[Dave K]

If you have a note of it or suitable data retrieval...

Surprised that my site's biggest diurnal range is "only" 19.6C which was on 23rd April 2011 ( Tmax 28.7 °C and Tmin 9.1 °C ). I thought it would be more than 20C though perhaps such a range isn't that common.

This post has been edited by Big Dave's Gusset: 18 February 2012 - 13:02

[00ctober]

Here, it was 20.9C on July 18th 2006 (12.3C, 33.2C). That 33.2c is also my highest ever max and also recorded the lowest RH on this day, got down to 20%.

[00ctober]

A further look in my records shows I haven't had a range of even 17C or more since 2006. Below are all the diurnal ranges above 17C in my records (from March 2005).

20.9C, 18.7.06
19.1C, 10.5.06
18.2C, 15.7.06
18.0C, 11.5.06
17.8C, 17.7.06
17.7C, 16.7.06
17.3C, 28.6.05

[Dave K]

00ctober, on 18 February 2012 - 13:17, said:

Here, it was 20.9C on July 18th 2006 (12.3C, 33.2C). That 33.2c is also my highest ever max and also recorded the lowest RH on this day, got down to 20%.

Quite impressive given that you ar not too far from the coast. Doesn't look like you are in a hollow either, is your soil rather sandy?

[00ctober]

Not particularly Dave. We're about 17-18 miles from the coast though so we get similar conditions to more inland areas when the wind direction is from the land.

[chapmanslade]

00ctober, on 18 February 2012 - 13:17, said:

Here, it was 20.9C on July 18th 2006 (12.3C, 33.2C). That 33.2c is also my highest ever max and also recorded the lowest RH on this day, got down to 20%.

RH explains the range as well - very dry air easily changes temperature

[Mothman]

21.2 16th Jul 2006 26.5/5.3
19.4 19th Jul 2006
18.3 14th Jun 2004
17.9 5th May 2007 17.7 6th Jun 2006
16.9 10th Jul 2006
16.6 22nd May 2010
16.5 1st Aug 2004
16.4 29th Sep 2005
16.4 16th Jun 2004

16th July max is my 3rd highest and min is 4th lowest in my records for July. Recording commenced late 1999

[Summertumn1]

I'll be checking Philip Eden's weather uk site when he puts the stats up for Chesham in February, as I have a feeling last Sat (11th) was a huge one, with -18C reported in the morning but around 4-5C by mid afternoon... then down to -15 again in the evening!

[BUTTERFLY]

I dont have the exact figures but remember that on a sunny day in late May 1994 the temperature varied from about 0.6 deg. c. to I think a little above 23 deg. C. in my garden (I did not commence temperature or rainfall readings at my place of work until about a year later in late May 1995). Since then I have recorded more than 1 range in the high teens C.; I think this included mid-July 2006, September 1998 and at least one othe month. Daily ranges of 20 deg. C. or more, though rare at any one individual site, can be expected from time to time, but those of 25 deg. C. occur much more rarely; there are at least 3 in Britain in the range of 28-29 deg. C. (29.0 deg. C. at Tummel Bridge in Scotland on 9th May 1978, from -7.0 deg. C. to +22.0 deg. C., 28.9 deg. C. from -27.2 deg. C. to +1.7 deg. C. on 30th December 1995 at Altnaharra, Scotland, and 28.3 deg. C. from +1.1 deg. C. to +29.4 deg. C. at Rickmansworth, Hertordshire, on 29th August 1936 - see http://www.personal....ther_in_may.htm, http://www.personal....in_december.htm and http://www.personal....r_in_august.htm

Large ranges could I think potentially occcur in any month. There seem to be two basic causes - where the sun is still fairly strong and can thus raise the temperature to a respectably high level (+20-30 deg. C.), but the air and ground are dry and thus the temperature can fall quite low at night (even in early May when the nights are quite short in Scotland, or late August in Southern England), or when milder air displaces very cold stagnant air in winter, as happened at Altnaharra in December 1995. In January 1958, there was a large range of temperature in a few days, with -21 deg. C. at Grantown-on-Spey in Scotland on 25th and 17 deg. C. later at Onich, Highland, and +18.3 deg. C. at Aber in North Wales on 27th; March 1965 had the highest overall range of temperature for any month, with -21.7 deg. C. at Corwen in Clwyd, Wales, on 3rd and +25.0 deg. C. at Wakefield and Whitby in Yorkshire on 29th (although the accuracy of the figures on the latter date is disputed and they may have been in the range of 22-23 deg. C.); see http://www.personal...._in_january.htm and http://www.personal....er_in_march.htm

[Les]

Ive had a look through my records and noticable events Ive come across are as follows.

Date..................Max........Min.....Diurnal Range
June 20th 2010........23.0c.......2.3C.......20.7C
May 11th 2009.........14.9C......-2.1C.......17.0C
June 3rd 2010.........23.1C.......6.4C.......16.7C
May 1st 2011..........16.6C......-0.6C.......16.0C

The narrowest diranal range I could find was;

November 19th 2009....11.6C.......10.4C.......1.2C

It cant be ruled out I may of missed some others ,but the above figures are correct.

This post has been edited by Les: 20 February 2012 - 17:42

[Dave K]

Thanks for the replies so far everyone

For my own site I thought it would be a good location for large diurnal ranges but seemingly not, which could be due to the far from standard instrument siting of course and perhaps a little UHI.

With regard to the Rickmansworth reading in 1936, for more info there is a whole thread dedicated to it at http://www.ukweather...th-august-1936/

[John Robert Mellor]

This is my top 10 - sorry about the formatting...

Date MaxTemp MinTemp Range
2006-07-01 32.0 11.2 20.8
2007-08-01 32.0 11.2 20.8
2006-07-19 35.2 14.6 20.6
2007-08-19 35.2 14.6 20.6
2006-07-18 32.8 12.8 20.0
2007-08-18 32.8 12.8 20.0
2006-06-10 29.2 10.1 19.1
2006-05-12 25.5 6.5 19.0
2011-09-30 29.1 10.1 19.0
2006-07-17 31.8 13.0 18.8

This post has been edited by John Robert Mellor: 26 February 2012 - 22:44

[BUTTERFLY]

http://www.weatherca...es_changes.html, which mentions a daily range of 24.0 deg. C. from 4.3 deg. C. to 28.3 deg. C. at Chesham, Buckinghamshire, on 23rd May 2010, also states that the highest daily range in Britain is from Altnaharra in Sutherland where the range was 29.3C on 30th December 1995. This would imply a range from -27.2 deg. C. to +2.1 deg. C. http://www.personal....in_december.htm states that the range on 30.12.1995 was from -27.2 deg. C. to +1.7 deg. C.

Strictly speaking, although no doubt it was within a 24 hour period, the -27.2 deg. C. and the +1.7 deg. C. (or +2.1 deg. C.)were within different 0900 to 0900 GMT periods (this of course also presumably applies to the Tummel Bridge range of +29.0 deg. C. from -7.0 deg. c. to +22.0 deg. C. on 9th May 1978 and the range of 28.3 deg. C. from +1.1 deg. C. to +29.4 deg. C. at Rickmansworth on 29th August 1936, so strictly one should only consider ranges where there has been a considerable drop from one afternoon through the following evening and night, and although this is probably too purist for most, it is to me equivalent to the difference between the wettest 0900 to 0900 GMT period in Britain (279 mm at Martinstown, Dorset, on 18th/19th July 1955) compared with the 316.4 mm which fell at Seathwaite in Cumbria in a non-standard 24 hour period around 19th and 20th November 2009 (see http://www.personal....in_november.htm, 142.6 mm falling in the 24 hours from 0900 GMT on 18th to 0900 GMT on 19th, and 246.6 mm falling in the 24 hours from 0900 GMT on 19th to 0900 GMT on 20th.

I think in the British climate, the fall in temperature would not be as much as the potential rise in temperature, as it often takes several days to reach an extremely low mininimum in winter, e.g. when there is a heavy snowfall, followed by several calm clear nights; at other times of year snow is much less likely. In the case of Rickmansworth in August 1936, I think the succeeding night fell to about 40 deg. F. or c. 4.4 deg. C., still giving a large daily range of about 25.0 deg. C. However the largest daily range in the world, of 100 deg. F. (c. 55.6 deg. C.) from +44 deg. F. (c. 6.7 deg. C.) to -56 deg. F. (c. -48.9 deg. C.) at Browning, Montana, U.S.A., from 23rd to 24th January 1916 - see http://en.wikipedia....Montana#Climate (although this only states that it is the USA's, not the world's, greatest daily range).

[Dave K]

Today I have a new record for the greatest diurnal range at my site: 20.4C

Min 1.9 °C max 22.3 °C. First time range has exceeded 20C.

[grahamread]

21.8C range today.
2C at 7.14 this morning - max of 23:8 at 16:14.

[Jez Meyer]

22.2C today, from -0.2 to 22.0