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 2024-10-20.

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 4 6% 8% 59%	100973
	Night	5% 5% 2 5% 3 3 4 4 5% 7% 58%	97916
Transparency	Day	23% 4 8% 24% 26% 15%	100719
	Night	26% 3 9% 23% 25% 13%	97761
Seeing	Day	6% 7% 24% 31% 23% 8%	15395
	Night	7% 5% 32% 41% 14% 1	25354

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 6% 2 5% 3 3 2 3 5% 8% 62%	2538
	11th to 20th	Day	1 3 1 3 3 3 5% 4 7% 7% 61%	2668
	21st to end	Day	3 6% 2 5% 3 4 4 4 4 6% 59%	3146
February	1st to 10th	Day	3 6% 3 5% 4 3 3 3 5% 8% 57%	1819
	11th to 20th	Day	1 5% 2 5% 4 4 4 3 5% 6% 61%	1849
	21st to end	Day	2 6% 2 4 3 4 3 3 6% 4 63%	1570
March	1st to 10th	Day	2 5% 2 4 2 3 3 3 4 6% 66%	3130
	11th to 20th	Day	7% 7% 2 4 3 3 4 3 5% 7% 54%	3349
	21st to end	Day	4 5% 2 5% 3 3 4 3 5% 7% 59%	4127
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	6% 4 1 3 2 3 3 3 5% 6% 65%	2014
	11th to 20th	Day	2 2 1 3 2 2 3 2 4 4 74%	1890
	21st to end	Day	6% 5% 2 3 2 2 3 2 3 4 68%	1906
November	1st to 10th	Day	2 3 1 2 1 2 3 3 5% 7% 72%	1673
	11th to 20th	Day	2 5% 1 4 3 2 2 2 4 6% 70%	1710
	21st to end	Day	5% 5% 2 4 3 2 2 2 4 5% 65%	1710
December	1st to 10th	Day	2 5% 2 5% 2 2 3 3 4 7% 64%	1609
	11th to 20th	Day	3 5% 1 4 3 3 3 4 5% 9% 60%	1926
	21st to end	Day	3 7% 3 7% 4 4 4 3 4 6% 56%	2794
January	1st to 10th	Night	3 7% 3 6% 3 3 3 3 5% 6% 56%	4417
	11th to 20th	Night	2 4 2 3 3 2 3 3 5% 6% 66%	4330
	21st to end	Night	3 5% 2 5% 3 3 3 4 4 7% 60%	4521
February	1st to 10th	Night	3 7% 3 6% 4 3 3 3 4 5% 59%	2359
	11th to 20th	Night	5% 6% 3 5% 4 4 3 3 5% 7% 56%	2218
	21st to end	Night	4 6% 2 3 2 2 3 3 4 5% 65%	1884
March	1st to 10th	Night	5% 6% 1 3 2 3 3 3 4 6% 65%	3734
	11th to 20th	Night	10% 8% 2 4 3 3 4 3 5% 6% 52%	3624
	21st to end	Night	5% 6% 1 4 3 3 4 3 5% 7% 60%	3514
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	7% 4 1 3 2 2 3 2 4 6% 66%	2162
	11th to 20th	Night	2 3 1 3 2 2 2 2 3 5% 75%	2274
	21st to end	Night	5% 5% 2 4 3 3 2 2 3 5% 67%	2430
November	1st to 10th	Night	3 2 1 2 2 2 3 3 4 6% 71%	2405
	11th to 20th	Night	3 5% 2 3 2 2 2 1 3 5% 73%	2470
	21st to end	Night	4 6% 2 4 3 3 3 2 4 6% 63%	2470
December	1st to 10th	Night	2 5% 3 5% 2 2 3 3 6% 7% 63%	2569
	11th to 20th	Night	2 5% 2 4 3 3 3 4 5% 7% 61%	3271
	21st to end	Night	3 6% 3 7% 5% 4 4 3 4 6% 56%	4873

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	22% 1 6% 32% 33% 6%	2539
	11th to 20th	Day	21% 1 8% 31% 31% 8%	2668
	21st to end	Day	28% 1 6% 30% 28% 7%	3146
February	1st to 10th	Day	26% 3 6% 26% 25% 14%	1819
	11th to 20th	Day	25% 3 6% 24% 30% 13%	1859
	21st to end	Day	23% 3 3 19% 28% 24%	1570
March	1st to 10th	Day	20% 3 4 16% 35% 22%	3130
	11th to 20th	Day	32% 3 7% 21% 30% 8%	3349
	21st to end	Day	26% 3 3 30% 28% 10%	4127
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	21% 3 9% 20% 28% 20%	2014
	11th to 20th	Day	13% 2 5% 18% 32% 28%	1890
	21st to end	Day	21% 2 3 23% 30% 21%	1906
November	1st to 10th	Day	13% 2 5% 23% 32% 25%	1673
	11th to 20th	Day	18% 2 4 26% 35% 15%	1710
	21st to end	Day	22% 1 5% 16% 32% 23%	1710
December	1st to 10th	Day	21% 3 9% 26% 28% 13%	1609
	11th to 20th	Day	21% 5% 5% 24% 31% 14%	1924
	21st to end	Day	32% 2 4 23% 23% 16%	2794
January	1st to 10th	Night	29% 1 4 29% 30% 7%	4417
	11th to 20th	Night	21% 1 9% 30% 28% 11%	4330
	21st to end	Night	25% 1 9% 30% 29% 5%	4521
February	1st to 10th	Night	28% 2 6% 24% 27% 13%	2359
	11th to 20th	Night	28% 3 7% 26% 25% 12%	2218
	21st to end	Night	22% 2 3 21% 35% 17%	1884
March	1st to 10th	Night	22% 2 2 16% 33% 24%	3734
	11th to 20th	Night	34% 2 9% 19% 25% 10%	3624
	21st to end	Night	26% 3 6% 30% 28% 8%	3514
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	21% 3 10% 20% 28% 19%	2162
	11th to 20th	Night	15% 2 5% 18% 34% 27%	2274
	21st to end	Night	22% 2 5% 21% 30% 20%	2430
November	1st to 10th	Night	15% 3 5% 24% 30% 23%	2405
	11th to 20th	Night	17% 2 4 25% 36% 17%	2470
	21st to end	Night	23% 2 5% 18% 31% 20%	2470
December	1st to 10th	Night	22% 3 8% 29% 27% 11%	2569
	11th to 20th	Night	23% 3 5% 19% 37% 12%	3272
	21st to end	Night	31% 2 6% 22% 29% 11%	4873

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	4 7% 27% 36% 21% 4	270
	11th to 20th	Day	7% 9% 29% 37% 14% 4	270
	21st to end	Day	3 7% 30% 35% 19% 6%	297
February	1st to 10th	Day	3 11% 37% 34% 12% 2	270
	11th to 20th	Day	4 8% 37% 37% 14%	270
	21st to end	Day	6% 9% 41% 34% 10%	225
March	1st to 10th	Day	6% 8% 31% 37% 17% 1	270
	11th to 20th	Day	9% 13% 29% 27% 16% 5%	371
	21st to end	Day	11% 20% 32% 25% 10% 2	506
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 6% 25% 33% 22% 11%	297
	21st to end	Day	9% 5% 23% 28% 28% 7%	297
November	1st to 10th	Day	4 6% 27% 31% 26% 6%	270
	11th to 20th	Day	6% 4 25% 31% 27% 5%	270
	21st to end	Day	10% 7% 25% 31% 20% 6%	270
December	1st to 10th	Day	2 7% 34% 36% 15% 6%	270
	11th to 20th	Day	8% 7% 26% 38% 19% 3	270
	21st to end	Day	5% 8% 43% 32% 9% 3	297
January	1st to 10th	Night	4 5% 34% 41% 14% 2	950
	11th to 20th	Night	6% 6% 36% 37% 13% 1	889
	21st to end	Night	6% 4 33% 45% 12% 1	836
February	1st to 10th	Night	7% 5% 36% 43% 8%	760
	11th to 20th	Night	7% 8% 40% 36% 8%	744
	21st to end	Night	7% 9% 43% 36% 5%	628
March	1st to 10th	Night	7% 6% 42% 37% 7% 1	760
	11th to 20th	Night	10% 9% 35% 38% 8% 1	760
	21st to end	Night	8% 10% 42% 34% 6%	651
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	758
	21st to end	Night	7% 4 28% 39% 19% 3	846
November	1st to 10th	Night	4 4 26% 48% 16% 1	925
	11th to 20th	Night	4 7% 29% 44% 14% 1	950
	21st to end	Night	8% 5% 27% 44% 14% 2	950
December	1st to 10th	Night	4 3 36% 44% 11% 1	950
	11th to 20th	Night	5% 5% 34% 44% 11% 1	950
	21st to end	Night	6% 8% 37% 40% 9% 1	1045

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