Aldergrove, 12:00 to 14:00, 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 4 out of the 21 years, 1.1% of daylight visibility records missing, 0.6% of daylight wind records missing.

This is the analysis for the average of 21 years  (1997–2017).
Time slot: 12:00 to 14:00  (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 2 1 2 2 1 2 2 3 2 2 2 3  24  6%
≤ 10 mph 7 4 6 7 8 9 10 9 9 7 7 7  89  24%
≤ 15 mph 12 10 13 13 15 16 18 16 16 14 13 13  169  46%
≤ 20 mph 14 12 16 16 18 18 19 18 18 17 15 15  195  53%
≤ 30 mph 15 13 17 18 18 19 19 18 19 18 16 16  204  56%
≤ 40 mph 15 13 17 18 18 19 19 18 19 18 17 16  207  57%
any wind 15 13 17 18 18 19 19 18 19 18 17 16  208  57%
‘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 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 −0.1     −0.1 −0.5
≤ 10 mph −0.1 +0.2 +0.2 +0.2 −0.1 +0.1     +0.1 +0.2 +0.2 −0.1 +0.8
≤ 15 mph   +0.2 +0.2 +0.3 +0.1 +0.3 +0.1 −0.1 +0.1 +0.1 +0.4 −0.1 +1.8
≤ 20 mph   +0.2 +0.2 +0.2 +0.2 +0.2   −0.1 +0.1 +0.1 +0.2   +1.4
≤ 30 mph −0.1 +0.2 +0.2 +0.3 +0.2 +0.1 +0.1 −0.1 +0.1   +0.2   +1.2
≤ 40 mph −0.1 +0.2 +0.2 +0.3 +0.2 +0.2 +0.1 −0.1 +0.1 +0.1 +0.2   +1.4
any wind −0.1 +0.2 +0.2 +0.3 +0.2 +0.2 +0.1 −0.1 +0.1 +0.1 +0.2   +1.4
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 26 23 27 28 29 28 29 28 27 27 26 26  324  89%

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 19 19 19 19 20 19 20 19 18 18  221  61%

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 4 3 3 3 2 3 3 3 3 2 3 5  37  10%
≤ 10 mph 11 8 8 10 11 13 14 13 12 10 11 13  134  37%
≤ 15 mph 21 18 20 21 23 25 27 27 23 22 22 22  272  75%
≤ 20 mph 26 23 27 26 28 28 30 30 27 28 26 27  326  89%
≤ 30 mph 29 27 29 29 30 30 31 31 29 30 29 29  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, 2018. All rights reserved. The pages and data here are for non-commercial use only.
This page was last edited on 2018-02-09.