Wind speed, wind direction, temperature, pressure, rainfall, relative humidity,  and insolation are measured minute-by-minute on the ERU test site. Data since 1987 are archived and are available to researchers.

The current data are also available in real time at www.elm.eru.rl.ac.uk. The screen is refreshed at two minute intervals, and data is currently shown from an anemometer 18m above the ground, a wind vane 18m above the ground, a 3m thermometer, a humidity probe at 3m, a barometer, a pyranometer, and a rain gauge.

This kind of data is very important when considering the siting of a wind turbine. For example, average windspeed will be slower closer to the ground and faster higher up due to the effect of friction - knowing the windspeed at the potential hub height will help estimate the power that might be generated by a wind turbine - the power that can be generated is proportional to the cube of the wind speed i.e. doubling the windspeed produces eight times as much power.

Temperature obviously varies through the year, and the amount of power in the wind is inversely proportional to its temperature i.e. a cold wind produces more power than a warm one.