April 1917 – Perishingly cold at Durham
Towards the end of World War 1, with fighting still going on in the trenches, April 1917 was quite extraordinary and was the coldest April recorded at Durham.
The mean temperature for the month was 4.4C, which is -3.9C when compared to the 1990-2010 normal for April. This was 0.1C colder than the next coldest, April 1922.
The month began very cold over the entire UK, with deep snowfall in places. On the 1st April 1917, the temperature in Durham never rose above -1.1C. This is still the coldest April day on record at the Durham Observatory. It is the only April day on the record to have remained below freezing all day. The following day was also cold, peaking at 0.7C. These remain the two coldest April days at Durham.
As I said, there was a snow cover, and the following night, in clear and calm conditions, the minimum air temperature fell to -11.1C. The minimum on the grass was even colder at -17.8C.
This was the lowest grass minimum in all months at Durham. Snow laid for 11 mornings in April 1917, resulting in many farming losses in Northumberland. The temperature never rose above 10C until 19th April 1917, with air frosts on 16 days.