What is the UKs definition of Drought?

Does anyone know what constitutes drought in the UK.

We seem to have hardly had any rain this Winter in the South and the Spring looks like being just as dry. We have had around 170mm of rain so far this year.

Won’t need to move to Spain if this continues

http://www.defra.gov.uk/environment/water/resources/drought/guidance.pdf tells you more than you probably wanted to know #-o If I’ve read it correctly a drought doesn’t have a numerical definition. Its basic definition appears to be…

either a serious deficiency of supplies of water in any area or such a deficiency in the flow or level of water in any inland waterway as to pose a serious threat to any flora or fauna which are dependent on those waters exists or is threatened

and that…

the reason for the deficiency is an exceptional shortage of rain

I guess it’s difficult to define it any better than that and I don’t think you can just call a drought a lack of rain. For example, if you lived on a small island in the middle of a large river, you may not have had any rain for years, but if it rains a lot 50 miles upriver you may have been flooded almost every day.

Thanks Chris.

These things always appear simple on face value, then when you really start to question it you realise that they are far from simple.

I like your example, it demonstrates the point very well.

Because I have a weather station and weather web site, people think I know everything about weather! when in fact, I know very little. The reason I got one in the first place was because I wanted to learn more. Someone asked me the question at work yesterday and I realised I really had no clear answer for them.

Thanks for your help.


a better way is to actual use soil moisture deficit as well
because in a cooler cloudy climate, then 120mm for year to date will be OK, but in a hot dry climate, then the evoptranspiration loss each day will mean the soil will be less than wilting point most likely with 120mm for the year to date…which is a bit what its like here at the moment,…the soil is in a big soil moisture defict at the moment

170 mm. Pah - jungle conditions. Over in Great Bealings, East Anglia I’m recording 137mm and that includes some proper rain today of 13mm, and it look like Julian (Softvark) in Colchester has only had 106mm.

There is a definition of a drought as a period of 15 days with no measurable rain. That’s what used to be the met office definition and is documented in “Weather Patterns of East Anglia” by Alfred Glenn.

We’ve had about 30mm less rain compared to last year so far. Although it doesn’t sound much we get so little every drop is important! Today though has been a mixture of sunshine and showers with quite a lot of hail mixed in.


here in NZ, a drought is 30 days with no rain (officialy)
in california, they go for 3 to 5 months with no rain every year, or more!

In the Atacama Desert they define a non-drought if it’s rained since 1600 (that’s the year, not the time!)

what about Galway, in Ireland, which has the world record for the number of rain days in a year,365, LOL
7 days without rain in Ireland must be drought?

I think it’s 7 days without Guiness in Ireland :wink:

That has not been the case lately though…

Downtown Los Angeles needs just 1.13 inches of rain to match the record of 38.18 inches set in 1883-84.

San Diego already set their all time record at 21.76in

Other records:

Records and Totals

Los Angeles

[ul][]had its wettest 15-day period on record as a result of the storms. Rainfall from December 27th 2004-January 10th 2005 totalled 16.97 inches, wetter than any 15 consecutive days since records began in 1877. The previous record was set in January 1969 when 14.63 inches fell between the 13th and 27th.
]had its second highest seasonal (July-June) total (through January 10th) on record - 22.35 inches. In the 1889-1890 season, 26.73 inches fell through January 10th. Even if LA received no more rain through the end of the season, it would still be the 16th wettest season on record.
[]has already surpassed its seasonal average rainfall by over 7 inches (as of January 10th), and exceeds the season-to-date (July 1st-January 10th) by over 17 inches. More rain fell in during the December 27th-January 10th period than during a normal season in LA.
]For the 5-day period January 6th-11th, over 20 inches of rain was recorded at some mountain weather stations in Santa Barbara, Ventura and LA County locations, and over 12 inches fell in Beverly Hills. LA Airport received over 5 inches and downtown LA, over 6 inches. For downtown LA, this is more rain in 5 days than you would expect in the entire season up to January 10th.

In the Mojave Desert, Barstow, California has already received 119% of its seasonal (July-June) rainfall total with 5.15 inches falling from July 1st to January 18th. This translates to a season-to-date percentage of 505%.

Las Vegas, Nevada reached 96% of its seasonal rainfall total by January 18th. A total of 4.42 inches and 475% of its season-to-date total

The North Hills of Reno received nearly 7 feet of snow between December 28th and January 11th, with over 38 inches falling between January 7th-11th.

Ski resorts in the Sierra Nevada received between 6-8 feet of snow, and even below 7000 feet, the average was 4-6 feet for January 7th-11th. Tahoe City received nearly 4.5 feet during the same period. For the entire period of the storms (Dec 28th-Jan 11th), Tahoe City received 118 inches of snow, or nearly 10 feet.

They have a great loop of the storms that hit this year…

That’s nothing. Queen Elizabeth II has been reigning since Feb 6th 1952 #-o

GROAN :smiley: :smiley: :smiley: :smiley:

Hi All.

I can’t tell you the total rain for this year in Ascot, only had my station running for one week and no rain :frowning: :frowning:
I can say however that my grass is showing the first signs of ‘drought’ , a live weather station up the road in Aldershot gives the yearly rain as 119.1 mm.
If some rain does not arrive soon, I shall have to set up some sort of gizmo to test the rain collector, thinking of an I.V. bag dripping at a known rate.