Buck Hall Recreation Centre
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Buck Hall Recreation Centre clear sky chart from 2005-11-06 to 2026-07-16.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	11% 6% 2 6% 4 4 5% 4 6% 9% 42%	137874
	Night	11% 6% 2 6% 4 4 4 4 6% 8% 44%	134845
Transparency	Day	25% 37% 11% 13% 11% 3	141477
	Night	25% 36% 9% 13% 12% 5%	139314
Seeing	Day	13% 10% 27% 27% 17% 6%	17915
	Night	13% 9% 24% 31% 20% 4	28000

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	11% 5% 2 4 4 3 4 3 5% 7% 51%	5258
	11th to 20th	Day	13% 5% 2 5% 4 3 3 3 4 7% 51%	5280
	21st to end	Day	16% 8% 2 6% 4 3 3 3 5% 7% 41%	5780
February	1st to 10th	Day	14% 6% 2 6% 5% 5% 5% 4 6% 6% 42%	1890
	11th to 20th	Day	19% 7% 2 5% 3 3 4 3 4 4 45%	1983
	21st to end	Day	14% 7% 2 7% 3 4 3 3 5% 6% 45%	1903
March	1st to 10th	Day	21% 8% 3 7% 4 3 4 3 4 6% 37%	5045
	11th to 20th	Day	9% 4 2 4 4 4 4 4 5% 8% 54%	5090
	21st to end	Day	14% 4 2 5% 4 4 4 3 5% 5% 49%	5586
April	1st to 10th	Day	8% 5% 1 4 4 4 5% 4 6% 7% 52%	2367
	11th to 20th	Day	9% 3 1 5% 4 3 4 4 5% 7% 54%	2494
	21st to end	Day	6% 3 1 5% 4 3 4 4 6% 9% 54%	2520
May	1st to 10th	Day	12% 6% 3 6% 4 4 5% 4 7% 9% 40%	7379
	11th to 20th	Day	12% 5% 2 6% 4 5% 5% 4 7% 8% 42%	7626
	21st to end	Day	8% 5% 3 7% 5% 5% 6% 5% 8% 10% 39%	8391
June	1st to 10th	Day	10% 6% 2 7% 5% 5% 6% 6% 8% 11% 33%	2730
	11th to 20th	Day	8% 4 2 5% 5% 5% 6% 6% 10% 12% 38%	2730
	21st to end	Day	6% 4 2 6% 6% 6% 7% 6% 10% 12% 35%	2730
July	1st to 10th	Day	11% 6% 3 8% 6% 6% 7% 6% 9% 11% 27%	6030
	11th to 20th	Day	5% 4 2 7% 6% 6% 8% 7% 10% 15% 32%	5965
	21st to end	Day	5% 5% 2 7% 6% 6% 7% 6% 9% 14% 32%	6424
August	1st to 10th	Day	18% 8% 3 8% 6% 6% 5% 5% 8% 10% 23%	4234
	11th to 20th	Day	6% 5% 2 7% 5% 6% 7% 7% 9% 13% 34%	4010
	21st to end	Day	11% 6% 2 7% 5% 4 5% 5% 8% 9% 39%	4312
September	1st to 10th	Day	11% 6% 2 6% 5% 4 6% 5% 8% 10% 38%	2347
	11th to 20th	Day	13% 7% 3 7% 5% 5% 5% 4 6% 9% 36%	2200
	21st to end	Day	14% 8% 3 6% 4 4 4 3 6% 8% 40%	2200
October	1st to 10th	Day	14% 5% 2 6% 4 4 4 2 5% 6% 47%	2007
	11th to 20th	Day	9% 3 2 4 4 3 3 2 4 7% 59%	2000
	21st to end	Day	10% 4 2 4 3 3 4 2 4 7% 57%	2200
November	1st to 10th	Day	11% 4 2 4 4 4 3 3 5% 6% 56%	2057
	11th to 20th	Day	12% 6% 2 5% 5% 4 3 3 5% 6% 50%	2100
	21st to end	Day	12% 5% 2 5% 3 3 5% 3 4 7% 52%	1958
December	1st to 10th	Day	9% 4 2 5% 4 4 5% 4 5% 6% 52%	3020
	11th to 20th	Day	13% 6% 2 6% 4 4 4 4 4 5% 47%	3463
	21st to end	Day	17% 8% 2 6% 4 3 4 3 5% 6% 43%	4565
January	1st to 10th	Night	9% 5% 2 6% 4 4 4 3 5% 5% 53%	7635
	11th to 20th	Night	11% 6% 2 6% 4 4 4 3 5% 7% 47%	7680
	21st to end	Night	15% 8% 3 7% 4 4 4 3 4 5% 43%	8401
February	1st to 10th	Night	15% 6% 2 6% 4 3 4 3 5% 6% 44%	2730
	11th to 20th	Night	17% 7% 2 7% 4 4 3 3 5% 5% 42%	2517
	21st to end	Night	13% 9% 3 6% 3 5% 5% 3 5% 6% 42%	1903
March	1st to 10th	Night	17% 10% 3 7% 4 4 3 3 4 5% 40%	5028
	11th to 20th	Night	10% 4 2 5% 3 3 3 3 6% 9% 52%	5090
	21st to end	Night	13% 5% 2 5% 3 4 3 3 5% 7% 51%	5588
April	1st to 10th	Night	10% 6% 2 4 4 5% 4 4 5% 8% 49%	2252
	11th to 20th	Night	10% 4 1 5% 3 4 4 4 6% 7% 52%	2075
	21st to end	Night	6% 5% 2 5% 4 4 4 4 5% 8% 53%	2100
May	1st to 10th	Night	10% 7% 2 6% 4 5% 4 4 6% 9% 42%	5516
	11th to 20th	Night	12% 6% 2 5% 3 4 4 4 7% 10% 43%	5234
	21st to end	Night	9% 5% 3 7% 5% 5% 6% 5% 8% 9% 38%	5761
June	1st to 10th	Night	9% 7% 3 6% 5% 4 5% 5% 9% 12% 36%	1890
	11th to 20th	Night	7% 5% 2 5% 5% 4 6% 5% 9% 13% 39%	1890
	21st to end	Night	5% 5% 2 5% 6% 5% 6% 7% 10% 14% 37%	1890
July	1st to 10th	Night	10% 6% 3 7% 6% 7% 7% 6% 9% 11% 30%	4148
	11th to 20th	Night	6% 4 2 8% 6% 6% 6% 6% 9% 15% 34%	4102
	21st to end	Night	6% 5% 2 6% 5% 6% 7% 5% 9% 14% 34%	4427
August	1st to 10th	Night	16% 9% 4 7% 5% 5% 5% 5% 8% 13% 24%	2915
	11th to 20th	Night	7% 5% 2 6% 5% 6% 6% 5% 8% 13% 36%	3005
	21st to end	Night	8% 5% 2 7% 5% 5% 5% 4 6% 9% 44%	3586
September	1st to 10th	Night	10% 5% 2 7% 6% 6% 5% 5% 7% 10% 36%	2048
	11th to 20th	Night	11% 6% 3 7% 6% 4 5% 4 7% 11% 37%	2200
	21st to end	Night	15% 6% 2 7% 5% 4 4 4 5% 9% 40%	2200
October	1st to 10th	Night	12% 5% 2 6% 4 4 4 4 5% 7% 46%	2391
	11th to 20th	Night	9% 4 1 4 3 4 3 3 4 7% 58%	2400
	21st to end	Night	10% 5% 2 4 3 3 3 3 5% 6% 56%	2640
November	1st to 10th	Night	10% 5% 2 5% 4 3 3 3 5% 6% 55%	2461
	11th to 20th	Night	12% 7% 2 5% 4 4 3 3 5% 6% 51%	2520
	21st to end	Night	10% 5% 2 6% 4 4 4 4 6% 8% 47%	2657
December	1st to 10th	Night	11% 6% 2 5% 3 3 3 3 4 6% 55%	4380
	11th to 20th	Night	15% 7% 3 8% 6% 4 3 3 4 5% 43%	4952
	21st to end	Night	15% 6% 2 6% 4 4 4 4 5% 6% 44%	6633

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	27% 22% 8% 17% 23% 5%	5259
	11th to 20th	Day	28% 21% 4 12% 24% 11%	5280
	21st to end	Day	33% 24% 8% 14% 14% 7%	5780
February	1st to 10th	Day	17% 60% 3 10% 8% 1	1890
	11th to 20th	Day	18% 58% 4 9% 8% 2	1992
	21st to end	Day	19% 59% 3 5% 9% 5%	1903
March	1st to 10th	Day	38% 30% 6% 8% 12% 5%	5045
	11th to 20th	Day	17% 31% 6% 10% 22% 15%	5090
	21st to end	Day	27% 29% 7% 15% 14% 8%	5586
April	1st to 10th	Day	14% 60% 6% 10% 7% 4	2367
	11th to 20th	Day	13% 60% 4 12% 7% 4	2494
	21st to end	Day	10% 60% 7% 14% 8% 1	2520
May	1st to 10th	Day	33% 27% 15% 18% 6% 1	7411
	11th to 20th	Day	31% 24% 16% 20% 9% 1	7630
	21st to end	Day	30% 28% 16% 14% 12%	8405
June	1st to 10th	Day	15% 62% 8% 9% 5% 1	2730
	11th to 20th	Day	11% 62% 12% 11% 4	2730
	21st to end	Day	13% 62% 13% 11% 1	2730
July	1st to 10th	Day	37% 30% 23% 10% 1	5965
	11th to 20th	Day	27% 34% 33% 6% 1	5896
	21st to end	Day	29% 31% 20% 18% 2	6240
August	1st to 10th	Day	41% 39% 16% 4	4221
	11th to 20th	Day	21% 41% 16% 15% 8%	4049
	21st to end	Day	21% 37% 12% 27% 3	4312
September	1st to 10th	Day	15% 61% 9% 8% 7% 1	2347
	11th to 20th	Day	20% 59% 5% 10% 5% 1	2200
	21st to end	Day	20% 59% 9% 8% 4	2200
October	1st to 10th	Day	29% 36% 5% 10% 18% 3	3267
	11th to 20th	Day	8% 36% 3 9% 23% 21%	3240
	21st to end	Day	15% 36% 5% 13% 28% 4	3538
November	1st to 10th	Day	18% 54% 6% 8% 12% 3	2057
	11th to 20th	Day	17% 55% 4 9% 11% 5%	2100
	21st to end	Day	15% 54% 5% 10% 12% 3	1958
December	1st to 10th	Day	21% 35% 5% 10% 16% 13%	3020
	11th to 20th	Day	29% 30% 6% 14% 17% 4	3460
	21st to end	Day	32% 27% 8% 19% 13% 1	4565
January	1st to 10th	Night	25% 23% 7% 15% 24% 5%	7636
	11th to 20th	Night	29% 22% 4 12% 25% 8%	7680
	21st to end	Night	34% 23% 5% 11% 19% 8%	8401
February	1st to 10th	Night	16% 59% 4 11% 8% 3	2730
	11th to 20th	Night	19% 58% 4 8% 8% 2	2519
	21st to end	Night	20% 59% 3 4 8% 5%	1903
March	1st to 10th	Night	37% 30% 6% 9% 14% 5%	5028
	11th to 20th	Night	20% 29% 6% 9% 22% 14%	5090
	21st to end	Night	24% 29% 8% 15% 15% 8%	5588
April	1st to 10th	Night	15% 60% 6% 9% 6% 3	2252
	11th to 20th	Night	13% 60% 3 12% 8% 4	2075
	21st to end	Night	12% 60% 5% 13% 8% 1	2100
May	1st to 10th	Night	31% 26% 16% 20% 6% 1	5546
	11th to 20th	Night	28% 25% 17% 18% 9% 2	5235
	21st to end	Night	33% 27% 15% 15% 10%	5771
June	1st to 10th	Night	15% 62% 9% 8% 5% 1	1890
	11th to 20th	Night	12% 63% 11% 9% 4	1890
	21st to end	Night	13% 62% 12% 10% 2	1890
July	1st to 10th	Night	35% 29% 23% 13% 1	4105
	11th to 20th	Night	29% 32% 32% 6% 1	4051
	21st to end	Night	29% 31% 20% 18% 2	4297
August	1st to 10th	Night	38% 40% 17% 4	2904
	11th to 20th	Night	20% 40% 18% 17% 5%	3032
	21st to end	Night	19% 38% 11% 30% 2	3586
September	1st to 10th	Night	17% 60% 8% 9% 5% 1	2048
	11th to 20th	Night	20% 59% 6% 10% 5% 1	2200
	21st to end	Night	19% 59% 8% 10% 4	2200
October	1st to 10th	Night	26% 36% 6% 12% 17% 4	3911
	11th to 20th	Night	7% 36% 2 8% 19% 27%	3899
	21st to end	Night	15% 36% 3 15% 22% 9%	4252
November	1st to 10th	Night	18% 53% 6% 8% 11% 4	2461
	11th to 20th	Night	16% 54% 5% 8% 11% 5%	2520
	21st to end	Night	15% 55% 5% 9% 12% 4	2657
December	1st to 10th	Night	20% 35% 4 10% 21% 11%	4380
	11th to 20th	Night	32% 31% 7% 10% 14% 6%	4954
	21st to end	Night	30% 28% 8% 19% 13% 1	6633

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	16% 18% 44% 20% 2	330
	11th to 20th	Day	12% 22% 40% 20% 6%	330
	21st to end	Day	21% 24% 43% 10% 1 1	363
February	1st to 10th	Day	15% 20% 44% 19% 3	330
	11th to 20th	Day	25% 19% 41% 13% 2	351
	21st to end	Day	18% 18% 41% 18% 4 1	446
March	1st to 10th	Day	15% 19% 32% 25% 8%	540
	11th to 20th	Day	14% 19% 40% 20% 7% 1	540
	21st to end	Day	14% 18% 40% 19% 9% 2	594
April	1st to 10th	Day	14% 18% 36% 21% 9% 2	540
	11th to 20th	Day	8% 15% 34% 24% 14% 5%	532
	21st to end	Day	8% 11% 29% 32% 13% 7%	540
May	1st to 10th	Day	6% 14% 38% 25% 12% 4	543
	11th to 20th	Day	11% 6% 29% 31% 18% 5%	567
	21st to end	Day	11% 6% 23% 32% 19% 9%	617
June	1st to 10th	Day	10% 5% 21% 33% 23% 8%	570
	11th to 20th	Day	8% 4 23% 32% 23% 11%	570
	21st to end	Day	8% 3 15% 36% 27% 11%	570
July	1st to 10th	Day	8% 1 9% 36% 34% 12%	565
	11th to 20th	Day	8% 2 6% 33% 36% 14%	544
	21st to end	Day	6% 1 11% 39% 32% 10%	576
August	1st to 10th	Day	15% 3 12% 29% 29% 12%	526
	11th to 20th	Day	10% 2 10% 28% 34% 17%	519
	21st to end	Day	15% 3 12% 28% 29% 12%	583
September	1st to 10th	Day	11% 2 16% 33% 28% 11%	530
	11th to 20th	Day	14% 4 18% 33% 23% 6%	530
	21st to end	Day	18% 1 19% 29% 24% 9%	530
October	1st to 10th	Day	17% 6% 26% 31% 13% 7%	530
	11th to 20th	Day	10% 8% 24% 34% 19% 6%	530
	21st to end	Day	11% 7% 27% 34% 17% 4	583
November	1st to 10th	Day	15% 8% 31% 25% 17% 3	535
	11th to 20th	Day	16% 11% 39% 24% 9% 1	540
	21st to end	Day	14% 15% 34% 27% 10% 1	398
December	1st to 10th	Day	20% 8% 42% 24% 5% 1	330
	11th to 20th	Day	16% 20% 35% 22% 7% 1	330
	21st to end	Day	20% 15% 36% 20% 8% 1	363
January	1st to 10th	Night	13% 18% 34% 29% 6%	840
	11th to 20th	Night	13% 18% 31% 28% 10%	840
	21st to end	Night	19% 17% 36% 24% 3	924
February	1st to 10th	Night	17% 12% 36% 28% 7%	840
	11th to 20th	Night	21% 15% 33% 28% 4	823
	21st to end	Night	18% 14% 34% 27% 7% 1	692
March	1st to 10th	Night	12% 14% 34% 30% 9%	840
	11th to 20th	Night	14% 13% 35% 30% 8% 1	840
	21st to end	Night	14% 12% 35% 27% 12%	924
April	1st to 10th	Night	12% 12% 33% 31% 11% 1	840
	11th to 20th	Night	12% 10% 28% 31% 16% 2	831
	21st to end	Night	7% 9% 29% 37% 17% 1	840
May	1st to 10th	Night	9% 8% 29% 33% 18% 2	730
	11th to 20th	Night	10% 5% 25% 33% 23% 4	621
	21st to end	Night	11% 2 15% 32% 31% 9%	683
June	1st to 10th	Night	11% 3 13% 39% 29% 5%	630
	11th to 20th	Night	8% 3 13% 34% 33% 10%	630
	21st to end	Night	6% 2 12% 39% 35% 7%	630
July	1st to 10th	Night	9% 2 8% 33% 43% 6%	615
	11th to 20th	Night	9% 2 5% 31% 41% 13%	597
	21st to end	Night	6% 1 6% 38% 41% 8%	657
August	1st to 10th	Night	13% 2 4 32% 40% 10%	597
	11th to 20th	Night	10% 2 8% 31% 39% 11%	672
	21st to end	Night	13% 2 9% 27% 37% 11%	880
September	1st to 10th	Night	11% 2 14% 26% 40% 7%	800
	11th to 20th	Night	14% 2 12% 33% 32% 7%	800
	21st to end	Night	18% 2 14% 28% 31% 7%	800
October	1st to 10th	Night	15% 5% 21% 30% 23% 6%	800
	11th to 20th	Night	11% 7% 23% 32% 23% 5%	800
	21st to end	Night	13% 7% 21% 33% 21% 4	880
November	1st to 10th	Night	11% 7% 27% 34% 17% 3	820
	11th to 20th	Night	17% 11% 27% 31% 13% 2	840
	21st to end	Night	12% 12% 30% 28% 17% 2	840
December	1st to 10th	Night	17% 13% 29% 29% 11% 1	840
	11th to 20th	Night	19% 13% 27% 27% 13% 1	840
	21st to end	Night	19% 13% 29% 29% 9% 1	924

Page generated at 2026-07-13 03:14:54. Version ac07

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