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 2026-07-16.

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%	138403
	Night	17% 10% 3 8% 5% 4 4 3 5% 6% 33%	134233
Transparency	Day	49% 6% 11% 21% 11% 1	141993
	Night	49% 5% 12% 21% 12% 2	138731
Seeing	Day	25% 16% 27% 19% 10% 3	16893
	Night	23% 14% 25% 27% 10% 1	26222

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	15% 14% 5% 13% 7% 5% 5% 3 4 5% 24%	4661
	11th to 20th	Day	10% 14% 7% 19% 9% 6% 5% 3 4 5% 19%	4965
	21st to end	Day	15% 12% 6% 9% 6% 5% 4 3 5% 6% 29%	5780
February	1st to 10th	Day	15% 16% 4 9% 6% 5% 5% 4 6% 4 26%	1890
	11th to 20th	Day	15% 12% 5% 10% 7% 5% 4 3 5% 6% 28%	1860
	21st to end	Day	18% 14% 4 9% 5% 4 4 2 5% 5% 30%	1730
March	1st to 10th	Day	21% 11% 3 8% 4 4 3 3 4 4 35%	4853
	11th to 20th	Day	13% 11% 4 8% 4 5% 5% 3 4 6% 38%	5090
	21st to end	Day	14% 11% 3 8% 5% 4 5% 4 5% 6% 35%	5725
April	1st to 10th	Day	19% 11% 3 7% 5% 5% 4 3 5% 6% 31%	2520
	11th to 20th	Day	17% 10% 3 7% 5% 5% 4 4 6% 6% 33%	2494
	21st to end	Day	19% 8% 3 6% 5% 5% 4 4 5% 6% 36%	2556
May	1st to 10th	Day	26% 7% 2 8% 5% 5% 5% 4 5% 7% 27%	7796
	11th to 20th	Day	22% 8% 3 8% 4 5% 5% 4 5% 7% 30%	8221
	21st to end	Day	23% 6% 2 6% 5% 5% 5% 5% 6% 7% 31%	9060
June	1st to 10th	Day	15% 6% 2 6% 6% 6% 5% 4 6% 8% 35%	2940
	11th to 20th	Day	17% 6% 2 7% 5% 5% 5% 4 6% 8% 35%	2940
	21st to end	Day	14% 6% 2 5% 5% 5% 6% 5% 7% 9% 36%	2940
July	1st to 10th	Day	9% 6% 2 8% 6% 6% 5% 5% 6% 9% 38%	6500
	11th to 20th	Day	10% 6% 3 7% 6% 6% 6% 5% 8% 11% 32%	6430
	21st to end	Day	12% 6% 2 7% 5% 5% 6% 5% 6% 8% 39%	6618
August	1st to 10th	Day	21% 7% 3 7% 5% 6% 5% 4 5% 7% 31%	4234
	11th to 20th	Day	17% 6% 3 6% 6% 5% 6% 5% 7% 8% 32%	4080
	21st to end	Day	17% 4 2 4 4 4 5% 4 6% 9% 40%	4312
September	1st to 10th	Day	18% 5% 2 5% 4 4 5% 4 5% 6% 41%	2400
	11th to 20th	Day	15% 5% 2 5% 4 4 4 4 4 6% 48%	2400
	21st to end	Day	26% 6% 2 6% 3 4 3 3 5% 7% 34%	2108
October	1st to 10th	Day	19% 8% 2 5% 4 3 4 3 5% 7% 41%	2000
	11th to 20th	Day	21% 7% 3 6% 5% 4 5% 4 6% 7% 33%	2000
	21st to end	Day	21% 9% 3 6% 5% 4 5% 5% 5% 6% 32%	2200
November	1st to 10th	Day	14% 7% 3 7% 4 4 4 3 4 7% 42%	1856
	11th to 20th	Day	17% 12% 3 8% 5% 4 4 4 6% 5% 34%	1770
	21st to end	Day	17% 13% 3 8% 5% 4 3 4 6% 5% 31%	1680
December	1st to 10th	Day	18% 16% 6% 10% 6% 4 5% 3 4 5% 22%	2680
	11th to 20th	Day	23% 13% 4 7% 5% 4 3 3 4 5% 29%	3066
	21st to end	Day	20% 16% 4 11% 6% 5% 5% 3 4 6% 21%	4048
January	1st to 10th	Night	14% 12% 4 13% 7% 6% 5% 4 5% 6% 24%	8234
	11th to 20th	Night	12% 13% 5% 14% 6% 6% 5% 4 6% 6% 23%	7903
	21st to end	Night	14% 12% 4 9% 6% 6% 5% 4 5% 5% 29%	8401
February	1st to 10th	Night	15% 12% 4 8% 6% 6% 5% 3 6% 6% 29%	2730
	11th to 20th	Night	15% 11% 4 10% 6% 5% 6% 3 5% 7% 28%	2645
	21st to end	Night	17% 11% 3 10% 6% 5% 5% 3 6% 5% 28%	2076
March	1st to 10th	Night	21% 13% 3 7% 5% 4 4 3 5% 5% 32%	5203
	11th to 20th	Night	14% 10% 3 6% 4 3 4 4 5% 7% 40%	5089
	21st to end	Night	16% 10% 3 8% 4 5% 5% 3 4 5% 36%	5448
April	1st to 10th	Night	21% 14% 4 7% 4 4 4 3 4 6% 31%	2100
	11th to 20th	Night	18% 10% 2 6% 4 4 4 5% 5% 7% 35%	2075
	21st to end	Night	18% 8% 2 6% 4 4 4 3 5% 7% 39%	2081
May	1st to 10th	Night	29% 7% 2 6% 3 4 4 3 5% 6% 29%	5089
	11th to 20th	Night	23% 8% 2 6% 4 4 4 4 5% 6% 34%	4639
	21st to end	Night	25% 6% 2 5% 4 4 4 3 5% 7% 35%	5114
June	1st to 10th	Night	15% 6% 2 6% 4 3 5% 3 4 9% 42%	1680
	11th to 20th	Night	14% 6% 3 5% 4 5% 5% 4 6% 9% 38%	1680
	21st to end	Night	14% 5% 2 6% 5% 4 4 4 7% 9% 40%	1680
July	1st to 10th	Night	12% 7% 3 7% 4 4 4 4 6% 9% 40%	3680
	11th to 20th	Night	13% 7% 2 7% 5% 4 5% 5% 7% 9% 36%	3640
	21st to end	Night	13% 5% 2 5% 4 4 4 3 5% 7% 48%	4217
August	1st to 10th	Night	20% 6% 1 6% 4 5% 5% 4 6% 8% 36%	2915
	11th to 20th	Night	18% 7% 2 6% 4 4 3 3 5% 6% 42%	2936
	21st to end	Night	16% 4 2 5% 4 4 4 4 6% 8% 45%	3586
September	1st to 10th	Night	16% 6% 2 5% 4 3 4 3 5% 6% 46%	2000
	11th to 20th	Night	14% 5% 1 5% 3 3 3 3 4 7% 51%	2000
	21st to end	Night	22% 6% 2 5% 4 4 3 3 5% 6% 39%	2287
October	1st to 10th	Night	19% 7% 2 5% 3 4 4 3 4 6% 43%	2400
	11th to 20th	Night	19% 8% 2 5% 3 4 4 4 4 6% 40%	2400
	21st to end	Night	21% 9% 2 6% 4 3 4 3 5% 7% 36%	2640
November	1st to 10th	Night	12% 8% 3 6% 4 3 4 3 6% 7% 44%	2661
	11th to 20th	Night	19% 10% 3 8% 4 4 4 4 6% 6% 31%	2846
	21st to end	Night	16% 11% 4 8% 6% 4 5% 4 6% 6% 30%	2940
December	1st to 10th	Night	15% 14% 5% 8% 5% 5% 5% 4 6% 8% 25%	4720
	11th to 20th	Night	23% 11% 3 8% 5% 4 4 4 4 5% 29%	5348
	21st to end	Night	21% 15% 5% 9% 5% 4 4 3 5% 5% 24%	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	60% 5% 10% 17% 6% 2	4662
	11th to 20th	Day	68% 5% 7% 12% 8% 1	4998
	21st to end	Day	55% 4 11% 20% 10%	5780
February	1st to 10th	Day	60% 4 10% 17% 8% 1	1890
	11th to 20th	Day	58% 4 8% 22% 8% 1	1869
	21st to end	Day	57% 2 9% 21% 8% 2	1730
March	1st to 10th	Day	53% 4 10% 20% 10% 4	4856
	11th to 20th	Day	48% 4 16% 20% 8% 4	5090
	21st to end	Day	50% 5% 9% 18% 16% 3	5725
April	1st to 10th	Day	54% 4 9% 19% 12% 3	2520
	11th to 20th	Day	50% 5% 12% 18% 14% 2	2494
	21st to end	Day	49% 4 9% 21% 14% 4	2556
May	1st to 10th	Day	56% 6% 10% 17% 9% 1	7805
	11th to 20th	Day	52% 6% 10% 22% 9% 1	8225
	21st to end	Day	50% 6% 10% 22% 11% 1	9061
June	1st to 10th	Day	46% 6% 12% 21% 14% 1	2940
	11th to 20th	Day	45% 6% 15% 20% 13% 1	2940
	21st to end	Day	42% 6% 14% 25% 12% 1	2940
July	1st to 10th	Day	40% 8% 14% 25% 12% 1	6430
	11th to 20th	Day	41% 10% 17% 22% 11%	6355
	21st to end	Day	39% 8% 12% 23% 17% 1	6429
August	1st to 10th	Day	51% 6% 12% 19% 11%	4221
	11th to 20th	Day	45% 8% 14% 25% 7%	4119
	21st to end	Day	39% 6% 13% 31% 10% 2	4312
September	1st to 10th	Day	41% 6% 11% 26% 15% 2	2400
	11th to 20th	Day	37% 4 11% 27% 20% 2	2400
	21st to end	Day	49% 4 12% 18% 16% 1	2108
October	1st to 10th	Day	40% 6% 10% 24% 18% 2	3260
	11th to 20th	Day	42% 5% 9% 24% 17% 3	3240
	21st to end	Day	36% 6% 16% 29% 13% 1	3538
November	1st to 10th	Day	43% 5% 12% 22% 15% 3	1856
	11th to 20th	Day	51% 4 12% 21% 9% 2	1770
	21st to end	Day	54% 4 13% 21% 6% 1	1680
December	1st to 10th	Day	64% 5% 10% 17% 4 1	2680
	11th to 20th	Day	58% 3 13% 18% 8% 1	3066
	21st to end	Day	65% 5% 11% 12% 7% 1	4048
January	1st to 10th	Night	58% 6% 13% 16% 7% 1	8234
	11th to 20th	Night	58% 6% 11% 13% 10% 2	7945
	21st to end	Night	56% 4 8% 17% 13% 1	8401
February	1st to 10th	Night	54% 5% 12% 19% 9%	2730
	11th to 20th	Night	55% 4 10% 19% 10% 1	2647
	21st to end	Night	57% 3 9% 18% 11% 2	2076
March	1st to 10th	Night	55% 3 12% 18% 10% 2	5213
	11th to 20th	Night	45% 4 16% 23% 8% 4	5090
	21st to end	Night	49% 5% 8% 18% 18% 3	5448
April	1st to 10th	Night	56% 4 8% 18% 12% 2	2100
	11th to 20th	Night	47% 5% 11% 21% 14% 2	2075
	21st to end	Night	45% 4 10% 24% 15% 2	2081
May	1st to 10th	Night	54% 5% 9% 20% 10% 2	5096
	11th to 20th	Night	50% 6% 13% 19% 11% 1	4640
	21st to end	Night	49% 5% 12% 21% 11% 2	5115
June	1st to 10th	Night	41% 5% 10% 27% 16% 1	1680
	11th to 20th	Night	42% 6% 13% 25% 13% 2	1680
	21st to end	Night	39% 7% 12% 27% 14% 1	1680
July	1st to 10th	Night	40% 7% 12% 24% 15% 1	3640
	11th to 20th	Night	41% 9% 15% 23% 12%	3592
	21st to end	Night	34% 6% 13% 24% 22% 1	4092
August	1st to 10th	Night	45% 8% 14% 23% 9% 1	2904
	11th to 20th	Night	42% 5% 13% 27% 12%	2963
	21st to end	Night	37% 6% 12% 32% 11% 1	3586
September	1st to 10th	Night	39% 5% 10% 28% 16% 3	2000
	11th to 20th	Night	34% 5% 12% 29% 19% 2	2000
	21st to end	Night	45% 4 11% 23% 16% 1	2287
October	1st to 10th	Night	42% 5% 10% 23% 19% 1	3920
	11th to 20th	Night	36% 5% 11% 25% 17% 6%	3899
	21st to end	Night	35% 4 17% 28% 16% 2	4252
November	1st to 10th	Night	39% 5% 14% 25% 16% 2	2661
	11th to 20th	Night	52% 4 11% 21% 11% 2	2846
	21st to end	Night	53% 5% 12% 23% 7% 1	2940
December	1st to 10th	Night	56% 6% 14% 21% 4	4720
	11th to 20th	Night	57% 4 12% 17% 9%	5348
	21st to end	Night	62% 4 11% 15% 8% 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	33% 26% 28% 10% 2 1	220
	11th to 20th	Day	39% 23% 29% 6% 1	278
	21st to end	Day	34% 28% 27% 9% 2 1	363
February	1st to 10th	Day	33% 26% 29% 10% 2	330
	11th to 20th	Day	40% 23% 32% 5% 1	347
	21st to end	Day	35% 24% 27% 13% 2	446
March	1st to 10th	Day	34% 21% 27% 15% 3	540
	11th to 20th	Day	33% 24% 26% 13% 3 1	540
	21st to end	Day	32% 25% 25% 12% 4 2	594
April	1st to 10th	Day	34% 23% 25% 13% 4 1	540
	11th to 20th	Day	27% 26% 23% 14% 7% 3	532
	21st to end	Day	27% 21% 31% 14% 6% 2	540
May	1st to 10th	Day	34% 18% 24% 14% 7% 3	543
	11th to 20th	Day	26% 17% 27% 19% 8% 4	567
	21st to end	Day	24% 12% 27% 20% 13% 4	617
June	1st to 10th	Day	18% 16% 29% 23% 12% 2	570
	11th to 20th	Day	21% 14% 28% 23% 12% 2	570
	21st to end	Day	19% 11% 33% 23% 11% 3	570
July	1st to 10th	Day	14% 7% 28% 28% 18% 5%	565
	11th to 20th	Day	10% 9% 30% 29% 17% 5%	544
	21st to end	Day	14% 9% 30% 30% 14% 5%	576
August	1st to 10th	Day	13% 7% 24% 28% 21% 6%	526
	11th to 20th	Day	18% 6% 23% 29% 16% 8%	519
	21st to end	Day	16% 8% 25% 25% 16% 10%	583
September	1st to 10th	Day	18% 10% 21% 26% 18% 7%	530
	11th to 20th	Day	15% 7% 23% 24% 20% 11%	530
	21st to end	Day	29% 12% 22% 20% 14% 4	530
October	1st to 10th	Day	27% 8% 23% 22% 14% 6%	530
	11th to 20th	Day	27% 17% 27% 21% 8% 2	530
	21st to end	Day	28% 15% 29% 20% 6% 1	583
November	1st to 10th	Day	25% 16% 27% 21% 10% 1	428
	11th to 20th	Day	28% 23% 27% 16% 6% 1	310
	21st to end	Day	32% 22% 32% 11% 2	220
December	1st to 10th	Day	35% 22% 31% 10% 2 1	220
	11th to 20th	Day	37% 19% 31% 11% 2	220
	21st to end	Day	36% 21% 29% 12% 2	242
January	1st to 10th	Night	24% 19% 38% 17% 3	840
	11th to 20th	Night	27% 19% 29% 22% 3	840
	21st to end	Night	24% 22% 32% 20% 2	924
February	1st to 10th	Night	26% 19% 31% 22% 2	840
	11th to 20th	Night	28% 21% 35% 15% 1	823
	21st to end	Night	29% 19% 32% 18% 2	692
March	1st to 10th	Night	28% 21% 29% 20% 3	840
	11th to 20th	Night	28% 19% 27% 21% 4	840
	21st to end	Night	25% 21% 32% 16% 5% 1	924
April	1st to 10th	Night	31% 18% 27% 20% 3	840
	11th to 20th	Night	24% 17% 29% 23% 7% 1	831
	21st to end	Night	23% 14% 30% 28% 6%	821
May	1st to 10th	Night	30% 9% 20% 28% 12% 1	577
	11th to 20th	Night	19% 11% 27% 34% 9%	414
	21st to end	Night	20% 7% 20% 33% 18% 1	455
June	1st to 10th	Night	15% 7% 20% 41% 15% 1	420
	11th to 20th	Night	16% 8% 23% 38% 15%	420
	21st to end	Night	14% 4 22% 43% 17%	420
July	1st to 10th	Night	12% 6% 18% 43% 20% 2	410
	11th to 20th	Night	11% 5% 12% 46% 24% 3	398
	21st to end	Night	15% 3 14% 43% 23% 2	563
August	1st to 10th	Night	14% 3 13% 41% 26% 3	597
	11th to 20th	Night	16% 5% 12% 35% 29% 3	629
	21st to end	Night	14% 5% 17% 35% 27% 2	880
September	1st to 10th	Night	18% 7% 19% 35% 20% 2	800
	11th to 20th	Night	15% 5% 16% 32% 27% 5%	800
	21st to end	Night	23% 8% 18% 31% 17% 3	800
October	1st to 10th	Night	24% 9% 18% 27% 20% 3	800
	11th to 20th	Night	22% 13% 25% 30% 10% 1	800
	21st to end	Night	27% 12% 26% 29% 6%	880
November	1st to 10th	Night	19% 11% 30% 31% 9%	820
	11th to 20th	Night	28% 16% 25% 23% 6% 1	840
	21st to end	Night	25% 17% 28% 26% 4	840
December	1st to 10th	Night	29% 18% 28% 21% 4	840
	11th to 20th	Night	28% 16% 28% 24% 3	840
	21st to end	Night	30% 17% 28% 23% 2	924

Page generated at 2026-07-13 03:14:47. Version ac07

Copyright © 2026 Attilla Danko.