September
First date to crack 35: 20th December
First date to crack 40: 20th January

I'm going for an up and down, mild-ish summer
 
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Jac0b

Hard Yards
Jul 5, 2019
49
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Western Sydney
Does anyone here reckon there'll be any 45 degree days this summer in any of Greater Sydney? My gut feel is that will get close 3 or 4 times in places like Penrith but not quite there.

I think the max temp for summer 2021-22 will be 43.7 at Penrith on January 11th.
I'm thinking highest temps in the far west a 43, maybe 42 at Parramatta, and 38 near the coast. My prediction for hottest day is 1st Feb.

tbh what I love about weather is there is really no way to tell! Only time.
 

AshestoAshes

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Jul 3, 2019
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Voyager Point NSW
My understanding is similar to those mentioned above, very strong heat leading up to the Northern Monsoon. La Nina is probably kicking in again + Residual IOD temps are fodder for a great monsoon.

First 30: 8th September (models saying some wet weather kicking in for most of September)
First 35: 4th November (looking like a stormy and wet October)
First 40: 13th December (Early Monsoon it seems), along with Penrith seeing monster temps in recent years
 
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Billy Bob

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Nov 23, 2020
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Bungendore
My guesses were for Obs Hill only, but I guess it doesn't change the outcome. It failed to reach 30 yesterday there but just made it today with 30.1. So only 2 days out. I thought I was being bullish but my hunch paid off; there's a lot of heat in the tropics and a good NW'ly will bring that down. The negative IOD doesn't really affect Sydney as much.

I will stay with October 9 for 35, but could easily go on the October long weekend or on October 5. There is almost always some heat on the October long weekend with October 5 usually a hot day.
 
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