Yeovilton, any hour sunrise to sunset, 1997–2017
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Met Office station 1302: Yeovilton, Somerset  (BA22 8); OS grid reference: ST 551232.
Coordinates:  N51°00'22" W2°38'24"  (51.006 -2.640), elevation 20 m.
Note: gusts not recorded in 6 out of the 21 years, 0.9% of daylight visibility records missing, 1.6% of daylight precipitation records missing, 0.6% of daylight wind records missing.

This is the analysis for the average of 21 years  (1997–2017).
Time slot: sunrise to sunset  (any daylight hour); click below on the start time for a specific 2-hour slot, or on all-day for whole day analysis (all times are GMT):

any-hour  06:00  08:00  10:00  12:00  14:00  16:00  18:00  all-day

‘Flyable days’ analysis

This is the number of days in each month, on average, for which (in some daylight hour) the visibility was adequate, and there was no bad weather, and the wind speed was less than or equal to that shown on the left.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total Hours
≤ 5 mph 11 10 14 17 18 21 22 21 19 15 13 11  192  53%  721  15%
≤ 10 mph 20 18 22 24 26 27 28 29 26 23 21 19  285  78%  1668  34%
≤ 15 mph 25 23 28 28 30 29 30 31 29 28 26 24  331  91%  2700  55%
≤ 20 mph 27 25 29 29 30 30 30 31 29 29 27 26  341  93%  3048  63%
≤ 30 mph 27 26 29 29 30 30 31 31 29 29 27 26  345  94%  3187  65%
≤ 40 mph 27 26 30 29 30 30 31 31 29 30 27 26  346  95%  3212  66%
any wind 27 26 30 29 30 30 31 31 29 30 27 26  346  95%  3220  66%
‘Total’ shows the total flyable days, on average, in a year, and the same as a percentage.
‘Hours’ shows the total flyable hours, on average, in a year, and the same as a percentage of total daylight hours.

Trend analysis

This is the average change (per year, over the 21 years) in the average number of days in each month for which (in some daylight hour) the visibility was adequate, and there was no bad weather, and the wind speed was less than or equal to that shown on the left.

For example, if a value of +0.5 is shown for a given month then that implies that since 1997 the number of flyable days in that month has increased by (on average) half a day per year.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
≤ 5 mph +0.1 +0.1 −0.1 +0.2 −0.2   −0.2 −0.2 −0.1     −0.1 −0.5
≤ 10 mph −0.1     +0.2 −0.1 +0.1 −0.1   +0.1 +0.1     +0.1
≤ 15 mph   +0.1   +0.1         +0.1   −0.1 +0.1 +0.3
≤ 20 mph +0.1               +0.1   −0.1 +0.1 +0.2
≤ 30 mph +0.1 −0.1             +0.1   −0.1 +0.1 +0.1
≤ 40 mph +0.1 −0.1             +0.1   −0.1 +0.1 +0.2
any wind +0.1 −0.1             +0.1     +0.1 +0.2
Empty cells indicate negligible change; ‘Total’ shows the sum of the trends over the whole year.

Visibility analysis

This is the number of days in each month, on average, for which (in some daylight hour) the visibility was adequate. That is, for the entire hour:
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
Good days 29 27 30 30 31 30 31 31 30 30 29 28  355  97%

Bad weather analysis

This is the number of days in each month, on average, for which (in some daylight hour) no bad weather occurred. That is, for the entire hour, there was no rain, hail, snow, snow on the ground, icing conditions, thunderstorms, etc.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
Good days 29 27 31 30 31 30 31 31 30 30 29 29  357  98%

Wind speed analysis

This is the number of days in each month, on average, for which (in some daylight hour) the maximum (gust) wind speed was less than or equal to the value shown on the left.
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
≤ 5 mph 11 10 14 17 18 21 22 21 19 15 13 11  192  53%
≤ 10 mph 20 18 22 24 26 27 28 29 26 23 21 19  285  78%
≤ 15 mph 25 23 28 28 30 29 30 31 29 28 26 24  331  91%
≤ 20 mph 27 25 29 29 30 30 30 31 29 29 27 26  341  93%
≤ 30 mph 27 26 29 29 30 30 31 31 29 29 27 26  345  94%
≤ 40 mph 27 26 30 29 30 30 31 31 29 30 27 26  346  95%

Please send any comments, questions, or corrections to me, Mike Cowlishaw, at mfc@speleotrove.com.

All text Copyright © Mike Cowlishaw 2008, 2018. All rights reserved. The pages and data here are for non-commercial use only.
This page was last edited on 2018-02-09.