Kirkwall, any hour sunrise to sunset, 1997–2017
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Met Office station 23: Kirkwall, Orkney  (KW17 2); OS grid reference: SY 482077.
Coordinates:  N58°57'14" W2°54'00"  (58.954 -2.900), elevation 26 m.
Note: gusts not recorded in 6 out of the 21 years, 2.2% of daylight visibility records missing, 15.1% of daylight precipitation records missing, 1.7% 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 4 3 5 6 8 9 10 10 6 5 4 4  73  20%  215  4%
≤ 10 mph 9 8 12 13 18 19 20 20 14 11 9 9  160  44%  771  16%
≤ 15 mph 16 15 21 21 26 26 27 27 22 19 16 15  249  68%  1673  34%
≤ 20 mph 20 19 24 25 29 28 29 29 25 23 21 19  290  80%  2207  45%
≤ 30 mph 25 24 28 28 30 29 29 30 27 27 25 23  325  89%  2619  53%
≤ 40 mph 26 25 29 28 30 29 29 30 27 27 25 24  329  90%  2664  54%
any wind 26 25 29 28 30 29 29 30 27 27 25 25  331  91%  2684  55%
‘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 −0.2 +0.1 +0.2 +0.1 +0.1 +0.1 +0.2 +0.1   +0.1   +0.1 +0.9
≤ 10 mph −0.3 +0.2 +0.1 +0.2 +0.2 +0.4 +0.4 +0.1 +0.3 +0.4 +0.1 +0.2 +2.3
≤ 15 mph −0.3 +0.3 +0.3 +0.2 +0.1 +0.4 +0.4 +0.2 +0.3 +0.4 +0.2 +0.2 +2.8
≤ 20 mph −0.1 +0.5 +0.3 +0.3 +0.1 +0.2 +0.3 +0.2 +0.3 +0.4   +0.2 +2.7
≤ 30 mph −0.2 +0.2 +0.2 +0.2 +0.1 +0.2 +0.3 +0.1 +0.3 +0.3 +0.1 +0.1 +1.8
≤ 40 mph −0.2 +0.1 +0.2 +0.2   +0.2 +0.3 +0.1 +0.3 +0.3 +0.1 +0.1 +1.6
any wind −0.2 +0.1 +0.2 +0.2   +0.2 +0.3 +0.1 +0.3 +0.3 +0.1 +0.2 +1.7
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 30 28 30 29 30 29 30 31 29 29 29 29  353  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 27 26 29 29 31 30 30 31 29 29 26 26  343  94%

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 4 3 5 6 8 9 10 10 6 5 4 4  73  20%
≤ 10 mph 9 8 12 13 18 19 20 20 14 11 9 9  160  44%
≤ 15 mph 16 15 21 21 26 26 27 27 22 19 16 15  249  68%
≤ 20 mph 20 19 24 25 29 28 29 29 25 23 21 19  290  80%
≤ 30 mph 25 24 28 28 30 29 29 30 27 27 25 23  325  89%
≤ 40 mph 26 25 29 28 30 29 29 30 27 27 25 24  329  90%

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.