Cow Canyon Saddle
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cow Canyon Saddle clear sky chart from 2005-11-06 to 2025-07-06.

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 3 2 2 2 2 4 5% 71%	124445
	Night	4 4 1 3 2 2 2 2 4 5% 71%	123257
Transparency	Day	16% 4 7% 15% 27% 31%	124206
	Night	16% 5% 7% 15% 26% 31%	123084
Seeing	Day	8% 15% 35% 28% 10% 3	16551
	Night	6% 7% 22% 34% 26% 5%	26402

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	4 4 1 3 2 2 2 2 3 5% 72%	3681
	11th to 20th	Day	6% 3 1 2 2 1 2 2 3 6% 71%	4235
	21st to end	Day	8% 9% 2 4 3 2 3 3 5% 8% 54%	5016
February	1st to 10th	Day	10% 7% 2 4 2 2 3 3 4 4 59%	2000
	11th to 20th	Day	10% 8% 1 2 2 2 3 3 4 5% 59%	1950
	21st to end	Day	9% 11% 2 5% 3 3 2 2 4 6% 53%	1650
March	1st to 10th	Day	10% 11% 2 4 3 3 3 3 5% 7% 48%	4518
	11th to 20th	Day	6% 9% 2 5% 4 3 3 3 5% 6% 54%	4687
	21st to end	Day	6% 7% 1 4 3 3 4 4 6% 8% 55%	5922
April	1st to 10th	Day	7% 6% 2 4 3 3 2 3 4 7% 59%	2400
	11th to 20th	Day	4 6% 2 3 3 3 2 2 4 6% 65%	2369
	21st to end	Day	3 7% 1 3 3 1 3 3 4 5% 67%	2400
May	1st to 10th	Day	3 6% 2 3 2 2 2 2 3 4 71%	5694
	11th to 20th	Day	2 3 1 3 1 2 2 2 4 5% 74%	5841
	21st to end	Day	2 2 1 2 1 1 2 1 3 5% 79%	6423
June	1st to 10th	Day	3 4 1 2 1 1 2 2 4 6% 74%	2600
	11th to 20th	Day	2 1 1 1 1 1 2 4 85%	2735
	21st to end	Day	1 2 1 2 1 1 1 1 2 3 85%	2800
July	1st to 10th	Day	1 1 1 1 1 1 1 2 2 88%	4491
	11th to 20th	Day	2 2 2 1 1 2 2 3 4 80%	4248
	21st to end	Day	2 1 1 2 1 2 2 3 4 81%	4254
August	1st to 10th	Day	1 1 2 1 1 1 2 3 4 83%	3783
	11th to 20th	Day	1 1 1 1 1 1 2 3 90%	3724
	21st to end	Day	1 1 1 1 1 1 1 2 2 89%	4180
September	1st to 10th	Day	2 1 1 2 1 2 2 2 3 4 81%	2280
	11th to 20th	Day	1 1 1 1 1 1 1 2 2 3 86%	2114
	21st to end	Day	2 2 1 2 1 2 2 2 3 4 80%	2090
October	1st to 10th	Day	2 2 1 1 2 1 1 2 3 4 80%	3490
	11th to 20th	Day	2 2 1 1 1 2 2 4 4 81%	3330
	21st to end	Day	3 4 1 3 2 2 3 3 4 4 71%	3307
November	1st to 10th	Day	3 4 1 2 3 2 3 3 4 5% 70%	1764
	11th to 20th	Day	4 4 1 3 3 3 3 3 3 5% 68%	1800
	21st to end	Day	5% 5% 2 4 4 4 3 3 4 7% 59%	1800
December	1st to 10th	Day	4 3 2 3 3 4 4 4 5% 6% 63%	2950
	11th to 20th	Day	9% 6% 2 3 3 3 6% 4 5% 7% 51%	3409
	21st to end	Day	8% 7% 2 5% 4 3 4 3 4 7% 51%	4510
January	1st to 10th	Night	5% 4 1 3 2 2 2 2 3 5% 71%	6235
	11th to 20th	Night	4 3 1 4 2 2 2 2 4 5% 71%	5707
	21st to end	Night	7% 8% 2 5% 3 3 3 3 5% 5% 55%	5984
February	1st to 10th	Night	9% 7% 2 4 3 3 3 2 4 6% 58%	2400
	11th to 20th	Night	7% 6% 2 3 3 3 3 3 4 5% 62%	2338
	21st to end	Night	8% 10% 2 5% 4 4 3 3 4 3 56%	1980
March	1st to 10th	Night	6% 11% 3 6% 4 3 3 3 5% 6% 50%	5376
	11th to 20th	Night	4 8% 2 4 2 3 3 3 5% 7% 59%	5313
	21st to end	Night	4 7% 2 4 3 3 3 3 5% 6% 60%	5036
April	1st to 10th	Night	5% 6% 2 4 3 3 2 2 5% 7% 62%	2000
	11th to 20th	Night	3 5% 2 4 3 2 3 2 4 5% 66%	1979
	21st to end	Night	2 6% 2 3 3 3 2 3 4 5% 68%	2000
May	1st to 10th	Night	2 5% 1 4 3 2 2 2 2 4 73%	4294
	11th to 20th	Night	1 2 1 2 2 2 2 2 4 6% 76%	4074
	21st to end	Night	1 1 1 2 1 1 2 1 3 4 83%	4474
June	1st to 10th	Night	1 4 1 2 1 1 2 2 3 5% 79%	1800
	11th to 20th	Night	1 1 1 1 1 2 1 1 2 3 88%	1656
	21st to end	Night	1 1 1 1 1 1 1 2 3 87%	1600
July	1st to 10th	Night	1 1 1 1 1 2 93%	2580
	11th to 20th	Night	1 1 1 1 1 2 2 2 3 85%	2697
	21st to end	Night	1 2 1 1 1 1 2 1 3 3 84%	3313
August	1st to 10th	Night	1 1 1 1 1 1 1 2 2 3 86%	3166
	11th to 20th	Night	1 1 1 1 1 2 4 89%	3126
	21st to end	Night	1 1 1 1 1 1 1 2 91%	3498
September	1st to 10th	Night	2 2 1 2 1 1 2 2 2 3 83%	1900
	11th to 20th	Night	1 1 1 1 1 1 1 2 2 89%	2064
	21st to end	Night	1 2 1 1 1 1 1 2 2 2 85%	2090
October	1st to 10th	Night	2 2 1 2 1 1 1 1 2 2 85%	3490
	11th to 20th	Night	2 2 1 1 1 2 2 2 3 5% 81%	3591
	21st to end	Night	2 3 2 3 2 2 1 1 2 4 77%	4242
November	1st to 10th	Night	3 4 1 2 2 2 2 2 3 5% 72%	2535
	11th to 20th	Night	2 5% 2 3 2 3 2 2 4 6% 69%	2600
	21st to end	Night	5% 6% 1 4 3 4 4 3 5% 7% 58%	2600
December	1st to 10th	Night	5% 4 1 4 3 3 3 2 4 5% 66%	4240
	11th to 20th	Night	8% 6% 2 4 3 4 4 4 5% 8% 52%	4811
	21st to end	Night	6% 4 2 5% 3 3 4 4 6% 10% 52%	6468

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	16% 3 6% 20% 36% 20%	3681
	11th to 20th	Day	16% 4 10% 14% 20% 36%	4235
	21st to end	Day	27% 6% 7% 13% 23% 25%	5016
February	1st to 10th	Day	26% 4 6% 13% 25% 26%	2000
	11th to 20th	Day	26% 4 5% 16% 26% 23%	1960
	21st to end	Day	30% 5% 7% 14% 23% 21%	1650
March	1st to 10th	Day	28% 7% 10% 16% 19% 20%	4518
	11th to 20th	Day	27% 8% 9% 24% 20% 12%	4687
	21st to end	Day	22% 9% 13% 25% 22% 9%	5922
April	1st to 10th	Day	24% 5% 11% 23% 24% 14%	2400
	11th to 20th	Day	21% 4 8% 20% 29% 19%	2372
	21st to end	Day	18% 4 10% 21% 35% 12%	2400
May	1st to 10th	Day	16% 5% 8% 17% 32% 22%	5694
	11th to 20th	Day	11% 4 12% 20% 38% 14%	5844
	21st to end	Day	9% 3 8% 19% 39% 22%	6424
June	1st to 10th	Day	12% 3 11% 18% 34% 21%	2600
	11th to 20th	Day	7% 1 5% 15% 29% 43%	2735
	21st to end	Day	8% 2 3 7% 26% 53%	2800
July	1st to 10th	Day	5% 1 2 6% 11% 74%	4422
	11th to 20th	Day	9% 2 4 11% 25% 49%	4174
	21st to end	Day	7% 3 6% 17% 27% 40%	4120
August	1st to 10th	Day	7% 2 4 10% 37% 41%	3770
	11th to 20th	Day	4 1 2 11% 29% 53%	3760
	21st to end	Day	5% 1 3 6% 23% 61%	4179
September	1st to 10th	Day	8% 3 5% 10% 29% 45%	2280
	11th to 20th	Day	6% 1 4 11% 33% 45%	2114
	21st to end	Day	9% 1 5% 13% 31% 41%	2090
October	1st to 10th	Day	10% 2 3 10% 19% 56%	3490
	11th to 20th	Day	8% 3 4 10% 36% 39%	3330
	21st to end	Day	16% 3 4 9% 28% 40%	3307
November	1st to 10th	Day	17% 3 6% 13% 31% 31%	1764
	11th to 20th	Day	18% 3 6% 12% 24% 37%	1800
	21st to end	Day	25% 3 7% 12% 23% 30%	1800
December	1st to 10th	Day	20% 4 5% 12% 23% 35%	2950
	11th to 20th	Day	28% 7% 7% 15% 27% 17%	3408
	21st to end	Day	30% 7% 8% 19% 24% 12%	4510
January	1st to 10th	Night	17% 4 5% 15% 35% 25%	6235
	11th to 20th	Night	15% 6% 9% 15% 20% 35%	5707
	21st to end	Night	28% 6% 9% 11% 21% 25%	5984
February	1st to 10th	Night	27% 4 7% 15% 22% 25%	2400
	11th to 20th	Night	24% 5% 7% 16% 24% 23%	2339
	21st to end	Night	31% 6% 5% 13% 21% 23%	1980
March	1st to 10th	Night	28% 11% 10% 16% 15% 20%	5376
	11th to 20th	Night	22% 9% 12% 23% 23% 11%	5313
	21st to end	Night	22% 8% 12% 25% 24% 9%	5036
April	1st to 10th	Night	23% 6% 10% 21% 23% 18%	2000
	11th to 20th	Night	19% 6% 9% 20% 27% 21%	1979
	21st to end	Night	17% 6% 9% 22% 33% 13%	2000
May	1st to 10th	Night	14% 7% 8% 20% 32% 19%	4291
	11th to 20th	Night	8% 4 12% 26% 36% 14%	4075
	21st to end	Night	7% 6% 10% 16% 41% 21%	4474
June	1st to 10th	Night	10% 5% 9% 25% 28% 24%	1800
	11th to 20th	Night	5% 2 7% 15% 29% 41%	1656
	21st to end	Night	5% 2 5% 7% 23% 58%	1600
July	1st to 10th	Night	3 1 1 7% 11% 77%	2540
	11th to 20th	Night	7% 2 4 9% 18% 60%	2649
	21st to end	Night	8% 2 5% 17% 26% 44%	3209
August	1st to 10th	Night	6% 2 4 10% 37% 42%	3156
	11th to 20th	Night	3 1 3 12% 30% 52%	3156
	21st to end	Night	5% 1 2 6% 19% 68%	3498
September	1st to 10th	Night	8% 2 5% 9% 29% 47%	1900
	11th to 20th	Night	5% 2 5% 11% 33% 44%	2064
	21st to end	Night	7% 2 6% 13% 28% 44%	2090
October	1st to 10th	Night	9% 2 3 9% 16% 62%	3490
	11th to 20th	Night	8% 3 4 8% 32% 45%	3591
	21st to end	Night	14% 2 3 6% 26% 48%	4242
November	1st to 10th	Night	16% 3 5% 13% 30% 33%	2535
	11th to 20th	Night	17% 3 6% 12% 24% 38%	2600
	21st to end	Night	24% 5% 8% 14% 19% 30%	2600
December	1st to 10th	Night	20% 4 5% 10% 22% 39%	4240
	11th to 20th	Night	27% 7% 7% 16% 24% 18%	4811
	21st to end	Night	24% 9% 11% 21% 23% 11%	6468

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	15% 22% 36% 22% 5%	208
	11th to 20th	Day	20% 15% 32% 27% 5% 1	383
	21st to end	Day	16% 26% 32% 20% 5% 1	550
February	1st to 10th	Day	17% 24% 31% 19% 7% 2	500
	11th to 20th	Day	17% 24% 36% 17% 6%	495
	21st to end	Day	15% 25% 38% 18% 3	414
March	1st to 10th	Day	21% 24% 34% 15% 5%	500
	11th to 20th	Day	19% 22% 35% 17% 6% 1	500
	21st to end	Day	18% 26% 36% 16% 4 1	550
April	1st to 10th	Day	13% 22% 34% 22% 9% 1	500
	11th to 20th	Day	9% 28% 38% 18% 5% 2	492
	21st to end	Day	7% 22% 36% 24% 8% 3	500
May	1st to 10th	Day	10% 20% 39% 23% 7% 1	503
	11th to 20th	Day	9% 16% 40% 26% 8% 2	528
	21st to end	Day	7% 14% 41% 27% 8% 3	573
June	1st to 10th	Day	2 13% 38% 31% 12% 4	530
	11th to 20th	Day	2 11% 40% 30% 13% 4	530
	21st to end	Day	3 9% 39% 33% 11% 5%	530
July	1st to 10th	Day	1 5% 33% 39% 15% 7%	507
	11th to 20th	Day	2 1 28% 44% 13% 12%	484
	21st to end	Day	2 2 30% 42% 13% 11%	531
August	1st to 10th	Day	2 4 34% 40% 12% 8%	487
	11th to 20th	Day	1 3 31% 43% 12% 9%	477
	21st to end	Day	1 3 31% 42% 16% 8%	539
September	1st to 10th	Day	2 6% 38% 37% 15% 3	490
	11th to 20th	Day	3 10% 38% 33% 14% 2	490
	21st to end	Day	2 12% 35% 33% 14% 3	490
October	1st to 10th	Day	5% 13% 39% 33% 10%	490
	11th to 20th	Day	4 12% 39% 32% 12% 1	490
	21st to end	Day	7% 16% 33% 29% 14% 2	460
November	1st to 10th	Day	9% 14% 27% 37% 13%	300
	11th to 20th	Day	8% 17% 35% 26% 13% 1	300
	21st to end	Day	9% 17% 36% 25% 12% 1	300
December	1st to 10th	Day	8% 18% 36% 28% 9%	300
	11th to 20th	Day	9% 20% 32% 28% 10% 1	300
	21st to end	Day	17% 25% 32% 20% 6% 1	330
January	1st to 10th	Night	14% 12% 28% 30% 14% 3	800
	11th to 20th	Night	10% 10% 33% 31% 15% 1	800
	21st to end	Night	14% 13% 32% 28% 11% 2	880
February	1st to 10th	Night	11% 14% 28% 29% 16% 2	800
	11th to 20th	Night	11% 11% 30% 32% 13% 3	784
	21st to end	Night	13% 10% 35% 27% 13% 2	660
March	1st to 10th	Night	11% 11% 30% 34% 14% 1	800
	11th to 20th	Night	10% 9% 28% 31% 19% 5%	800
	21st to end	Night	9% 11% 30% 34% 15% 1	880
April	1st to 10th	Night	8% 8% 26% 36% 19% 2	800
	11th to 20th	Night	5% 8% 33% 34% 19% 2	791
	21st to end	Night	4 7% 27% 36% 21% 5%	800
May	1st to 10th	Night	5% 5% 27% 40% 19% 3	690
	11th to 20th	Night	3 5% 25% 35% 29% 3	591
	21st to end	Night	2 4 22% 44% 24% 4	650
June	1st to 10th	Night	1 3 17% 44% 33% 2	600
	11th to 20th	Night	1 1 15% 43% 35% 4	456
	21st to end	Night	2 1 10% 39% 43% 6%	400
July	1st to 10th	Night	1 4 26% 61% 9%	380
	11th to 20th	Night	3 3 35% 52% 8%	460
	21st to end	Night	3 1 5% 32% 51% 9%	740
August	1st to 10th	Night	2 4 35% 47% 11%	756
	11th to 20th	Night	1 4 29% 54% 12%	752
	21st to end	Night	3 5% 30% 51% 11%	836
September	1st to 10th	Night	2 2 7% 34% 44% 12%	760
	11th to 20th	Night	1 1 10% 37% 41% 10%	760
	21st to end	Night	1 2 18% 33% 38% 8%	760
October	1st to 10th	Night	4 3 20% 44% 27% 2	760
	11th to 20th	Night	4 5% 20% 39% 28% 4	760
	21st to end	Night	4 9% 23% 35% 21% 8%	836
November	1st to 10th	Night	5% 7% 22% 37% 25% 4	780
	11th to 20th	Night	5% 7% 26% 39% 18% 6%	800
	21st to end	Night	7% 10% 29% 33% 16% 4	800
December	1st to 10th	Night	10% 8% 29% 35% 16% 2	800
	11th to 20th	Night	12% 11% 29% 33% 13% 2	800
	21st to end	Night	10% 14% 32% 31% 11% 2	880

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