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 2026-07-31.

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% 6% 59%	146329
	Night	3 6% 3 7% 4 4 4 3 5% 7% 56%	144072
Transparency	Day	23% 5% 7% 17% 25% 22%	141278
	Night	25% 6% 9% 19% 24% 18%	140109
Seeing	Day	7% 9% 24% 30% 22% 8%	17126
	Night	6% 6% 19% 42% 24% 4	26563

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 10% 6% 13% 6% 3 4 3 5% 7% 41%	4722
	11th to 20th	Day	2 6% 2 7% 4 3 4 3 4 6% 60%	4740
	21st to end	Day	2 7% 4 8% 4 4 5% 4 8% 10% 44%	5388
February	1st to 10th	Day	2 8% 3 10% 5% 4 4 3 6% 8% 47%	2100
	11th to 20th	Day	4 7% 4 9% 5% 4 4 4 6% 9% 43%	2050
	21st to end	Day	1 8% 3 8% 4 4 5% 4 6% 7% 48%	1730
March	1st to 10th	Day	2 10% 5% 11% 5% 6% 5% 4 7% 11% 34%	4618
	11th to 20th	Day	1 7% 3 8% 4 4 5% 4 6% 9% 50%	4840
	21st to end	Day	2 9% 5% 11% 5% 5% 5% 4 6% 8% 41%	5962
April	1st to 10th	Day	2 7% 3 7% 5% 4 4 4 4 7% 52%	2520
	11th to 20th	Day	3 8% 2 6% 4 4 3 3 5% 8% 53%	2489
	21st to end	Day	5% 8% 3 6% 3 3 4 3 5% 7% 52%	2635
May	1st to 10th	Day	4 4 2 5% 3 3 3 3 4 5% 63%	7626
	11th to 20th	Day	3 5% 2 5% 3 3 3 3 4 5% 65%	7596
	21st to end	Day	4 5% 2 6% 4 4 4 3 4 6% 59%	8744
June	1st to 10th	Day	4 4 1 5% 4 4 4 4 6% 8% 56%	2940
	11th to 20th	Day	3 3 1 3 3 3 3 2 4 6% 70%	2940
	21st to end	Day	2 3 1 4 3 2 3 2 3 5% 71%	2940
July	1st to 10th	Day	1 1 1 3 2 2 2 2 3 3 79%	6459
	11th to 20th	Day	4 3 1 4 4 4 4 3 5% 6% 60%	6460
	21st to end	Day	2 3 1 4 3 3 4 3 4 6% 65%	6962
August	1st to 10th	Day	2 2 1 2 2 2 3 3 4 5% 75%	5766
	11th to 20th	Day	3 2 1 3 2 2 2 2 3 4 77%	5364
	21st to end	Day	3 3 1 4 3 4 3 3 4 5% 67%	5984
September	1st to 10th	Day	2 3 1 3 3 3 3 3 4 5% 71%	2400
	11th to 20th	Day	2 3 1 4 3 3 4 2 5% 5% 67%	2230
	21st to end	Day	3 3 2 3 2 2 3 2 3 5% 73%	2200
October	1st to 10th	Day	3 3 1 5% 3 3 3 2 4 6% 67%	3600
	11th to 20th	Day	3 3 1 4 3 3 2 2 4 5% 70%	3335
	21st to end	Day	2 3 2 5% 3 3 3 4 7% 8% 61%	3200
November	1st to 10th	Day	3 7% 2 5% 4 3 4 4 6% 8% 54%	1854
	11th to 20th	Day	3 6% 2 5% 4 3 3 4 6% 8% 55%	1890
	21st to end	Day	3 8% 3 7% 4 3 3 4 5% 8% 52%	1890
December	1st to 10th	Day	2 4 2 4 3 2 4 2 4 7% 66%	2955
	11th to 20th	Day	3 11% 4 9% 6% 4 4 5% 7% 10% 38%	3108
	21st to end	Day	3 9% 4 8% 7% 6% 5% 4 7% 9% 38%	4092
January	1st to 10th	Night	2 9% 4 12% 6% 6% 4 4 6% 10% 38%	8172
	11th to 20th	Night	2 6% 3 7% 4 4 3 2 4 7% 58%	8220
	21st to end	Night	2 7% 3 8% 4 4 4 4 7% 9% 46%	8783
February	1st to 10th	Night	4 8% 4 9% 5% 4 4 3 5% 7% 47%	2520
	11th to 20th	Night	2 8% 3 9% 5% 4 5% 4 7% 11% 43%	2458
	21st to end	Night	1 6% 3 8% 6% 5% 4 5% 6% 9% 47%	2076
March	1st to 10th	Night	2 8% 4 10% 6% 6% 4 4 5% 6% 46%	5496
	11th to 20th	Night	1 6% 3 9% 5% 5% 5% 4 7% 8% 48%	5380
	21st to end	Night	2 7% 3 7% 5% 5% 6% 5% 7% 9% 45%	5251
April	1st to 10th	Night	4 7% 3 7% 4 4 4 4 6% 7% 49%	2100
	11th to 20th	Night	4 8% 3 6% 4 4 4 3 5% 6% 54%	2079
	21st to end	Night	6% 8% 3 5% 4 3 3 3 5% 7% 54%	1983
May	1st to 10th	Night	4 6% 3 5% 3 3 3 3 4 5% 61%	5321
	11th to 20th	Night	3 4 1 4 3 2 2 2 4 6% 69%	5296
	21st to end	Night	5% 5% 3 7% 4 4 4 4 5% 6% 54%	5424
June	1st to 10th	Night	4 4 2 4 4 4 4 5% 6% 6% 57%	1680
	11th to 20th	Night	4 3 1 4 2 2 3 2 4 5% 70%	1680
	21st to end	Night	2 3 1 4 3 2 3 3 4 5% 72%	1680
July	1st to 10th	Night	3 2 1 3 2 2 2 2 3 4 76%	3720
	11th to 20th	Night	5% 4 3 7% 4 5% 4 4 5% 5% 54%	3720
	21st to end	Night	3 4 2 5% 4 4 4 3 5% 7% 60%	4112
August	1st to 10th	Night	3 2 1 4 2 2 3 2 4 5% 71%	4033
	11th to 20th	Night	2 3 1 4 2 3 3 2 3 3 74%	4503
	21st to end	Night	4 4 1 4 3 3 3 3 4 4 66%	5015
September	1st to 10th	Night	3 2 1 4 3 3 3 3 4 6% 69%	2000
	11th to 20th	Night	3 4 1 5% 3 2 3 3 4 5% 66%	2170
	21st to end	Night	4 3 1 3 2 2 3 2 3 3 75%	2200
October	1st to 10th	Night	3 3 1 4 3 3 3 3 3 4 69%	3600
	11th to 20th	Night	3 4 2 4 2 3 2 2 3 4 71%	3817
	21st to end	Night	2 3 1 4 3 3 3 3 4 5% 69%	4600
November	1st to 10th	Night	4 5% 2 5% 3 3 3 3 5% 7% 59%	2665
	11th to 20th	Night	3 5% 2 5% 4 4 4 4 5% 8% 58%	2730
	21st to end	Night	3 6% 3 7% 4 4 5% 3 5% 8% 52%	2730
December	1st to 10th	Night	2 4 2 5% 4 3 4 3 4 5% 63%	4436
	11th to 20th	Night	2 7% 3 10% 5% 4 5% 4 7% 13% 40%	5316
	21st to end	Night	3 8% 5% 13% 7% 7% 7% 5% 7% 9% 30%	7106

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	38% 7% 18% 23% 14%	4723
	11th to 20th	Day	24% 5% 9% 17% 25% 21%	4740
	21st to end	Day	31% 7% 9% 17% 27% 8%	5388
February	1st to 10th	Day	32% 6% 12% 25% 18% 8%	2100
	11th to 20th	Day	33% 6% 11% 23% 21% 5%	2060
	21st to end	Day	31% 7% 13% 25% 19% 6%	1730
March	1st to 10th	Day	35% 10% 9% 22% 18% 7%	4618
	11th to 20th	Day	26% 6% 17% 31% 17% 2	4840
	21st to end	Day	35% 9% 13% 21% 18% 4	5962
April	1st to 10th	Day	30% 6% 12% 24% 21% 7%	2520
	11th to 20th	Day	29% 6% 11% 24% 23% 8%	2492
	21st to end	Day	29% 6% 10% 29% 22% 4	2635
May	1st to 10th	Day	22% 4 6% 26% 34% 7%	7626
	11th to 20th	Day	18% 6% 4 20% 38% 14%	7599
	21st to end	Day	24% 6% 5% 17% 39% 11%	8745
June	1st to 10th	Day	22% 6% 10% 17% 29% 15%	2940
	11th to 20th	Day	16% 3 5% 14% 32% 31%	2940
	21st to end	Day	15% 3 4 10% 29% 40%	2940
July	1st to 10th	Day	12% 2 3 4 12% 67%	6391
	11th to 20th	Day	21% 5% 2 5% 16% 51%	6385
	21st to end	Day	18% 4 3 8% 19% 48%	6764
August	1st to 10th	Day	16% 3 3 10% 25% 43%	4195
	11th to 20th	Day	11% 2 3 6% 15% 63%	3880
	21st to end	Day	14% 2 2 7% 28% 47%	4311
September	1st to 10th	Day	16% 3 4 10% 26% 41%	2400
	11th to 20th	Day	18% 4 5% 15% 28% 30%	2230
	21st to end	Day	16% 2 4 15% 30% 33%	2200
October	1st to 10th	Day	19% 5% 4 9% 32% 31%	3600
	11th to 20th	Day	18% 2 3 15% 36% 25%	3335
	21st to end	Day	16% 4 5% 24% 39% 11%	3200
November	1st to 10th	Day	24% 5% 10% 26% 23% 11%	1854
	11th to 20th	Day	24% 5% 12% 24% 28% 7%	1890
	21st to end	Day	30% 5% 9% 26% 23% 8%	1890
December	1st to 10th	Day	18% 4 9% 21% 29% 18%	2955
	11th to 20th	Day	36% 8% 12% 19% 20% 6%	3108
	21st to end	Day	33% 10% 16% 24% 15% 3	4092
January	1st to 10th	Night	36% 7% 16% 26% 15% 1	8172
	11th to 20th	Night	25% 6% 8% 15% 24% 22%	8220
	21st to end	Night	29% 8% 10% 17% 25% 11%	8783
February	1st to 10th	Night	34% 5% 12% 26% 17% 6%	2520
	11th to 20th	Night	29% 7% 13% 22% 22% 5%	2459
	21st to end	Night	27% 8% 16% 22% 20% 6%	2076
March	1st to 10th	Night	31% 8% 8% 23% 19% 10%	5496
	11th to 20th	Night	25% 7% 12% 33% 20% 3	5380
	21st to end	Night	28% 9% 18% 27% 17% 2	5251
April	1st to 10th	Night	31% 6% 12% 24% 19% 7%	2100
	11th to 20th	Night	27% 6% 9% 27% 22% 9%	2079
	21st to end	Night	27% 6% 10% 27% 26% 4	1983
May	1st to 10th	Night	24% 5% 6% 20% 38% 7%	5319
	11th to 20th	Night	16% 3 4 19% 42% 16%	5297
	21st to end	Night	27% 6% 6% 17% 35% 9%	5425
June	1st to 10th	Night	22% 7% 9% 20% 29% 13%	1680
	11th to 20th	Night	16% 4 5% 14% 34% 27%	1680
	21st to end	Night	14% 3 4 12% 28% 39%	1680
July	1st to 10th	Night	14% 2 3 4 12% 65%	3680
	11th to 20th	Night	27% 6% 3 5% 12% 47%	3672
	21st to end	Night	22% 4 4 11% 19% 40%	3998
August	1st to 10th	Night	22% 4 3 11% 20% 40%	2928
	11th to 20th	Night	15% 3 3 6% 13% 60%	3253
	21st to end	Night	14% 2 3 7% 26% 49%	3608
September	1st to 10th	Night	17% 4 4 10% 25% 41%	2000
	11th to 20th	Night	19% 4 5% 14% 27% 31%	2170
	21st to end	Night	15% 2 4 14% 29% 36%	2200
October	1st to 10th	Night	18% 4 4 12% 32% 31%	3600
	11th to 20th	Night	16% 5% 4 13% 35% 28%	3817
	21st to end	Night	16% 4 4 23% 42% 12%	4600
November	1st to 10th	Night	21% 6% 11% 24% 26% 11%	2665
	11th to 20th	Night	22% 5% 11% 25% 29% 7%	2730
	21st to end	Night	28% 5% 9% 25% 25% 7%	2730
December	1st to 10th	Night	23% 5% 9% 21% 28% 15%	4436
	11th to 20th	Night	31% 8% 15% 21% 19% 6%	5316
	21st to end	Night	43% 8% 13% 19% 13% 3	7106

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% 11% 28% 29% 15% 3	220
	11th to 20th	Day	7% 9% 30% 24% 21% 10%	220
	21st to end	Day	10% 6% 16% 33% 25% 9%	308
February	1st to 10th	Day	9% 12% 25% 31% 17% 6%	540
	11th to 20th	Day	10% 11% 29% 30% 18% 3	535
	21st to end	Day	5% 12% 30% 36% 15% 1	446
March	1st to 10th	Day	11% 10% 24% 36% 18% 1	540
	11th to 20th	Day	5% 14% 25% 31% 21% 5%	540
	21st to end	Day	11% 11% 27% 34% 13% 3	594
April	1st to 10th	Day	6% 11% 24% 32% 22% 4	540
	11th to 20th	Day	10% 12% 28% 30% 14% 5%	532
	21st to end	Day	10% 13% 27% 26% 18% 6%	540
May	1st to 10th	Day	7% 12% 32% 29% 15% 5%	543
	11th to 20th	Day	13% 11% 25% 25% 20% 5%	568
	21st to end	Day	12% 11% 20% 25% 21% 11%	617
June	1st to 10th	Day	6% 9% 26% 24% 23% 12%	570
	11th to 20th	Day	8% 14% 27% 28% 17% 7%	570
	21st to end	Day	5% 8% 25% 31% 24% 8%	570
July	1st to 10th	Day	2 6% 26% 29% 26% 10%	566
	11th to 20th	Day	4 4 22% 30% 28% 13%	564
	21st to end	Day	4 3 18% 32% 29% 13%	616
August	1st to 10th	Day	6% 5% 21% 31% 22% 15%	527
	11th to 20th	Day	5% 6% 24% 27% 23% 14%	517
	21st to end	Day	4 6% 20% 30% 28% 11%	583
September	1st to 10th	Day	3 5% 22% 30% 25% 14%	530
	11th to 20th	Day	7% 10% 22% 26% 25% 11%	530
	21st to end	Day	6% 5% 23% 30% 28% 7%	530
October	1st to 10th	Day	8% 11% 19% 29% 23% 11%	530
	11th to 20th	Day	8% 8% 18% 31% 25% 9%	520
	21st to end	Day	8% 7% 18% 34% 26% 7%	363
November	1st to 10th	Day	8% 6% 23% 31% 25% 7%	330
	11th to 20th	Day	5% 12% 23% 32% 23% 6%	330
	21st to end	Day	11% 9% 17% 35% 24% 5%	330
December	1st to 10th	Day	6% 7% 23% 31% 24% 9%	305
	11th to 20th	Day	8% 10% 20% 33% 24% 5%	220
	21st to end	Day	18% 9% 24% 29% 15% 5%	242
January	1st to 10th	Night	8% 8% 26% 34% 20% 4	840
	11th to 20th	Night	4 6% 24% 41% 21% 3	840
	21st to end	Night	8% 5% 19% 44% 19% 5%	924
February	1st to 10th	Night	8% 8% 22% 40% 19% 3	840
	11th to 20th	Night	6% 10% 22% 41% 18% 2	824
	21st to end	Night	5% 7% 26% 47% 14% 1	692
March	1st to 10th	Night	6% 7% 25% 44% 15% 2	840
	11th to 20th	Night	6% 6% 22% 39% 24% 3	840
	21st to end	Night	9% 7% 22% 42% 18% 1	924
April	1st to 10th	Night	7% 7% 22% 44% 18% 1	840
	11th to 20th	Night	8% 10% 22% 38% 18% 4	831
	21st to end	Night	10% 7% 17% 42% 20% 4	723
May	1st to 10th	Night	6% 7% 24% 42% 17% 3	630
	11th to 20th	Night	9% 8% 18% 39% 24% 2	621
	21st to end	Night	7% 8% 16% 39% 26% 3	543
June	1st to 10th	Night	5% 3 14% 45% 29% 4	420
	11th to 20th	Night	4 4 17% 48% 25% 2	420
	21st to end	Night	3 2 14% 51% 26% 4	420
July	1st to 10th	Night	4 1 12% 48% 32% 3	410
	11th to 20th	Night	4 2 10% 48% 35% 3	408
	21st to end	Night	6% 3 6% 47% 36% 1	483
August	1st to 10th	Night	5% 3 14% 46% 29% 2	597
	11th to 20th	Night	3 2 11% 45% 34% 5%	789
	21st to end	Night	4 2 10% 43% 38% 4	880
September	1st to 10th	Night	4 2 10% 40% 39% 5%	800
	11th to 20th	Night	5% 4 10% 42% 31% 8%	800
	21st to end	Night	6% 2 13% 41% 33% 6%	800
October	1st to 10th	Night	8% 4 14% 42% 28% 4	800
	11th to 20th	Night	6% 5% 15% 40% 29% 5%	800
	21st to end	Night	5% 4 16% 41% 28% 6%	880
November	1st to 10th	Night	7% 4 19% 42% 24% 6%	820
	11th to 20th	Night	5% 5% 22% 45% 19% 4	840
	21st to end	Night	5% 6% 23% 39% 22% 5%	840
December	1st to 10th	Night	6% 6% 22% 44% 18% 4	840
	11th to 20th	Night	8% 8% 23% 43% 18% 1	840
	21st to end	Night	10% 11% 25% 39% 13% 2	924

Page generated at 2026-07-28 00:25:23. Version ac07

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