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 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	6% 10% 4 8% 5% 4 4 3 5% 6% 47%	112928
	Night	6% 10% 4 8% 5% 4 4 4 5% 6% 45%	115147
Transparency	Day	38% 5% 8% 20% 18% 11%	112671
	Night	40% 5% 10% 21% 17% 7%	114993
Seeing	Day	15% 15% 27% 25% 14% 4	14966
	Night	13% 11% 20% 32% 20% 3	24228

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% 13% 7% 6% 5% 4 5% 4 20%	3639
	11th to 20th	Day	6% 15% 6% 10% 5% 4 4 3 4 4 39%	3640
	21st to end	Day	8% 13% 4 8% 6% 4 3 2 5% 6% 39%	4114
February	1st to 10th	Day	8% 15% 8% 11% 6% 4 5% 4 5% 7% 26%	1800
	11th to 20th	Day	7% 17% 6% 10% 6% 6% 4 3 5% 6% 29%	1830
	21st to end	Day	6% 16% 6% 12% 7% 6% 7% 4 6% 6% 24%	1650
March	1st to 10th	Day	5% 15% 7% 13% 8% 6% 5% 4 5% 5% 27%	3238
	11th to 20th	Day	5% 11% 4 8% 5% 4 3 3 4 5% 49%	3493
	21st to end	Day	6% 18% 6% 13% 8% 7% 6% 4 5% 5% 22%	4165
April	1st to 10th	Day	11% 18% 6% 9% 6% 6% 4 4 5% 5% 27%	2280
	11th to 20th	Day	9% 16% 5% 10% 4 4 5% 4 5% 5% 34%	2249
	21st to end	Day	8% 14% 4 8% 5% 5% 4 3 5% 7% 37%	2354
May	1st to 10th	Day	10% 13% 3 8% 4 5% 3 3 4 5% 41%	4381
	11th to 20th	Day	6% 6% 2 5% 3 3 3 3 4 5% 59%	4377
	21st to end	Day	9% 11% 3 7% 6% 5% 4 4 5% 7% 39%	4813
June	1st to 10th	Day	14% 10% 3 6% 5% 4 4 4 5% 7% 37%	2660
	11th to 20th	Day	9% 8% 2 7% 4 4 3 3 6% 7% 47%	2660
	21st to end	Day	4 4 1 4 3 3 3 4 5% 6% 63%	2660
July	1st to 10th	Day	1 1 1 2 2 2 2 2 3 4 81%	4420
	11th to 20th	Day	1 2 1 2 2 2 2 2 3 4 78%	4420
	21st to end	Day	1 2 1 3 2 2 4 3 4 4 75%	4790
August	1st to 10th	Day	4 4 1 4 3 3 3 3 5% 6% 64%	4370
	11th to 20th	Day	2 3 1 3 2 2 3 2 4 5% 73%	3890
	21st to end	Day	3 3 2 4 3 2 3 3 3 5% 69%	4180
September	1st to 10th	Day	2 2 1 3 2 3 3 2 4 5% 72%	2280
	11th to 20th	Day	6% 5% 2 6% 4 4 4 3 4 5% 57%	2258
	21st to end	Day	7% 7% 2 5% 3 3 4 3 5% 5% 55%	2087
October	1st to 10th	Day	6% 6% 2 5% 3 2 2 3 3 6% 61%	3180
	11th to 20th	Day	6% 7% 3 8% 5% 5% 4 4 5% 8% 45%	3161
	21st to end	Day	7% 12% 6% 11% 5% 5% 4 4 5% 6% 34%	3173
November	1st to 10th	Day	11% 15% 4 9% 5% 5% 5% 3 5% 7% 31%	1764
	11th to 20th	Day	8% 15% 4 11% 7% 6% 5% 4 6% 6% 26%	1700
	21st to end	Day	6% 15% 5% 9% 6% 6% 5% 4 4 6% 33%	1600
December	1st to 10th	Day	5% 10% 5% 9% 4 4 3 4 5% 6% 46%	2620
	11th to 20th	Day	8% 19% 7% 13% 7% 6% 5% 4 7% 6% 20%	3028
	21st to end	Day	8% 16% 6% 14% 8% 7% 6% 5% 6% 6% 17%	4004
January	1st to 10th	Night	10% 16% 6% 12% 7% 6% 6% 4 5% 6% 21%	6306
	11th to 20th	Night	8% 13% 5% 8% 5% 4 4 3 4 5% 40%	6320
	21st to end	Night	7% 13% 4 9% 5% 4 4 3 5% 6% 40%	6846
February	1st to 10th	Night	8% 15% 5% 12% 6% 5% 5% 4 6% 6% 28%	2600
	11th to 20th	Night	8% 13% 5% 12% 6% 5% 4 4 5% 7% 31%	2457
	21st to end	Night	6% 15% 7% 11% 6% 6% 5% 5% 6% 7% 26%	1980
March	1st to 10th	Night	4 11% 4 10% 6% 6% 6% 5% 7% 8% 32%	3856
	11th to 20th	Night	4 9% 3 7% 6% 4 4 4 4 6% 48%	3706
	21st to end	Night	5% 13% 5% 12% 8% 6% 7% 6% 7% 7% 24%	3626
April	1st to 10th	Night	10% 13% 3 9% 6% 5% 4 4 5% 6% 35%	1900
	11th to 20th	Night	7% 13% 4 8% 5% 5% 5% 3 5% 5% 40%	1879
	21st to end	Night	7% 11% 4 7% 4 5% 4 5% 7% 8% 39%	1824
May	1st to 10th	Night	6% 11% 4 9% 4 4 4 3 5% 6% 42%	2577
	11th to 20th	Night	5% 5% 2 4 3 3 3 3 3 6% 64%	2516
	21st to end	Night	7% 10% 3 5% 3 4 4 3 4 6% 52%	2762
June	1st to 10th	Night	11% 7% 1 4 5% 4 4 4 5% 7% 47%	1520
	11th to 20th	Night	7% 5% 2 5% 4 4 3 3 4 6% 56%	1520
	21st to end	Night	4 3 1 4 3 3 4 2 4 5% 66%	1520
July	1st to 10th	Night	1 1 1 1 2 2 2 3 4 83%	2540
	11th to 20th	Night	2 1 1 2 2 2 2 1 4 4 78%	2540
	21st to end	Night	2 2 1 2 2 2 2 2 3 4 78%	2761
August	1st to 10th	Night	3 4 2 4 3 3 4 3 4 6% 63%	2556
	11th to 20th	Night	2 2 1 4 2 2 3 3 4 5% 71%	2940
	21st to end	Night	2 2 1 3 2 3 3 2 3 5% 74%	3498
September	1st to 10th	Night	2 2 1 2 2 2 3 3 4 5% 74%	1900
	11th to 20th	Night	3 4 2 4 3 3 4 4 4 5% 62%	1921
	21st to end	Night	5% 5% 2 6% 3 3 3 3 5% 6% 59%	2090
October	1st to 10th	Night	5% 6% 2 4 2 2 2 2 3 4 67%	3800
	11th to 20th	Night	6% 7% 3 6% 4 4 3 3 5% 7% 51%	3777
	21st to end	Night	5% 9% 4 12% 5% 4 4 4 5% 7% 41%	4387
November	1st to 10th	Night	11% 12% 3 8% 5% 5% 5% 5% 5% 6% 34%	2535
	11th to 20th	Night	10% 11% 4 9% 7% 6% 6% 4 7% 6% 31%	2699
	21st to end	Night	6% 13% 4 9% 6% 5% 6% 4 6% 7% 36%	2800
December	1st to 10th	Night	4 8% 3 7% 5% 5% 3 3 4 7% 50%	4560
	11th to 20th	Night	8% 18% 6% 15% 7% 6% 6% 4 6% 6% 18%	5176
	21st to end	Night	10% 14% 5% 11% 8% 7% 7% 5% 5% 6% 23%	6952

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	66% 5% 9% 13% 7% 1	3639
	11th to 20th	Day	50% 2 10% 21% 14% 3	3640
	21st to end	Day	47% 5% 7% 15% 15% 12%	4114
February	1st to 10th	Day	56% 6% 15% 17% 7% 1	1800
	11th to 20th	Day	55% 5% 12% 16% 9% 3	1839
	21st to end	Day	58% 6% 12% 14% 6% 2	1650
March	1st to 10th	Day	54% 8% 7% 18% 11% 1	3238
	11th to 20th	Day	39% 4 10% 35% 13%	3493
	21st to end	Day	62% 6% 11% 16% 5%	4165
April	1st to 10th	Day	58% 4 12% 16% 9% 2	2280
	11th to 20th	Day	51% 4 11% 19% 12% 2	2252
	21st to end	Day	48% 5% 9% 24% 13% 2	2354
May	1st to 10th	Day	45% 5% 8% 28% 13% 1	4381
	11th to 20th	Day	27% 4 6% 26% 30% 7%	4380
	21st to end	Day	42% 5% 16% 26% 10% 1	4814
June	1st to 10th	Day	45% 5% 9% 30% 12% 1	2660
	11th to 20th	Day	35% 4 9% 29% 19% 4	2660
	21st to end	Day	22% 3 10% 26% 29% 10%	2660
July	1st to 10th	Day	10% 2 4 12% 20% 52%	4351
	11th to 20th	Day	11% 3 3 8% 22% 53%	4345
	21st to end	Day	12% 5% 2 14% 36% 30%	4639
August	1st to 10th	Day	20% 4 3 14% 32% 27%	4354
	11th to 20th	Day	14% 3 3 23% 40% 17%	3929
	21st to end	Day	18% 4 4 26% 25% 23%	4179
September	1st to 10th	Day	15% 2 4 26% 31% 22%	2280
	11th to 20th	Day	28% 5% 6% 23% 24% 14%	2258
	21st to end	Day	30% 4 9% 24% 24% 9%	2087
October	1st to 10th	Day	27% 3 7% 21% 31% 11%	3180
	11th to 20th	Day	37% 5% 13% 25% 18% 2	3161
	21st to end	Day	49% 6% 7% 20% 17% 1	3173
November	1st to 10th	Day	53% 4 11% 20% 11% 1	1764
	11th to 20th	Day	57% 6% 11% 18% 8%	1700
	21st to end	Day	52% 5% 11% 15% 14% 3	1600
December	1st to 10th	Day	38% 6% 8% 20% 25% 2	2620
	11th to 20th	Day	62% 6% 13% 13% 5% 1	3028
	21st to end	Day	63% 10% 10% 12% 5%	4004
January	1st to 10th	Night	62% 6% 11% 15% 6% 1	6306
	11th to 20th	Night	46% 2 10% 20% 18% 2	6320
	21st to end	Night	46% 3 12% 11% 16% 12%	6846
February	1st to 10th	Night	55% 6% 14% 15% 9% 1	2600
	11th to 20th	Night	51% 6% 12% 18% 10% 3	2459
	21st to end	Night	54% 8% 10% 17% 9% 2	1980
March	1st to 10th	Night	45% 8% 9% 24% 13% 2	3856
	11th to 20th	Night	36% 6% 9% 35% 13% 1	3706
	21st to end	Night	56% 7% 15% 17% 4 1	3626
April	1st to 10th	Night	49% 5% 14% 23% 8% 1	1900
	11th to 20th	Night	45% 5% 13% 25% 10% 2	1879
	21st to end	Night	41% 7% 15% 22% 12% 2	1824
May	1st to 10th	Night	42% 3 10% 29% 15%	2577
	11th to 20th	Night	22% 3 10% 35% 28% 1	2516
	21st to end	Night	33% 3 26% 30% 7% 1	2762
June	1st to 10th	Night	36% 5% 13% 31% 13% 1	1520
	11th to 20th	Night	30% 4 13% 33% 17% 3	1520
	21st to end	Night	21% 3 10% 30% 27% 9%	1520
July	1st to 10th	Night	8% 2 6% 14% 19% 51%	2500
	11th to 20th	Night	11% 3 5% 11% 24% 47%	2492
	21st to end	Night	12% 3 1 16% 39% 29%	2674
August	1st to 10th	Night	21% 4 4 17% 32% 22%	2548
	11th to 20th	Night	15% 4 4 27% 37% 13%	2967
	21st to end	Night	15% 2 7% 28% 27% 21%	3498
September	1st to 10th	Night	13% 3 5% 27% 33% 19%	1900
	11th to 20th	Night	23% 4 7% 25% 27% 14%	1921
	21st to end	Night	26% 4 8% 26% 24% 12%	2090
October	1st to 10th	Night	22% 2 7% 21% 37% 11%	3800
	11th to 20th	Night	33% 4 16% 22% 22% 3	3777
	21st to end	Night	42% 6% 8% 24% 18% 2	4387
November	1st to 10th	Night	49% 6% 10% 17% 15% 2	2535
	11th to 20th	Night	51% 7% 12% 19% 10% 1	2699
	21st to end	Night	47% 5% 11% 17% 17% 3	2800
December	1st to 10th	Night	36% 5% 8% 20% 29% 3	4560
	11th to 20th	Night	64% 7% 9% 14% 6%	5176
	21st to end	Night	57% 10% 11% 14% 7% 1	6952

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	30% 20% 26% 14% 10% 2	200
	11th to 20th	Day	21% 22% 25% 20% 10% 4	200
	21st to end	Day	16% 17% 32% 21% 10% 3	265
February	1st to 10th	Day	22% 23% 30% 19% 6% 1	400
	11th to 20th	Day	22% 24% 29% 17% 6% 1	432
	21st to end	Day	21% 22% 31% 19% 7%	414
March	1st to 10th	Day	23% 21% 32% 18% 6%	500
	11th to 20th	Day	23% 21% 28% 19% 8% 2	500
	21st to end	Day	25% 20% 28% 21% 5% 1	531
April	1st to 10th	Day	24% 20% 26% 20% 7% 3	460
	11th to 20th	Day	19% 25% 26% 17% 8% 4	452
	21st to end	Day	15% 20% 31% 22% 10% 2	460
May	1st to 10th	Day	17% 20% 29% 19% 11% 4	463
	11th to 20th	Day	22% 15% 23% 25% 12% 4	488
	21st to end	Day	18% 13% 23% 25% 16% 5%	529
June	1st to 10th	Day	16% 15% 22% 23% 18% 6%	490
	11th to 20th	Day	14% 20% 28% 24% 12% 2	490
	21st to end	Day	4 10% 32% 31% 17% 6%	490
July	1st to 10th	Day	4 7% 31% 35% 19% 4	486
	11th to 20th	Day	4 9% 31% 32% 20% 5%	484
	21st to end	Day	2 8% 28% 35% 20% 6%	531
August	1st to 10th	Day	3 6% 27% 36% 19% 9%	487
	11th to 20th	Day	4 7% 21% 33% 25% 11%	477
	21st to end	Day	6% 9% 23% 34% 19% 8%	539
September	1st to 10th	Day	4 7% 27% 31% 22% 9%	490
	11th to 20th	Day	9% 11% 21% 32% 20% 6%	490
	21st to end	Day	13% 12% 24% 27% 20% 4	490
October	1st to 10th	Day	16% 13% 21% 28% 16% 7%	490
	11th to 20th	Day	14% 16% 22% 28% 14% 7%	490
	21st to end	Day	17% 16% 29% 20% 13% 5%	378
November	1st to 10th	Day	22% 15% 25% 23% 14%	300
	11th to 20th	Day	23% 16% 25% 22% 12% 2	250
	21st to end	Day	19% 19% 25% 25% 11% 2	200
December	1st to 10th	Day	15% 20% 27% 20% 13% 7%	200
	11th to 20th	Day	27% 17% 32% 18% 6% 1	200
	21st to end	Day	23% 21% 27% 21% 6% 2	220
January	1st to 10th	Night	17% 18% 24% 23% 16% 2	800
	11th to 20th	Night	18% 16% 18% 25% 19% 4	800
	21st to end	Night	16% 11% 19% 32% 19% 2	880
February	1st to 10th	Night	17% 16% 23% 29% 14% 2	800
	11th to 20th	Night	16% 14% 23% 29% 16% 2	784
	21st to end	Night	15% 17% 24% 32% 11% 1	660
March	1st to 10th	Night	14% 17% 24% 30% 15% 2	800
	11th to 20th	Night	14% 15% 21% 31% 17% 2	800
	21st to end	Night	15% 16% 23% 30% 14% 1	862
April	1st to 10th	Night	18% 15% 19% 29% 17% 2	760
	11th to 20th	Night	12% 15% 27% 27% 17% 3	751
	21st to end	Night	12% 12% 26% 33% 16% 2	684
May	1st to 10th	Night	8% 11% 27% 34% 16% 2	404
	11th to 20th	Night	11% 9% 18% 30% 28% 3	374
	21st to end	Night	12% 7% 21% 34% 22% 3	411
June	1st to 10th	Night	14% 7% 18% 38% 21% 1	380
	11th to 20th	Night	10% 9% 25% 37% 18% 1	380
	21st to end	Night	6% 6% 20% 44% 23% 2	380
July	1st to 10th	Night	1 4 22% 45% 25% 2	370
	11th to 20th	Night	2 3 27% 46% 21% 1	368
	21st to end	Night	2 3 22% 43% 29% 2	416
August	1st to 10th	Night	4 1 21% 41% 31% 2	392
	11th to 20th	Night	3 3 13% 37% 37% 7%	640
	21st to end	Night	3 5% 19% 39% 31% 3	836
September	1st to 10th	Night	3 3 16% 39% 34% 4	760
	11th to 20th	Night	5% 5% 17% 35% 29% 9%	760
	21st to end	Night	8% 6% 15% 34% 31% 6%	760
October	1st to 10th	Night	11% 5% 18% 35% 25% 5%	760
	11th to 20th	Night	12% 9% 17% 34% 23% 6%	760
	21st to end	Night	13% 12% 18% 33% 18% 6%	836
November	1st to 10th	Night	18% 12% 18% 34% 17% 1	780
	11th to 20th	Night	19% 16% 20% 27% 16% 2	800
	21st to end	Night	15% 14% 19% 29% 17% 5%	800
December	1st to 10th	Night	17% 11% 19% 31% 18% 4	800
	11th to 20th	Night	18% 15% 20% 30% 16% 1	800
	21st to end	Night	24% 18% 22% 24% 11% 1	880

Page generated at 2025-03-24 06:04:28. Version ac07

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