Speleotrove weather analyses

Odiham, 18:00 to 20:00, 1997–2020

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Met Office station 862: Odiham, Hampshire (RG25 1); OS grid reference: SU 737494.
Coordinates: N51°14'17" W0°56'38" (51.238 -0.944), elevation 118 m.
Note: gusts not recorded in 6 out of the 24 years.

This is the analysis for the average of 24 years (1997–2020).
Time slot: 18:00 to 20:00 (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.

	May	Jun	Jul	Aug	Total
≤ 5 mph	2	1	1	1	4	1%
≤ 10 mph	9	8	9	4	30	8%
≤ 15 mph	19	19	20	9	67	18%
≤ 20 mph	21	21	24	10	77	21%
≤ 30 mph	22	22	24	11	79	22%
≤ 40 mph	22	22	24	11	79	22%
any wind	22	22	24	11	79	22%

‘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 −0.1
≤ 10 mph +0.1 −0.1 −0.1 −0.2
≤ 15 mph +0.2 +0.2 +0.2 −0.1 +0.4
≤ 20 mph +0.1 +0.2 +0.1 +0.4
≤ 30 mph +0.1 +0.2 +0.1 +0.4
≤ 40 mph +0.1 +0.2 +0.1 +0.4
any wind +0.1 +0.2 +0.1 +0.4
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:

both hours were daylight (no more than 30 minutes before sunrise or after sunset)
horizontal visibility was at least 5000m (UK VFR rules » for class F or G »)
cloudbase was above 1000′ or less than 6/8 coverage.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Total
Good days	0	0	0	0	27	27	29	13	0	0	0	0	96	26%

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	21	20	22	23	23	23	24	24	24	22	21	21	267	73%

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	3	3	3	2	2	2	1	2	3	4	4	3	32	9%
≤ 10 mph	12	11	13	12	12	11	11	12	16	16	14	12	151	41%
≤ 15 mph	20	20	23	24	25	25	25	27	26	26	23	22	287	79%
≤ 20 mph	26	24	28	28	29	29	30	30	29	29	27	26	335	92%
≤ 30 mph	29	27	30	30	30	30	31	31	30	31	29	29	356	97%
≤ 40 mph	30	28	31	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.

	May	Jun	Jul	Aug	Total
≤ 5 mph			−0.1		−0.1
≤ 10 mph	+0.1		−0.1	−0.1	−0.2
≤ 15 mph	+0.2	+0.2	+0.2	−0.1	+0.4
≤ 20 mph	+0.1	+0.2	+0.1		+0.4
≤ 30 mph	+0.1	+0.2	+0.1		+0.4
≤ 40 mph	+0.1	+0.2	+0.1		+0.4
any wind	+0.1	+0.2	+0.1		+0.4