Stokes Castle
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stokes Castle clear sky chart from 2005-11-06 to 2025-03-27.

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	3 5% 2 6% 4 3 4 3 5% 7% 58%	112712
	Night	3 6% 3 7% 4 4 4 3 5% 7% 54%	115375
Transparency	Day	24% 5% 9% 18% 24% 21%	112455
	Night	26% 6% 10% 18% 23% 17%	115222
Seeing	Day	7% 9% 23% 30% 22% 8%	15316
	Night	6% 5% 18% 42% 25% 4	24940

By Month

Percentage Cloud Cover SW (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	2 9% 7% 13% 6% 3 4 3 5% 7% 39%	3639
	11th to 20th	Day	2 8% 3 8% 5% 4 4 3 4 6% 53%	3640
	21st to end	Day	3 9% 5% 9% 4 4 5% 4 7% 8% 43%	4149
February	1st to 10th	Day	3 9% 3 10% 5% 4 4 4 6% 8% 47%	2000
	11th to 20th	Day	4 7% 3 9% 5% 4 4 4 6% 9% 44%	1950
	21st to end	Day	1 9% 3 8% 4 4 5% 4 6% 7% 49%	1650
March	1st to 10th	Day	2 9% 4 10% 5% 5% 5% 5% 8% 11% 35%	3238
	11th to 20th	Day	1 5% 3 7% 3 4 4 3 5% 8% 55%	3408
	21st to end	Day	3 10% 6% 12% 6% 5% 6% 4 7% 9% 34%	4139
April	1st to 10th	Day	3 8% 3 6% 5% 4 4 4 4 7% 51%	2280
	11th to 20th	Day	4 8% 3 6% 4 4 3 3 5% 7% 53%	2249
	21st to end	Day	5% 8% 2 6% 3 3 4 3 5% 7% 54%	2384
May	1st to 10th	Day	3 5% 3 5% 3 3 3 3 4 6% 62%	4110
	11th to 20th	Day	3 5% 1 4 3 3 3 2 4 5% 67%	4071
	21st to end	Day	4 6% 2 6% 4 4 3 3 4 5% 60%	4682
June	1st to 10th	Day	4 4 1 5% 4 4 4 4 6% 8% 56%	2660
	11th to 20th	Day	3 3 1 3 3 3 3 2 4 7% 68%	2660
	21st to end	Day	2 3 1 4 3 2 3 2 3 5% 71%	2660
July	1st to 10th	Day	1 2 1 3 2 3 2 2 3 4 78%	4420
	11th to 20th	Day	4 3 1 4 4 4 4 4 6% 7% 60%	4420
	21st to end	Day	3 3 2 5% 4 4 4 3 5% 6% 60%	4744
August	1st to 10th	Day	2 3 1 3 3 3 4 3 5% 5% 67%	4079
	11th to 20th	Day	2 2 1 3 2 2 2 2 2 4 79%	3724
	21st to end	Day	3 2 1 3 2 2 2 1 3 4 78%	4180
September	1st to 10th	Day	2 3 1 2 3 3 3 3 4 5% 72%	2280
	11th to 20th	Day	3 3 1 4 3 3 4 2 4 5% 68%	2119
	21st to end	Day	3 3 2 3 2 2 2 2 3 5% 74%	2090
October	1st to 10th	Day	3 3 1 5% 3 3 3 2 4 6% 67%	3490
	11th to 20th	Day	3 3 1 4 2 3 2 2 4 5% 71%	3233
	21st to end	Day	2 3 2 5% 3 3 3 4 7% 8% 61%	3101
November	1st to 10th	Day	3 7% 2 6% 4 3 4 4 6% 8% 52%	1764
	11th to 20th	Day	3 6% 2 5% 4 4 3 4 6% 8% 56%	1800
	21st to end	Day	3 8% 3 8% 4 3 3 4 5% 8% 51%	1800
December	1st to 10th	Day	2 4 2 4 3 2 3 2 4 7% 67%	2867
	11th to 20th	Day	3 11% 4 9% 6% 4 5% 5% 7% 10% 38%	3028
	21st to end	Day	3 9% 4 8% 7% 6% 5% 4 7% 9% 38%	4004
January	1st to 10th	Night	2 8% 4 12% 6% 6% 5% 4 6% 10% 36%	6306
	11th to 20th	Night	2 7% 4 10% 5% 4 4 3 4 7% 50%	6320
	21st to end	Night	3 9% 4 9% 5% 4 4 4 6% 9% 44%	6793
February	1st to 10th	Night	4 9% 4 10% 5% 4 4 3 5% 7% 46%	2400
	11th to 20th	Night	2 7% 3 9% 4 4 5% 4 8% 11% 44%	2338
	21st to end	Night	1 6% 3 8% 6% 5% 4 5% 6% 9% 47%	1980
March	1st to 10th	Night	1 8% 4 9% 6% 5% 5% 4 6% 8% 43%	3856
	11th to 20th	Night	1 6% 2 10% 5% 5% 4 4 6% 7% 50%	3792
	21st to end	Night	3 9% 3 7% 5% 5% 5% 5% 7% 9% 42%	3648
April	1st to 10th	Night	4 8% 3 7% 4 4 4 4 6% 6% 49%	1900
	11th to 20th	Night	4 8% 3 6% 4 4 3 3 5% 6% 54%	1879
	21st to end	Night	6% 8% 2 4 3 3 3 3 5% 7% 54%	1795
May	1st to 10th	Night	3 7% 4 5% 4 3 3 3 4 7% 57%	2860
	11th to 20th	Night	3 4 1 4 3 2 2 2 4 6% 69%	2834
	21st to end	Night	4 5% 2 7% 4 4 5% 4 6% 7% 54%	2893
June	1st to 10th	Night	4 4 2 4 4 4 4 5% 6% 6% 57%	1520
	11th to 20th	Night	4 3 1 4 2 2 3 2 5% 5% 68%	1520
	21st to end	Night	2 3 1 4 3 3 3 3 4 4 71%	1520
July	1st to 10th	Night	2 2 1 3 3 2 2 3 3 4 74%	2540
	11th to 20th	Night	4 4 3 7% 5% 5% 5% 4 6% 6% 50%	2540
	21st to end	Night	3 5% 2 6% 4 4 5% 4 5% 6% 55%	2809
August	1st to 10th	Night	4 4 2 5% 3 3 4 3 5% 6% 60%	2847
	11th to 20th	Night	2 2 1 4 2 2 3 2 4 4 74%	3123
	21st to end	Night	3 2 1 3 2 2 2 2 3 3 78%	3498
September	1st to 10th	Night	3 2 1 3 3 3 3 3 3 5% 71%	1900
	11th to 20th	Night	3 4 1 5% 3 2 3 3 4 5% 66%	2061
	21st to end	Night	4 3 1 3 1 2 2 2 2 3 76%	2090
October	1st to 10th	Night	3 3 1 4 3 3 3 3 4 4 69%	3490
	11th to 20th	Night	3 4 2 4 2 3 2 2 3 3 71%	3699
	21st to end	Night	2 3 1 4 3 3 3 3 4 5% 69%	4457
November	1st to 10th	Night	4 6% 2 5% 3 3 3 3 5% 7% 58%	2535
	11th to 20th	Night	3 5% 2 4 4 4 3 4 5% 8% 59%	2600
	21st to end	Night	3 6% 3 8% 4 4 5% 4 5% 8% 51%	2600
December	1st to 10th	Night	2 4 2 5% 4 3 4 3 4 5% 63%	4304
	11th to 20th	Night	2 7% 3 10% 5% 4 5% 4 7% 13% 39%	5176
	21st to end	Night	3 9% 5% 13% 7% 7% 7% 5% 7% 9% 29%	6952

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	39% 8% 19% 18% 16% 1	3639
	11th to 20th	Day	30% 6% 11% 19% 23% 11%	3640
	21st to end	Day	36% 8% 11% 14% 23% 8%	4149
February	1st to 10th	Day	32% 6% 12% 25% 17% 8%	2000
	11th to 20th	Day	33% 6% 12% 23% 21% 5%	1960
	21st to end	Day	30% 7% 13% 24% 19% 6%	1650
March	1st to 10th	Day	33% 11% 12% 26% 11% 7%	3238
	11th to 20th	Day	24% 7% 18% 33% 15% 3	3408
	21st to end	Day	39% 11% 17% 19% 12% 2	4139
April	1st to 10th	Day	31% 6% 13% 25% 18% 7%	2280
	11th to 20th	Day	29% 6% 12% 25% 21% 7%	2252
	21st to end	Day	28% 6% 10% 31% 22% 3	2384
May	1st to 10th	Day	21% 5% 8% 32% 26% 8%	4110
	11th to 20th	Day	19% 5% 7% 20% 38% 11%	4074
	21st to end	Day	23% 6% 8% 20% 37% 6%	4682
June	1st to 10th	Day	23% 6% 11% 18% 28% 15%	2660
	11th to 20th	Day	17% 3 5% 15% 33% 27%	2660
	21st to end	Day	15% 3 5% 11% 27% 40%	2660
July	1st to 10th	Day	12% 2 4 5% 10% 67%	4351
	11th to 20th	Day	20% 5% 3 7% 20% 46%	4345
	21st to end	Day	22% 4 4 11% 19% 40%	4594
August	1st to 10th	Day	16% 4 3 10% 24% 43%	4065
	11th to 20th	Day	11% 2 3 6% 15% 63%	3760
	21st to end	Day	13% 2 2 6% 28% 49%	4179
September	1st to 10th	Day	15% 3 4 9% 25% 43%	2280
	11th to 20th	Day	17% 4 6% 15% 28% 30%	2119
	21st to end	Day	16% 2 4 14% 30% 34%	2090
October	1st to 10th	Day	19% 5% 4 9% 32% 31%	3490
	11th to 20th	Day	18% 2 3 15% 36% 26%	3233
	21st to end	Day	16% 4 5% 24% 39% 12%	3101
November	1st to 10th	Day	25% 6% 10% 25% 23% 11%	1764
	11th to 20th	Day	24% 5% 12% 24% 29% 7%	1800
	21st to end	Day	31% 5% 9% 24% 22% 8%	1800
December	1st to 10th	Day	18% 4 9% 20% 29% 19%	2867
	11th to 20th	Day	37% 8% 12% 19% 20% 5%	3028
	21st to end	Day	33% 10% 16% 24% 15% 3	4004
January	1st to 10th	Night	36% 9% 16% 19% 18% 2	6306
	11th to 20th	Night	31% 8% 11% 16% 24% 10%	6320
	21st to end	Night	33% 9% 10% 15% 24% 10%	6793
February	1st to 10th	Night	35% 5% 12% 26% 16% 6%	2400
	11th to 20th	Night	28% 7% 14% 22% 23% 6%	2339
	21st to end	Night	28% 9% 15% 22% 21% 7%	1980
March	1st to 10th	Night	32% 10% 12% 24% 15% 8%	3856
	11th to 20th	Night	28% 7% 14% 32% 16% 3	3792
	21st to end	Night	29% 10% 20% 26% 14% 2	3648
April	1st to 10th	Night	32% 6% 13% 25% 16% 7%	1900
	11th to 20th	Night	28% 6% 10% 27% 20% 8%	1879
	21st to end	Night	27% 6% 11% 27% 25% 4	1795
May	1st to 10th	Night	22% 8% 9% 25% 30% 7%	2860
	11th to 20th	Night	16% 4 8% 18% 41% 13%	2835
	21st to end	Night	23% 8% 11% 21% 31% 6%	2893
June	1st to 10th	Night	21% 7% 10% 21% 28% 13%	1520
	11th to 20th	Night	18% 3 5% 15% 34% 24%	1520
	21st to end	Night	15% 3 5% 12% 26% 39%	1520
July	1st to 10th	Night	13% 3 4 5% 12% 64%	2500
	11th to 20th	Night	29% 6% 4 7% 15% 40%	2492
	21st to end	Night	26% 4 5% 13% 13% 38%	2721
August	1st to 10th	Night	22% 5% 3 11% 19% 40%	2838
	11th to 20th	Night	14% 3 4 6% 13% 60%	3153
	21st to end	Night	13% 2 3 6% 26% 50%	3498
September	1st to 10th	Night	15% 4 4 10% 25% 43%	1900
	11th to 20th	Night	19% 4 5% 14% 27% 32%	2061
	21st to end	Night	14% 2 4 13% 29% 36%	2090
October	1st to 10th	Night	18% 4 4 11% 32% 31%	3490
	11th to 20th	Night	16% 5% 4 12% 34% 28%	3699
	21st to end	Night	16% 4 4 22% 42% 13%	4457
November	1st to 10th	Night	22% 6% 11% 23% 26% 11%	2535
	11th to 20th	Night	21% 5% 11% 25% 30% 7%	2600
	21st to end	Night	29% 5% 10% 24% 25% 7%	2600
December	1st to 10th	Night	23% 4 8% 20% 29% 15%	4304
	11th to 20th	Night	31% 8% 15% 21% 19% 6%	5176
	21st to end	Night	44% 9% 13% 19% 13% 3	6952

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	14% 10% 28% 30% 15% 4	200
	11th to 20th	Day	8% 10% 32% 24% 19% 9%	200
	21st to end	Day	11% 6% 15% 32% 26% 10%	282
February	1st to 10th	Day	10% 12% 25% 30% 17% 6%	500
	11th to 20th	Day	9% 9% 29% 31% 19% 3	495
	21st to end	Day	5% 11% 29% 38% 17% 1	414
March	1st to 10th	Day	10% 10% 23% 37% 19% 1	500
	11th to 20th	Day	5% 13% 24% 31% 21% 5%	500
	21st to end	Day	11% 10% 26% 36% 13% 3	531
April	1st to 10th	Day	6% 12% 25% 31% 23% 4	460
	11th to 20th	Day	9% 11% 29% 31% 15% 6%	452
	21st to end	Day	10% 12% 27% 26% 19% 7%	460
May	1st to 10th	Day	7% 13% 31% 29% 15% 5%	463
	11th to 20th	Day	13% 9% 23% 27% 22% 6%	488
	21st to end	Day	13% 10% 19% 25% 22% 11%	529
June	1st to 10th	Day	6% 9% 24% 24% 24% 12%	490
	11th to 20th	Day	8% 15% 25% 28% 17% 7%	490
	21st to end	Day	3 8% 24% 32% 24% 8%	490
July	1st to 10th	Day	2 5% 26% 28% 28% 11%	486
	11th to 20th	Day	4 3 22% 30% 28% 13%	484
	21st to end	Day	5% 3 18% 32% 29% 13%	531
August	1st to 10th	Day	6% 3 21% 31% 23% 15%	487
	11th to 20th	Day	6% 6% 24% 27% 23% 14%	477
	21st to end	Day	4 6% 21% 29% 28% 11%	539
September	1st to 10th	Day	3 5% 21% 29% 26% 15%	490
	11th to 20th	Day	7% 10% 23% 24% 24% 11%	490
	21st to end	Day	7% 6% 22% 29% 28% 8%	490
October	1st to 10th	Day	7% 10% 19% 29% 23% 12%	490
	11th to 20th	Day	7% 7% 18% 31% 26% 10%	481
	21st to end	Day	8% 7% 18% 33% 27% 7%	330
November	1st to 10th	Day	7% 7% 24% 32% 24% 6%	300
	11th to 20th	Day	4 10% 21% 33% 25% 6%	300
	21st to end	Day	11% 9% 16% 35% 24% 5%	300
December	1st to 10th	Day	5% 7% 22% 31% 25% 9%	277
	11th to 20th	Day	7% 10% 22% 35% 24% 3	200
	21st to end	Day	15% 8% 26% 30% 16% 5%	220
January	1st to 10th	Night	8% 7% 25% 34% 21% 4	800
	11th to 20th	Night	5% 6% 26% 40% 20% 4	800
	21st to end	Night	9% 5% 19% 43% 20% 5%	880
February	1st to 10th	Night	9% 8% 21% 40% 19% 4	800
	11th to 20th	Night	5% 9% 22% 42% 19% 2	784
	21st to end	Night	5% 6% 25% 48% 15% 2	660
March	1st to 10th	Night	7% 8% 25% 43% 16% 2	800
	11th to 20th	Night	6% 6% 21% 39% 25% 4	800
	21st to end	Night	10% 7% 21% 42% 19% 1	862
April	1st to 10th	Night	8% 7% 23% 43% 18% 2	760
	11th to 20th	Night	8% 9% 21% 39% 19% 4	751
	21st to end	Night	10% 7% 16% 42% 22% 4	655
May	1st to 10th	Night	6% 8% 24% 42% 17% 3	570
	11th to 20th	Night	9% 7% 16% 39% 26% 3	561
	21st to end	Night	8% 8% 16% 38% 27% 4	491
June	1st to 10th	Night	4 3 14% 44% 30% 4	380
	11th to 20th	Night	4 4 18% 46% 26% 2	380
	21st to end	Night	3 2 13% 51% 28% 4	380
July	1st to 10th	Night	4 1 10% 47% 35% 3	370
	11th to 20th	Night	4 2 9% 46% 36% 3	368
	21st to end	Night	6% 3 5% 46% 39% 1	440
August	1st to 10th	Night	6% 3 13% 46% 30% 2	567
	11th to 20th	Night	3 2 10% 45% 35% 5%	749
	21st to end	Night	4 2 10% 43% 38% 4	836
September	1st to 10th	Night	4 2 10% 39% 40% 5%	760
	11th to 20th	Night	5% 4 9% 41% 32% 9%	760
	21st to end	Night	6% 2 13% 40% 34% 6%	760
October	1st to 10th	Night	7% 4 13% 43% 28% 5%	760
	11th to 20th	Night	6% 4 14% 40% 31% 5%	760
	21st to end	Night	6% 4 16% 40% 29% 6%	836
November	1st to 10th	Night	7% 3 19% 42% 23% 6%	780
	11th to 20th	Night	5% 4 22% 46% 20% 4	800
	21st to end	Night	6% 6% 22% 39% 23% 5%	800
December	1st to 10th	Night	7% 6% 22% 43% 19% 5%	800
	11th to 20th	Night	8% 8% 23% 43% 18% 1	800
	21st to end	Night	10% 11% 25% 40% 13% 2	880

Page generated at 2025-03-24 06:04:30. Version ac07

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