Aldergrove, any hour sunrise to sunset, 1997–2017
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Met Office station 1450: Aldergrove, County Antrim  (BT29 4); IRL grid reference: 314562E 380950N.
Coordinates:  N54°39'50" W6°13'26"  (54.664 -6.224), elevation 63 m.
Note: gusts not recorded in 3 out of the 21 years, 0.8% of daylight visibility records missing, 0.5% 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 9 8 11 13 14 17 18 16 13 10 9 8  146  40%  598  12%
≤ 10 mph 17 16 20 22 25 26 28 26 24 21 19 17  261  71%  1659  34%
≤ 15 mph 23 22 27 28 30 29 30 30 28 27 25 24  323  89%  2625  54%
≤ 20 mph 26 24 29 29 30 29 31 30 29 29 26 26  338  93%  2866  59%
≤ 30 mph 27 25 29 29 30 29 31 30 29 29 27 26  343  94%  2948  60%
≤ 40 mph 27 25 29 29 30 29 31 30 29 30 27 27  344  94%  2968  61%
any wind 27 25 29 29 30 29 31 30 29 30 27 27  344  94%  2971  61%
‘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 +0.3 +0.1 +0.2 −0.2 +0.3 +0.2 −0.1   +0.2 +0.1 −0.2 +0.8
≤ 10 mph +0.1 +0.4 +0.1 +0.1 +0.1 +0.2 +0.2 +0.1 +0.1 +0.3 +0.3 −0.1 +1.9
≤ 15 mph +0.1 +0.3 +0.1 +0.1 +0.1 +0.1 +0.1 +0.1   +0.2 +0.2 −0.1 +1.6
≤ 20 mph +0.1 +0.2 +0.1 +0.1 +0.1 +0.1 +0.1 +0.1   +0.1 +0.2   +1.1
≤ 30 mph +0.1 +0.2 +0.1   +0.1     +0.1   +0.1 +0.1   +0.8
≤ 40 mph +0.1 +0.2 +0.1   +0.1     +0.1   +0.1 +0.1   +0.9
any wind +0.1 +0.2 +0.1   +0.1     +0.1   +0.1 +0.1   +0.9
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 27 30 30 31 30 31 31 30 31 29 30  358  98%

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 30 30 31 30 31 31 30 30 28 28  352  97%

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 9 8 11 13 14 17 18 16 13 10 9 8  146  40%
≤ 10 mph 17 16 20 22 25 26 28 26 24 21 19 17  261  71%
≤ 15 mph 23 22 27 28 30 29 30 30 28 27 25 24  323  89%
≤ 20 mph 26 24 29 29 30 29 31 30 29 29 26 26  338  93%
≤ 30 mph 27 25 29 29 30 29 31 30 29 29 27 26  343  94%
≤ 40 mph 27 25 29 29 30 29 31 30 29 30 27 27  344  94%

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.