Ring Place
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ring Place clear sky chart from 2005-11-06 to 2026-02-01.

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 4 2 5% 4 4 5% 4 6% 8% 57%	135841
	Night	3 4 1 4 3 3 3 3 5% 7% 64%	133602
Transparency	Day	23% 6% 9% 21% 26% 15%	130858
	Night	19% 5% 10% 23% 28% 15%	129589
Seeing	Day	11% 20% 30% 24% 13% 3	16946
	Night	7% 15% 34% 28% 14% 2	27105

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	5% 4 6% 2 2 2 2 5% 7% 64%	3718
	11th to 20th	Day	1 2 2 5% 3 3 3 2 5% 6% 69%	4190
	21st to end	Day	1 8% 2 5% 3 3 3 3 5% 6% 62%	4609
February	1st to 10th	Day	1 3 2 5% 2 3 3 3 5% 9% 65%	1865
	11th to 20th	Day	3 1 4 3 2 3 4 4 8% 68%	1949
	21st to end	Day	3 2 3 3 4 3 4 5% 6% 66%	1650
March	1st to 10th	Day	1 6% 3 4 2 2 2 3 4 6% 69%	4500
	11th to 20th	Day	3 10% 3 7% 4 4 4 3 5% 7% 50%	5000
	21st to end	Day	1 4 2 4 3 3 4 3 6% 9% 61%	5792
April	1st to 10th	Day	1 5% 1 3 3 3 4 3 8% 9% 60%	2400
	11th to 20th	Day	3 6% 2 4 3 3 4 3 5% 6% 60%	2371
	21st to end	Day	4 6% 1 4 5% 4 5% 4 6% 9% 54%	2400
May	1st to 10th	Day	9% 7% 2 4 3 3 4 3 6% 7% 52%	5455
	11th to 20th	Day	5% 4 1 4 3 4 4 4 5% 6% 60%	5949
	21st to end	Day	2 3 1 4 3 4 4 4 7% 8% 59%	6925
June	1st to 10th	Day	3 3 1 4 4 5% 5% 5% 8% 10% 52%	2800
	11th to 20th	Day	2 2 1 3 3 4 4 5% 8% 8% 61%	2800
	21st to end	Day	5% 4 2 4 5% 5% 7% 5% 8% 9% 46%	2800
July	1st to 10th	Day	3 2 1 4 4 5% 6% 6% 8% 9% 52%	6339
	11th to 20th	Day	3 3 2 5% 5% 7% 9% 7% 10% 10% 38%	6298
	21st to end	Day	5% 5% 2 8% 7% 8% 8% 6% 9% 9% 32%	6401
August	1st to 10th	Day	5% 3 2 5% 5% 6% 7% 6% 8% 10% 42%	5566
	11th to 20th	Day	3 3 2 6% 5% 7% 8% 6% 9% 10% 41%	5366
	21st to end	Day	4 4 2 7% 6% 6% 7% 5% 8% 11% 40%	5984
September	1st to 10th	Day	6% 6% 2 6% 4 5% 5% 5% 7% 7% 47%	2400
	11th to 20th	Day	6% 4 1 4 4 4 4 3 5% 8% 58%	2372
	21st to end	Day	5% 3 1 3 3 4 3 3 5% 7% 63%	2200
October	1st to 10th	Day	4 2 1 4 3 2 3 3 4 7% 67%	3321
	11th to 20th	Day	5% 3 1 4 3 3 4 4 5% 8% 60%	3250
	21st to end	Day	2 3 1 2 2 2 2 1 3 5% 78%	3548
November	1st to 10th	Day	1 2 2 2 2 2 2 5% 6% 75%	1863
	11th to 20th	Day	1 2 1 3 2 2 3 3 3 7% 73%	1890
	21st to end	Day	1 4 1 4 3 3 2 3 5% 6% 67%	1890
December	1st to 10th	Day	2 1 2 1 1 2 2 3 7% 80%	2782
	11th to 20th	Day	1 3 2 3 2 2 2 3 4 7% 71%	3106
	21st to end	Day	1 2 1 3 2 3 3 3 5% 7% 71%	4092
January	1st to 10th	Night	3 2 7% 4 3 3 3 5% 6% 64%	6467
	11th to 20th	Night	3 2 4 2 2 2 2 4 6% 72%	6039
	21st to end	Night	4 2 5% 3 3 3 3 5% 6% 66%	6611
February	1st to 10th	Night	3 2 4 3 3 3 3 4 6% 69%	2535
	11th to 20th	Night	1 5% 2 5% 3 2 2 2 4 8% 66%	2338
	21st to end	Night	1 3 1 4 3 2 3 3 4 6% 70%	1980
March	1st to 10th	Night	1 6% 2 4 2 1 2 2 4 6% 71%	5359
	11th to 20th	Night	3 9% 2 4 2 2 3 3 4 6% 62%	5000
	21st to end	Night	1 4 1 3 2 2 2 2 3 6% 74%	5168
April	1st to 10th	Night	1 4 1 3 2 2 3 2 4 7% 70%	2000
	11th to 20th	Night	3 6% 1 3 3 3 4 3 4 6% 64%	1977
	21st to end	Night	3 5% 1 4 3 3 3 3 5% 7% 65%	2000
May	1st to 10th	Night	8% 6% 1 3 2 2 3 2 5% 7% 60%	4522
	11th to 20th	Night	6% 4 1 3 2 2 3 3 5% 7% 64%	3950
	21st to end	Night	3 5% 1 4 3 2 3 3 5% 7% 64%	3972
June	1st to 10th	Night	2 3 1 4 3 3 3 4 6% 12% 58%	1600
	11th to 20th	Night	2 1 1 2 2 3 4 4 6% 7% 68%	1600
	21st to end	Night	7% 3 1 3 4 3 5% 4 8% 10% 52%	1600
July	1st to 10th	Night	7% 5% 2 5% 4 4 5% 5% 7% 8% 49%	3640
	11th to 20th	Night	2 3 1 5% 4 5% 6% 6% 10% 12% 47%	3677
	21st to end	Night	4 4 1 6% 4 5% 7% 6% 10% 12% 42%	4472
August	1st to 10th	Night	4 4 2 5% 4 5% 5% 6% 8% 11% 47%	4242
	11th to 20th	Night	3 2 1 4 3 4 5% 5% 10% 15% 47%	4483
	21st to end	Night	6% 4 2 5% 4 5% 6% 6% 9% 12% 40%	4993
September	1st to 10th	Night	5% 3 1 4 4 3 5% 3 5% 10% 57%	2000
	11th to 20th	Night	5% 3 1 3 2 3 3 3 5% 7% 66%	2026
	21st to end	Night	4 4 1 3 3 3 3 3 4 7% 65%	2200
October	1st to 10th	Night	3 3 1 2 2 3 3 2 4 5% 73%	3851
	11th to 20th	Night	6% 3 1 3 2 2 2 2 4 6% 69%	3898
	21st to end	Night	2 3 1 3 2 2 2 2 3 4 78%	4252
November	1st to 10th	Night	1 3 2 2 1 2 3 3 5% 76%	2630
	11th to 20th	Night	1 2 1 2 2 2 2 2 4 6% 77%	2730
	21st to end	Night	1 4 1 3 2 3 3 3 5% 6% 69%	2730
December	1st to 10th	Night	2 2 3 2 1 2 1 3 6% 78%	4611
	11th to 20th	Night	1 3 1 3 2 2 2 2 3 7% 74%	5321
	21st to end	Night	1 3 2 4 3 3 3 3 5% 7% 67%	7128

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	19% 4 7% 27% 32% 12%	3719
	11th to 20th	Day	16% 4 5% 26% 32% 17%	4190
	21st to end	Day	23% 4 6% 20% 30% 17%	4609
February	1st to 10th	Day	17% 3 9% 27% 28% 16%	1865
	11th to 20th	Day	16% 4 7% 27% 30% 14%	1959
	21st to end	Day	18% 4 5% 20% 31% 23%	1650
March	1st to 10th	Day	16% 5% 3 14% 34% 28%	4500
	11th to 20th	Day	31% 6% 5% 15% 30% 13%	5000
	21st to end	Day	19% 5% 5% 36% 29% 5%	5792
April	1st to 10th	Day	18% 5% 7% 26% 29% 15%	2400
	11th to 20th	Day	24% 5% 6% 25% 25% 17%	2374
	21st to end	Day	23% 6% 10% 23% 27% 11%	2400
May	1st to 10th	Day	30% 5% 10% 18% 20% 17%	5455
	11th to 20th	Day	23% 6% 7% 13% 30% 22%	5953
	21st to end	Day	19% 7% 11% 17% 21% 25%	6926
June	1st to 10th	Day	23% 9% 13% 20% 20% 14%	2800
	11th to 20th	Day	18% 6% 9% 17% 23% 27%	2800
	21st to end	Day	29% 8% 11% 18% 18% 16%	2800
July	1st to 10th	Day	23% 8% 14% 16% 20% 18%	6271
	11th to 20th	Day	33% 9% 19% 26% 9% 3	6223
	21st to end	Day	40% 10% 16% 20% 11% 4	6217
August	1st to 10th	Day	40% 10% 19% 18% 8% 5%	4050
	11th to 20th	Day	30% 7% 17% 21% 13% 12%	3882
	21st to end	Day	34% 7% 18% 24% 15% 3	4311
September	1st to 10th	Day	32% 6% 12% 21% 20% 9%	2400
	11th to 20th	Day	25% 5% 10% 17% 26% 17%	2372
	21st to end	Day	21% 4 7% 21% 31% 15%	2200
October	1st to 10th	Day	17% 5% 5% 19% 33% 22%	3321
	11th to 20th	Day	22% 5% 6% 20% 32% 15%	3250
	21st to end	Day	12% 2 4 16% 41% 25%	3548
November	1st to 10th	Day	12% 3 4 24% 37% 20%	1863
	11th to 20th	Day	13% 4 5% 26% 37% 16%	1890
	21st to end	Day	19% 3 6% 18% 35% 19%	1890
December	1st to 10th	Day	8% 3 7% 24% 43% 15%	2782
	11th to 20th	Day	14% 4 6% 23% 37% 15%	3104
	21st to end	Day	11% 5% 6% 27% 39% 13%	4092
January	1st to 10th	Night	21% 4 5% 21% 37% 11%	6467
	11th to 20th	Night	17% 3 6% 24% 33% 18%	6039
	21st to end	Night	20% 4 8% 22% 29% 17%	6611
February	1st to 10th	Night	17% 5% 7% 29% 27% 14%	2535
	11th to 20th	Night	20% 5% 8% 28% 28% 12%	2338
	21st to end	Night	16% 3 5% 22% 34% 20%	1980
March	1st to 10th	Night	17% 3 4 14% 35% 28%	5359
	11th to 20th	Night	24% 4 6% 17% 30% 17%	5000
	21st to end	Night	14% 4 5% 39% 31% 7%	5168
April	1st to 10th	Night	15% 4 8% 28% 27% 16%	2000
	11th to 20th	Night	20% 5% 7% 25% 28% 16%	1977
	21st to end	Night	20% 5% 13% 26% 25% 11%	2000
May	1st to 10th	Night	24% 4 10% 24% 21% 16%	4519
	11th to 20th	Night	20% 6% 8% 21% 25% 20%	3951
	21st to end	Night	20% 5% 12% 15% 22% 25%	3972
June	1st to 10th	Night	19% 8% 15% 23% 19% 16%	1600
	11th to 20th	Night	14% 5% 9% 19% 26% 26%	1600
	21st to end	Night	24% 8% 15% 19% 20% 15%	1600
July	1st to 10th	Night	30% 8% 14% 18% 14% 16%	3600
	11th to 20th	Night	25% 8% 29% 27% 7% 4	3629
	21st to end	Night	31% 8% 23% 23% 12% 3	4344
August	1st to 10th	Night	36% 10% 24% 17% 8% 5%	3082
	11th to 20th	Night	23% 7% 25% 23% 15% 7%	3243
	21st to end	Night	29% 8% 26% 24% 11% 2	3597
September	1st to 10th	Night	22% 7% 15% 29% 19% 8%	2000
	11th to 20th	Night	18% 5% 13% 18% 30% 16%	2026
	21st to end	Night	18% 5% 9% 24% 31% 13%	2200
October	1st to 10th	Night	16% 4 6% 19% 37% 19%	3851
	11th to 20th	Night	18% 3 8% 21% 35% 15%	3898
	21st to end	Night	14% 2 4 18% 39% 23%	4252
November	1st to 10th	Night	12% 3 5% 24% 37% 18%	2630
	11th to 20th	Night	10% 4 5% 29% 35% 17%	2730
	21st to end	Night	16% 5% 7% 23% 30% 19%	2730
December	1st to 10th	Night	12% 3 6% 28% 39% 12%	4611
	11th to 20th	Night	12% 3 5% 24% 36% 20%	5322
	21st to end	Night	17% 5% 7% 26% 32% 13%	7128

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	17% 28% 29% 18% 7% 1	330
	11th to 20th	Day	17% 26% 32% 21% 4	330
	21st to end	Day	9% 28% 35% 21% 7% 1	363
February	1st to 10th	Day	19% 32% 30% 14% 4 1	300
	11th to 20th	Day	16% 38% 31% 12% 4	300
	21st to end	Day	19% 35% 31% 12% 3	249
March	1st to 10th	Day	16% 33% 28% 18% 5% 1	300
	11th to 20th	Day	17% 29% 32% 17% 5% 1	500
	21st to end	Day	21% 39% 27% 10% 2 1	550
April	1st to 10th	Day	15% 35% 33% 12% 4 1	500
	11th to 20th	Day	21% 35% 30% 12% 1	492
	21st to end	Day	14% 37% 35% 12% 3	500
May	1st to 10th	Day	14% 29% 39% 14% 4 1	505
	11th to 20th	Day	11% 20% 33% 23% 10% 2	725
	21st to end	Day	8% 22% 32% 24% 12% 2	789
June	1st to 10th	Day	4 12% 32% 32% 19% 2	730
	11th to 20th	Day	4 15% 33% 29% 16% 3	730
	21st to end	Day	6% 10% 32% 29% 18% 5%	730
July	1st to 10th	Day	4 6% 24% 34% 26% 7%	721
	11th to 20th	Day	6% 3 16% 28% 36% 11%	702
	21st to end	Day	10% 2 15% 34% 30% 8%	575
August	1st to 10th	Day	10% 5% 21% 37% 19% 7%	527
	11th to 20th	Day	5% 7% 23% 38% 23% 4	517
	21st to end	Day	7% 5% 25% 38% 20% 5%	583
September	1st to 10th	Day	8% 8% 28% 31% 22% 4	530
	11th to 20th	Day	6% 10% 35% 30% 16% 3	502
	21st to end	Day	8% 14% 33% 22% 18% 5%	330
October	1st to 10th	Day	9% 20% 26% 25% 15% 5%	330
	11th to 20th	Day	14% 24% 30% 21% 6% 5%	330
	21st to end	Day	15% 20% 34% 22% 7% 2	363
November	1st to 10th	Day	10% 28% 34% 21% 7% 1	330
	11th to 20th	Day	12% 25% 31% 20% 10% 2	330
	21st to end	Day	12% 25% 35% 20% 7% 2	330
December	1st to 10th	Day	12% 32% 31% 18% 6% 1	330
	11th to 20th	Day	13% 26% 37% 18% 5%	330
	21st to end	Day	22% 30% 31% 15% 2	363
January	1st to 10th	Night	9% 21% 34% 25% 9% 2	1050
	11th to 20th	Night	8% 22% 37% 23% 8% 2	856
	21st to end	Night	5% 19% 41% 25% 9% 1	924
February	1st to 10th	Night	7% 22% 45% 20% 7%	800
	11th to 20th	Night	8% 25% 42% 20% 5%	784
	21st to end	Night	5% 30% 46% 17% 2	660
March	1st to 10th	Night	8% 26% 39% 21% 5% 1	800
	11th to 20th	Night	10% 17% 37% 28% 8% 1	800
	21st to end	Night	8% 26% 43% 19% 3	740
April	1st to 10th	Night	7% 24% 47% 19% 3	600
	11th to 20th	Night	9% 19% 44% 22% 6%	593
	21st to end	Night	8% 17% 43% 27% 5%	600
May	1st to 10th	Night	8% 13% 43% 29% 8%	600
	11th to 20th	Night	10% 9% 33% 32% 14% 1	591
	21st to end	Night	6% 13% 34% 34% 12% 1	650
June	1st to 10th	Night	4 6% 28% 42% 18% 2	600
	11th to 20th	Night	2 6% 35% 44% 11% 1	600
	21st to end	Night	8% 3 24% 36% 27% 2	600
July	1st to 10th	Night	6% 2 16% 40% 32% 3	585
	11th to 20th	Night	3 2 11% 34% 43% 6%	582
	21st to end	Night	5% 1 10% 28% 47% 9%	657
August	1st to 10th	Night	6% 2 11% 35% 41% 6%	597
	11th to 20th	Night	7% 1 13% 40% 35% 4	594
	21st to end	Night	6% 2 16% 41% 31% 5%	660
September	1st to 10th	Night	6% 2 19% 40% 29% 4	600
	11th to 20th	Night	6% 3 26% 40% 24% 2	600
	21st to end	Night	7% 5% 27% 39% 20% 2	600
October	1st to 10th	Night	6% 8% 34% 36% 13% 3	757
	11th to 20th	Night	5% 11% 41% 28% 12% 3	800
	21st to end	Night	9% 15% 34% 25% 14% 4	880
November	1st to 10th	Night	6% 15% 37% 29% 10% 2	990
	11th to 20th	Night	6% 17% 37% 28% 9% 2	1050
	21st to end	Night	7% 18% 37% 25% 11% 2	1050
December	1st to 10th	Night	6% 22% 42% 23% 6% 2	1050
	11th to 20th	Night	9% 22% 38% 24% 7% 1	1050
	21st to end	Night	11% 22% 41% 20% 5% 1	1155

Page generated at 2026-01-28 23:21:46. Version ac07

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