How these notes are kept
Anyone reading a long record should know how it was made, including where it is weak.
Instruments
Temperature and humidity come from a shielded sensor two metres above short grass, read at 07:00, 14:00 and 21:00. Rainfall is measured with a manual gauge emptied at 07:00 and recorded against the previous day. Wind is estimated, not measured, and is recorded on a four-point scale only.
Definitions held constant
A rain day is 0.2 mm or more. A fog day is visibility under one kilometre at 07:00 against fixed landmarks. A frost day is a grass minimum at or below zero. These have not changed since 2016 and will not be changed retroactively.
Known errors
Three periods are unreliable and are marked as such in the tables: eleven days in August 2018 when the shield was damaged, the whole of February 2021 when the observer was away, and a six-week stretch in 2023 when the gauge was found to be sited too close to a new hedge. The 2023 figures were corrected downward by comparison with a neighbouring record; the method is described in the note for that year.
No figure in this record has been adjusted to make a trend clearer. Where a reading looks wrong it is either kept with a note or removed entirely, never smoothed.