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 2025-03-12.

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	12% 6% 2 6% 4 4 5% 4 6% 8% 42%	109306
	Night	11% 6% 2 6% 4 4 4 4 6% 8% 44%	109713
Transparency	Day	21% 45% 8% 11% 10% 3	112953
	Night	22% 44% 7% 11% 12% 4	114205
Seeing	Day	13% 10% 26% 27% 18% 6%	16039
	Night	13% 8% 23% 30% 21% 4	26213

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	12% 5% 1 4 3 3 4 3 5% 7% 53%	4056
	11th to 20th	Day	13% 5% 2 5% 4 3 3 3 4 7% 51%	4060
	21st to end	Day	15% 8% 2 6% 4 3 3 3 4 7% 44%	4466
February	1st to 10th	Day	14% 6% 2 6% 5% 5% 5% 4 6% 6% 41%	1800
	11th to 20th	Day	20% 7% 2 5% 3 3 3 3 4 4 45%	1886
	21st to end	Day	13% 6% 2 7% 3 4 4 3 5% 6% 46%	1815
March	1st to 10th	Day	22% 10% 3 7% 4 3 3 3 4 6% 35%	3545
	11th to 20th	Day	9% 4 2 5% 4 4 4 4 5% 8% 52%	3491
	21st to end	Day	19% 5% 2 5% 4 3 3 4 5% 5% 45%	3815
April	1st to 10th	Day	9% 5% 1 4 4 4 4 4 6% 7% 53%	2141
	11th to 20th	Day	10% 3 1 5% 4 3 5% 4 5% 7% 52%	2254
	21st to end	Day	6% 3 1 4 3 3 4 4 6% 9% 56%	2280
May	1st to 10th	Day	7% 5% 2 5% 5% 5% 5% 5% 7% 10% 45%	3957
	11th to 20th	Day	13% 6% 2 7% 5% 5% 4 4 6% 7% 40%	4081
	21st to end	Day	6% 4 2 4 3 4 5% 5% 8% 11% 49%	4476
June	1st to 10th	Day	10% 6% 3 7% 6% 5% 6% 6% 8% 11% 32%	2470
	11th to 20th	Day	9% 4 2 4 5% 5% 6% 5% 9% 12% 39%	2470
	21st to end	Day	6% 5% 2 6% 6% 6% 7% 7% 10% 12% 34%	2470
July	1st to 10th	Day	13% 6% 3 7% 6% 6% 7% 6% 8% 11% 28%	4120
	11th to 20th	Day	6% 4 3 8% 6% 6% 8% 7% 10% 13% 30%	4120
	21st to end	Day	6% 6% 2 8% 7% 7% 7% 7% 10% 14% 27%	4466
August	1st to 10th	Day	18% 7% 3 8% 6% 6% 6% 5% 8% 10% 23%	4104
	11th to 20th	Day	6% 5% 2 7% 5% 6% 7% 7% 9% 12% 34%	3885
	21st to end	Day	10% 6% 2 6% 5% 4 5% 5% 8% 9% 39%	4180
September	1st to 10th	Day	11% 6% 2 5% 5% 4 6% 5% 8% 10% 38%	2230
	11th to 20th	Day	13% 7% 3 8% 5% 5% 5% 4 6% 9% 35%	2090
	21st to end	Day	13% 7% 3 6% 4 4 4 4 6% 8% 41%	2090
October	1st to 10th	Day	13% 5% 2 6% 4 4 4 2 5% 6% 48%	1907
	11th to 20th	Day	9% 3 2 4 4 3 3 2 4 7% 59%	1900
	21st to end	Day	10% 4 2 4 3 3 4 2 4 7% 56%	2090
November	1st to 10th	Day	12% 4 2 4 4 4 3 3 5% 6% 55%	1957
	11th to 20th	Day	12% 7% 2 6% 5% 4 4 3 5% 6% 48%	2000
	21st to end	Day	12% 5% 2 5% 3 3 5% 3 4 7% 52%	1865
December	1st to 10th	Day	8% 4 2 5% 4 4 5% 4 5% 6% 53%	2930
	11th to 20th	Day	14% 6% 2 6% 4 4 4 4 4 5% 46%	3373
	21st to end	Day	17% 8% 3 6% 4 3 3 3 5% 6% 42%	4466
January	1st to 10th	Night	10% 5% 1 4 3 3 3 3 4 5% 56%	5889
	11th to 20th	Night	13% 7% 2 6% 4 5% 4 4 6% 8% 42%	5900
	21st to end	Night	13% 7% 2 6% 4 4 4 4 5% 6% 45%	6490
February	1st to 10th	Night	15% 6% 3 7% 4 3 4 3 6% 7% 44%	2600
	11th to 20th	Night	18% 7% 2 6% 4 4 3 3 5% 5% 43%	2394
	21st to end	Night	13% 8% 3 6% 3 5% 5% 4 5% 6% 43%	1815
March	1st to 10th	Night	20% 12% 3 7% 4 4 3 3 4 5% 34%	3528
	11th to 20th	Night	11% 4 2 6% 4 3 3 4 6% 7% 50%	3498
	21st to end	Night	16% 5% 2 5% 3 4 4 3 5% 8% 45%	3817
April	1st to 10th	Night	10% 5% 2 4 4 5% 4 3 5% 8% 50%	2038
	11th to 20th	Night	11% 5% 2 5% 3 4 4 4 6% 7% 50%	1875
	21st to end	Night	7% 5% 1 5% 4 4 4 4 5% 7% 54%	1900
May	1st to 10th	Night	6% 5% 2 5% 4 4 4 4 7% 9% 51%	2952
	11th to 20th	Night	13% 6% 2 6% 4 4 4 4 6% 8% 44%	2812
	21st to end	Night	7% 3 2 4 5% 4 5% 4 7% 9% 52%	3079
June	1st to 10th	Night	9% 7% 3 6% 5% 4 5% 4 9% 12% 35%	1710
	11th to 20th	Night	8% 5% 2 5% 4 4 5% 5% 9% 12% 40%	1710
	21st to end	Night	6% 5% 2 5% 6% 5% 6% 7% 10% 14% 34%	1710
July	1st to 10th	Night	10% 6% 2 7% 6% 6% 7% 5% 9% 11% 30%	2840
	11th to 20th	Night	7% 5% 3 8% 6% 6% 6% 6% 9% 13% 31%	2840
	21st to end	Night	5% 6% 2 7% 5% 6% 6% 6% 10% 16% 30%	3087
August	1st to 10th	Night	16% 8% 4 7% 5% 5% 5% 5% 8% 13% 24%	2825
	11th to 20th	Night	7% 5% 2 6% 5% 6% 6% 5% 9% 13% 36%	2911
	21st to end	Night	8% 4 2 7% 5% 5% 5% 4 6% 9% 44%	3476
September	1st to 10th	Night	10% 5% 2 7% 6% 6% 5% 5% 7% 11% 35%	1945
	11th to 20th	Night	11% 6% 3 7% 5% 4 5% 4 7% 10% 37%	2090
	21st to end	Night	15% 7% 2 7% 5% 4 4 4 5% 9% 40%	2090
October	1st to 10th	Night	12% 5% 2 6% 4 4 4 4 5% 7% 47%	2271
	11th to 20th	Night	8% 4 1 4 3 4 3 3 5% 7% 58%	2280
	21st to end	Night	10% 4 2 5% 3 3 4 3 5% 6% 56%	2508
November	1st to 10th	Night	10% 5% 1 5% 4 3 3 3 5% 6% 54%	2341
	11th to 20th	Night	13% 7% 2 5% 4 4 3 3 5% 6% 50%	2400
	21st to end	Night	10% 5% 2 5% 4 4 4 3 6% 8% 48%	2530
December	1st to 10th	Night	10% 5% 2 5% 3 3 3 3 4 6% 56%	4250
	11th to 20th	Night	15% 7% 3 8% 6% 4 3 3 4 5% 43%	4822
	21st to end	Night	15% 7% 2 6% 4 4 4 4 5% 6% 44%	6490

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	23% 28% 4 11% 28% 6%	4057
	11th to 20th	Day	26% 27% 4 11% 24% 8%	4060
	21st to end	Day	29% 31% 6% 13% 15% 7%	4466
February	1st to 10th	Day	16% 63% 4 9% 7% 1	1800
	11th to 20th	Day	17% 61% 4 8% 8% 2	1895
	21st to end	Day	17% 62% 3 5% 8% 5%	1815
March	1st to 10th	Day	37% 42% 6% 7% 5% 2	3545
	11th to 20th	Day	13% 44% 6% 9% 18% 10%	3491
	21st to end	Day	25% 42% 4 10% 14% 5%	3815
April	1st to 10th	Day	12% 66% 5% 7% 7% 3	2141
	11th to 20th	Day	13% 66% 4 8% 4 4	2254
	21st to end	Day	7% 66% 6% 12% 8% 2	2280
May	1st to 10th	Day	19% 47% 12% 15% 6% 1	3992
	11th to 20th	Day	26% 42% 8% 18% 6%	4085
	21st to end	Day	11% 44% 13% 20% 12%	4489
June	1st to 10th	Day	13% 68% 7% 8% 4	2470
	11th to 20th	Day	8% 68% 9% 10% 4	2470
	21st to end	Day	12% 68% 10% 9% 1	2470
July	1st to 10th	Day	31% 40% 16% 12% 1	4055
	11th to 20th	Day	26% 44% 23% 6% 1	4051
	21st to end	Day	29% 42% 17% 9% 2	4324
August	1st to 10th	Day	40% 40% 16% 4	4091
	11th to 20th	Day	20% 41% 15% 15% 8%	3924
	21st to end	Day	20% 39% 12% 27% 2	4180
September	1st to 10th	Day	15% 64% 9% 6% 5% 1	2230
	11th to 20th	Day	20% 62% 5% 8% 5% 1	2090
	21st to end	Day	18% 62% 8% 8% 4	2090
October	1st to 10th	Day	28% 37% 5% 9% 18% 3	3167
	11th to 20th	Day	7% 37% 3 8% 23% 22%	3140
	21st to end	Day	15% 37% 5% 13% 27% 3	3428
November	1st to 10th	Day	18% 56% 6% 8% 10% 2	1957
	11th to 20th	Day	18% 58% 3 7% 10% 4	2000
	21st to end	Day	14% 57% 5% 10% 12% 3	1865
December	1st to 10th	Day	19% 36% 5% 10% 16% 13%	2930
	11th to 20th	Day	29% 31% 6% 13% 17% 3	3370
	21st to end	Day	33% 28% 8% 18% 13% 1	4466
January	1st to 10th	Night	20% 29% 4 9% 30% 7%	5889
	11th to 20th	Night	30% 28% 4 12% 22% 4	5900
	21st to end	Night	27% 30% 5% 9% 20% 8%	6490
February	1st to 10th	Night	15% 62% 4 11% 7% 2	2600
	11th to 20th	Night	18% 61% 4 7% 8% 2	2396
	21st to end	Night	18% 62% 3 4 7% 5%	1815
March	1st to 10th	Night	39% 42% 7% 6% 4 2	3528
	11th to 20th	Night	19% 41% 5% 9% 18% 9%	3498
	21st to end	Night	23% 42% 6% 12% 12% 5%	3817
April	1st to 10th	Night	13% 66% 5% 6% 7% 3	2038
	11th to 20th	Night	14% 66% 3 8% 5% 3	1875
	21st to end	Night	10% 66% 4 11% 7% 2	1900
May	1st to 10th	Night	15% 47% 13% 17% 6% 2	2982
	11th to 20th	Night	23% 45% 8% 15% 9%	2813
	21st to end	Night	13% 43% 10% 19% 14% 1	3087
June	1st to 10th	Night	12% 68% 9% 8% 3	1710
	11th to 20th	Night	8% 68% 9% 10% 5%	1710
	21st to end	Night	13% 68% 9% 8% 2	1710
July	1st to 10th	Night	31% 39% 13% 16% 1	2795
	11th to 20th	Night	28% 42% 23% 5% 1	2786
	21st to end	Night	26% 43% 17% 12% 2	2988
August	1st to 10th	Night	37% 41% 17% 4	2814
	11th to 20th	Night	20% 41% 18% 17% 5%	2938
	21st to end	Night	17% 39% 11% 30% 2	3476
September	1st to 10th	Night	15% 63% 8% 7% 4 1	1945
	11th to 20th	Night	20% 62% 6% 7% 4 1	2090
	21st to end	Night	18% 62% 6% 10% 4	2090
October	1st to 10th	Night	25% 37% 6% 12% 17% 4	3791
	11th to 20th	Night	6% 37% 2 8% 19% 28%	3779
	21st to end	Night	14% 37% 3 15% 21% 9%	4120
November	1st to 10th	Night	18% 56% 6% 8% 10% 3	2341
	11th to 20th	Night	17% 57% 5% 7% 10% 4	2400
	21st to end	Night	14% 57% 5% 9% 11% 4	2530
December	1st to 10th	Night	18% 36% 4 10% 21% 11%	4250
	11th to 20th	Night	33% 32% 7% 9% 14% 5%	4824
	21st to end	Night	31% 28% 8% 19% 13% 1	6490

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% 20% 45% 17% 2	300
	11th to 20th	Day	10% 22% 40% 20% 7%	300
	21st to end	Day	20% 24% 44% 10% 1 1	330
February	1st to 10th	Day	14% 20% 42% 21% 3	300
	11th to 20th	Day	26% 19% 39% 14% 3	320
	21st to end	Day	15% 18% 42% 19% 5% 1	414
March	1st to 10th	Day	16% 20% 32% 24% 7%	500
	11th to 20th	Day	13% 18% 40% 20% 7% 1	464
	21st to end	Day	15% 17% 39% 19% 9% 2	506
April	1st to 10th	Day	13% 19% 36% 21% 9% 2	460
	11th to 20th	Day	8% 16% 32% 24% 15% 5%	452
	21st to end	Day	7% 12% 29% 32% 13% 7%	460
May	1st to 10th	Day	5% 13% 37% 26% 13% 5%	463
	11th to 20th	Day	11% 5% 27% 32% 20% 5%	487
	21st to end	Day	10% 5% 22% 33% 20% 10%	529
June	1st to 10th	Day	11% 4 20% 33% 24% 8%	490
	11th to 20th	Day	9% 4 22% 29% 24% 13%	490
	21st to end	Day	8% 4 14% 35% 27% 12%	490
July	1st to 10th	Day	8% 1 8% 34% 36% 13%	485
	11th to 20th	Day	7% 2 7% 33% 37% 14%	484
	21st to end	Day	6% 1 11% 39% 33% 9%	532
August	1st to 10th	Day	13% 3 12% 29% 30% 13%	486
	11th to 20th	Day	10% 2 10% 27% 34% 17%	479
	21st to end	Day	15% 4 10% 28% 30% 13%	539
September	1st to 10th	Day	11% 2 13% 34% 29% 11%	490
	11th to 20th	Day	15% 4 17% 32% 24% 6%	490
	21st to end	Day	17% 1 19% 29% 24% 10%	490
October	1st to 10th	Day	17% 6% 26% 31% 13% 8%	490
	11th to 20th	Day	9% 8% 25% 33% 20% 6%	490
	21st to end	Day	10% 7% 25% 36% 18% 4	539
November	1st to 10th	Day	16% 7% 31% 24% 18% 3	495
	11th to 20th	Day	17% 11% 37% 24% 10% 2	500
	21st to end	Day	15% 14% 33% 28% 10% 1	365
December	1st to 10th	Day	18% 8% 42% 25% 6% 1	300
	11th to 20th	Day	17% 20% 35% 21% 6% 1	300
	21st to end	Day	22% 16% 35% 18% 8% 1	330
January	1st to 10th	Night	14% 18% 34% 28% 6%	800
	11th to 20th	Night	14% 17% 30% 28% 10%	800
	21st to end	Night	19% 17% 36% 24% 4	880
February	1st to 10th	Night	17% 12% 36% 29% 7%	800
	11th to 20th	Night	21% 15% 33% 27% 4	783
	21st to end	Night	16% 13% 34% 29% 7% 1	660
March	1st to 10th	Night	12% 15% 35% 30% 8%	800
	11th to 20th	Night	14% 12% 34% 30% 9% 1	767
	21st to end	Night	14% 13% 34% 27% 12%	836
April	1st to 10th	Night	12% 12% 33% 31% 11% 1	760
	11th to 20th	Night	13% 10% 27% 30% 17% 2	751
	21st to end	Night	7% 9% 30% 36% 17% 1	760
May	1st to 10th	Night	8% 8% 29% 33% 20% 2	660
	11th to 20th	Night	9% 5% 24% 34% 23% 4	561
	21st to end	Night	10% 1 15% 31% 33% 10%	617
June	1st to 10th	Night	11% 2 13% 40% 30% 5%	570
	11th to 20th	Night	8% 2 13% 31% 36% 11%	570
	21st to end	Night	6% 2 13% 38% 34% 7%	570
July	1st to 10th	Night	9% 2 7% 32% 44% 6%	555
	11th to 20th	Night	9% 1 5% 30% 42% 13%	552
	21st to end	Night	6% 1 7% 38% 41% 7%	624
August	1st to 10th	Night	12% 2 4 31% 41% 10%	567
	11th to 20th	Night	9% 2 8% 32% 40% 9%	638
	21st to end	Night	13% 2 8% 27% 38% 12%	836
September	1st to 10th	Night	12% 2 12% 26% 41% 8%	760
	11th to 20th	Night	14% 2 11% 33% 32% 7%	760
	21st to end	Night	18% 2 14% 27% 32% 8%	760
October	1st to 10th	Night	15% 4 20% 30% 24% 7%	760
	11th to 20th	Night	10% 7% 24% 31% 23% 5%	760
	21st to end	Night	13% 7% 20% 34% 22% 4	836
November	1st to 10th	Night	11% 7% 26% 34% 18% 3	780
	11th to 20th	Night	17% 11% 27% 30% 14% 2	800
	21st to end	Night	13% 12% 29% 28% 18% 2	800
December	1st to 10th	Night	15% 13% 29% 30% 12% 1	800
	11th to 20th	Night	19% 12% 27% 27% 13% 2	800
	21st to end	Night	20% 13% 29% 28% 9% 1	880

Page generated at 2025-03-09 08:08:45. Version ac07

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