Yeovilton, sunrise to sunset, 1997–2020
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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 24 years, 0.9% of daylight visibility records missing, 1.6% of daylight precipitation records missing, 0.7% of daylight wind records missing.

This is the analysis for the average of 24 years  (1997–2020).
Time slot: sunrise to sunset  (all daylight hours); click below on any-hour, or on the start time for a specific 2-hour slot (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 all daylight hours) 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
≤ 5 mph 0 0 0 0 0 0 0 0 0 0 0 1 ​ 2  1%
≤ 10 mph 2 1 1 1 1 1 1 1 2 2 2 3 ​ 19  5%
≤ 15 mph 6 4 5 6 6 7 8 6 6 6 4 7 ​ 71  19%
≤ 20 mph 8 6 7 9 9 10 11 8 9 7 6 8 ​ 99  27%
≤ 30 mph 8 7 9 11 11 10 12 9 10 9 7 9 ​ 110  30%
≤ 40 mph 9 8 9 11 11 11 12 9 10 9 7 10 ​ 113  31%
any wind 9 8 9 11 11 11 12 9 10 9 7 10 ​ 114  31%
‘Total’ shows the total flyable days, on average, in a year, and the same as a percentage.

Trend analysis

This is the average change (per year, over the 24 years) in the average number of days in each month for which (in all daylight hours) 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                          
≤ 10 mph             −0.1           ​−0.1
≤ 15 mph     −0.1 +0.3 +0.2   +0.1 −0.1 −0.1     −0.1 ​+0.4
≤ 20 mph   +0.1 −0.1 +0.3 +0.3 +0.1 +0.2     +0.1   −0.1 ​+0.9
≤ 30 mph   +0.1 −0.1 +0.3 +0.3 +0.1 +0.2   +0.1     −0.1 ​+0.9
≤ 40 mph   +0.1   +0.3 +0.3 +0.1 +0.2   +0.1     −0.1 ​+1.1
any wind   +0.1   +0.3 +0.3 +0.1 +0.2   +0.1     −0.1 ​+1.1
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 all daylight hours) the visibility was adequate. That is, for the entire day:
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
Good days 18 15 16 17 18 17 18 18 16 17 15 18 ​ 201  55%

Bad weather analysis

This is the number of days in each month, on average, for which (in all daylight hours) no bad weather occurred. That is, for the entire day, 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 12 12 14 15 16 14 16 14 16 13 11 13 ​ 165  45%

Wind speed analysis

This is the number of days in each month, on average, for which (in all daylight hours) 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 2 1 1 0 0 0 0 0 0 1 2 3 ​ 11  3%
≤ 10 mph 7 5 4 4 4 3 3 4 6 6 8 9 ​ 64  18%
≤ 15 mph 16 14 15 16 16 18 17 18 18 17 19 19 ​ 203  56%
≤ 20 mph 22 20 23 23 24 25 26 26 25 24 24 23 ​ 284  78%
≤ 30 mph 27 24 27 28 29 29 30 30 29 28 27 28 ​ 336  92%
≤ 40 mph 29 27 29 30 31 30 31 31 30 30 29 30 ​ 356  98%
Please send any comments, questions, or corrections to me, Mike Cowlishaw, at mfc@speleotrove.com.

All text Copyright © Mike Cowlishaw 2008, 2021. All rights reserved. The pages and data here are for non-commercial use only.
This page was last edited on 2021-05-09.