Royston (Iceni) Weather Station

The weather station is located on the eastern edge of the market town of Royston in the county of Hertfordshire, Great Britain. It is approximately 65 km north of London and 20 km south-west of Cambridge, and lies just a few hundred metres inside the Western Hemisphere, and close to the Hertfordshire/Cambridgeshire border.

The weather station site is situated near to the foot of the northern slope of the East Anglian Heights. The underlying rock of the area is chalk and in consequence Royston is extremely well drained, there being no surface drainage in the town and around. The dry valleys which intersect Therfield Heath on the outskirts of Royston are an indication of streams flowing in wetter past times, however. To the south lies undulating chalk upland whilst to the north is the flatter south Cambridgeshire plain. The surrounding country is almost exclusively given over to arable farming with cereal crops predominating.

The Chiltern Hills and their eastward extension into the East Anglian Heights to the south-west and south of Royston provide a barrier to the prevailing south-westerly winds and result in Royston being in a "rain shadow". The annual rainfall is just over 600 millimetres but higher totals are received further south in Hertfordshire.

Some 5 km to the south of Royston the land rises to over 150 metres and it is an interesting fact that following the Greenwich Meridian (0 Longitude) due northwards there is no higher ground between here and the North Pole, a distance of 4233 km!

Observations commenced at the current site on 1st May 1972 and daily records of maximum and minimum temperature, grass minimum temperature, earth temperature, rainfall and air pressure have been maintained since then. With effect from 1st January 1998 the manual observations have been supplemented with the addition of an automatic weather station giving 5 minute observations of temperature, air pressure, wind speed, wind direction, rainfall, sunshine and relative humidity.

The weather station is a reporting station of the Climatological Observers Link (COL) and provides weather information to the press and regional television.

The town of Royston is fortunate to have continuous rainfall records going back to January 1853. These measurements have been taken at several sites in the town within about 1 km of the present site.

Below is a picture of the Stevenson screen in which the thermometers are housed, both for manual and automatic observations. This photograph was taken at 1021 GMT on 11th August 1999, the time of the solar eclipse at its 95% maximum in Royston. As can be seen a 95% eclipse has had little effect on the lighting or the shadows. The station sunshine recorder soldiered on throughout the whole eclipse and suffered no diminution of sunshine value!

The instruments inside the Stevenson screen are shown in the next photograph. The near horizontal thermometers are the maximum and minimum thermometers, whilst the vertical thermometers are the dry and the wet bulbs. To the left of the enclosure is the automatic weather station temperature sensor which is connected by underground cable to a remote datalogger and computer. The rain gauge glass measure which is kept in the Stevenson screen for safety purposes when not in use can be seen in front of this sensor.

The two white and grey instuments are thermometers transmitting temperature readings by radio signal on 418 mHz to remote displays. Although the readings from these are not used for the official station records they have, in fact, proved to be remarkably accurate, and provide both a check on the manual and automatic instruments and a further source of interest.

A slide rule is also in view adjacent to the rain measure. This is used to determine the relative humidity from the readings shown by the dry and wet bulb thermometers. The glass bottle below the wet bulb contains distilled water which is transmitted to the wet bulb via a muslin wick.



Royston (Iceni) Weather station closed on 1st July 2013, but this website will continue to be maintained for the display of the 41 years of observations accumulated since the station opened on 1st May 1972. To view observations from a successor weather station in the Great Ouse catchment click here.

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(This page last updated 15th January 2014 2023 GMT)