Camp Samac
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Camp Samac clear sky chart from 2005-11-06 to 2025-07-21.

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	16% 9% 3 8% 5% 4 4 4 5% 7% 34%	120421
	Night	16% 10% 3 8% 5% 4 5% 4 5% 7% 34%	118676
Transparency	Day	46% 7% 14% 20% 11% 1	124051
	Night	48% 7% 14% 20% 11% 1	123205
Seeing	Day	20% 11% 29% 24% 12% 4	15297
	Night	20% 9% 28% 29% 12% 1	24640

By Month

Percentage Cloud Cover NE (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	14% 12% 5% 10% 5% 5% 4 3 4 5% 32%	3597
	11th to 20th	Day	10% 18% 7% 17% 8% 6% 5% 3 4 4 18%	3798
	21st to end	Day	17% 17% 6% 13% 6% 5% 4 3 4 4 20%	4466
February	1st to 10th	Day	15% 16% 5% 12% 5% 7% 5% 4 5% 5% 23%	1800
	11th to 20th	Day	13% 14% 7% 11% 7% 5% 4 3 5% 5% 26%	1753
	21st to end	Day	19% 14% 4 11% 5% 5% 4 3 4 4 27%	1530
March	1st to 10th	Day	20% 10% 4 8% 5% 4 4 3 4 5% 33%	4932
	11th to 20th	Day	13% 12% 4 8% 5% 5% 5% 4 5% 8% 30%	4980
	21st to end	Day	20% 11% 3 7% 4 4 4 2 5% 5% 36%	5465
April	1st to 10th	Day	18% 13% 4 7% 5% 4 3 4 5% 6% 30%	2390
	11th to 20th	Day	20% 9% 3 6% 4 4 4 4 5% 6% 35%	2418
	21st to end	Day	20% 9% 3 7% 5% 4 4 3 5% 6% 35%	2600
May	1st to 10th	Day	21% 9% 3 7% 4 5% 4 3 5% 7% 32%	5970
	11th to 20th	Day	18% 9% 3 8% 4 3 4 3 5% 7% 36%	6318
	21st to end	Day	19% 6% 2 6% 4 4 4 4 5% 7% 39%	6949
June	1st to 10th	Day	16% 7% 3 6% 4 5% 4 4 6% 8% 37%	2800
	11th to 20th	Day	12% 6% 2 6% 5% 5% 5% 5% 7% 9% 40%	2800
	21st to end	Day	15% 5% 2 5% 5% 4 4 5% 7% 8% 39%	2800
July	1st to 10th	Day	10% 4 2 6% 4 5% 5% 5% 7% 10% 42%	4580
	11th to 20th	Day	11% 4 2 5% 4 4 5% 5% 7% 9% 45%	4580
	21st to end	Day	7% 5% 2 6% 5% 6% 6% 5% 7% 9% 43%	4599
August	1st to 10th	Day	16% 7% 2 6% 4 4 5% 4 6% 7% 39%	4104
	11th to 20th	Day	12% 6% 3 6% 4 5% 5% 4 7% 10% 38%	4044
	21st to end	Day	9% 6% 2 5% 4 5% 5% 4 6% 9% 45%	4318
September	1st to 10th	Day	13% 5% 2 6% 4 5% 5% 4 6% 7% 44%	2280
	11th to 20th	Day	11% 4 2 5% 4 4 4 4 7% 8% 47%	2209
	21st to end	Day	14% 7% 2 7% 5% 4 6% 4 6% 7% 39%	2026
October	1st to 10th	Day	17% 8% 2 7% 5% 5% 5% 4 5% 6% 36%	1900
	11th to 20th	Day	20% 8% 3 8% 5% 4 5% 4 6% 5% 32%	1900
	21st to end	Day	23% 11% 4 9% 6% 5% 4 3 4 6% 26%	2090
November	1st to 10th	Day	15% 9% 3 8% 6% 5% 5% 3 7% 6% 33%	1679
	11th to 20th	Day	15% 13% 4 9% 6% 5% 5% 4 7% 7% 26%	1600
	21st to end	Day	20% 13% 4 9% 5% 5% 6% 4 5% 6% 25%	1600
December	1st to 10th	Day	18% 17% 5% 11% 6% 7% 6% 4 5% 6% 15%	2600
	11th to 20th	Day	21% 14% 5% 10% 4 4 4 3 4 5% 25%	2986
	21st to end	Day	27% 15% 7% 11% 5% 4 4 3 3 5% 16%	3960
January	1st to 10th	Night	16% 13% 5% 10% 5% 5% 4 4 5% 6% 27%	6349
	11th to 20th	Night	14% 13% 5% 14% 8% 5% 5% 4 5% 6% 20%	6070
	21st to end	Night	16% 14% 6% 10% 5% 4 5% 4 5% 6% 26%	6490
February	1st to 10th	Night	14% 15% 5% 10% 6% 5% 5% 3 5% 6% 25%	2600
	11th to 20th	Night	15% 13% 5% 10% 6% 4 4 4 5% 6% 29%	2533
	21st to end	Night	15% 11% 4 9% 5% 4 5% 5% 6% 5% 31%	2095
March	1st to 10th	Night	17% 10% 4 8% 5% 5% 5% 4 4 5% 33%	4908
	11th to 20th	Night	12% 8% 3 7% 5% 5% 5% 4 7% 8% 37%	4979
	21st to end	Night	21% 7% 3 6% 3 4 4 3 4 6% 39%	5467
April	1st to 10th	Night	19% 10% 3 7% 5% 5% 4 4 5% 6% 33%	2010
	11th to 20th	Night	16% 8% 3 7% 5% 4 5% 4 5% 5% 39%	1949
	21st to end	Night	16% 8% 3 7% 4 4 5% 4 6% 7% 36%	1800
May	1st to 10th	Night	25% 8% 2 6% 4 4 4 3 5% 5% 34%	3971
	11th to 20th	Night	16% 7% 2 6% 4 5% 5% 4 5% 6% 39%	3575
	21st to end	Night	19% 5% 2 5% 4 4 4 3 5% 8% 41%	3926
June	1st to 10th	Night	12% 5% 2 7% 4 5% 5% 4 7% 8% 41%	1600
	11th to 20th	Night	9% 5% 2 7% 4 5% 5% 5% 7% 8% 44%	1600
	21st to end	Night	12% 6% 2 6% 4 4 5% 5% 5% 8% 43%	1600
July	1st to 10th	Night	7% 5% 2 5% 4 4 5% 4 5% 9% 50%	2600
	11th to 20th	Night	12% 4 2 4 3 3 4 4 6% 9% 50%	2600
	21st to end	Night	9% 4 2 5% 3 4 4 4 6% 8% 53%	2950
August	1st to 10th	Night	10% 5% 2 5% 4 4 5% 4 5% 8% 48%	2825
	11th to 20th	Night	12% 4 2 5% 3 4 4 3 5% 7% 51%	2785
	21st to end	Night	10% 5% 2 6% 3 4 5% 3 5% 8% 49%	3306
September	1st to 10th	Night	11% 5% 2 6% 3 4 5% 4 6% 7% 47%	1900
	11th to 20th	Night	11% 4 2 4 4 3 3 3 4 7% 55%	1968
	21st to end	Night	17% 6% 2 6% 4 4 4 4 4 6% 43%	2152
October	1st to 10th	Night	15% 6% 2 7% 5% 4 4 4 5% 7% 41%	2280
	11th to 20th	Night	20% 9% 3 6% 5% 5% 5% 4 5% 6% 33%	2280
	21st to end	Night	21% 9% 3 6% 4 4 5% 4 5% 6% 31%	2508
November	1st to 10th	Night	18% 8% 2 6% 5% 4 4 3 6% 7% 37%	2616
	11th to 20th	Night	17% 11% 3 7% 6% 5% 4 4 6% 8% 30%	2800
	21st to end	Night	20% 11% 4 6% 5% 5% 5% 5% 7% 7% 25%	2800
December	1st to 10th	Night	18% 15% 4 10% 6% 5% 5% 4 6% 7% 20%	4580
	11th to 20th	Night	17% 17% 4 9% 5% 5% 5% 4 5% 6% 23%	5208
	21st to end	Night	26% 15% 6% 10% 5% 5% 4 3 4 5% 17%	6996

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	51% 7% 17% 15% 10% 1	3598
	11th to 20th	Day	70% 6% 12% 8% 3	3830
	21st to end	Day	65% 6% 11% 10% 7%	4466
February	1st to 10th	Day	63% 6% 12% 15% 4 1	1800
	11th to 20th	Day	58% 7% 10% 17% 7% 1	1762
	21st to end	Day	57% 6% 12% 18% 7%	1530
March	1st to 10th	Day	50% 6% 15% 14% 14%	4935
	11th to 20th	Day	48% 8% 18% 16% 8% 2	4980
	21st to end	Day	47% 6% 9% 21% 15% 1	5465
April	1st to 10th	Day	51% 7% 11% 19% 11% 2	2390
	11th to 20th	Day	47% 6% 9% 22% 14% 1	2418
	21st to end	Day	48% 6% 11% 19% 12% 3	2600
May	1st to 10th	Day	48% 8% 12% 17% 11% 4	5979
	11th to 20th	Day	48% 9% 12% 14% 15% 1	6322
	21st to end	Day	42% 7% 14% 23% 11% 3	6949
June	1st to 10th	Day	41% 8% 13% 22% 14% 1	2800
	11th to 20th	Day	36% 8% 14% 26% 15% 2	2800
	21st to end	Day	37% 8% 15% 24% 14% 1	2800
July	1st to 10th	Day	32% 8% 15% 27% 16% 2	4510
	11th to 20th	Day	30% 9% 15% 35% 11% 1	4505
	21st to end	Day	32% 10% 16% 25% 16% 1	4452
August	1st to 10th	Day	41% 8% 15% 23% 13% 1	4091
	11th to 20th	Day	37% 7% 17% 29% 10%	4083
	21st to end	Day	31% 9% 15% 34% 10% 1	4318
September	1st to 10th	Day	36% 8% 15% 29% 11% 1	2280
	11th to 20th	Day	32% 7% 15% 31% 15% 1	2209
	21st to end	Day	40% 8% 15% 26% 10%	2026
October	1st to 10th	Day	36% 6% 16% 28% 14% 1	3160
	11th to 20th	Day	36% 7% 19% 24% 14%	3140
	21st to end	Day	48% 8% 16% 21% 6%	3428
November	1st to 10th	Day	48% 8% 14% 21% 9% 1	1679
	11th to 20th	Day	54% 7% 15% 16% 8% 1	1600
	21st to end	Day	58% 7% 14% 17% 4	1600
December	1st to 10th	Day	67% 9% 13% 9% 2	2600
	11th to 20th	Day	59% 8% 13% 12% 8%	2986
	21st to end	Day	70% 7% 8% 9% 5%	3960
January	1st to 10th	Night	53% 8% 14% 18% 6%	6349
	11th to 20th	Night	62% 10% 14% 9% 4	6112
	21st to end	Night	59% 6% 16% 13% 6% 1	6490
February	1st to 10th	Night	59% 6% 13% 17% 4 1	2600
	11th to 20th	Night	56% 6% 11% 18% 8%	2535
	21st to end	Night	52% 6% 14% 20% 7% 1	2095
March	1st to 10th	Night	52% 5% 11% 18% 12% 3	4918
	11th to 20th	Night	43% 6% 19% 22% 10% 2	4980
	21st to end	Night	45% 6% 9% 21% 17% 2	5467
April	1st to 10th	Night	51% 6% 9% 20% 13% 1	2010
	11th to 20th	Night	46% 6% 10% 19% 17% 2	1949
	21st to end	Night	47% 5% 10% 21% 15% 2	1800
May	1st to 10th	Night	51% 5% 11% 14% 13% 5%	3978
	11th to 20th	Night	43% 8% 14% 19% 13% 2	3576
	21st to end	Night	41% 7% 14% 22% 15% 2	3927
June	1st to 10th	Night	39% 8% 11% 24% 16% 3	1600
	11th to 20th	Night	36% 7% 12% 23% 21% 2	1600
	21st to end	Night	36% 8% 13% 26% 16% 1	1600
July	1st to 10th	Night	30% 7% 16% 24% 21% 2	2560
	11th to 20th	Night	30% 6% 15% 33% 14% 1	2552
	21st to end	Night	28% 8% 15% 29% 17% 1	2856
August	1st to 10th	Night	35% 4 15% 29% 15% 2	2814
	11th to 20th	Night	33% 6% 16% 32% 12% 1	2812
	21st to end	Night	32% 6% 14% 32% 14% 1	3306
September	1st to 10th	Night	34% 6% 16% 28% 14% 1	1900
	11th to 20th	Night	30% 5% 14% 32% 19%	1968
	21st to end	Night	42% 5% 13% 27% 12% 1	2152
October	1st to 10th	Night	33% 5% 11% 28% 22% 1	3800
	11th to 20th	Night	41% 6% 15% 29% 9%	3779
	21st to end	Night	39% 7% 15% 28% 10% 1	4120
November	1st to 10th	Night	45% 5% 13% 23% 12% 1	2616
	11th to 20th	Night	51% 6% 15% 18% 10% 1	2800
	21st to end	Night	55% 8% 18% 15% 4	2800
December	1st to 10th	Night	60% 7% 16% 13% 3	4580
	11th to 20th	Night	60% 8% 11% 13% 8%	5208
	21st to end	Night	68% 7% 12% 8% 5%	6996

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	24% 18% 32% 20% 7% 1	200
	11th to 20th	Day	27% 21% 30% 16% 5% 1	250
	21st to end	Day	30% 17% 34% 15% 3 1	330
February	1st to 10th	Day	28% 24% 32% 12% 4	300
	11th to 20th	Day	27% 24% 36% 11% 2	300
	21st to end	Day	32% 18% 35% 13% 1	294
March	1st to 10th	Day	26% 15% 34% 19% 5%	500
	11th to 20th	Day	26% 16% 33% 19% 5%	500
	21st to end	Day	31% 12% 31% 19% 7% 1	550
April	1st to 10th	Day	23% 14% 37% 20% 5% 1	500
	11th to 20th	Day	29% 13% 27% 20% 9% 3	492
	21st to end	Day	27% 13% 34% 16% 8% 2	500
May	1st to 10th	Day	24% 8% 31% 23% 9% 5%	503
	11th to 20th	Day	17% 8% 28% 29% 14% 3	527
	21st to end	Day	16% 8% 25% 30% 17% 5%	573
June	1st to 10th	Day	17% 8% 32% 28% 13% 2	530
	11th to 20th	Day	13% 8% 28% 31% 18% 2	530
	21st to end	Day	18% 6% 28% 31% 13% 5%	530
July	1st to 10th	Day	10% 4 24% 35% 21% 6%	525
	11th to 20th	Day	14% 4 24% 33% 19% 8%	524
	21st to end	Day	8% 3 29% 37% 17% 7%	532
August	1st to 10th	Day	13% 4 22% 32% 19% 11%	486
	11th to 20th	Day	13% 3 21% 28% 27% 8%	479
	21st to end	Day	12% 6% 22% 32% 18% 10%	539
September	1st to 10th	Day	14% 7% 23% 29% 17% 10%	490
	11th to 20th	Day	11% 4 20% 28% 22% 15%	490
	21st to end	Day	16% 8% 29% 25% 15% 7%	490
October	1st to 10th	Day	20% 10% 26% 25% 14% 5%	490
	11th to 20th	Day	21% 14% 33% 22% 8% 1	490
	21st to end	Day	29% 12% 29% 22% 7% 1	539
November	1st to 10th	Day	24% 15% 27% 26% 7% 1	294
	11th to 20th	Day	23% 18% 35% 19% 5% 1	200
	21st to end	Day	28% 17% 36% 15% 4 1	200
December	1st to 10th	Day	26% 15% 33% 19% 5% 3	200
	11th to 20th	Day	30% 19% 29% 17% 5%	200
	21st to end	Day	30% 18% 34% 15% 3	220
January	1st to 10th	Night	24% 16% 38% 17% 5% 1	800
	11th to 20th	Night	28% 14% 32% 22% 4 1	800
	21st to end	Night	21% 12% 34% 27% 6%	880
February	1st to 10th	Night	21% 15% 38% 23% 3	800
	11th to 20th	Night	22% 15% 36% 22% 5%	783
	21st to end	Night	22% 13% 39% 22% 4	660
March	1st to 10th	Night	21% 13% 35% 26% 4 1	800
	11th to 20th	Night	22% 12% 35% 25% 5% 1	800
	21st to end	Night	22% 11% 31% 27% 9%	880
April	1st to 10th	Night	25% 11% 32% 27% 5%	800
	11th to 20th	Night	18% 12% 33% 27% 9% 1	765
	21st to end	Night	22% 7% 29% 32% 10%	600
May	1st to 10th	Night	23% 5% 25% 29% 16% 2	570
	11th to 20th	Night	17% 5% 28% 37% 13%	394
	21st to end	Night	12% 3 23% 40% 21% 1	433
June	1st to 10th	Night	15% 4 25% 39% 17% 1	400
	11th to 20th	Night	11% 6% 25% 40% 19% 1	400
	21st to end	Night	12% 5% 24% 42% 18% 1	400
July	1st to 10th	Night	6% 3 18% 47% 24% 1	390
	11th to 20th	Night	12% 2 18% 41% 26% 1	388
	21st to end	Night	11% 1 17% 47% 23% 2	539
August	1st to 10th	Night	10% 3 13% 42% 29% 3	567
	11th to 20th	Night	9% 1 14% 41% 30% 5%	564
	21st to end	Night	12% 3 20% 38% 25% 3	731
September	1st to 10th	Night	12% 6% 19% 37% 22% 5%	760
	11th to 20th	Night	13% 4 18% 32% 27% 6%	760
	21st to end	Night	19% 6% 19% 32% 21% 4	760
October	1st to 10th	Night	19% 5% 26% 29% 19% 2	760
	11th to 20th	Night	24% 9% 28% 29% 10% 1	760
	21st to end	Night	27% 7% 29% 31% 6%	836
November	1st to 10th	Night	23% 9% 26% 30% 11% 1	780
	11th to 20th	Night	22% 13% 30% 27% 7% 2	800
	21st to end	Night	25% 12% 31% 25% 7%	800
December	1st to 10th	Night	29% 13% 32% 22% 5%	800
	11th to 20th	Night	24% 13% 36% 23% 4	800
	21st to end	Night	30% 11% 35% 21% 3	880

Page generated at 2025-07-18 01:10:03. Version ac07

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