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 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	4 4 1 4 3 3 4 3 5% 8% 61%	112873
	Night	4 5% 2 4 3 3 4 3 5% 7% 59%	115255
Transparency	Day	22% 4 7% 23% 28% 16%	112619
	Night	25% 3 8% 23% 27% 14%	115100
Seeing	Day	6% 7% 25% 31% 23% 8%	15882
	Night	7% 5% 32% 41% 14% 1	26061

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	1 7% 3 5% 2 2 2 3 4 7% 63%	3638
	11th to 20th	Day	1 4 2 4 3 4 4 3 6% 6% 62%	3824
	21st to end	Day	3 6% 3 6% 3 3 3 3 3 5% 62%	4510
February	1st to 10th	Day	3 6% 3 5% 4 3 3 3 5% 8% 58%	1915
	11th to 20th	Day	1 5% 2 5% 4 4 4 3 5% 6% 61%	1949
	21st to end	Day	2 5% 2 4 3 4 3 3 6% 4 64%	1650
March	1st to 10th	Day	2 5% 2 4 2 3 3 3 4 6% 66%	3230
	11th to 20th	Day	7% 7% 2 4 4 4 5% 3 5% 7% 54%	3455
	21st to end	Day	4 5% 2 5% 3 3 4 3 5% 7% 60%	4199
April	1st to 10th	Day	4 5% 1 3 3 3 4 4 5% 7% 62%	2280
	11th to 20th	Day	6% 6% 1 4 3 4 4 3 5% 7% 56%	2251
	21st to end	Day	7% 5% 1 4 4 4 4 4 5% 7% 55%	2280
May	1st to 10th	Day	6% 4 1 4 3 3 4 3 5% 6% 62%	3987
	11th to 20th	Day	6% 4 2 4 3 4 5% 4 6% 8% 54%	4082
	21st to end	Day	3 3 1 2 3 3 4 4 6% 9% 62%	4817
June	1st to 10th	Day	5% 4 1 3 2 4 4 5% 7% 11% 54%	2660
	11th to 20th	Day	5% 2 2 3 3 3 4 4 7% 8% 61%	2660
	21st to end	Day	4 3 1 4 3 4 4 5% 8% 10% 53%	2660
July	1st to 10th	Day	3 3 1 3 3 3 5% 5% 8% 10% 55%	4430
	11th to 20th	Day	1 2 1 3 2 4 4 5% 8% 12% 55%	4430
	21st to end	Day	4 2 1 4 4 5% 5% 5% 8% 9% 54%	4663
August	1st to 10th	Day	5% 3 2 5% 4 5% 6% 5% 8% 11% 48%	3861
	11th to 20th	Day	3 2 1 4 4 4 5% 4 6% 11% 56%	3726
	21st to end	Day	2 2 1 4 4 4 5% 5% 8% 10% 54%	4180
September	1st to 10th	Day	5% 3 1 3 3 3 4 4 6% 8% 60%	2280
	11th to 20th	Day	4 2 1 3 2 3 4 3 4 8% 65%	2208
	21st to end	Day	5% 2 1 3 3 2 3 2 4 6% 68%	2090
October	1st to 10th	Day	4 2 1 2 1 2 2 2 3 4 78%	3356
	11th to 20th	Day	4 2 1 3 2 3 3 3 5% 6% 67%	3150
	21st to end	Day	4 3 2 3 2 2 2 1 3 4 75%	3298
November	1st to 10th	Day	3 3 1 2 1 2 2 3 5% 7% 70%	1763
	11th to 20th	Day	2 4 1 3 3 2 2 2 4 6% 71%	1800
	21st to end	Day	5% 5% 2 4 3 2 2 2 4 5% 66%	1800
December	1st to 10th	Day	1 4 2 3 2 1 2 2 3 6% 75%	2761
	11th to 20th	Day	2 4 1 3 2 2 3 3 4 8% 67%	3026
	21st to end	Day	2 5% 3 6% 4 4 4 2 3 6% 61%	4004
January	1st to 10th	Night	3 8% 3 7% 3 3 3 3 4 6% 56%	6327
	11th to 20th	Night	2 5% 2 4 3 3 3 3 5% 6% 65%	6184
	21st to end	Night	2 5% 2 5% 3 3 3 3 4 7% 64%	6468
February	1st to 10th	Night	3 7% 3 6% 4 3 3 3 4 5% 60%	2483
	11th to 20th	Night	4 6% 3 5% 3 4 4 3 5% 7% 55%	2338
	21st to end	Night	3 6% 2 3 2 2 3 3 4 5% 65%	1980
March	1st to 10th	Night	5% 6% 2 3 2 3 3 3 4 6% 65%	3854
	11th to 20th	Night	10% 8% 2 4 3 3 4 3 4 6% 53%	3738
	21st to end	Night	5% 6% 1 4 3 3 4 4 5% 7% 60%	3580
April	1st to 10th	Night	4 5% 2 4 3 3 3 3 6% 7% 61%	1900
	11th to 20th	Night	8% 6% 2 5% 3 3 4 3 5% 6% 55%	1877
	21st to end	Night	9% 5% 1 5% 4 4 4 3 5% 6% 54%	1900
May	1st to 10th	Night	8% 4 1 4 3 3 3 4 4 5% 62%	2979
	11th to 20th	Night	11% 5% 1 4 3 4 4 3 6% 8% 50%	2823
	21st to end	Night	5% 3 2 4 3 4 4 4 6% 6% 60%	2766
June	1st to 10th	Night	5% 3 1 5% 3 4 4 5% 6% 9% 55%	1520
	11th to 20th	Night	4 2 1 3 4 3 4 5% 6% 7% 61%	1520
	21st to end	Night	4 5% 2 6% 4 5% 5% 4 7% 10% 48%	1520
July	1st to 10th	Night	11% 5% 2 5% 3 4 5% 5% 8% 9% 45%	2540
	11th to 20th	Night	3 3 2 7% 5% 5% 6% 5% 9% 11% 46%	2540
	21st to end	Night	5% 4 2 6% 4 4 5% 5% 8% 9% 48%	2882
August	1st to 10th	Night	9% 5% 2 7% 6% 6% 6% 6% 8% 12% 34%	3063
	11th to 20th	Night	4 3 2 5% 5% 5% 6% 6% 10% 12% 43%	3113
	21st to end	Night	3 3 1 4 4 5% 6% 6% 10% 12% 45%	3487
September	1st to 10th	Night	5% 3 2 4 3 4 4 3 6% 8% 57%	1900
	11th to 20th	Night	6% 2 1 3 2 2 4 3 5% 8% 65%	1971
	21st to end	Night	5% 3 1 3 3 3 3 2 4 5% 67%	2090
October	1st to 10th	Night	5% 2 1 2 2 2 2 2 4 6% 72%	3604
	11th to 20th	Night	6% 3 1 3 2 3 3 3 4 7% 65%	3778
	21st to end	Night	3 4 1 3 2 2 3 2 3 4 73%	4213
November	1st to 10th	Night	4 3 1 3 2 2 3 3 4 6% 70%	2535
	11th to 20th	Night	2 5% 2 2 2 2 2 1 3 5% 74%	2600
	21st to end	Night	4 6% 2 4 3 2 3 2 4 6% 64%	2600
December	1st to 10th	Night	1 4 2 4 2 2 2 2 4 5% 72%	4427
	11th to 20th	Night	1 3 2 4 3 3 3 3 5% 8% 65%	5181
	21st to end	Night	3 6% 2 6% 4 4 4 3 5% 7% 57%	6974

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% 1 5% 31% 30% 10%	3639
	11th to 20th	Day	23% 1 6% 23% 32% 16%	3824
	21st to end	Day	27% 1 4 22% 33% 13%	4510
February	1st to 10th	Day	25% 3 6% 26% 25% 15%	1915
	11th to 20th	Day	25% 3 6% 25% 29% 12%	1959
	21st to end	Day	22% 3 3 19% 28% 25%	1650
March	1st to 10th	Day	20% 3 4 16% 35% 23%	3230
	11th to 20th	Day	31% 3 7% 20% 30% 9%	3455
	21st to end	Day	26% 3 3 30% 28% 10%	4199
April	1st to 10th	Day	22% 4 6% 22% 27% 19%	2280
	11th to 20th	Day	28% 4 5% 25% 22% 17%	2254
	21st to end	Day	28% 3 7% 24% 27% 10%	2280
May	1st to 10th	Day	24% 4 8% 24% 22% 18%	3987
	11th to 20th	Day	28% 4 13% 22% 21% 12%	4086
	21st to end	Day	18% 4 11% 22% 21% 24%	4817
June	1st to 10th	Day	24% 4 11% 26% 22% 13%	2660
	11th to 20th	Day	20% 4 8% 18% 25% 25%	2660
	21st to end	Day	24% 5% 8% 21% 24% 17%	2660
July	1st to 10th	Day	22% 6% 11% 21% 25% 15%	4361
	11th to 20th	Day	18% 7% 11% 25% 28% 10%	4355
	21st to end	Day	24% 6% 11% 23% 23% 13%	4516
August	1st to 10th	Day	27% 7% 18% 25% 14% 8%	3847
	11th to 20th	Day	23% 6% 12% 22% 21% 16%	3762
	21st to end	Day	22% 6% 11% 30% 20% 11%	4179
September	1st to 10th	Day	22% 5% 7% 23% 26% 16%	2280
	11th to 20th	Day	19% 3 8% 19% 26% 25%	2208
	21st to end	Day	19% 3 6% 19% 32% 22%	2090
October	1st to 10th	Day	12% 2 5% 16% 34% 31%	3356
	11th to 20th	Day	17% 3 5% 23% 33% 18%	3150
	21st to end	Day	16% 2 2 15% 41% 25%	3298
November	1st to 10th	Day	15% 2 5% 22% 32% 25%	1763
	11th to 20th	Day	17% 2 3 26% 35% 17%	1800
	21st to end	Day	22% 1 5% 17% 33% 23%	1800
December	1st to 10th	Day	15% 2 5% 26% 40% 13%	2761
	11th to 20th	Day	17% 3 4 23% 37% 15%	3024
	21st to end	Day	27% 2 3 25% 28% 15%	4004
January	1st to 10th	Night	31% 1 3 30% 25% 8%	6327
	11th to 20th	Night	22% 2 7% 24% 29% 17%	6184
	21st to end	Night	23% 2 8% 25% 31% 12%	6468
February	1st to 10th	Night	27% 2 6% 24% 27% 14%	2483
	11th to 20th	Night	29% 3 7% 26% 24% 12%	2338
	21st to end	Night	21% 2 3 20% 35% 18%	1980
March	1st to 10th	Night	23% 2 2 15% 33% 24%	3854
	11th to 20th	Night	33% 2 9% 19% 26% 11%	3738
	21st to end	Night	26% 3 6% 31% 27% 8%	3580
April	1st to 10th	Night	22% 3 7% 26% 26% 18%	1900
	11th to 20th	Night	29% 3 9% 23% 21% 15%	1877
	21st to end	Night	29% 4 11% 25% 21% 10%	1900
May	1st to 10th	Night	26% 3 8% 20% 20% 22%	2979
	11th to 20th	Night	34% 2 12% 27% 13% 13%	2824
	21st to end	Night	24% 4 11% 19% 19% 23%	2766
June	1st to 10th	Night	25% 5% 16% 23% 18% 14%	1520
	11th to 20th	Night	20% 5% 10% 19% 23% 23%	1520
	21st to end	Night	31% 5% 10% 19% 20% 15%	1520
July	1st to 10th	Night	35% 6% 10% 20% 16% 13%	2500
	11th to 20th	Night	29% 6% 17% 26% 18% 5%	2492
	21st to end	Night	32% 6% 12% 18% 23% 8%	2792
August	1st to 10th	Night	40% 8% 17% 20% 10% 5%	3054
	11th to 20th	Night	29% 7% 19% 22% 18% 5%	3143
	21st to end	Night	27% 7% 16% 28% 16% 6%	3487
September	1st to 10th	Night	23% 4 11% 24% 24% 13%	1900
	11th to 20th	Night	19% 4 9% 22% 25% 21%	1971
	21st to end	Night	21% 3 6% 19% 32% 19%	2090
October	1st to 10th	Night	16% 3 6% 18% 34% 23%	3604
	11th to 20th	Night	20% 3 7% 20% 31% 18%	3778
	21st to end	Night	18% 2 3 19% 37% 21%	4213
November	1st to 10th	Night	16% 3 5% 24% 30% 22%	2535
	11th to 20th	Night	16% 2 4 24% 36% 19%	2600
	21st to end	Night	22% 2 6% 19% 30% 20%	2600
December	1st to 10th	Night	17% 2 5% 30% 35% 11%	4427
	11th to 20th	Night	19% 3 4 20% 41% 14%	5182
	21st to end	Night	28% 2 5% 23% 30% 12%	6974

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% 7% 27% 37% 19% 4	300
	11th to 20th	Day	6% 10% 29% 37% 13% 4	300
	21st to end	Day	3 7% 31% 36% 18% 6%	330
February	1st to 10th	Day	3 12% 39% 33% 11% 2	300
	11th to 20th	Day	4 9% 38% 36% 13%	300
	21st to end	Day	5% 8% 41% 35% 11%	249
March	1st to 10th	Day	7% 9% 31% 36% 16% 2	300
	11th to 20th	Day	10% 14% 29% 27% 16% 4	407
	21st to end	Day	11% 20% 33% 25% 10% 2	531
April	1st to 10th	Day	8% 15% 36% 28% 10% 2	460
	11th to 20th	Day	12% 15% 35% 28% 8% 2	452
	21st to end	Day	11% 15% 35% 25% 13% 2	460
May	1st to 10th	Day	10% 13% 30% 32% 14% 2	572
	11th to 20th	Day	11% 8% 23% 33% 21% 4	675
	21st to end	Day	6% 8% 30% 30% 21% 5%	734
June	1st to 10th	Day	7% 5% 21% 28% 29% 10%	680
	11th to 20th	Day	5% 4 28% 33% 23% 8%	680
	21st to end	Day	6% 4 21% 32% 28% 9%	680
July	1st to 10th	Day	5% 2 15% 29% 36% 13%	671
	11th to 20th	Day	2 1 9% 32% 40% 16%	668
	21st to end	Day	3 2 8% 27% 36% 25%	662
August	1st to 10th	Day	4 2 14% 30% 31% 20%	487
	11th to 20th	Day	3 1 14% 32% 34% 15%	477
	21st to end	Day	3 2 13% 35% 34% 14%	539
September	1st to 10th	Day	4 2 17% 30% 33% 13%	490
	11th to 20th	Day	5% 2 21% 32% 28% 12%	418
	21st to end	Day	8% 3 17% 25% 31% 16%	300
October	1st to 10th	Day	7% 3 24% 26% 25% 16%	300
	11th to 20th	Day	4 5% 26% 33% 22% 11%	300
	21st to end	Day	9% 6% 22% 29% 27% 7%	330
November	1st to 10th	Day	6% 7% 27% 30% 24% 6%	300
	11th to 20th	Day	6% 4 27% 33% 25% 5%	300
	21st to end	Day	10% 7% 25% 32% 19% 6%	300
December	1st to 10th	Day	2 7% 32% 36% 16% 7%	300
	11th to 20th	Day	7% 7% 26% 39% 18% 3	300
	21st to end	Day	4 8% 43% 33% 9% 3	330
January	1st to 10th	Night	5% 5% 35% 40% 13% 2	1000
	11th to 20th	Night	6% 6% 37% 36% 13% 1	935
	21st to end	Night	6% 4 34% 44% 11% 1	880
February	1st to 10th	Night	7% 6% 38% 41% 8%	800
	11th to 20th	Night	7% 8% 41% 35% 8%	784
	21st to end	Night	7% 8% 43% 36% 5%	660
March	1st to 10th	Night	8% 6% 42% 37% 7% 1	800
	11th to 20th	Night	10% 9% 36% 37% 7% 1	800
	21st to end	Night	8% 10% 42% 35% 6%	672
April	1st to 10th	Night	7% 10% 51% 29% 3	570
	11th to 20th	Night	12% 10% 42% 32% 4	563
	21st to end	Night	11% 10% 38% 33% 7%	570
May	1st to 10th	Night	10% 9% 38% 35% 8% 1	570
	11th to 20th	Night	14% 6% 29% 35% 14% 1	561
	21st to end	Night	8% 8% 38% 37% 9% 1	617
June	1st to 10th	Night	4 5% 37% 37% 16% 1	570
	11th to 20th	Night	4 4 37% 45% 9%	570
	21st to end	Night	5% 3 29% 45% 18%	570
July	1st to 10th	Night	8% 3 21% 42% 25% 2	555
	11th to 20th	Night	3 1 16% 49% 28% 2	552
	21st to end	Night	8% 1 14% 39% 36% 2	624
August	1st to 10th	Night	7% 2 14% 38% 36% 3	567
	11th to 20th	Night	7% 2 16% 48% 26% 1	564
	21st to end	Night	4 2 18% 49% 24% 3	627
September	1st to 10th	Night	6% 3 21% 46% 24% 1	570
	11th to 20th	Night	6% 2 28% 41% 21% 2	570
	21st to end	Night	6% 7% 24% 43% 19% 1	570
October	1st to 10th	Night	9% 5% 28% 41% 16% 1	642
	11th to 20th	Night	4 4 27% 44% 18% 2	760
	21st to end	Night	7% 4 29% 39% 18% 3	893
November	1st to 10th	Night	5% 4 27% 47% 15% 1	975
	11th to 20th	Night	4 7% 30% 44% 14% 1	1000
	21st to end	Night	8% 5% 28% 43% 14% 2	1000
December	1st to 10th	Night	4 3 35% 45% 12% 1	1000
	11th to 20th	Night	5% 5% 36% 43% 11% 1	1000
	21st to end	Night	6% 8% 37% 40% 9% 1	1100

Page generated at 2025-03-24 07:04:27. Version ac07

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