Camp Highroad
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Camp Highroad clear sky chart from 2005-11-06 to 2026-02-01.

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	14% 6% 2 6% 4 4 5% 4 6% 8% 42%	127461
	Night	14% 6% 2 6% 4 4 4 4 5% 7% 43%	124585
Transparency	Day	38% 7% 12% 23% 16% 4	131058
	Night	38% 6% 11% 23% 18% 4	129057
Seeing	Day	21% 12% 27% 23% 13% 5%	16487
	Night	19% 12% 27% 29% 12% 1	26150

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	15% 4 2 5% 4 4 4 3 5% 6% 48%	3883
	11th to 20th	Day	14% 9% 3 6% 4 3 4 3 4 4 47%	4150
	21st to end	Day	14% 9% 3 5% 4 4 4 3 5% 6% 43%	4565
February	1st to 10th	Day	13% 8% 2 6% 6% 4 5% 5% 6% 6% 39%	1800
	11th to 20th	Day	18% 8% 2 6% 4 5% 3 4 4 6% 39%	1778
	21st to end	Day	16% 9% 2 5% 5% 3 4 4 4 6% 41%	1650
March	1st to 10th	Day	18% 7% 2 5% 4 5% 5% 3 4 6% 41%	4930
	11th to 20th	Day	10% 6% 2 5% 4 4 4 3 5% 7% 49%	4980
	21st to end	Day	16% 6% 2 6% 5% 5% 4 4 6% 7% 40%	5502
April	1st to 10th	Day	13% 7% 2 7% 5% 4 4 4 7% 7% 40%	2400
	11th to 20th	Day	13% 6% 2 6% 5% 4 4 3 5% 6% 46%	2374
	21st to end	Day	18% 6% 2 6% 5% 4 4 3 5% 6% 42%	2400
May	1st to 10th	Day	19% 6% 3 6% 4 5% 6% 4 7% 9% 31%	5857
	11th to 20th	Day	23% 6% 3 6% 4 4 4 4 7% 10% 30%	6060
	21st to end	Day	16% 5% 2 6% 4 4 4 4 7% 9% 39%	6934
June	1st to 10th	Day	11% 5% 2 5% 4 5% 5% 5% 6% 9% 43%	2800
	11th to 20th	Day	11% 5% 2 6% 5% 4 5% 5% 7% 9% 41%	2800
	21st to end	Day	8% 4 2 5% 5% 5% 5% 4 7% 10% 46%	2800
July	1st to 10th	Day	7% 5% 2 6% 5% 5% 6% 5% 7% 10% 44%	6360
	11th to 20th	Day	8% 6% 3 7% 6% 6% 6% 6% 9% 11% 32%	6045
	21st to end	Day	8% 5% 2 7% 5% 5% 5% 5% 7% 9% 41%	6424
August	1st to 10th	Day	15% 5% 2 7% 5% 5% 5% 5% 7% 10% 35%	4234
	11th to 20th	Day	10% 4 2 6% 5% 5% 6% 5% 7% 9% 41%	4047
	21st to end	Day	11% 4 2 5% 3 4 5% 4 6% 7% 49%	4312
September	1st to 10th	Day	14% 5% 3 4 5% 4 4 3 5% 6% 47%	2400
	11th to 20th	Day	13% 5% 2 5% 3 4 4 3 5% 8% 48%	2397
	21st to end	Day	21% 7% 3 6% 4 4 3 3 5% 6% 37%	2086
October	1st to 10th	Day	16% 5% 2 4 4 3 4 3 5% 6% 48%	2000
	11th to 20th	Day	16% 4 2 5% 4 3 4 3 4 6% 49%	2000
	21st to end	Day	14% 5% 2 4 3 3 4 3 4 6% 51%	2200
November	1st to 10th	Day	12% 5% 1 4 4 4 3 3 6% 7% 51%	1988
	11th to 20th	Day	14% 5% 3 5% 3 4 3 3 5% 6% 50%	1827
	21st to end	Day	15% 5% 2 5% 4 4 5% 4 5% 6% 46%	1680
December	1st to 10th	Day	12% 6% 2 5% 4 4 4 4 5% 6% 49%	2680
	11th to 20th	Day	17% 8% 2 5% 3 4 4 3 4 7% 41%	3070
	21st to end	Day	17% 7% 2 7% 5% 4 4 4 6% 8% 36%	4048
January	1st to 10th	Night	11% 7% 2 5% 4 4 4 4 4 6% 49%	6277
	11th to 20th	Night	14% 6% 2 5% 4 3 3 3 4 5% 51%	6030
	21st to end	Night	14% 8% 3 5% 3 2 3 3 4 6% 49%	6633
February	1st to 10th	Night	14% 8% 3 5% 5% 4 5% 4 5% 6% 41%	2601
	11th to 20th	Night	18% 8% 2 6% 4 4 4 3 4 6% 42%	2508
	21st to end	Night	17% 8% 3 5% 5% 4 3 3 5% 6% 41%	1980
March	1st to 10th	Night	16% 6% 2 6% 4 3 4 3 4 5% 47%	4918
	11th to 20th	Night	10% 6% 3 5% 4 4 4 3 6% 7% 50%	4980
	21st to end	Night	12% 7% 2 5% 5% 4 4 4 5% 6% 44%	5428
April	1st to 10th	Night	15% 8% 2 6% 4 5% 4 4 6% 7% 40%	2000
	11th to 20th	Night	13% 6% 2 6% 4 3 4 4 7% 6% 44%	1975
	21st to end	Night	15% 5% 2 5% 3 5% 4 4 5% 7% 45%	2000
May	1st to 10th	Night	22% 8% 3 7% 5% 4 5% 4 6% 7% 29%	4079
	11th to 20th	Night	24% 7% 2 6% 4 4 5% 3 6% 7% 30%	3832
	21st to end	Night	17% 6% 2 6% 4 5% 5% 4 7% 8% 35%	3920
June	1st to 10th	Night	10% 5% 2 6% 5% 4 4 4 7% 8% 45%	1600
	11th to 20th	Night	13% 4 2 5% 4 5% 5% 5% 6% 8% 42%	1600
	21st to end	Night	8% 5% 2 6% 4 5% 5% 5% 8% 9% 45%	1600
July	1st to 10th	Night	7% 6% 2 7% 6% 6% 5% 5% 7% 9% 40%	3598
	11th to 20th	Night	8% 7% 3 9% 6% 6% 7% 5% 8% 10% 30%	3907
	21st to end	Night	8% 5% 2 7% 4 5% 5% 6% 8% 9% 41%	4427
August	1st to 10th	Night	15% 6% 3 7% 5% 6% 5% 4 7% 9% 32%	2915
	11th to 20th	Night	10% 6% 3 7% 5% 5% 6% 4 6% 9% 39%	2968
	21st to end	Night	12% 4 1 5% 3 4 5% 3 5% 9% 48%	3586
September	1st to 10th	Night	14% 5% 2 6% 4 4 5% 4 5% 6% 46%	2000
	11th to 20th	Night	11% 6% 2 6% 4 3 4 3 4 7% 51%	2000
	21st to end	Night	21% 7% 2 6% 5% 4 4 3 4 6% 39%	2311
October	1st to 10th	Night	20% 5% 2 4 3 3 3 3 4 5% 48%	2400
	11th to 20th	Night	15% 5% 2 5% 3 3 3 3 4 5% 53%	2400
	21st to end	Night	14% 5% 2 4 4 3 3 2 4 7% 51%	2640
November	1st to 10th	Night	11% 6% 2 5% 4 3 3 3 4 6% 54%	2529
	11th to 20th	Night	14% 7% 2 4 3 3 3 4 5% 6% 49%	2788
	21st to end	Night	13% 4 2 5% 4 4 5% 3 5% 7% 47%	2940
December	1st to 10th	Night	10% 5% 2 5% 4 3 4 3 5% 7% 52%	4720
	11th to 20th	Night	19% 6% 2 5% 4 4 4 3 5% 7% 40%	5345
	21st to end	Night	16% 7% 2 7% 4 5% 5% 5% 6% 8% 35%	7150

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	36% 5% 6% 26% 20% 7%	3884
	11th to 20th	Day	39% 4 7% 22% 18% 10%	4150
	21st to end	Day	41% 5% 9% 27% 14% 3	4565
February	1st to 10th	Day	43% 6% 13% 23% 12% 2	1800
	11th to 20th	Day	45% 5% 10% 22% 16% 3	1787
	21st to end	Day	44% 6% 11% 20% 15% 4	1650
March	1st to 10th	Day	42% 5% 9% 21% 15% 8%	4930
	11th to 20th	Day	33% 6% 10% 26% 20% 6%	4980
	21st to end	Day	43% 5% 11% 18% 17% 6%	5502
April	1st to 10th	Day	40% 7% 11% 19% 18% 5%	2400
	11th to 20th	Day	38% 5% 11% 21% 20% 5%	2374
	21st to end	Day	43% 6% 10% 22% 16% 4	2400
May	1st to 10th	Day	46% 9% 15% 18% 10% 2	5892
	11th to 20th	Day	47% 8% 12% 24% 9% 1	6064
	21st to end	Day	39% 8% 15% 21% 16% 1	6949
June	1st to 10th	Day	35% 8% 15% 24% 17% 1	2800
	11th to 20th	Day	36% 11% 14% 23% 14% 2	2800
	21st to end	Day	31% 9% 16% 25% 17% 2	2800
July	1st to 10th	Day	33% 10% 17% 21% 14% 4	6290
	11th to 20th	Day	41% 11% 17% 23% 7% 1	5972
	21st to end	Day	37% 8% 10% 23% 22% 1	6240
August	1st to 10th	Day	43% 8% 17% 24% 8%	4221
	11th to 20th	Day	36% 9% 14% 27% 14% 1	4086
	21st to end	Day	33% 6% 14% 27% 17% 2	4312
September	1st to 10th	Day	37% 7% 12% 19% 20% 5%	2400
	11th to 20th	Day	34% 6% 9% 27% 21% 3	2397
	21st to end	Day	46% 6% 10% 19% 16% 2	2086
October	1st to 10th	Day	36% 4 7% 19% 28% 5%	3260
	11th to 20th	Day	26% 4 7% 29% 24% 10%	3240
	21st to end	Day	23% 3 11% 29% 28% 6%	3538
November	1st to 10th	Day	32% 5% 12% 25% 22% 5%	1988
	11th to 20th	Day	35% 4 11% 23% 21% 5%	1827
	21st to end	Day	38% 5% 10% 27% 16% 2	1680
December	1st to 10th	Day	36% 5% 12% 28% 15% 4	2680
	11th to 20th	Day	42% 5% 14% 26% 10% 3	3066
	21st to end	Day	43% 7% 15% 20% 14% 1	4048
January	1st to 10th	Night	35% 5% 7% 25% 24% 4	6277
	11th to 20th	Night	35% 4 8% 23% 23% 7%	6030
	21st to end	Night	37% 4 8% 30% 18% 3	6633
February	1st to 10th	Night	42% 6% 13% 23% 14% 2	2601
	11th to 20th	Night	43% 5% 9% 22% 16% 5%	2510
	21st to end	Night	43% 5% 10% 22% 16% 5%	1980
March	1st to 10th	Night	38% 5% 8% 25% 15% 8%	4918
	11th to 20th	Night	33% 6% 11% 25% 20% 6%	4980
	21st to end	Night	39% 5% 10% 22% 20% 5%	5428
April	1st to 10th	Night	42% 6% 9% 20% 19% 4	2000
	11th to 20th	Night	37% 7% 12% 20% 19% 6%	1975
	21st to end	Night	37% 7% 12% 25% 14% 4	2000
May	1st to 10th	Night	52% 7% 13% 16% 8% 4	4106
	11th to 20th	Night	51% 7% 11% 20% 10% 1	3833
	21st to end	Night	43% 9% 14% 23% 9% 2	3927
June	1st to 10th	Night	35% 8% 12% 25% 17% 2	1600
	11th to 20th	Night	38% 8% 15% 23% 14% 2	1600
	21st to end	Night	33% 8% 16% 23% 18% 3	1600
July	1st to 10th	Night	39% 10% 16% 18% 14% 3	3560
	11th to 20th	Night	47% 11% 17% 16% 8% 1	3860
	21st to end	Night	36% 8% 15% 22% 18%	4297
August	1st to 10th	Night	45% 8% 15% 22% 8% 1	2904
	11th to 20th	Night	40% 7% 12% 26% 14% 1	2995
	21st to end	Night	32% 6% 13% 30% 16% 2	3586
September	1st to 10th	Night	38% 7% 10% 22% 19% 5%	2000
	11th to 20th	Night	35% 5% 9% 27% 22% 3	2000
	21st to end	Night	47% 6% 10% 18% 16% 3	2311
October	1st to 10th	Night	40% 4 9% 21% 22% 4	3920
	11th to 20th	Night	24% 4 11% 22% 31% 7%	3899
	21st to end	Night	23% 3 9% 31% 26% 7%	4252
November	1st to 10th	Night	32% 5% 10% 25% 23% 5%	2529
	11th to 20th	Night	35% 5% 7% 25% 22% 6%	2788
	21st to end	Night	36% 5% 11% 25% 20% 4	2940
December	1st to 10th	Night	32% 5% 13% 28% 20% 2	4720
	11th to 20th	Night	44% 4 12% 20% 16% 4	5348
	21st to end	Night	43% 8% 16% 19% 14% 1	7150

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	36% 21% 27% 13% 2	267
	11th to 20th	Day	37% 22% 28% 12% 1	330
	21st to end	Day	29% 29% 29% 11% 2 1	363
February	1st to 10th	Day	25% 26% 35% 10% 3	300
	11th to 20th	Day	40% 24% 29% 5% 2	325
	21st to end	Day	29% 19% 32% 17% 2	414
March	1st to 10th	Day	27% 21% 31% 18% 3	500
	11th to 20th	Day	26% 22% 29% 16% 5% 2	500
	21st to end	Day	23% 21% 34% 16% 5% 1	550
April	1st to 10th	Day	25% 22% 29% 15% 7% 1	500
	11th to 20th	Day	21% 18% 29% 18% 12% 3	492
	21st to end	Day	25% 15% 31% 17% 9% 3	500
May	1st to 10th	Day	23% 17% 28% 19% 9% 4	503
	11th to 20th	Day	24% 10% 29% 21% 13% 4	527
	21st to end	Day	21% 7% 24% 23% 20% 6%	573
June	1st to 10th	Day	13% 8% 28% 26% 19% 6%	530
	11th to 20th	Day	17% 6% 26% 30% 16% 6%	530
	21st to end	Day	11% 5% 29% 31% 17% 7%	530
July	1st to 10th	Day	13% 3 16% 31% 26% 10%	525
	11th to 20th	Day	7% 2 22% 32% 27% 9%	524
	21st to end	Day	14% 2 22% 34% 20% 9%	576
August	1st to 10th	Day	15% 3 18% 29% 22% 12%	526
	11th to 20th	Day	14% 3 21% 30% 21% 11%	519
	21st to end	Day	10% 3 22% 32% 21% 12%	583
September	1st to 10th	Day	18% 7% 18% 26% 20% 10%	530
	11th to 20th	Day	16% 4 19% 32% 18% 11%	530
	21st to end	Day	29% 7% 22% 25% 14% 3	530
October	1st to 10th	Day	20% 6% 21% 26% 19% 8%	530
	11th to 20th	Day	19% 15% 25% 26% 13% 2	530
	21st to end	Day	18% 14% 32% 24% 10% 2	583
November	1st to 10th	Day	18% 14% 32% 24% 9% 3	498
	11th to 20th	Day	22% 14% 36% 19% 8% 1	367
	21st to end	Day	25% 20% 33% 15% 7% 1	220
December	1st to 10th	Day	21% 23% 38% 15% 3 1	220
	11th to 20th	Day	22% 25% 30% 18% 5%	220
	21st to end	Day	26% 19% 31% 17% 5%	242
January	1st to 10th	Night	22% 21% 35% 19% 3	840
	11th to 20th	Night	25% 17% 30% 23% 4	840
	21st to end	Night	19% 19% 39% 20% 2	924
February	1st to 10th	Night	19% 17% 35% 27% 2	801
	11th to 20th	Night	26% 24% 32% 16% 2	783
	21st to end	Night	26% 17% 35% 18% 3	660
March	1st to 10th	Night	22% 19% 35% 21% 3	800
	11th to 20th	Night	24% 20% 30% 21% 6% 1	800
	21st to end	Night	20% 20% 36% 20% 5%	880
April	1st to 10th	Night	20% 20% 34% 22% 4	800
	11th to 20th	Night	18% 13% 34% 27% 7% 1	791
	21st to end	Night	20% 12% 29% 30% 9%	800
May	1st to 10th	Night	23% 7% 25% 32% 12% 1	620
	11th to 20th	Night	22% 5% 23% 38% 12% 1	508
	21st to end	Night	16% 4 23% 38% 18% 1	433
June	1st to 10th	Night	12% 4 24% 39% 21% 1	400
	11th to 20th	Night	16% 3 19% 40% 21% 2	400
	21st to end	Night	9% 3 20% 47% 19% 2	400
July	1st to 10th	Night	12% 2 14% 39% 28% 5%	390
	11th to 20th	Night	7% 2 11% 42% 34% 4	514
	21st to end	Night	9% 2 15% 42% 28% 4	657
August	1st to 10th	Night	13% 1 11% 42% 30% 4	597
	11th to 20th	Night	11% 3 11% 41% 31% 3	648
	21st to end	Night	13% 2 16% 39% 27% 3	880
September	1st to 10th	Night	17% 2 17% 34% 26% 4	800
	11th to 20th	Night	14% 4 17% 33% 29% 4	800
	21st to end	Night	25% 5% 19% 30% 20% 1	800
October	1st to 10th	Night	21% 5% 21% 29% 21% 4	800
	11th to 20th	Night	17% 13% 23% 31% 15% 1	800
	21st to end	Night	19% 11% 30% 29% 11% 1	880
November	1st to 10th	Night	15% 12% 31% 31% 10% 1	820
	11th to 20th	Night	19% 15% 31% 28% 7% 1	840
	21st to end	Night	18% 16% 32% 27% 7%	840
December	1st to 10th	Night	22% 17% 33% 21% 6%	840
	11th to 20th	Night	21% 14% 36% 26% 4	840
	21st to end	Night	21% 14% 33% 29% 2	924

Page generated at 2026-01-29 01:21:43. Version ac07

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