Updated 1981-2010 Climatological Averages (climate, warm, recorded, temperatures)

[dhdh]

I came across the newly released data of 1981-2010 on Hong Kong Observatory for Hong Kong and I was wondering if any one possessed such data for other world cities. I think it would be interesting to compare them and see how different climates evolved from their 1971-2000 averages. Here's a comparison of selected data for Hong Kong from both sets, feel free to compare

Monthly average temps °C, 1981-2010 vs 1971-2000


JAN 14.5 - 18.6 vs. 14.1 - 18.6 (+0.4 and 0)
FEB 15.0 - 18.9 vs. 14.4 - 18.6 (+0.6 and +0.3)
MAR 17.2 - 21.4 vs. 16.9 - 21.5 (+0.3 and -0.1)
APR 20.8 - 25.0 vs 20.6 - 25.1 (+0.2 and -0.1)
MAY 24.1 - 28.4 vs 23.9 - 28.4 (+0.2 and 0)
JUN 26.2 - 30.2 vs 26.1 - 30.4 (+0.1 and -0.2)
JUL 26.8 - 31.4 vs 26.7 - 31.3 (+0.1 and +0.1)
AUG 26.6 - 31.1 vs 26.4 - 31.1 (+0.2 and 0)
SEP 25.8 - 30.1 vs 25.6 - 30.2 (+0.2 and -0.1)
OCT 23.7 - 27.8 vs 23.4 - 27.7 (+0.3 and +0.1)
NOV 19.8 - 24.1 vs 19.4 - 24.0 (+0.4 and +0.1)
DEC 15.9 - 20.2 vs 15.7 - 20.3 (+0.2 and +0.1)

YEAR 21.4 - 25.6 vs 21.1 - 25.6 (+0.3 and 0)

From this we can see that every month of the year enjoyed higher average low temperatures yet about half of them had slightly cooler days, mostly in spring, while autumn had warmer days. The effect on low temps can be easily explained (I guess) by urban heat island effect due to further urbanization in Hong Kong while the effect on max temps is more tricky to explain.



Rainfall in mm (rounded) :

JAN 25 vs 25 (no change)
FEB 54 vs 52 (+2)
MAR 82 vs 71 (+11)
APR 175 vs 189 (-14)
MAY 305 vs 330 (-25)
JUN 456 vs 388 (+68)
JUL 377 vs 374 (-4)
AUG 432 vs 445 (-12)
SEP 328 vs 288 (+40)
OCT 101 vs 152 (-51)
NOV 38 vs 35 (+3)
DEC 27 vs 35 (-8)

YEAR 2399 vs 2383 (+13mm)

The largest changes were for June (+68mm), October (-51mm) and September (+40mm). June has furthermore overthrown August as the wettest month of the year - this can be partly explained by the extremely wet June 2008 when more than 1 meter of rain was recorded ! Same thing for September, I recall September 2009 being extremely wet (I was there at that time) due to a powerful typhoon. I have no idea what caused the much drier October though.


Sunshine :

JAN 143 vs 142 (+1)
FEB 94 vs 94 (no change)
MAR 91 vs 90 (+1)
APR 102 vs 102 (no change)
MAY 140 vs 139 (-1)
JUN 146 vs 158 (-12)
JUL 212 vs 215 (-3)
AUG 189 vs 190 (-1)
SEP 172 vs 172 (no change)
OCT 194 vs 191 (-3)
NOV 180 vs 178 (-2)
DEC 172 vs 173 (-1)

YEAR 1836 vs 1843 (-7)

Mostly no or little change here, except for June getting noticeably gloomier, probably because of the aforementioned increase in rainfall.

Overall the most noticeable changes were June, for rainfall and sunshine; February for temperature and October for less rainfall and warmer temperatures.

Month by month :

JANUARY got a little milder, but stayed very similar otherwise
FEBRUARY got noticeably milder, similar otherwise
MARCH got wetter, and milder with warmer morning and cooler days
APRIL got drier, and milder with warmer morning and cooler days (does not really make sense if it was drier)
MAY got drier with warmer mornings
JUNE got much wetter, gloomier with cooler days
JULY got slightly hotter, drier yet more cloudy (does not really make sense)
AUGUST got drier with hotter mornings
SEPTEMBER got noticeably wetter yet retained the same sunshine, and had slightly cooler days
OCTOBER got much drier, and warmer
NOVEMBER got much milder, with warmer mornings
DECEMBER got slightly warmer and drier


Overall, Hong Kong got wetter, warmer and cloudier, which is consistent with the Observatory's forecast effect of climate change on Hong Kong's climate.

What are your thoughts?

Cheers

[Derek40]

I think that this merely shows that you need at least 40-50 years of climate data, for there to be representative ""averages"".
I don't buy into the climate change phenomenon, this year''s December is running as the coolest on record here, and that's on 43 years of records for temperatures. (although rainfall has been recorded since 1862).
There seems to be more seasonal lag in recent years, but not sure if this is objective.

[dunno what to put here]

Here in the UK, the 1971 - 2000 December average was 5.1C / 41.1F, but the 1981 - 2010 average has fallen to 4.6C / 40.2F! The only month to become colder and even colder then the 1961 - 1990 average

[deneb78]

Winters in the last few years here seem to be a bit below average lately but that might not be any significant trend...

[Flight Simmer]

The BOM offers 1981-2010 data for any location in Australia which recorded data during that period.

[Glacierx]

Originally Posted by Derek40

I think that this merely shows that you need at least 40-50 years of climate data, for there to be representative ""averages"".

I totally agree. The following graph shows how Kamloops has changed in just 10 years. For the first in history (records in Kamloops go back to the 1889), December is the coldest month of the year. This is largely the result of a lack of cold Januaries in 2000s compared to a slew of them in the 1970s. Going forward, I doubt the next 30 year period will also have December as the coldest month, so given the likelihood of a one-off occurrence, a 30 year time-frame is too short to truly capture an area's climate.

BTW, the 2000s decade was the first decade in Kamloops to record an average July max of over 30 degrees C (86F). This follows up the three coolest decades on record in terms of the July maximum. This is the reason why the July temperature has jumped so much, and points to the second reason why a 30 year period is likely too short.

The driest month of the year also tends to bounce around between February and March with each climatic update, which is the third reason we should be using a longer climatic period for determining the normals.