Seclusion Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Seclusion Ranch 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	4 4 1 4 3 3 4 3 6% 8% 60%	146632
	Night	5% 5% 2 5% 3 3 4 3 5% 7% 59%	143858
Transparency	Day	22% 4 7% 23% 28% 16%	141663
	Night	25% 3 8% 23% 27% 14%	139837
Seeing	Day	6% 7% 25% 31% 22% 8%	17834
	Night	7% 6% 33% 40% 14% 1	27779

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 7% 3 5% 3 3 2 3 4 7% 62%	4720
	11th to 20th	Day	1 3 2 4 3 3 3 3 5% 5% 68%	4980
	21st to end	Day	2 6% 3 6% 3 3 3 3 3 6% 62%	5844
February	1st to 10th	Day	3 6% 3 5% 4 3 3 3 5% 8% 59%	2011
	11th to 20th	Day	2 5% 2 5% 4 4 4 3 6% 6% 60%	2049
	21st to end	Day	2 5% 2 4 3 4 2 3 5% 4 65%	1730
March	1st to 10th	Day	2 5% 2 4 2 3 3 3 4 5% 67%	4600
	11th to 20th	Day	5% 6% 2 4 3 4 4 3 5% 8% 56%	4908
	21st to end	Day	3 4 2 5% 3 3 4 4 5% 7% 61%	6049
April	1st to 10th	Day	4 5% 1 3 3 3 4 3 5% 7% 62%	2520
	11th to 20th	Day	5% 6% 1 4 3 4 4 3 5% 7% 57%	2491
	21st to end	Day	7% 5% 1 4 3 4 4 3 5% 7% 56%	2520
May	1st to 10th	Day	11% 5% 1 4 3 3 4 3 4 6% 56%	7410
	11th to 20th	Day	4 3 1 4 3 3 4 4 6% 7% 62%	7627
	21st to end	Day	6% 4 1 4 3 3 4 4 6% 9% 56%	9018
June	1st to 10th	Day	5% 4 1 4 2 4 4 5% 7% 11% 54%	2940
	11th to 20th	Day	4 2 1 3 3 3 4 4 7% 8% 61%	2940
	21st to end	Day	4 3 1 4 3 4 4 5% 8% 10% 54%	2940
July	1st to 10th	Day	2 2 1 3 3 3 5% 5% 7% 10% 60%	6479
	11th to 20th	Day	2 2 1 3 2 4 4 5% 8% 12% 56%	6480
	21st to end	Day	3 2 1 5% 4 6% 6% 5% 8% 10% 48%	6846
August	1st to 10th	Day	4 2 1 4 4 5% 6% 5% 9% 11% 50%	5464
	11th to 20th	Day	2 2 1 4 3 5% 5% 4 7% 11% 56%	5366
	21st to end	Day	3 3 2 5% 4 5% 5% 5% 8% 10% 50%	5984
September	1st to 10th	Day	6% 3 1 3 3 3 4 4 6% 8% 61%	2400
	11th to 20th	Day	4 2 1 3 3 3 4 4 5% 8% 64%	2324
	21st to end	Day	5% 3 1 3 3 2 3 2 4 6% 67%	2200
October	1st to 10th	Day	4 2 1 2 1 2 2 2 3 4 78%	3462
	11th to 20th	Day	3 2 1 3 2 3 3 3 5% 7% 68%	3250
	21st to end	Day	4 3 2 3 2 2 2 1 3 4 75%	3404
November	1st to 10th	Day	3 3 1 2 1 2 2 3 5% 7% 70%	1853
	11th to 20th	Day	2 4 1 3 3 2 2 2 4 6% 71%	1890
	21st to end	Day	5% 5% 2 4 3 2 3 2 4 5% 66%	1890
December	1st to 10th	Day	1 4 2 3 2 1 2 2 3 6% 75%	2845
	11th to 20th	Day	2 3 1 3 2 2 3 3 4 8% 67%	3106
	21st to end	Day	2 5% 3 6% 4 4 4 2 3 6% 61%	4092
January	1st to 10th	Night	3 9% 3 6% 3 3 4 3 5% 6% 55%	8201
	11th to 20th	Night	1 4 1 4 3 2 3 2 4 6% 70%	8052
	21st to end	Night	2 5% 3 5% 3 3 3 3 3 7% 64%	8370
February	1st to 10th	Night	3 7% 2 6% 3 3 3 3 4 5% 60%	2607
	11th to 20th	Night	5% 6% 3 5% 3 3 3 3 5% 7% 56%	2458
	21st to end	Night	3 6% 2 3 2 2 3 3 4 5% 66%	2076
March	1st to 10th	Night	5% 6% 2 3 2 2 3 2 4 5% 66%	5494
	11th to 20th	Night	7% 8% 2 5% 3 3 3 3 4 6% 56%	5300
	21st to end	Night	4 5% 1 4 3 3 4 4 5% 8% 59%	5146
April	1st to 10th	Night	4 5% 1 4 3 3 3 3 6% 7% 61%	2100
	11th to 20th	Night	7% 6% 2 5% 3 3 4 3 5% 6% 56%	2077
	21st to end	Night	8% 5% 1 4 4 4 4 3 5% 7% 54%	2100
May	1st to 10th	Night	11% 5% 2 5% 4 3 3 3 3 6% 55%	5533
	11th to 20th	Night	8% 4 1 4 3 3 4 3 6% 7% 58%	5265
	21st to end	Night	9% 6% 2 6% 3 4 4 3 5% 6% 51%	5185
June	1st to 10th	Night	5% 4 1 5% 4 4 4 4 6% 9% 54%	1680
	11th to 20th	Night	4 2 1 3 4 4 4 5% 7% 8% 60%	1680
	21st to end	Night	4 5% 2 6% 4 5% 5% 4 6% 10% 49%	1680
July	1st to 10th	Night	8% 4 2 4 3 4 5% 5% 8% 10% 47%	3720
	11th to 20th	Night	4 3 1 6% 5% 5% 6% 6% 9% 11% 45%	3720
	21st to end	Night	6% 4 2 7% 5% 5% 6% 6% 9% 10% 40%	4230
August	1st to 10th	Night	7% 4 2 6% 5% 5% 6% 5% 8% 11% 41%	4333
	11th to 20th	Night	4 3 2 4 5% 5% 6% 6% 10% 13% 44%	4483
	21st to end	Night	6% 5% 2 6% 5% 6% 6% 6% 8% 10% 40%	4993
September	1st to 10th	Night	5% 3 2 4 4 4 4 3 6% 8% 57%	2000
	11th to 20th	Night	6% 2 1 3 2 2 4 3 5% 8% 64%	2075
	21st to end	Night	5% 3 1 3 3 3 3 3 4 5% 66%	2200
October	1st to 10th	Night	5% 2 1 3 2 2 2 2 4 6% 71%	3718
	11th to 20th	Night	6% 3 1 3 2 3 3 3 4 7% 65%	3898
	21st to end	Night	3 4 1 3 2 2 3 2 3 4 73%	4348
November	1st to 10th	Night	4 3 1 2 2 2 3 3 4 6% 70%	2665
	11th to 20th	Night	2 4 2 2 2 2 2 1 3 5% 74%	2730
	21st to end	Night	4 6% 2 4 3 2 3 2 4 6% 64%	2730
December	1st to 10th	Night	1 4 2 4 2 2 2 2 4 5% 71%	4562
	11th to 20th	Night	1 3 2 4 3 3 3 3 5% 8% 66%	5321
	21st to end	Night	3 6% 2 6% 4 4 4 3 5% 7% 57%	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	25% 1 4 29% 34% 8%	4723
	11th to 20th	Day	19% 1 6% 24% 33% 16%	4980
	21st to end	Day	27% 1 4 20% 34% 14%	5844
February	1st to 10th	Day	25% 3 6% 26% 27% 14%	2011
	11th to 20th	Day	25% 2 6% 25% 30% 12%	2059
	21st to end	Day	21% 3 3 18% 29% 26%	1730
March	1st to 10th	Day	20% 2 3 12% 34% 29%	4600
	11th to 20th	Day	28% 2 5% 15% 33% 16%	4908
	21st to end	Day	23% 3 4 35% 28% 8%	6049
April	1st to 10th	Day	23% 4 6% 22% 28% 18%	2520
	11th to 20th	Day	27% 4 5% 24% 22% 18%	2494
	21st to end	Day	27% 3 7% 24% 27% 11%	2520
May	1st to 10th	Day	30% 4 7% 24% 24% 11%	7410
	11th to 20th	Day	22% 3 8% 17% 28% 23%	7631
	21st to end	Day	25% 4 11% 23% 17% 20%	9019
June	1st to 10th	Day	25% 4 11% 25% 22% 13%	2940
	11th to 20th	Day	19% 4 8% 19% 26% 24%	2940
	21st to end	Day	24% 5% 8% 21% 24% 19%	2940
July	1st to 10th	Day	18% 5% 10% 20% 28% 18%	6411
	11th to 20th	Day	18% 7% 13% 27% 27% 8%	6405
	21st to end	Day	28% 7% 13% 22% 20% 11%	6652
August	1st to 10th	Day	27% 7% 18% 25% 15% 8%	3970
	11th to 20th	Day	23% 6% 12% 23% 21% 16%	3882
	21st to end	Day	22% 6% 12% 29% 20% 10%	4311
September	1st to 10th	Day	22% 5% 7% 23% 27% 16%	2400
	11th to 20th	Day	19% 3 8% 19% 26% 24%	2324
	21st to end	Day	20% 3 6% 19% 32% 21%	2200
October	1st to 10th	Day	13% 2 5% 16% 35% 30%	3462
	11th to 20th	Day	16% 3 6% 23% 33% 18%	3250
	21st to end	Day	16% 2 2 16% 41% 24%	3404
November	1st to 10th	Day	14% 2 5% 22% 33% 24%	1853
	11th to 20th	Day	17% 2 3 26% 36% 16%	1890
	21st to end	Day	22% 1 6% 18% 32% 21%	1890
December	1st to 10th	Day	15% 1 5% 26% 40% 12%	2845
	11th to 20th	Day	17% 3 4 23% 38% 16%	3104
	21st to end	Day	27% 2 3 25% 28% 15%	4092
January	1st to 10th	Night	31% 2 3 28% 29% 7%	8202
	11th to 20th	Night	18% 1 7% 26% 31% 17%	8052
	21st to end	Night	23% 1 7% 22% 32% 13%	8370
February	1st to 10th	Night	26% 2 5% 23% 29% 14%	2607
	11th to 20th	Night	28% 2 7% 25% 24% 12%	2458
	21st to end	Night	21% 2 3 21% 36% 18%	2076
March	1st to 10th	Night	23% 2 2 12% 35% 26%	5494
	11th to 20th	Night	31% 2 6% 14% 29% 17%	5300
	21st to end	Night	24% 3 5% 35% 26% 7%	5146
April	1st to 10th	Night	22% 3 7% 25% 27% 17%	2100
	11th to 20th	Night	28% 3 9% 23% 21% 16%	2077
	21st to end	Night	29% 4 10% 25% 21% 11%	2100
May	1st to 10th	Night	33% 3 8% 27% 18% 12%	5531
	11th to 20th	Night	26% 3 8% 26% 20% 18%	5266
	21st to end	Night	34% 5% 13% 17% 12% 20%	5186
June	1st to 10th	Night	25% 5% 16% 23% 17% 14%	1680
	11th to 20th	Night	20% 4 10% 20% 23% 23%	1680
	21st to end	Night	30% 5% 10% 19% 20% 16%	1680
July	1st to 10th	Night	31% 6% 13% 22% 19% 10%	3680
	11th to 20th	Night	30% 7% 18% 24% 17% 4	3672
	21st to end	Night	36% 7% 14% 17% 20% 6%	4113
August	1st to 10th	Night	39% 7% 17% 21% 10% 5%	3151
	11th to 20th	Night	29% 7% 18% 23% 18% 5%	3243
	21st to end	Night	27% 7% 16% 28% 16% 6%	3597
September	1st to 10th	Night	24% 4 11% 24% 24% 13%	2000
	11th to 20th	Night	20% 4 9% 22% 25% 20%	2075
	21st to end	Night	21% 3 6% 20% 32% 19%	2200
October	1st to 10th	Night	16% 3 6% 18% 35% 23%	3718
	11th to 20th	Night	21% 3 7% 20% 31% 19%	3898
	21st to end	Night	18% 2 3 20% 38% 20%	4348
November	1st to 10th	Night	16% 3 5% 24% 31% 22%	2665
	11th to 20th	Night	16% 2 4 24% 37% 18%	2730
	21st to end	Night	23% 2 6% 20% 30% 19%	2730
December	1st to 10th	Night	17% 2 5% 30% 35% 11%	4562
	11th to 20th	Night	18% 3 4 20% 41% 15%	5322
	21st to end	Night	28% 2 4 24% 30% 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	5% 9% 29% 36% 18% 4	330
	11th to 20th	Day	6% 9% 30% 38% 13% 4	330
	21st to end	Day	3 6% 32% 37% 16% 5%	363
February	1st to 10th	Day	3 11% 40% 33% 12% 2	330
	11th to 20th	Day	6% 9% 39% 35% 12%	330
	21st to end	Day	5% 10% 39% 35% 11%	273
March	1st to 10th	Day	6% 8% 32% 38% 15% 2	330
	11th to 20th	Day	10% 14% 30% 26% 15% 4	442
	21st to end	Day	10% 18% 35% 26% 10% 2	594
April	1st to 10th	Day	8% 16% 35% 29% 10% 3	540
	11th to 20th	Day	11% 16% 37% 27% 8% 2	532
	21st to end	Day	11% 16% 36% 24% 12% 2	540
May	1st to 10th	Day	11% 13% 29% 31% 14% 2	664
	11th to 20th	Day	10% 9% 25% 32% 20% 4	775
	21st to end	Day	7% 8% 30% 30% 20% 5%	844
June	1st to 10th	Day	7% 5% 22% 28% 28% 9%	780
	11th to 20th	Day	5% 4 29% 32% 22% 8%	780
	21st to end	Day	5% 5% 24% 32% 26% 8%	780
July	1st to 10th	Day	5% 2 16% 31% 34% 12%	771
	11th to 20th	Day	2 1 10% 32% 40% 15%	768
	21st to end	Day	3 1 7% 27% 37% 24%	761
August	1st to 10th	Day	4 3 14% 31% 30% 18%	527
	11th to 20th	Day	3 1 14% 31% 35% 15%	517
	21st to end	Day	4 2 13% 35% 33% 14%	583
September	1st to 10th	Day	5% 2 17% 30% 33% 13%	530
	11th to 20th	Day	5% 2 21% 33% 27% 12%	454
	21st to end	Day	7% 2 19% 25% 30% 16%	330
October	1st to 10th	Day	7% 3 23% 27% 24% 15%	330
	11th to 20th	Day	3 7% 28% 31% 20% 10%	330
	21st to end	Day	8% 6% 23% 31% 26% 6%	363
November	1st to 10th	Day	6% 7% 28% 30% 24% 5%	330
	11th to 20th	Day	5% 4 27% 34% 25% 5%	330
	21st to end	Day	10% 7% 26% 33% 18% 5%	330
December	1st to 10th	Day	3 8% 32% 36% 15% 6%	330
	11th to 20th	Day	7% 7% 28% 38% 18% 3	330
	21st to end	Day	4 9% 41% 34% 9% 2	363
January	1st to 10th	Night	5% 6% 36% 39% 12% 2	1050
	11th to 20th	Night	6% 6% 38% 36% 13% 1	982
	21st to end	Night	6% 4 35% 44% 11% 1	924
February	1st to 10th	Night	7% 6% 37% 42% 8%	840
	11th to 20th	Night	7% 9% 41% 35% 8%	824
	21st to end	Night	7% 8% 44% 36% 4	692
March	1st to 10th	Night	7% 6% 43% 37% 6% 1	840
	11th to 20th	Night	9% 9% 36% 37% 7%	840
	21st to end	Night	8% 10% 43% 34% 6%	719
April	1st to 10th	Night	7% 10% 51% 29% 3	630
	11th to 20th	Night	11% 11% 43% 31% 4	623
	21st to end	Night	11% 10% 39% 33% 7%	630
May	1st to 10th	Night	10% 9% 36% 35% 8%	630
	11th to 20th	Night	13% 7% 31% 34% 13% 1	621
	21st to end	Night	10% 8% 37% 36% 8% 1	683
June	1st to 10th	Night	4 5% 37% 38% 16% 1	630
	11th to 20th	Night	4 5% 38% 44% 9%	630
	21st to end	Night	6% 4 31% 42% 17%	630
July	1st to 10th	Night	7% 3 24% 42% 23% 1	615
	11th to 20th	Night	4 1 16% 48% 28% 2	612
	21st to end	Night	7% 1 14% 39% 36% 2	687
August	1st to 10th	Night	7% 2 15% 39% 35% 3	597
	11th to 20th	Night	7% 2 17% 48% 25% 1	594
	21st to end	Night	5% 2 18% 49% 23% 3	660
September	1st to 10th	Night	6% 3 21% 46% 23% 1	600
	11th to 20th	Night	6% 2 29% 41% 20% 2	600
	21st to end	Night	6% 7% 24% 44% 19% 1	600
October	1st to 10th	Night	9% 5% 29% 41% 16% 1	676
	11th to 20th	Night	4 5% 29% 43% 17% 2	800
	21st to end	Night	6% 4 30% 40% 17% 2	940
November	1st to 10th	Night	5% 4 29% 47% 15% 1	1025
	11th to 20th	Night	4 7% 31% 44% 13% 1	1050
	21st to end	Night	8% 5% 29% 43% 14% 2	1050
December	1st to 10th	Night	4 4 36% 43% 12% 1	1050
	11th to 20th	Night	5% 5% 36% 43% 11% 1	1050
	21st to end	Night	6% 8% 37% 40% 9% 1	1155

Page generated at 2026-07-28 01:25:27. Version ac07

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