A dry-ish year, helped by July heat

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A summary of 2021 weather statistics recorded at Benmore Garden, by Loch Eck in Cowal, operated by the Royal Botanic Garden Edinburgh

A relatively dry year, 2021 had a total precipitation of 2,402.2 mm (94.6 inches), eight millimetres shy of the 90-year average but a more impressive 415.7mm (16.4 inches) below the 10-year norm.

Eight months of the year had precipitation below the long-term average but February, August and October saw significantly more rain than would normally be expected.

Worth noting is that five of the top dozen wettest years on record have occurred in the last decade. Depending on your outlook, 2021 had 108 days without measurable rain or 257 days with it.

July 2021 was the driest on record, with just 25 mm of precipitation recorded and despite having Benmore Garden’s wettest day ever in February 2021 (132mm), the whole month’s rainfall did not compete with the same period in 2020.

The highest temperature of 27.3°C was observed on July 22 during an extended settled period of warm and dry weather. January saw the coldest air temperature of the year with -5.5°C on January 9.

Air frosts were down across the year. In November, for example, there were two occurrences compared to an average six, and in December there were seven as opposed to nine, which is the expected seasonal norm.

January, though, had six more days with air frost than expected compared to the 50-year norm.

There were 115 occurrences of ground frost throughout the year which is as expected in comparison with trends for the last 50 years, with the first ground frost of the autumn arriving on September 29 there was a longer than average ground frost-free period of 122 days.

Weather summary for 2021

Temperatures

Highest maximum air temperature: 27.3ºC on July 22
Lowest maximum air temperature: 1.0ºC on January 9
Lowest minimum air temperature: -5.5ºC on January 9
Highest minimum air temperature: 15.6ºC on September 10
Highest minimum at grass level: 15.2ºC on September 10
Lowest minimum at grass level: -12.1ºC on January 24

Frost

Air frost on: 52 days
Last air frost: May 6
First air frost: November 28
Between last and first air frost: 206 days
Bround frost on: 115 days
Last ground frost: May 25
First ground frost: September 29
Between last and first ground frost: 122 days

Precipitation

Total rainfall for year: 2,402.2mm (94.6 inches)
Greatest rainfall on one day: 132mm on February 4
0.2mm or more on: 236 days
1.0mm or more on: 195 days
5.0mm or more on: 121 days
Trace (between 0.0mm and 0.1mm) on: 70 days
Measureable rain on: 257 days

Other phenomena

Gale on:  One day – this refers to full gale conditions and does not include sporadic gusts or overnight events where wind speeds cannot be verified by observation.
Hail on: Two days
Snow/sleet on: 18 days
Thunder on: One day