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ECN records wettest December at Snowdon since 1945

Provisional ECN data confirm record-breaking December rainfall in Snowdon, North Wales
ECN records wettest December at Snowdon since 1945

Photo: Jonathan Yeardley

The UK Met Office has confirmed that December 2015 was a record-breaking month in terms of rainfall and temperature, and the latest data from the ECN team on Snowdon reveal just how wet it has been there.

A succession of winter storms has brought flooding and misery to many parts of northern and western UK, including the ECN Snowdon (Yr Wyddfa) site in North Wales, which is operated by Natural Resources Wales (NRW).

The ECN data remain to be validated, but initial results indicate that this month was the wettest December recorded on Snowdon since NRW’s rainfall records began in 1945. The site also experienced an extremely wet November. There are several rain gauges within the ECN site boundary on Snowdon, including the current highest rain gauge in Wales, situated just below Crib Goch (713 m), and the gauges within the ECN meteorological station (altitude approximately 500 m).

Checking the ECN Snowdon weather station. Photo: Jonny Easter
Photo:Jonny Easter

The ECN station recorded 686 mm of rain in November and 1131 mm in December1 giving a total of 1817 mm for the two months combined. The total annual rainfall for 2015 measured at the Snowdon ECN station was 4541 mm (over 4.5 m), substantially more than the annual average of 3784 mm calculated from available ECN data (May 1995-Dec 2012).

The higher altitude station at Crib Goch recorded 1128 mm for November and 1396 mm for December, a total of 2524 mm for the two months. To put this into context, the average monthly rainfall on Crib Goch (1945-2015) is 376mm, making December’s rainfall 370% of the mean monthly rainfall. Crib Goch received 6185 mm (nearly 6.2 m) during the whole of 2015.

It is clearly too early to determine the extent to which these remarkably extreme recent conditions may have affected wildlife on Snowdon. However, two decades of detailed ECN measurements of biota, such as ground beetles, butterflies and vegetation provide a robust baseline against which we will begin to test for evidence of effects in the coming months.  

Whilst we are still awaiting December’s data from other northern ECN sites (Hillsborough, Moor House-Upper Teesdale, Glensaugh, Sourhope and Cairngorms), we anticipate most, if not all, will also have experienced high December rainfall totals. We’ll report any interesting data in due course. In the meantime, we are grateful to our hardy Site Managers who visit these sites weekly on behalf of ECN.

1 Data to 30 December


Further information

  • According to the Met Office, it was the UK’s wettest December on record and the wettest calendar month since records began in 1910. The mean UK temperature for December was a record-breaking 7.9 °C, more than 4°C above the long-term average. 2015 was the sixth wettest year since 1910
  • Following the floods caused by Storm Desmond in early December, hydrologists at the Centre for Ecology & Hydrology provided an informative hydrological update. In the article, they address the question ‘Was the flooding event due to climate change?’
  • A series of datasets is now available, including meteorological data, covering 20 years of continuous monitoring at ECN terrestrial sites
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