Brize Norton, sunrise to sunset, 1997–2017
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Met Office station 605: Brize Norton, Oxfordshire  (OX18 3); OS grid reference: SP 292067.
Coordinates:  N51°45'29" W1°34'34"  (51.758 -1.576), elevation 81 m.
Note: gusts not recorded in 4 out of the 21 years.

This is the analysis for the average of 21 years  (1997–2017).
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 1 1 1  4  1%
≤ 10 mph 3 2 3 3 2 4 4 4 4 3 3 4  39  11%
≤ 15 mph 6 5 6 8 6 9 10 8 8 7 7 8  89  24%
≤ 20 mph 7 7 8 9 8 10 10 9 9 8 8 9  101  28%
≤ 30 mph 8 7 9 10 9 11 11 9 10 9 8 10  111  30%
≤ 40 mph 8 8 9 10 9 11 11 10 10 9 8 10  113  31%
any wind 8 8 9 10 9 11 11 10 10 9 8 10  113  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 21 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                         −0.2
≤ 10 mph +0.1               −0.1     +0.1  
≤ 15 mph −0.1 −0.2   +0.2 +0.1   −0.1 −0.1 −0.1       −0.2
≤ 20 mph −0.2 −0.2   +0.2 +0.1 +0.1   −0.1 −0.2 −0.1   −0.1 −0.3
≤ 30 mph −0.2 −0.1 +0.1 +0.3 +0.2 +0.1     −0.1     −0.1 +0.3
≤ 40 mph −0.1   +0.1 +0.3 +0.3 +0.2 +0.1   −0.1       +0.5
any wind −0.1   +0.1 +0.3 +0.3 +0.2 +0.1   −0.1       +0.5
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 17 15 16 18 17 18 18 17 16 17 16 17  200  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 11 15 15 14 14 15 14 16 14 12 14  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 3 1 1 0 0 0 0 1 1 1 3 3  15  4%
≤ 10 mph 10 7 8 7 6 9 8 10 10 9 11 12  109  30%
≤ 15 mph 21 18 20 20 21 22 23 24 23 21 22 22  257  70%
≤ 20 mph 24 22 24 24 25 25 26 26 25 25 25 25  296  81%
≤ 30 mph 28 26 28 29 29 29 30 31 29 30 28 29  346  95%
≤ 40 mph 30 28 30 30 31 30 31 31 30 31 30 31  362  99%

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.