Camp Wood Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Camp Wood Observatory clear sky chart from 2005-11-06 to 2026-04-17.

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	12% 6% 2 5% 3 3 4 3 5% 7% 51%	131908
	Night	12% 5% 2 4 3 3 3 3 5% 7% 55%	130601
Transparency	Day	33% 4 9% 21% 20% 13%	135794
	Night	30% 4 10% 20% 20% 15%	134779
Seeing	Day	14% 8% 25% 33% 17% 3	16563
	Night	13% 7% 28% 38% 13% 1	26666

By Month

Percentage Cloud Cover SE (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% 5% 1 3 2 3 3 2 4 5% 62%	5289
	11th to 20th	Day	10% 5% 2 4 2 2 3 2 4 5% 60%	5667
	21st to end	Day	19% 7% 2 4 2 3 3 2 3 6% 49%	6468
February	1st to 10th	Day	12% 8% 2 6% 3 3 3 3 4 5% 51%	2100
	11th to 20th	Day	13% 7% 2 5% 3 4 3 3 6% 5% 49%	2049
	21st to end	Day	12% 6% 2 4 2 2 3 3 3 7% 57%	1730
March	1st to 10th	Day	13% 6% 2 4 3 3 3 3 4 5% 55%	4690
	11th to 20th	Day	15% 6% 2 5% 3 2 2 2 3 5% 55%	5090
	21st to end	Day	14% 7% 2 4 2 3 3 2 5% 7% 51%	5583
April	1st to 10th	Day	14% 7% 2 5% 3 3 4 3 6% 6% 48%	2347
	11th to 20th	Day	15% 5% 2 5% 5% 3 3 3 5% 6% 48%	2447
	21st to end	Day	14% 6% 2 5% 4 3 3 3 5% 6% 48%	2400
May	1st to 10th	Day	19% 6% 2 6% 4 3 4 3 5% 6% 41%	5811
	11th to 20th	Day	10% 4 2 5% 3 3 4 3 6% 9% 51%	5862
	21st to end	Day	15% 7% 3 7% 4 5% 5% 4 6% 9% 37%	6434
June	1st to 10th	Day	7% 4 2 4 3 4 4 4 6% 9% 52%	2600
	11th to 20th	Day	8% 5% 1 4 4 4 4 4 6% 9% 50%	2600
	21st to end	Day	9% 5% 2 5% 6% 6% 7% 5% 7% 8% 41%	2600
July	1st to 10th	Day	15% 6% 2 6% 5% 4 4 4 6% 7% 40%	5900
	11th to 20th	Day	8% 4 2 5% 4 4 5% 4 7% 9% 47%	5900
	21st to end	Day	7% 5% 2 5% 4 4 5% 4 6% 8% 50%	6207
August	1st to 10th	Day	2 2 1 3 3 3 3 3 5% 8% 69%	3905
	11th to 20th	Day	4 2 1 3 3 3 4 3 5% 9% 63%	3846
	21st to end	Day	6% 4 2 5% 4 5% 5% 4 5% 9% 51%	4312
September	1st to 10th	Day	12% 6% 2 6% 5% 5% 5% 4 7% 8% 40%	2220
	11th to 20th	Day	11% 6% 2 7% 4 5% 5% 3 6% 7% 43%	2200
	21st to end	Day	9% 5% 2 6% 4 4 5% 4 7% 6% 49%	2200
October	1st to 10th	Day	8% 4 1 5% 4 4 3 3 5% 8% 56%	2200
	11th to 20th	Day	14% 5% 2 4 3 3 3 3 4 6% 53%	2200
	21st to end	Day	13% 5% 2 4 3 2 3 2 4 4 59%	2220
November	1st to 10th	Day	14% 7% 2 4 4 3 4 3 4 6% 50%	1953
	11th to 20th	Day	13% 6% 2 4 3 3 3 2 4 6% 54%	1890
	21st to end	Day	15% 9% 2 4 3 3 3 3 4 5% 49%	1890
December	1st to 10th	Day	22% 8% 3 6% 3 3 3 2 4 4 41%	3030
	11th to 20th	Day	16% 8% 2 6% 4 3 4 3 4 5% 46%	3481
	21st to end	Day	14% 5% 1 4 2 2 2 2 3 5% 61%	4587
January	1st to 10th	Night	10% 4 1 3 2 2 3 2 4 6% 62%	7634
	11th to 20th	Night	9% 4 1 3 2 2 2 2 4 5% 66%	7366
	21st to end	Night	24% 6% 2 4 3 2 2 2 3 4 47%	7746
February	1st to 10th	Night	10% 7% 1 3 2 2 3 3 5% 6% 57%	2520
	11th to 20th	Night	14% 6% 1 4 2 3 3 3 4 5% 54%	2458
	21st to end	Night	12% 5% 2 4 3 3 3 3 5% 6% 54%	2076
March	1st to 10th	Night	10% 6% 2 4 3 3 3 3 6% 7% 54%	5400
	11th to 20th	Night	12% 5% 2 5% 3 3 3 2 3 5% 57%	5090
	21st to end	Night	14% 7% 2 5% 2 2 3 3 4 6% 52%	5588
April	1st to 10th	Night	10% 5% 2 4 4 3 3 3 5% 7% 52%	2268
	11th to 20th	Night	16% 5% 2 4 3 4 3 3 5% 5% 50%	2037
	21st to end	Night	15% 6% 2 5% 4 3 3 3 4 5% 50%	2000
May	1st to 10th	Night	20% 7% 2 5% 3 3 3 2 5% 5% 45%	4099
	11th to 20th	Night	8% 3 2 4 3 3 4 3 6% 7% 57%	4053
	21st to end	Night	12% 6% 2 5% 4 4 4 4 7% 10% 43%	4443
June	1st to 10th	Night	3 3 1 3 3 3 3 3 6% 11% 61%	1800
	11th to 20th	Night	5% 3 1 4 3 3 4 3 6% 8% 59%	1800
	21st to end	Night	7% 5% 1 4 4 4 3 3 6% 11% 52%	1800
July	1st to 10th	Night	11% 4 2 5% 4 4 4 4 7% 9% 47%	4078
	11th to 20th	Night	6% 4 1 5% 3 4 4 4 6% 9% 56%	4077
	21st to end	Night	9% 4 1 5% 4 3 4 3 6% 9% 53%	4645
August	1st to 10th	Night	1 1 1 2 2 2 2 3 4 8% 74%	3255
	11th to 20th	Night	3 2 1 3 2 3 4 3 5% 9% 65%	3213
	21st to end	Night	5% 3 2 5% 3 4 5% 4 6% 10% 53%	3597
September	1st to 10th	Night	9% 6% 2 6% 3 4 4 4 6% 9% 48%	2180
	11th to 20th	Night	9% 6% 2 6% 4 3 4 4 5% 8% 50%	2200
	21st to end	Night	8% 4 2 4 3 4 3 4 6% 8% 54%	2200
October	1st to 10th	Night	7% 4 2 3 3 2 3 3 5% 7% 62%	2200
	11th to 20th	Night	12% 5% 1 3 2 3 3 3 4 6% 58%	2200
	21st to end	Night	11% 4 1 3 2 2 2 2 3 3 67%	2598
November	1st to 10th	Night	13% 6% 2 3 2 2 3 2 4 5% 58%	2561
	11th to 20th	Night	10% 5% 2 4 3 3 3 2 5% 6% 59%	2730
	21st to end	Night	16% 6% 2 3 3 3 4 3 4 6% 52%	2730
December	1st to 10th	Night	24% 7% 2 4 3 4 3 3 4 5% 40%	4380
	11th to 20th	Night	19% 6% 2 4 3 3 3 2 3 4 51%	4946
	21st to end	Night	14% 5% 1 3 2 2 2 2 4 6% 60%	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	27% 2 4 22% 27% 18%	5290
	11th to 20th	Day	29% 3 3 15% 26% 24%	5667
	21st to end	Day	40% 2 5% 14% 27% 12%	6468
February	1st to 10th	Day	37% 3 5% 13% 21% 20%	2100
	11th to 20th	Day	37% 3 6% 18% 21% 15%	2059
	21st to end	Day	31% 3 7% 16% 24% 19%	1730
March	1st to 10th	Day	34% 2 4 16% 16% 28%	4690
	11th to 20th	Day	35% 3 3 10% 15% 34%	5090
	21st to end	Day	35% 4 7% 17% 19% 19%	5585
April	1st to 10th	Day	38% 4 7% 16% 18% 17%	2347
	11th to 20th	Day	37% 4 7% 20% 16% 17%	2447
	21st to end	Day	38% 4 8% 18% 17% 14%	2400
May	1st to 10th	Day	43% 5% 8% 19% 16% 9%	5849
	11th to 20th	Day	31% 4 10% 19% 22% 13%	5866
	21st to end	Day	42% 6% 9% 24% 16% 3	6447
June	1st to 10th	Day	27% 6% 13% 31% 19% 4	2600
	11th to 20th	Day	30% 6% 12% 26% 21% 6%	2600
	21st to end	Day	38% 7% 13% 23% 16% 4	2600
July	1st to 10th	Day	42% 5% 16% 27% 9% 1	5836
	11th to 20th	Day	31% 7% 18% 31% 12% 1	5831
	21st to end	Day	29% 6% 19% 26% 18% 2	6030
August	1st to 10th	Day	15% 4 11% 41% 28% 1	3892
	11th to 20th	Day	18% 5% 22% 41% 12% 2	3882
	21st to end	Day	28% 7% 16% 27% 21% 2	4311
September	1st to 10th	Day	41% 7% 11% 18% 16% 7%	2220
	11th to 20th	Day	38% 6% 12% 22% 18% 4	2200
	21st to end	Day	33% 5% 10% 21% 18% 12%	2200
October	1st to 10th	Day	19% 4 6% 15% 23% 33%	3590
	11th to 20th	Day	32% 4 6% 16% 18% 25%	3568
	21st to end	Day	29% 3 4 17% 34% 13%	3570
November	1st to 10th	Day	36% 3 8% 18% 22% 12%	1953
	11th to 20th	Day	34% 3 6% 19% 20% 18%	1890
	21st to end	Day	40% 2 5% 19% 19% 15%	1890
December	1st to 10th	Day	50% 2 6% 15% 17% 11%	3030
	11th to 20th	Day	42% 4 6% 14% 19% 16%	3479
	21st to end	Day	30% 2 3 15% 29% 21%	4587
January	1st to 10th	Night	25% 2 6% 18% 30% 18%	7635
	11th to 20th	Night	23% 1 3 16% 29% 28%	7366
	21st to end	Night	43% 2 3 12% 22% 17%	7746
February	1st to 10th	Night	29% 3 8% 16% 21% 24%	2520
	11th to 20th	Night	34% 3 6% 19% 21% 17%	2458
	21st to end	Night	31% 4 6% 16% 23% 20%	2076
March	1st to 10th	Night	30% 4 8% 19% 18% 20%	5400
	11th to 20th	Night	32% 3 5% 12% 16% 32%	5090
	21st to end	Night	34% 3 8% 18% 18% 18%	5588
April	1st to 10th	Night	31% 5% 11% 19% 16% 19%	2268
	11th to 20th	Night	37% 4 9% 16% 16% 18%	2037
	21st to end	Night	38% 4 9% 18% 16% 15%	2000
May	1st to 10th	Night	41% 5% 8% 18% 15% 13%	4125
	11th to 20th	Night	27% 4 13% 20% 22% 15%	4054
	21st to end	Night	36% 5% 14% 25% 14% 6%	4452
June	1st to 10th	Night	18% 4 19% 36% 20% 3	1800
	11th to 20th	Night	22% 6% 13% 29% 24% 6%	1800
	21st to end	Night	27% 7% 19% 26% 17% 5%	1800
July	1st to 10th	Night	34% 7% 23% 28% 8% 1	4035
	11th to 20th	Night	25% 7% 22% 31% 14% 2	4026
	21st to end	Night	27% 7% 20% 29% 16% 2	4512
August	1st to 10th	Night	10% 4 16% 42% 27% 1	3244
	11th to 20th	Night	17% 5% 26% 40% 10% 2	3243
	21st to end	Night	25% 8% 20% 28% 17% 2	3597
September	1st to 10th	Night	33% 6% 14% 22% 17% 8%	2180
	11th to 20th	Night	30% 7% 18% 23% 16% 6%	2200
	21st to end	Night	28% 7% 11% 23% 19% 11%	2200
October	1st to 10th	Night	16% 3 8% 16% 22% 35%	3590
	11th to 20th	Night	26% 3 7% 15% 24% 25%	3570
	21st to end	Night	22% 2 5% 16% 38% 17%	4186
November	1st to 10th	Night	30% 3 6% 19% 25% 16%	2561
	11th to 20th	Night	28% 4 7% 21% 21% 19%	2730
	21st to end	Night	36% 3 7% 17% 21% 17%	2730
December	1st to 10th	Night	47% 3 9% 13% 14% 14%	4380
	11th to 20th	Night	38% 3 6% 15% 20% 18%	4947
	21st to end	Night	29% 3 4 18% 27% 19%	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	18% 12% 37% 24% 7% 1	330
	11th to 20th	Day	20% 13% 33% 26% 7% 1	330
	21st to end	Day	18% 15% 37% 21% 8%	363
February	1st to 10th	Day	23% 14% 27% 24% 10% 1	330
	11th to 20th	Day	22% 15% 36% 20% 7%	330
	21st to end	Day	18% 17% 42% 20% 4	273
March	1st to 10th	Day	23% 18% 41% 15% 3	330
	11th to 20th	Day	18% 19% 41% 18% 3	330
	21st to end	Day	20% 16% 40% 20% 3 1	363
April	1st to 10th	Day	16% 19% 42% 22% 2	367
	11th to 20th	Day	16% 20% 40% 21% 3	517
	21st to end	Day	15% 17% 46% 19% 3	500
May	1st to 10th	Day	16% 13% 41% 27% 4	678
	11th to 20th	Day	18% 10% 37% 28% 6% 1	725
	21st to end	Day	16% 9% 35% 33% 7%	789
June	1st to 10th	Day	7% 3 23% 51% 14% 1	730
	11th to 20th	Day	10% 2 25% 47% 14% 1	730
	21st to end	Day	9% 3 20% 38% 26% 4	730
July	1st to 10th	Day	14% 3 12% 38% 28% 5%	721
	11th to 20th	Day	7% 2 7% 44% 37% 3	718
	21st to end	Day	4 2 8% 43% 38% 5%	706
August	1st to 10th	Day	2 6% 47% 37% 8%	527
	11th to 20th	Day	7% 1 7% 38% 39% 8%	517
	21st to end	Day	6% 2 7% 37% 39% 9%	583
September	1st to 10th	Day	10% 2 9% 32% 37% 9%	350
	11th to 20th	Day	8% 1 8% 33% 42% 10%	330
	21st to end	Day	9% 2 7% 41% 34% 7%	330
October	1st to 10th	Day	6% 5% 12% 41% 30% 6%	330
	11th to 20th	Day	14% 4 18% 46% 16% 2	330
	21st to end	Day	18% 11% 26% 30% 12% 3	363
November	1st to 10th	Day	19% 7% 26% 32% 15% 1	330
	11th to 20th	Day	22% 9% 25% 26% 15% 4	330
	21st to end	Day	23% 12% 32% 22% 9% 2	330
December	1st to 10th	Day	20% 8% 29% 30% 10% 2	330
	11th to 20th	Day	20% 17% 27% 25% 10% 2	330
	21st to end	Day	19% 10% 31% 28% 11% 1	363
January	1st to 10th	Night	14% 8% 31% 37% 9%	1050
	11th to 20th	Night	17% 10% 29% 37% 8%	944
	21st to end	Night	21% 10% 29% 33% 7%	924
February	1st to 10th	Night	18% 10% 31% 34% 7%	840
	11th to 20th	Night	19% 13% 36% 26% 5%	824
	21st to end	Night	17% 10% 43% 28% 2	692
March	1st to 10th	Night	19% 14% 38% 25% 3 1	798
	11th to 20th	Night	16% 13% 36% 31% 4	630
	21st to end	Night	15% 12% 45% 24% 4	693
April	1st to 10th	Night	11% 13% 47% 27% 2	630
	11th to 20th	Night	16% 15% 49% 19% 2	611
	21st to end	Night	17% 14% 45% 22% 3 1	600
May	1st to 10th	Night	14% 13% 42% 29% 2	600
	11th to 20th	Night	14% 8% 43% 30% 5%	591
	21st to end	Night	12% 8% 42% 31% 6%	650
June	1st to 10th	Night	4 3 37% 48% 8%	600
	11th to 20th	Night	7% 2 42% 42% 7%	600
	21st to end	Night	6% 3 27% 50% 14%	600
July	1st to 10th	Night	7% 3 17% 54% 18% 1	585
	11th to 20th	Night	5% 1 17% 56% 21%	582
	21st to end	Night	5% 2 11% 59% 23% 1	657
August	1st to 10th	Night	1 1 8% 61% 28% 1	597
	11th to 20th	Night	4 2 10% 56% 27% 1	594
	21st to end	Night	5% 1 11% 49% 32% 2	660
September	1st to 10th	Night	8% 1 11% 45% 33% 2	600
	11th to 20th	Night	11% 1 9% 48% 30% 1	600
	21st to end	Night	9% 2 14% 44% 29% 3	600
October	1st to 10th	Night	9% 1 17% 48% 24% 2	600
	11th to 20th	Night	12% 4 23% 42% 19% 1	600
	21st to end	Night	12% 8% 25% 35% 19% 1	838
November	1st to 10th	Night	15% 7% 20% 39% 18% 1	921
	11th to 20th	Night	13% 6% 25% 38% 16% 2	1050
	21st to end	Night	19% 9% 25% 36% 10% 1	1050
December	1st to 10th	Night	17% 7% 25% 40% 10% 1	1050
	11th to 20th	Night	21% 11% 24% 33% 11%	1050
	21st to end	Night	17% 9% 26% 39% 8% 1	1155

Page generated at 2026-04-14 01:44:28. Version ac07

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