Aldergrove, 16:00 to 18:00, 1997–2020
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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 4 out of the 24 years, 0.9% of daylight visibility records missing, 0.4% of daylight wind records missing.

This is the analysis for the average of 24 years  (1997–2020).
Time slot: 16:00 to 18:00  (two hours); click below for any-hour analysis, or a different start time, or 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 this timeslot) 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 1 2 2 1 2 2 2 3 1 0 0 ​ 15  4%
≤ 10 mph 0 3 7 6 7 9 10 9 10 5 0 0 ​ 67  18%
≤ 15 mph 0 6 14 14 16 16 17 17 17 8 0 0 ​ 126  34%
≤ 20 mph 0 7 16 17 19 18 19 18 18 9 0 0 ​ 141  39%
≤ 30 mph 0 8 17 18 20 19 19 18 19 9 0 0 ​ 147  40%
≤ 40 mph 0 8 17 18 20 19 19 19 19 9 0 0 ​ 149  41%
any wind 0 8 17 18 20 19 19 19 19 9 0 0 ​ 149  41%
‘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 this timeslot) 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         ​−0.2
≤ 10 mph     +0.1 +0.1 +0.1 +0.3 +0.2     +0.1     ​+0.8
≤ 15 mph   +0.1 +0.2 +0.2 +0.2 +0.2 +0.3 −0.2 +0.1       ​+1.2
≤ 20 mph   +0.1 +0.2 +0.3 +0.3 +0.1 +0.2 −0.2         ​+1.0
≤ 30 mph   +0.1 +0.2 +0.3 +0.2 +0.1 +0.2 −0.2         ​+0.8
≤ 40 mph   +0.1 +0.2 +0.3 +0.2 +0.1 +0.2 −0.2         ​+0.9
any wind   +0.1 +0.2 +0.3 +0.2 +0.1 +0.2 −0.2         ​+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 this timeslot) the visibility was adequate. That is, for the entire timeslot:
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
Good days 0 14 28 28 30 29 29 29 28 14 0 0 ​ 228  63%

Bad weather analysis

This is the number of days in each month, on average, for which (in this timeslot) no bad weather occurred. That is, for the entire timeslot, 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 17 15 18 19 21 19 20 19 19 19 16 17 ​ 219  60%

Wind speed analysis

This is the number of days in each month, on average, for which (in this timeslot) 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 5 3 2 2 2 2 3 3 4 4 5 6 ​ 40  11%
≤ 10 mph 13 10 10 9 11 13 16 15 14 14 14 14 ​ 151  41%
≤ 15 mph 23 20 22 21 24 25 27 27 25 25 23 24 ​ 287  79%
≤ 20 mph 27 24 27 27 29 28 30 30 28 28 27 28 ​ 333  91%
≤ 30 mph 30 26 29 29 30 29 31 31 29 30 29 30 ​ 353  97%
≤ 40 mph 31 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, 2021. All rights reserved. The pages and data here are for non-commercial use only.
This page was last edited on 2021-05-09.