Camp Susque Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Camp Susque Observatory clear sky chart from 2005-11-06 to 2025-03-12.

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	17% 9% 3 8% 5% 5% 5% 4 5% 7% 32%	108933
	Night	17% 10% 3 8% 5% 4 4 4 5% 6% 33%	110063
Transparency	Day	49% 5% 11% 22% 11% 1	112567
	Night	49% 5% 12% 21% 12% 2	114592
Seeing	Day	25% 15% 27% 20% 10% 3	15102
	Night	23% 13% 25% 27% 10% 1	24597

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	13% 15% 6% 11% 7% 5% 5% 3 5% 6% 25%	3597
	11th to 20th	Day	12% 15% 8% 18% 8% 6% 4 3 4 5% 17%	3815
	21st to end	Day	18% 15% 7% 9% 5% 4 4 3 4 6% 26%	4466
February	1st to 10th	Day	16% 16% 4 9% 7% 5% 5% 4 5% 4 25%	1800
	11th to 20th	Day	14% 12% 5% 10% 7% 5% 4 3 5% 6% 29%	1769
	21st to end	Day	19% 13% 4 9% 5% 4 4 2 5% 5% 30%	1650
March	1st to 10th	Day	24% 11% 3 7% 5% 4 4 3 4 5% 31%	3409
	11th to 20th	Day	11% 12% 4 8% 5% 4 4 3 4 6% 37%	3491
	21st to end	Day	16% 11% 3 6% 5% 3 4 3 5% 5% 37%	3909
April	1st to 10th	Day	18% 11% 3 7% 6% 5% 4 3 5% 6% 32%	2280
	11th to 20th	Day	18% 10% 3 7% 4 4 3 4 5% 6% 34%	2254
	21st to end	Day	19% 8% 2 7% 4 5% 4 4 5% 6% 35%	2312
May	1st to 10th	Day	28% 7% 2 6% 4 4 4 3 5% 7% 31%	4194
	11th to 20th	Day	25% 9% 3 8% 5% 4 4 4 5% 7% 26%	4398
	21st to end	Day	16% 5% 2 5% 4 5% 4 4 6% 8% 41%	4837
June	1st to 10th	Day	15% 6% 3 6% 6% 6% 5% 4 6% 8% 34%	2660
	11th to 20th	Day	16% 6% 2 7% 6% 5% 5% 4 6% 8% 35%	2660
	21st to end	Day	14% 5% 3 6% 5% 5% 6% 5% 7% 9% 36%	2660
July	1st to 10th	Day	9% 7% 2 7% 6% 6% 6% 5% 7% 10% 36%	4440
	11th to 20th	Day	8% 6% 3 6% 6% 5% 5% 5% 8% 12% 36%	4440
	21st to end	Day	12% 6% 2 8% 7% 6% 6% 5% 7% 7% 34%	4604
August	1st to 10th	Day	21% 7% 3 7% 5% 6% 5% 4 5% 7% 29%	4104
	11th to 20th	Day	17% 6% 3 7% 6% 5% 6% 5% 7% 8% 31%	3953
	21st to end	Day	17% 4 2 4 4 4 5% 5% 6% 9% 40%	4180
September	1st to 10th	Day	18% 5% 2 5% 4 4 5% 4 5% 6% 40%	2280
	11th to 20th	Day	16% 5% 2 5% 4 3 4 4 4 5% 48%	2280
	21st to end	Day	25% 6% 2 6% 3 4 3 3 5% 6% 35%	2003
October	1st to 10th	Day	20% 8% 2 5% 5% 3 4 3 5% 7% 39%	1900
	11th to 20th	Day	22% 7% 3 6% 5% 4 4 4 6% 7% 34%	1900
	21st to end	Day	21% 9% 3 6% 5% 4 5% 5% 5% 6% 32%	2090
November	1st to 10th	Day	15% 7% 2 7% 4 4 4 3 4 7% 43%	1766
	11th to 20th	Day	17% 11% 2 7% 5% 4 4 4 6% 5% 34%	1686
	21st to end	Day	18% 12% 3 7% 5% 4 3 4 6% 5% 31%	1600
December	1st to 10th	Day	19% 16% 6% 10% 6% 4 5% 3 4 5% 22%	2600
	11th to 20th	Day	23% 13% 4 6% 4 4 3 3 4 5% 29%	2986
	21st to end	Day	20% 16% 4 10% 6% 5% 5% 3 4 6% 20%	3960
January	1st to 10th	Night	14% 11% 4 12% 6% 5% 5% 4 5% 6% 27%	6349
	11th to 20th	Night	12% 13% 5% 14% 6% 6% 5% 4 6% 6% 23%	6067
	21st to end	Night	18% 12% 5% 11% 5% 6% 6% 3 5% 5% 25%	6490
February	1st to 10th	Night	16% 12% 4 8% 5% 6% 5% 3 6% 6% 29%	2600
	11th to 20th	Night	15% 11% 3 10% 6% 5% 6% 3 5% 6% 29%	2516
	21st to end	Night	18% 11% 3 10% 6% 5% 5% 3 6% 5% 29%	1980
March	1st to 10th	Night	24% 14% 3 6% 4 4 4 3 5% 5% 29%	3647
	11th to 20th	Night	13% 13% 4 7% 4 4 4 4 6% 7% 34%	3497
	21st to end	Night	16% 10% 2 7% 4 4 4 3 4 5% 40%	3722
April	1st to 10th	Night	20% 13% 4 7% 4 4 4 3 5% 6% 31%	1900
	11th to 20th	Night	18% 9% 2 6% 4 4 4 5% 5% 7% 36%	1875
	21st to end	Night	18% 8% 2 6% 4 4 5% 3 5% 7% 40%	1883
May	1st to 10th	Night	31% 7% 2 6% 3 4 3 3 4 5% 31%	2747
	11th to 20th	Night	27% 9% 2 6% 4 4 4 4 5% 6% 30%	2495
	21st to end	Night	16% 5% 2 6% 4 4 5% 3 6% 8% 40%	2738
June	1st to 10th	Night	15% 6% 2 6% 4 3 5% 4 4 9% 42%	1520
	11th to 20th	Night	13% 6% 3 5% 4 5% 5% 4 7% 9% 39%	1520
	21st to end	Night	13% 5% 2 6% 5% 4 4 4 7% 9% 41%	1520
July	1st to 10th	Night	10% 7% 3 7% 5% 4 4 4 7% 8% 41%	2520
	11th to 20th	Night	9% 5% 2 6% 5% 4 5% 5% 7% 10% 41%	2520
	21st to end	Night	15% 6% 2 6% 4 4 4 3 5% 6% 43%	2946
August	1st to 10th	Night	20% 6% 1 6% 5% 5% 5% 4 6% 8% 36%	2825
	11th to 20th	Night	18% 7% 2 6% 4 3 4 3 5% 6% 42%	2844
	21st to end	Night	16% 4 2 5% 4 4 5% 4 6% 8% 44%	3476
September	1st to 10th	Night	16% 6% 2 5% 4 4 4 3 5% 6% 44%	1900
	11th to 20th	Night	15% 5% 1 5% 3 3 3 3 4 7% 50%	1900
	21st to end	Night	21% 6% 2 5% 4 4 3 3 5% 6% 40%	2173
October	1st to 10th	Night	20% 7% 2 6% 3 4 4 3 4 6% 41%	2280
	11th to 20th	Night	19% 7% 2 5% 4 4 4 4 4 6% 40%	2280
	21st to end	Night	22% 9% 2 6% 3 3 4 3 5% 7% 35%	2508
November	1st to 10th	Night	12% 8% 3 6% 4 3 4 3 5% 7% 45%	2531
	11th to 20th	Night	20% 10% 3 7% 4 4 4 4 5% 6% 32%	2710
	21st to end	Night	16% 10% 4 8% 6% 4 5% 4 6% 6% 31%	2800
December	1st to 10th	Night	15% 14% 5% 8% 5% 5% 5% 4 6% 8% 25%	4580
	11th to 20th	Night	23% 11% 3 8% 5% 4 4 4 4 5% 29%	5208
	21st to end	Night	21% 15% 5% 9% 5% 4 4 3 5% 5% 24%	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	57% 5% 10% 18% 7% 2	3598
	11th to 20th	Day	70% 4 6% 12% 6% 1	3848
	21st to end	Day	60% 3 10% 19% 8% 1	4466
February	1st to 10th	Day	61% 4 10% 16% 8% 1	1800
	11th to 20th	Day	57% 4 8% 22% 8% 1	1778
	21st to end	Day	57% 2 9% 21% 8% 2	1650
March	1st to 10th	Day	56% 3 9% 23% 7% 1	3412
	11th to 20th	Day	48% 4 14% 22% 9% 3	3491
	21st to end	Day	50% 3 9% 23% 15% 2	3909
April	1st to 10th	Day	53% 4 9% 20% 11% 3	2280
	11th to 20th	Day	50% 4 11% 19% 14% 2	2254
	21st to end	Day	49% 4 8% 20% 15% 4	2312
May	1st to 10th	Day	54% 4 8% 22% 10% 1	4206
	11th to 20th	Day	58% 5% 10% 19% 7% 1	4402
	21st to end	Day	40% 6% 11% 27% 14% 2	4837
June	1st to 10th	Day	47% 6% 12% 20% 13% 1	2660
	11th to 20th	Day	45% 6% 15% 21% 13% 2	2660
	21st to end	Day	42% 6% 14% 26% 12%	2660
July	1st to 10th	Day	40% 8% 16% 24% 11% 1	4370
	11th to 20th	Day	36% 9% 18% 24% 12% 1	4365
	21st to end	Day	44% 8% 12% 22% 13% 1	4457
August	1st to 10th	Day	52% 6% 12% 19% 11%	4091
	11th to 20th	Day	45% 8% 14% 25% 7%	3992
	21st to end	Day	39% 6% 13% 31% 10% 2	4180
September	1st to 10th	Day	42% 6% 11% 25% 14% 2	2280
	11th to 20th	Day	38% 4 11% 25% 20% 2	2280
	21st to end	Day	48% 4 12% 19% 15% 2	2003
October	1st to 10th	Day	41% 6% 10% 23% 18% 2	3160
	11th to 20th	Day	42% 5% 9% 24% 17% 3	3140
	21st to end	Day	35% 6% 16% 29% 13% 1	3428
November	1st to 10th	Day	42% 4 13% 22% 16% 3	1766
	11th to 20th	Day	51% 4 12% 22% 10% 2	1686
	21st to end	Day	53% 4 13% 22% 7% 1	1600
December	1st to 10th	Day	64% 5% 10% 17% 4 1	2600
	11th to 20th	Day	58% 4 12% 17% 8% 1	2986
	21st to end	Day	65% 5% 11% 12% 7% 1	3960
January	1st to 10th	Night	55% 5% 12% 17% 8% 1	6349
	11th to 20th	Night	58% 5% 12% 14% 8% 2	6109
	21st to end	Night	61% 4 8% 14% 12% 1	6490
February	1st to 10th	Night	55% 4 12% 20% 8%	2600
	11th to 20th	Night	55% 4 10% 20% 10% 1	2518
	21st to end	Night	57% 3 9% 18% 11% 2	1980
March	1st to 10th	Night	58% 3 9% 21% 8% 1	3657
	11th to 20th	Night	50% 4 13% 24% 8% 1	3498
	21st to end	Night	47% 3 8% 22% 17% 3	3722
April	1st to 10th	Night	55% 4 8% 19% 12% 2	1900
	11th to 20th	Night	46% 5% 11% 21% 15% 2	1875
	21st to end	Night	45% 3 10% 23% 16% 2	1883
May	1st to 10th	Night	56% 4 8% 23% 8% 2	2754
	11th to 20th	Night	56% 5% 13% 16% 9% 1	2496
	21st to end	Night	41% 6% 14% 20% 14% 4	2739
June	1st to 10th	Night	41% 5% 11% 26% 15% 2	1520
	11th to 20th	Night	40% 5% 14% 26% 12% 2	1520
	21st to end	Night	39% 7% 12% 28% 14% 1	1520
July	1st to 10th	Night	39% 7% 13% 23% 17% 2	2480
	11th to 20th	Night	35% 8% 16% 25% 16% 1	2472
	21st to end	Night	40% 6% 12% 20% 20% 1	2852
August	1st to 10th	Night	46% 8% 14% 23% 9% 1	2814
	11th to 20th	Night	42% 5% 13% 27% 12%	2871
	21st to end	Night	37% 6% 13% 32% 11% 1	3476
September	1st to 10th	Night	40% 5% 10% 27% 16% 3	1900
	11th to 20th	Night	34% 5% 12% 28% 20% 2	1900
	21st to end	Night	44% 4 11% 24% 16% 1	2173
October	1st to 10th	Night	43% 5% 10% 23% 18% 1	3800
	11th to 20th	Night	36% 5% 11% 25% 17% 6%	3779
	21st to end	Night	35% 3 17% 28% 15% 2	4120
November	1st to 10th	Night	39% 4 14% 25% 16% 2	2531
	11th to 20th	Night	51% 4 11% 21% 11% 2	2710
	21st to end	Night	52% 5% 13% 23% 7% 1	2800
December	1st to 10th	Night	55% 6% 14% 21% 4	4580
	11th to 20th	Night	58% 4 13% 17% 9%	5208
	21st to end	Night	62% 4 11% 15% 8%	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	33% 25% 29% 11% 2 1	200
	11th to 20th	Day	38% 22% 32% 7% 1	253
	21st to end	Day	31% 27% 29% 10% 2 1	330
February	1st to 10th	Day	33% 27% 29% 9% 2	300
	11th to 20th	Day	40% 23% 32% 5% 1	316
	21st to end	Day	36% 21% 27% 14% 2	414
March	1st to 10th	Day	32% 21% 27% 16% 3	500
	11th to 20th	Day	30% 24% 27% 14% 3 1	464
	21st to end	Day	32% 23% 25% 14% 5% 2	506
April	1st to 10th	Day	31% 22% 27% 14% 5% 1	460
	11th to 20th	Day	25% 27% 20% 16% 8% 3	452
	21st to end	Day	28% 20% 30% 14% 6% 2	460
May	1st to 10th	Day	34% 15% 23% 16% 8% 3	463
	11th to 20th	Day	25% 16% 25% 20% 9% 4	487
	21st to end	Day	21% 10% 26% 22% 15% 5%	529
June	1st to 10th	Day	18% 15% 29% 22% 13% 2	490
	11th to 20th	Day	17% 13% 29% 25% 14% 2	490
	21st to end	Day	18% 11% 33% 23% 11% 4	490
July	1st to 10th	Day	14% 6% 27% 29% 19% 6%	485
	11th to 20th	Day	11% 9% 29% 29% 18% 5%	484
	21st to end	Day	14% 8% 30% 29% 14% 5%	532
August	1st to 10th	Day	14% 8% 23% 27% 21% 6%	486
	11th to 20th	Day	18% 6% 23% 28% 17% 8%	479
	21st to end	Day	17% 7% 24% 25% 16% 10%	539
September	1st to 10th	Day	19% 10% 21% 25% 18% 8%	490
	11th to 20th	Day	17% 7% 23% 24% 20% 11%	490
	21st to end	Day	29% 11% 22% 20% 14% 4	490
October	1st to 10th	Day	28% 9% 22% 22% 13% 6%	490
	11th to 20th	Day	26% 15% 27% 22% 8% 2	490
	21st to end	Day	29% 13% 29% 21% 7% 1	539
November	1st to 10th	Day	23% 15% 28% 22% 11% 1	398
	11th to 20th	Day	27% 22% 28% 17% 6% 1	286
	21st to end	Day	31% 21% 34% 13% 3	200
December	1st to 10th	Day	32% 22% 33% 11% 2 1	200
	11th to 20th	Day	38% 18% 31% 12% 2 1	200
	21st to end	Day	35% 19% 30% 14% 2	220
January	1st to 10th	Night	24% 19% 38% 17% 3	800
	11th to 20th	Night	27% 18% 29% 23% 3	800
	21st to end	Night	23% 22% 32% 21% 2	880
February	1st to 10th	Night	26% 19% 31% 22% 2	800
	11th to 20th	Night	28% 21% 34% 16% 1	783
	21st to end	Night	29% 18% 31% 18% 2	660
March	1st to 10th	Night	27% 21% 29% 20% 3	800
	11th to 20th	Night	27% 19% 27% 22% 5%	767
	21st to end	Night	24% 20% 31% 18% 6% 1	836
April	1st to 10th	Night	29% 19% 27% 22% 4	760
	11th to 20th	Night	23% 17% 29% 24% 7% 1	751
	21st to end	Night	22% 15% 28% 28% 7%	743
May	1st to 10th	Night	30% 9% 19% 28% 13% 1	523
	11th to 20th	Night	19% 11% 27% 33% 10% 1	374
	21st to end	Night	18% 7% 19% 35% 20% 1	411
June	1st to 10th	Night	16% 7% 19% 42% 16% 1	380
	11th to 20th	Night	14% 8% 21% 40% 16%	380
	21st to end	Night	14% 4 21% 44% 15% 1	380
July	1st to 10th	Night	12% 6% 19% 42% 20% 2	370
	11th to 20th	Night	11% 4 12% 47% 24% 2	368
	21st to end	Night	15% 2 14% 43% 24% 2	535
August	1st to 10th	Night	15% 3 13% 41% 26% 3	567
	11th to 20th	Night	16% 5% 12% 35% 29% 3	597
	21st to end	Night	14% 5% 17% 34% 28% 3	836
September	1st to 10th	Night	18% 6% 19% 35% 20% 2	760
	11th to 20th	Night	16% 5% 17% 30% 27% 5%	760
	21st to end	Night	23% 8% 18% 30% 18% 3	760
October	1st to 10th	Night	24% 9% 17% 28% 19% 3	760
	11th to 20th	Night	22% 12% 25% 31% 10% 1	760
	21st to end	Night	28% 13% 24% 29% 6%	836
November	1st to 10th	Night	18% 12% 30% 31% 9%	780
	11th to 20th	Night	27% 16% 26% 24% 6% 2	800
	21st to end	Night	24% 17% 29% 26% 5% 1	800
December	1st to 10th	Night	30% 17% 28% 21% 4	800
	11th to 20th	Night	27% 16% 29% 25% 4	800
	21st to end	Night	29% 17% 28% 24% 3	880

Page generated at 2025-03-09 08:08:49. Version ac07

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