SSEN's Weather Watch for May 2021

Our weather maps showed a high pressure anomaly across the UK and Ireland during April. This gave us some pleasant dry, sunny weather but it was also mostly chilly with night frosts; the cold nights have been particularly challenging for the farmers and growers.

Much of the time we had winds blowing from the north or northeast and April 2021 has provisionally been the frostiest in at least 60 years for the UK, topping the previous frostiest April in 1970, with records going back to 1960. 

The night time temperatures have averaged the lowest on record at Glasgow Bishopton since records began in 1967, and interestingly this is the second consecutive April with well below average rainfall. 

The Speedwell Weather cone chart above shows the cumulative rainfall in Glasgow for April 2021 (black line), with last year (blue line) and both years sit on the very lowest side of the historical spread (which is shown as the grey shading). 

The first couple of days of May will start cold with sunny intervals and showers. The very light winds will allow temperatures to fall to around zero at night giving some local air and ground frost. 

Then it’s all change for the week commencing 3 May, as it turns much more unsettled. New Atlantic low pressure systems will develop during the week and one will likely cross the centre of Ireland and the UK on Monday/Tuesday with the second low coming for the end of the week or the weekend of 8 to 9 May. During this time we can expect some spells of rain and strong winds. The nights won’t be quite so cold but the risk of local frost is still around, notably for north east England and parts of Scotland.

The MetDesk map in our summary image shows the forecast five-day rainfall anomaly, expressed as a percentage of the long term average, for the period of 3 to 7 May. The blue and purple colours show the locations which are likely to see above or well above average values. This area covers most of north west Europe, but the red colours indicate very dry conditions for Portugal, Spain and Greece. 

The middle of the month is likely to see a return to high pressure and this should help to bring some dry pleasant days, but still with cold nights. The low pressure from the Atlantic will likely drift across Scotland to bring some wet and windy spells for the last week of the month, but southern areas could stay fine. 

So another mixed month of weather to come and we’ll be back in a few weeks to see if the weather patterns show any indication of settling down for June. 

About the author

Headshot of Simon Cardy

Simon Cardy Senior Meteorologist for SSE

Simon is the Senior Meteorologist at SSE and a Fellow Member of the Royal Meteorological Society. Through detailed analysis of the weather and climate, Simon provides valuable information to departments across SSE, including Networks (power distribution), Renewable Energy (wind farms and hydro dams) and Energy Demand Forecasting (how much electricity and gas we need each hour).

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