Cottonwood Pit Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cottonwood Pit Campground 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	6% 9% 3 8% 5% 4 4 3 5% 6% 47%	147332
	Night	6% 9% 3 8% 5% 4 4 3 5% 6% 46%	142994
Transparency	Day	37% 5% 8% 21% 19% 10%	142108
	Night	38% 6% 10% 21% 18% 8%	139218
Seeing	Day	15% 15% 27% 25% 13% 4	16738
	Night	13% 11% 21% 32% 20% 3	25793

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	10% 20% 7% 14% 8% 6% 5% 4 4 5% 18%	4722
	11th to 20th	Day	5% 12% 4 7% 4 3 3 2 4 5% 50%	4740
	21st to end	Day	7% 12% 4 8% 6% 5% 4 3 6% 7% 38%	5325
February	1st to 10th	Day	8% 14% 8% 11% 6% 4 5% 4 5% 8% 26%	1890
	11th to 20th	Day	7% 16% 6% 11% 7% 6% 4 3 5% 6% 29%	1924
	21st to end	Day	6% 16% 5% 12% 6% 6% 7% 4 6% 6% 25%	1730
March	1st to 10th	Day	5% 14% 6% 13% 7% 6% 5% 4 5% 7% 27%	4618
	11th to 20th	Day	5% 14% 5% 13% 7% 5% 4 3 4 4 36%	4963
	21st to end	Day	5% 17% 6% 15% 8% 7% 6% 4 5% 6% 21%	6000
April	1st to 10th	Day	10% 17% 6% 10% 6% 6% 5% 4 4 5% 28%	2520
	11th to 20th	Day	9% 16% 5% 10% 4 4 5% 4 5% 5% 35%	2489
	21st to end	Day	8% 14% 4 8% 5% 5% 4 3 5% 7% 39%	2602
May	1st to 10th	Day	7% 8% 2 6% 4 4 3 3 5% 6% 52%	8130
	11th to 20th	Day	6% 9% 3 8% 4 4 4 3 4 6% 47%	8160
	21st to end	Day	7% 8% 3 6% 5% 4 4 3 5% 8% 47%	8992
June	1st to 10th	Day	13% 10% 3 6% 4 4 4 4 5% 7% 40%	2940
	11th to 20th	Day	8% 8% 2 6% 4 4 4 3 6% 7% 48%	2940
	21st to end	Day	4 4 2 4 3 3 3 4 5% 7% 61%	2940
July	1st to 10th	Day	2 2 1 3 2 2 2 2 4 4 75%	6459
	11th to 20th	Day	1 2 1 2 2 2 2 2 3 3 81%	6460
	21st to end	Day	1 2 1 4 2 3 4 3 4 5% 71%	7021
August	1st to 10th	Day	4 4 2 5% 3 4 4 4 5% 7% 59%	6167
	11th to 20th	Day	4 2 1 2 2 2 2 2 3 4 76%	5608
	21st to end	Day	5% 4 2 5% 3 3 3 4 4 5% 61%	5984
September	1st to 10th	Day	2 3 1 4 2 3 3 3 4 5% 70%	2400
	11th to 20th	Day	6% 5% 2 6% 4 4 4 3 5% 5% 58%	2377
	21st to end	Day	6% 8% 2 5% 3 3 4 3 5% 5% 56%	2197
October	1st to 10th	Day	6% 6% 2 5% 3 2 2 3 3 5% 61%	3280
	11th to 20th	Day	5% 7% 3 9% 5% 5% 4 3 5% 8% 45%	3261
	21st to end	Day	7% 12% 6% 11% 5% 5% 4 4 5% 6% 34%	3274
November	1st to 10th	Day	10% 15% 4 10% 5% 5% 5% 3 5% 7% 31%	1854
	11th to 20th	Day	8% 15% 5% 11% 7% 6% 5% 4 6% 6% 26%	1785
	21st to end	Day	6% 16% 5% 9% 6% 6% 5% 4 4 7% 33%	1680
December	1st to 10th	Day	5% 11% 5% 9% 4 4 3 4 5% 6% 45%	2700
	11th to 20th	Day	8% 19% 7% 13% 7% 5% 5% 4 7% 7% 20%	3108
	21st to end	Day	9% 16% 6% 14% 8% 7% 6% 5% 6% 6% 17%	4092
January	1st to 10th	Night	9% 15% 6% 13% 9% 6% 6% 4 5% 6% 20%	8172
	11th to 20th	Night	6% 10% 4 7% 4 4 4 3 4 6% 50%	8220
	21st to end	Night	6% 12% 4 9% 5% 5% 4 3 5% 8% 38%	8849
February	1st to 10th	Night	8% 15% 5% 12% 6% 5% 5% 4 6% 6% 29%	2730
	11th to 20th	Night	7% 12% 5% 12% 6% 6% 5% 4 5% 7% 31%	2583
	21st to end	Night	6% 14% 7% 11% 6% 6% 5% 5% 6% 7% 26%	2076
March	1st to 10th	Night	3 11% 4 11% 6% 6% 6% 5% 7% 8% 33%	5496
	11th to 20th	Night	4 10% 4 10% 7% 5% 5% 4 5% 7% 40%	5255
	21st to end	Night	5% 13% 5% 13% 8% 6% 6% 5% 7% 8% 25%	5217
April	1st to 10th	Night	9% 12% 3 9% 6% 5% 4 4 5% 7% 36%	2100
	11th to 20th	Night	7% 13% 3 9% 5% 5% 5% 3 5% 5% 41%	2079
	21st to end	Night	6% 10% 3 7% 4 5% 4 5% 7% 8% 41%	2016
May	1st to 10th	Night	5% 7% 3 7% 4 4 3 3 4 6% 54%	4788
	11th to 20th	Night	5% 9% 3 7% 4 3 3 3 3 6% 54%	4700
	21st to end	Night	8% 7% 2 4 3 3 3 3 4 7% 56%	5181
June	1st to 10th	Night	10% 7% 1 5% 5% 4 4 4 5% 7% 49%	1680
	11th to 20th	Night	7% 6% 2 5% 5% 4 3 3 4 6% 56%	1680
	21st to end	Night	4 4 1 5% 3 3 4 2 4 5% 65%	1680
July	1st to 10th	Night	1 2 1 3 2 3 2 2 3 4 77%	3720
	11th to 20th	Night	1 1 2 2 1 2 1 3 4 83%	3720
	21st to end	Night	3 3 1 3 2 3 3 2 4 4 72%	4050
August	1st to 10th	Night	4 4 2 5% 4 3 4 3 5% 7% 59%	3623
	11th to 20th	Night	2 3 1 4 2 2 3 3 4 4 73%	4236
	21st to end	Night	4 4 1 4 2 3 3 3 4 5% 66%	5015
September	1st to 10th	Night	2 2 1 3 2 2 3 3 4 5% 71%	2000
	11th to 20th	Night	3 4 2 4 3 3 4 4 4 5% 62%	2022
	21st to end	Night	5% 5% 2 6% 3 3 3 3 5% 6% 60%	2200
October	1st to 10th	Night	5% 6% 2 4 2 2 3 2 3 4 67%	3920
	11th to 20th	Night	6% 7% 3 7% 4 4 3 3 5% 7% 51%	3897
	21st to end	Night	5% 9% 4 12% 6% 4 4 4 5% 7% 41%	4528
November	1st to 10th	Night	12% 12% 3 8% 5% 5% 5% 5% 5% 7% 34%	2665
	11th to 20th	Night	10% 12% 4 9% 7% 6% 6% 4 7% 6% 30%	2834
	21st to end	Night	6% 13% 4 9% 6% 5% 5% 4 5% 7% 36%	2940
December	1st to 10th	Night	4 8% 3 8% 6% 5% 3 3 5% 7% 49%	4700
	11th to 20th	Night	8% 18% 6% 15% 7% 6% 6% 4 6% 6% 18%	5316
	21st to end	Night	9% 14% 5% 12% 8% 7% 7% 5% 5% 6% 23%	7106

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	63% 8% 10% 12% 6%	4723
	11th to 20th	Day	39% 2 8% 20% 20% 11%	4740
	21st to end	Day	45% 6% 7% 12% 17% 12%	5325
February	1st to 10th	Day	55% 6% 14% 18% 7% 1	1890
	11th to 20th	Day	55% 5% 12% 17% 8% 3	1933
	21st to end	Day	58% 7% 11% 15% 7% 3	1730
March	1st to 10th	Day	53% 8% 8% 19% 9% 4	4618
	11th to 20th	Day	47% 9% 8% 26% 10%	4963
	21st to end	Day	58% 10% 12% 15% 4	6000
April	1st to 10th	Day	57% 5% 11% 17% 8% 1	2520
	11th to 20th	Day	50% 4 10% 20% 13% 2	2492
	21st to end	Day	45% 5% 9% 25% 14% 2	2602
May	1st to 10th	Day	33% 5% 5% 29% 25% 3	8130
	11th to 20th	Day	36% 6% 7% 23% 23% 4	8163
	21st to end	Day	34% 5% 12% 33% 13% 3	8994
June	1st to 10th	Day	42% 5% 8% 30% 14% 1	2940
	11th to 20th	Day	34% 4 9% 28% 21% 5%	2940
	21st to end	Day	23% 4 10% 26% 28% 10%	2940
July	1st to 10th	Day	12% 3 3 17% 26% 38%	6391
	11th to 20th	Day	10% 3 3 8% 25% 51%	6385
	21st to end	Day	15% 5% 3 24% 32% 21%	6822
August	1st to 10th	Day	20% 4 3 15% 32% 26%	4493
	11th to 20th	Day	14% 3 3 23% 40% 17%	4055
	21st to end	Day	19% 4 4 26% 24% 23%	4311
September	1st to 10th	Day	17% 3 4 25% 30% 21%	2400
	11th to 20th	Day	28% 5% 6% 23% 25% 13%	2377
	21st to end	Day	30% 4 9% 24% 24% 10%	2197
October	1st to 10th	Day	27% 4 7% 21% 31% 10%	3280
	11th to 20th	Day	37% 5% 13% 25% 18% 2	3261
	21st to end	Day	48% 6% 7% 21% 16% 1	3274
November	1st to 10th	Day	52% 5% 12% 20% 10% 1	1854
	11th to 20th	Day	57% 6% 11% 18% 8%	1785
	21st to end	Day	52% 5% 11% 16% 14% 2	1680
December	1st to 10th	Day	39% 6% 8% 20% 24% 2	2700
	11th to 20th	Day	62% 6% 13% 13% 5% 1	3108
	21st to end	Day	62% 10% 10% 13% 5%	4092
January	1st to 10th	Night	57% 11% 12% 14% 5% 1	8172
	11th to 20th	Night	37% 2 8% 19% 21% 12%	8220
	21st to end	Night	46% 3 11% 10% 16% 15%	8849
February	1st to 10th	Night	54% 6% 14% 16% 9% 1	2730
	11th to 20th	Night	51% 6% 12% 18% 9% 3	2585
	21st to end	Night	53% 8% 10% 17% 10% 2	2076
March	1st to 10th	Night	44% 8% 8% 22% 13% 5%	5496
	11th to 20th	Night	39% 10% 9% 29% 12% 1	5255
	21st to end	Night	52% 11% 12% 19% 4 1	5217
April	1st to 10th	Night	47% 5% 13% 25% 8% 1	2100
	11th to 20th	Night	44% 5% 12% 26% 11% 2	2079
	21st to end	Night	40% 7% 14% 23% 14% 1	2016
May	1st to 10th	Night	30% 4 7% 29% 29% 1	4786
	11th to 20th	Night	33% 4 10% 32% 21% 1	4700
	21st to end	Night	29% 4 18% 33% 14% 2	5182
June	1st to 10th	Night	34% 6% 12% 31% 15% 2	1680
	11th to 20th	Night	30% 4 12% 31% 19% 4	1680
	21st to end	Night	22% 3 10% 29% 27% 9%	1680
July	1st to 10th	Night	13% 3 4 19% 26% 36%	3680
	11th to 20th	Night	9% 2 5% 11% 27% 47%	3672
	21st to end	Night	17% 4 1 26% 32% 20%	3937
August	1st to 10th	Night	21% 4 4 18% 32% 21%	2629
	11th to 20th	Night	15% 4 4 27% 37% 13%	3061
	21st to end	Night	15% 2 7% 28% 26% 21%	3608
September	1st to 10th	Night	14% 4 5% 26% 33% 18%	2000
	11th to 20th	Night	23% 5% 7% 25% 27% 14%	2022
	21st to end	Night	25% 4 8% 25% 25% 13%	2200
October	1st to 10th	Night	23% 2 7% 21% 36% 10%	3920
	11th to 20th	Night	33% 4 16% 22% 22% 3	3897
	21st to end	Night	41% 6% 8% 25% 18% 2	4528
November	1st to 10th	Night	49% 6% 11% 17% 14% 2	2665
	11th to 20th	Night	51% 7% 13% 19% 10% 1	2834
	21st to end	Night	47% 5% 11% 17% 16% 3	2940
December	1st to 10th	Night	36% 5% 8% 20% 28% 3	4700
	11th to 20th	Night	64% 7% 9% 14% 6%	5316
	21st to end	Night	57% 10% 11% 14% 7% 1	7106

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	32% 19% 25% 13% 9% 2	220
	11th to 20th	Day	19% 20% 24% 21% 12% 4	220
	21st to end	Day	15% 18% 32% 21% 10% 3	289
February	1st to 10th	Day	21% 23% 30% 20% 6% 1	430
	11th to 20th	Day	22% 24% 29% 18% 6% 1	466
	21st to end	Day	23% 22% 29% 18% 7%	446
March	1st to 10th	Day	24% 22% 31% 18% 5%	540
	11th to 20th	Day	24% 21% 28% 18% 7% 2	540
	21st to end	Day	25% 22% 28% 19% 6% 1	594
April	1st to 10th	Day	23% 20% 25% 20% 8% 4	540
	11th to 20th	Day	20% 25% 26% 17% 7% 4	532
	21st to end	Day	15% 18% 33% 22% 10% 2	540
May	1st to 10th	Day	16% 19% 30% 20% 11% 3	543
	11th to 20th	Day	24% 17% 21% 23% 11% 3	568
	21st to end	Day	17% 14% 24% 25% 16% 6%	617
June	1st to 10th	Day	17% 15% 22% 24% 17% 6%	570
	11th to 20th	Day	13% 19% 30% 25% 11% 2	570
	21st to end	Day	5% 11% 31% 30% 17% 5%	570
July	1st to 10th	Day	4 7% 31% 34% 19% 5%	566
	11th to 20th	Day	4 10% 32% 30% 19% 4	564
	21st to end	Day	2 9% 28% 35% 20% 6%	616
August	1st to 10th	Day	3 6% 26% 35% 20% 9%	527
	11th to 20th	Day	4 7% 21% 33% 24% 11%	517
	21st to end	Day	7% 8% 22% 34% 20% 9%	583
September	1st to 10th	Day	5% 7% 27% 32% 22% 9%	530
	11th to 20th	Day	9% 11% 21% 32% 20% 7%	530
	21st to end	Day	12% 12% 24% 27% 21% 5%	530
October	1st to 10th	Day	16% 13% 22% 27% 15% 6%	530
	11th to 20th	Day	14% 16% 24% 26% 13% 6%	530
	21st to end	Day	18% 16% 29% 21% 13% 4	413
November	1st to 10th	Day	23% 15% 26% 22% 13%	330
	11th to 20th	Day	24% 16% 25% 21% 12% 2	275
	21st to end	Day	19% 18% 26% 25% 10% 2	220
December	1st to 10th	Day	19% 19% 26% 18% 11% 6%	220
	11th to 20th	Day	29% 16% 30% 18% 6%	220
	21st to end	Day	26% 20% 26% 21% 6% 2	242
January	1st to 10th	Night	18% 18% 23% 23% 15% 2	840
	11th to 20th	Night	17% 15% 19% 26% 19% 4	840
	21st to end	Night	16% 11% 19% 33% 19% 2	924
February	1st to 10th	Night	17% 16% 22% 29% 15% 2	840
	11th to 20th	Night	15% 14% 23% 29% 16% 2	824
	21st to end	Night	16% 17% 23% 32% 10% 1	692
March	1st to 10th	Night	14% 17% 24% 29% 14% 2	840
	11th to 20th	Night	14% 15% 22% 30% 17% 2	840
	21st to end	Night	16% 17% 23% 29% 13% 1	924
April	1st to 10th	Night	17% 15% 19% 29% 17% 2	840
	11th to 20th	Night	13% 15% 26% 27% 16% 3	831
	21st to end	Night	12% 13% 27% 33% 15% 1	756
May	1st to 10th	Night	8% 11% 28% 34% 17% 2	446
	11th to 20th	Night	11% 10% 22% 28% 26% 3	414
	21st to end	Night	12% 7% 22% 34% 21% 3	455
June	1st to 10th	Night	14% 9% 19% 38% 19% 1	420
	11th to 20th	Night	10% 9% 28% 36% 16% 1	420
	21st to end	Night	7% 6% 22% 42% 22% 1	420
July	1st to 10th	Night	2 5% 23% 44% 25% 2	410
	11th to 20th	Night	2 4 28% 45% 19% 1	408
	21st to end	Night	2 3 25% 40% 28% 2	458
August	1st to 10th	Night	4 1 22% 41% 30% 2	413
	11th to 20th	Night	3 3 14% 37% 36% 7%	674
	21st to end	Night	4 4 19% 39% 31% 3	880
September	1st to 10th	Night	3 4 17% 40% 33% 4	800
	11th to 20th	Night	5% 5% 18% 35% 29% 9%	800
	21st to end	Night	8% 7% 16% 33% 31% 6%	800
October	1st to 10th	Night	11% 5% 19% 34% 25% 5%	800
	11th to 20th	Night	12% 9% 18% 33% 22% 6%	800
	21st to end	Night	13% 12% 18% 34% 18% 5%	880
November	1st to 10th	Night	19% 12% 18% 33% 16% 1	820
	11th to 20th	Night	19% 17% 20% 27% 15% 2	840
	21st to end	Night	15% 14% 20% 29% 17% 5%	840
December	1st to 10th	Night	18% 11% 20% 30% 18% 4	840
	11th to 20th	Night	19% 14% 20% 30% 16% 1	840
	21st to end	Night	25% 18% 22% 24% 11% 1	924

Page generated at 2026-07-28 00:25:22. Version ac07

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