Caprock Canyons Trailway
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Caprock Canyons Trailway clear sky chart from 2005-11-06 to 2026-10-29.

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	7% 4 1 4 3 3 3 3 5% 7% 61%	157770
	Night	6% 4 1 4 3 3 3 3 5% 7% 62%	151831
Transparency	Day	24% 4 8% 22% 28% 15%	152809
	Night	22% 4 8% 21% 28% 16%	147804
Seeing	Day	8% 7% 24% 33% 22% 6%	17935
	Night	8% 7% 30% 40% 14% 1	27773

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% 5% 2 6% 3 3 4 3 5% 5% 58%	5287
	11th to 20th	Day	3 4 1 3 2 2 2 2 3 5% 73%	5310
	21st to end	Day	11% 5% 1 3 3 3 3 3 4 6% 58%	6385
February	1st to 10th	Day	7% 6% 1 4 3 3 3 2 3 6% 63%	2100
	11th to 20th	Day	7% 6% 2 6% 3 3 3 2 4 7% 58%	2049
	21st to end	Day	6% 7% 2 4 3 2 3 3 3 5% 63%	1730
March	1st to 10th	Day	9% 4 2 5% 3 2 2 2 4 6% 61%	4600
	11th to 20th	Day	8% 4 2 4 2 3 2 3 5% 6% 61%	4999
	21st to end	Day	4 5% 2 4 3 3 4 3 5% 8% 59%	5623
April	1st to 10th	Day	7% 4 1 4 3 2 3 2 4 6% 64%	2520
	11th to 20th	Day	10% 4 2 4 3 4 3 3 4 5% 58%	2491
	21st to end	Day	9% 3 1 3 3 3 3 3 4 6% 61%	2579
May	1st to 10th	Day	14% 5% 1 3 2 3 3 3 4 6% 55%	7655
	11th to 20th	Day	9% 4 1 3 2 2 3 2 4 5% 65%	7627
	21st to end	Day	12% 6% 2 5% 4 4 4 3 5% 6% 49%	8404
June	1st to 10th	Day	6% 4 1 4 3 3 4 4 6% 9% 55%	2730
	11th to 20th	Day	6% 3 1 3 3 3 4 3 6% 8% 61%	2730
	21st to end	Day	3 3 1 4 3 4 4 4 6% 7% 61%	2730
July	1st to 10th	Day	8% 4 2 6% 5% 5% 5% 5% 6% 8% 47%	7679
	11th to 20th	Day	3 2 1 4 3 4 5% 4 7% 10% 58%	7680
	21st to end	Day	2 2 1 3 3 3 4 3 5% 8% 67%	8339
August	1st to 10th	Day	3 2 1 3 2 2 3 3 5% 7% 68%	7232
	11th to 20th	Day	3 2 1 3 3 3 4 4 6% 9% 64%	7003
	21st to end	Day	7% 3 1 4 3 3 4 3 5% 7% 60%	7751
September	1st to 10th	Day	8% 3 2 4 3 3 3 3 5% 7% 57%	2441
	11th to 20th	Day	8% 4 1 5% 3 4 4 4 5% 8% 55%	2310
	21st to end	Day	7% 3 1 4 3 3 3 3 5% 6% 62%	2310
October	1st to 10th	Day	5% 2 1 3 2 2 2 2 2 4 75%	3700
	11th to 20th	Day	10% 4 2 4 2 3 3 2 3 5% 64%	3652
	21st to end	Day	5% 3 1 3 1 2 2 2 3 5% 72%	3393
November	1st to 10th	Day	7% 3 1 3 1 2 3 2 4 6% 68%	1853
	11th to 20th	Day	4 3 1 2 2 2 3 3 4 5% 71%	1890
	21st to end	Day	9% 5% 1 4 2 2 3 2 4 6% 63%	1890
December	1st to 10th	Day	5% 4 2 4 3 3 3 3 5% 6% 63%	3030
	11th to 20th	Day	5% 2 1 3 2 3 3 4 4 5% 68%	3481
	21st to end	Day	7% 7% 3 5% 3 3 3 2 3 4 62%	4587
January	1st to 10th	Night	6% 6% 2 5% 3 3 3 3 5% 7% 58%	7634
	11th to 20th	Night	2 2 1 3 2 2 2 2 4 5% 74%	7680
	21st to end	Night	10% 6% 2 6% 3 3 3 2 4 5% 55%	7884
February	1st to 10th	Night	7% 6% 1 5% 3 3 2 3 4 6% 62%	2520
	11th to 20th	Night	7% 5% 2 5% 4 3 3 3 4 7% 58%	2458
	21st to end	Night	6% 4 1 3 3 3 3 3 5% 7% 62%	2076
March	1st to 10th	Night	5% 5% 2 4 3 3 3 3 4 5% 63%	5494
	11th to 20th	Night	5% 3 1 4 2 3 3 3 4 5% 67%	5184
	21st to end	Night	3 4 2 5% 3 3 4 3 5% 7% 60%	5548
April	1st to 10th	Night	6% 4 1 3 3 3 3 3 5% 7% 63%	2100
	11th to 20th	Night	8% 5% 1 4 3 3 3 3 5% 7% 58%	2077
	21st to end	Night	9% 3 1 3 3 3 3 3 5% 6% 62%	2037
May	1st to 10th	Night	13% 4 2 4 3 2 3 3 4 6% 57%	5292
	11th to 20th	Night	6% 3 1 3 3 3 3 3 5% 6% 63%	5265
	21st to end	Night	12% 6% 2 5% 3 3 3 3 5% 7% 52%	5803
June	1st to 10th	Night	5% 3 1 4 4 3 4 4 8% 11% 53%	1890
	11th to 20th	Night	4 3 1 2 3 4 3 4 8% 10% 58%	1890
	21st to end	Night	4 2 1 4 3 3 4 4 6% 9% 59%	1890
July	1st to 10th	Night	5% 4 2 6% 4 6% 6% 5% 8% 9% 45%	5310
	11th to 20th	Night	2 3 1 4 4 4 4 4 7% 11% 56%	5310
	21st to end	Night	2 2 1 3 3 3 4 3 6% 9% 65%	5770
August	1st to 10th	Night	2 1 1 2 2 2 3 3 5% 10% 67%	5572
	11th to 20th	Night	2 2 1 3 3 4 5% 4 7% 10% 58%	5853
	21st to end	Night	6% 3 1 4 3 3 3 3 5% 10% 59%	6465
September	1st to 10th	Night	7% 4 1 4 4 3 4 4 5% 6% 58%	2178
	11th to 20th	Night	10% 4 2 5% 4 3 4 4 6% 7% 53%	2310
	21st to end	Night	7% 3 2 3 2 2 3 4 5% 5% 63%	2310
October	1st to 10th	Night	5% 2 1 2 1 2 2 1 2 4 78%	3700
	11th to 20th	Night	8% 4 2 4 3 2 3 2 4 6% 63%	3680
	21st to end	Night	4 2 1 2 2 1 2 2 3 6% 76%	4567
November	1st to 10th	Night	7% 2 1 2 2 2 2 3 4 6% 71%	2665
	11th to 20th	Night	4 3 1 2 2 2 2 2 4 6% 72%	2730
	21st to end	Night	7% 4 1 4 2 3 3 3 4 5% 64%	2730
December	1st to 10th	Night	5% 3 1 3 2 3 3 2 4 6% 66%	4380
	11th to 20th	Night	4 3 1 2 3 2 3 2 4 7% 68%	4946
	21st to end	Night	5% 6% 2 4 3 3 3 3 5% 6% 61%	6633

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	28% 3 5% 23% 27% 14%	5290
	11th to 20th	Day	17% 2 5% 19% 34% 23%	5310
	21st to end	Day	29% 3 6% 17% 32% 12%	6385
February	1st to 10th	Day	24% 3 7% 23% 27% 16%	2100
	11th to 20th	Day	28% 3 6% 24% 24% 15%	2059
	21st to end	Day	25% 3 4 16% 31% 21%	1730
March	1st to 10th	Day	25% 3 4 10% 25% 32%	4600
	11th to 20th	Day	24% 2 5% 18% 26% 24%	4999
	21st to end	Day	23% 4 8% 25% 28% 11%	5623
April	1st to 10th	Day	23% 4 6% 18% 28% 21%	2520
	11th to 20th	Day	28% 4 6% 18% 23% 20%	2494
	21st to end	Day	23% 4 8% 23% 29% 13%	2579
May	1st to 10th	Day	30% 4 8% 22% 23% 13%	7655
	11th to 20th	Day	23% 3 5% 18% 26% 26%	7631
	21st to end	Day	35% 6% 10% 17% 15% 17%	8405
June	1st to 10th	Day	25% 6% 15% 28% 18% 8%	2730
	11th to 20th	Day	22% 6% 10% 23% 26% 14%	2730
	21st to end	Day	21% 5% 12% 29% 22% 11%	2730
July	1st to 10th	Day	33% 6% 9% 23% 24% 4	7616
	11th to 20th	Day	20% 7% 13% 30% 25% 6%	7611
	21st to end	Day	15% 5% 14% 30% 31% 5%	8155
August	1st to 10th	Day	14% 4 9% 23% 34% 16%	5725
	11th to 20th	Day	14% 3 8% 27% 35% 12%	5519
	21st to end	Day	20% 4 9% 24% 32% 10%	6078
September	1st to 10th	Day	26% 6% 9% 24% 24% 12%	2441
	11th to 20th	Day	28% 6% 10% 23% 28% 5%	2310
	21st to end	Day	22% 5% 7% 21% 32% 13%	2310
October	1st to 10th	Day	16% 3 5% 13% 35% 28%	3700
	11th to 20th	Day	25% 3 4 22% 24% 21%	3652
	21st to end	Day	17% 2 3 25% 39% 13%	3393
November	1st to 10th	Day	19% 3 6% 18% 33% 20%	1853
	11th to 20th	Day	16% 4 5% 23% 34% 18%	1890
	21st to end	Day	25% 3 5% 17% 32% 19%	1890
December	1st to 10th	Day	23% 2 5% 31% 27% 12%	3030
	11th to 20th	Day	19% 3 5% 16% 39% 18%	3479
	21st to end	Day	28% 3 4 21% 31% 13%	4587
January	1st to 10th	Night	27% 3 5% 30% 29% 8%	7635
	11th to 20th	Night	15% 2 8% 20% 36% 20%	7680
	21st to end	Night	32% 3 5% 17% 31% 12%	7884
February	1st to 10th	Night	26% 3 7% 17% 30% 17%	2520
	11th to 20th	Night	28% 3 7% 21% 24% 17%	2458
	21st to end	Night	23% 3 5% 17% 28% 24%	2076
March	1st to 10th	Night	24% 3 3 13% 23% 34%	5494
	11th to 20th	Night	20% 3 6% 18% 18% 36%	5184
	21st to end	Night	23% 4 8% 22% 28% 15%	5548
April	1st to 10th	Night	21% 4 8% 18% 25% 23%	2100
	11th to 20th	Night	26% 5% 8% 17% 26% 18%	2077
	21st to end	Night	22% 4 10% 23% 26% 14%	2037
May	1st to 10th	Night	30% 4 9% 24% 20% 14%	5293
	11th to 20th	Night	20% 5% 7% 15% 29% 25%	5266
	21st to end	Night	33% 6% 13% 16% 12% 21%	5805
June	1st to 10th	Night	23% 6% 19% 28% 17% 7%	1890
	11th to 20th	Night	19% 6% 11% 25% 25% 13%	1890
	21st to end	Night	22% 4 11% 27% 21% 14%	1890
July	1st to 10th	Night	33% 6% 10% 28% 20% 3	5265
	11th to 20th	Night	20% 6% 16% 27% 24% 7%	5256
	21st to end	Night	16% 4 10% 27% 37% 6%	5641
August	1st to 10th	Night	13% 3 8% 27% 31% 18%	4403
	11th to 20th	Night	18% 4 9% 22% 38% 9%	4613
	21st to end	Night	17% 4 12% 24% 33% 10%	5069
September	1st to 10th	Night	25% 5% 10% 24% 23% 13%	2178
	11th to 20th	Night	30% 6% 11% 18% 27% 8%	2310
	21st to end	Night	21% 5% 7% 21% 28% 17%	2310
October	1st to 10th	Night	14% 2 6% 13% 33% 33%	3700
	11th to 20th	Night	24% 3 6% 18% 28% 21%	3680
	21st to end	Night	13% 2 4 22% 39% 19%	4567
November	1st to 10th	Night	17% 3 6% 21% 30% 22%	2665
	11th to 20th	Night	16% 2 5% 21% 36% 20%	2730
	21st to end	Night	23% 4 4 19% 31% 19%	2730
December	1st to 10th	Night	21% 2 6% 28% 32% 11%	4380
	11th to 20th	Night	18% 2 4 16% 41% 19%	4947
	21st to end	Night	24% 4 6% 25% 29% 12%	6633

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	9% 11% 34% 34% 11% 2	330
	11th to 20th	Day	12% 14% 28% 33% 12% 2	330
	21st to end	Day	9% 10% 37% 32% 12% 1	363
February	1st to 10th	Day	10% 12% 34% 32% 12%	330
	11th to 20th	Day	10% 10% 42% 25% 12% 1	330
	21st to end	Day	14% 14% 36% 29% 7% 1	273
March	1st to 10th	Day	11% 9% 42% 30% 8%	330
	11th to 20th	Day	15% 12% 35% 28% 8% 2	330
	21st to end	Day	11% 12% 34% 32% 10% 1	376
April	1st to 10th	Day	10% 16% 41% 24% 8%	540
	11th to 20th	Day	11% 17% 46% 21% 5%	532
	21st to end	Day	11% 16% 34% 28% 8% 2	599
May	1st to 10th	Day	11% 9% 37% 33% 10%	753
	11th to 20th	Day	11% 8% 30% 32% 16% 3	775
	21st to end	Day	9% 8% 31% 32% 18% 3	844
June	1st to 10th	Day	8% 4 21% 38% 26% 4	780
	11th to 20th	Day	7% 3 25% 40% 21% 4	780
	21st to end	Day	4 3 17% 39% 31% 7%	780
July	1st to 10th	Day	6% 1 9% 37% 33% 13%	771
	11th to 20th	Day	3 1 9% 35% 40% 13%	768
	21st to end	Day	2 1 4 34% 43% 16%	849
August	1st to 10th	Day	3 2 8% 38% 41% 9%	657
	11th to 20th	Day	3 1 9% 39% 32% 16%	557
	21st to end	Day	6% 2 7% 33% 37% 14%	627
September	1st to 10th	Day	7% 2 9% 34% 33% 14%	491
	11th to 20th	Day	4 1 12% 40% 34% 9%	360
	21st to end	Day	11% 3 13% 32% 33% 10%	360
October	1st to 10th	Day	8% 2 22% 32% 25% 11%	360
	11th to 20th	Day	8% 6% 24% 34% 25% 4	360
	21st to end	Day	14% 7% 26% 27% 22% 4	387
November	1st to 10th	Day	13% 6% 30% 28% 18% 4	330
	11th to 20th	Day	7% 10% 26% 33% 18% 5%	330
	21st to end	Day	15% 11% 31% 24% 16% 3	330
December	1st to 10th	Day	7% 7% 40% 30% 15% 1	330
	11th to 20th	Day	5% 9% 31% 38% 15% 1	330
	21st to end	Day	13% 13% 35% 26% 12% 1	363
January	1st to 10th	Night	7% 8% 35% 40% 10%	1050
	11th to 20th	Night	8% 9% 34% 41% 9%	1050
	21st to end	Night	7% 9% 34% 43% 7% 1	971
February	1st to 10th	Night	10% 9% 34% 39% 7%	840
	11th to 20th	Night	9% 11% 40% 35% 4	824
	21st to end	Night	10% 11% 39% 37% 4	692
March	1st to 10th	Night	9% 13% 40% 33% 5%	840
	11th to 20th	Night	12% 13% 38% 30% 7%	672
	21st to end	Night	6% 14% 45% 31% 4	693
April	1st to 10th	Night	7% 13% 42% 35% 3	630
	11th to 20th	Night	10% 12% 49% 27% 2	623
	21st to end	Night	10% 9% 43% 33% 4	630
May	1st to 10th	Night	11% 8% 42% 34% 5%	630
	11th to 20th	Night	10% 7% 32% 39% 11% 1	621
	21st to end	Night	8% 6% 37% 38% 11% 1	683
June	1st to 10th	Night	6% 3 29% 45% 16%	630
	11th to 20th	Night	5% 3 39% 44% 9%	630
	21st to end	Night	6% 2 25% 46% 21% 1	630
July	1st to 10th	Night	6% 2 13% 46% 32% 2	615
	11th to 20th	Night	4 12% 50% 34% 1	612
	21st to end	Night	3 1 6% 47% 41% 2	690
August	1st to 10th	Night	3 1 9% 51% 36% 1	627
	11th to 20th	Night	7% 1 9% 47% 35% 1	624
	21st to end	Night	5% 1 8% 43% 41% 2	693
September	1st to 10th	Night	6% 2 10% 47% 32% 2	630
	11th to 20th	Night	11% 2 15% 45% 26% 1	630
	21st to end	Night	7% 2 19% 44% 26% 1	630
October	1st to 10th	Night	10% 3 23% 42% 20% 1	630
	11th to 20th	Night	9% 5% 31% 43% 13%	630
	21st to end	Night	8% 8% 30% 36% 17%	1043
November	1st to 10th	Night	8% 6% 29% 44% 13% 1	1025
	11th to 20th	Night	6% 7% 32% 42% 12%	1050
	21st to end	Night	8% 9% 33% 38% 12%	1050
December	1st to 10th	Night	10% 6% 32% 44% 8%	1050
	11th to 20th	Night	10% 8% 35% 39% 8%	1050
	21st to end	Night	10% 7% 35% 40% 7%	1155

Page generated at 2026-10-26 03:37:46. Version ac07

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