Camden
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Camden clear sky chart from 2005-11-06 to 2025-11-18.

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	19% 8% 2 6% 4 4 4 3 5% 7% 37%	126099
	Night	18% 9% 3 6% 4 4 4 3 5% 6% 38%	124280
Transparency	Day	45% 6% 12% 22% 13% 2	129622
	Night	46% 5% 11% 21% 14% 2	128833
Seeing	Day	22% 16% 32% 21% 7% 2	16959
	Night	22% 13% 31% 25% 8% 1	25387

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% 7% 3 7% 6% 6% 4 3 5% 6% 38%	3597
	11th to 20th	Day	14% 9% 3 6% 3 3 3 3 4 7% 45%	3570
	21st to end	Day	13% 10% 3 7% 4 4 3 3 4 5% 45%	4029
February	1st to 10th	Day	16% 10% 2 7% 5% 4 5% 3 5% 5% 37%	1800
	11th to 20th	Day	14% 9% 2 6% 5% 4 5% 4 6% 5% 39%	1884
	21st to end	Day	15% 10% 3 8% 5% 3 4 4 5% 6% 37%	1650
March	1st to 10th	Day	23% 12% 2 6% 4 4 4 3 5% 4 31%	4491
	11th to 20th	Day	18% 12% 3 6% 4 4 4 3 5% 5% 36%	4980
	21st to end	Day	27% 10% 3 5% 4 4 4 3 5% 6% 30%	5466
April	1st to 10th	Day	20% 13% 3 6% 4 4 4 3 4 6% 34%	2390
	11th to 20th	Day	19% 8% 2 6% 5% 4 4 3 5% 6% 38%	2528
	21st to end	Day	22% 8% 3 7% 5% 3 4 4 4 7% 36%	2600
May	1st to 10th	Day	30% 10% 4 7% 4 3 4 3 4 6% 25%	5886
	11th to 20th	Day	19% 9% 3 8% 5% 5% 4 4 5% 6% 33%	5861
	21st to end	Day	21% 8% 2 5% 4 4 4 3 6% 8% 34%	6928
June	1st to 10th	Day	22% 8% 3 7% 4 4 4 4 5% 7% 32%	3000
	11th to 20th	Day	18% 7% 2 6% 5% 4 4 3 6% 7% 38%	3000
	21st to end	Day	24% 7% 3 6% 4 4 5% 4 6% 7% 31%	2993
July	1st to 10th	Day	17% 8% 3 7% 5% 4 5% 4 7% 8% 32%	6360
	11th to 20th	Day	16% 9% 2 6% 4 4 4 4 6% 8% 38%	6360
	21st to end	Day	17% 5% 2 4 3 4 4 4 5% 8% 42%	6821
August	1st to 10th	Day	17% 8% 2 7% 4 4 5% 4 6% 8% 34%	4235
	11th to 20th	Day	17% 8% 3 7% 5% 5% 4 4 5% 7% 36%	4175
	21st to end	Day	10% 5% 2 5% 3 4 4 5% 6% 9% 46%	4614
September	1st to 10th	Day	11% 6% 2 5% 4 4 5% 3 5% 7% 49%	2310
	11th to 20th	Day	12% 5% 1 5% 3 3 4 2 5% 6% 54%	2200
	21st to end	Day	18% 7% 2 4 4 4 3 3 5% 7% 45%	2200
October	1st to 10th	Day	16% 7% 3 5% 4 4 4 3 4 6% 43%	2160
	11th to 20th	Day	20% 5% 2 6% 4 4 4 3 4 6% 43%	1976
	21st to end	Day	22% 9% 2 5% 4 3 4 3 4 6% 39%	1980
November	1st to 10th	Day	16% 7% 2 6% 4 4 4 2 5% 7% 43%	1851
	11th to 20th	Day	19% 5% 2 5% 3 3 4 4 4 6% 43%	1863
	21st to end	Day	20% 9% 2 5% 3 3 3 3 3 5% 43%	1622
December	1st to 10th	Day	16% 11% 2 4 3 3 3 3 4 6% 44%	2427
	11th to 20th	Day	19% 8% 2 4 4 3 3 2 4 5% 46%	2618
	21st to end	Day	22% 12% 3 6% 4 3 4 3 5% 5% 35%	3674
January	1st to 10th	Night	12% 9% 3 8% 5% 4 4 3 5% 6% 41%	6349
	11th to 20th	Night	13% 10% 4 9% 5% 5% 5% 4 5% 6% 35%	6315
	21st to end	Night	12% 12% 4 8% 4 4 4 3 5% 5% 41%	6926
February	1st to 10th	Night	16% 10% 4 6% 5% 5% 4 4 4 6% 35%	2600
	11th to 20th	Night	14% 9% 4 8% 4 4 5% 4 5% 6% 39%	2397
	21st to end	Night	14% 10% 4 6% 5% 4 4 3 4 6% 41%	1980
March	1st to 10th	Night	26% 11% 2 6% 4 4 3 3 4 4 31%	5347
	11th to 20th	Night	16% 10% 4 7% 5% 4 5% 4 6% 7% 33%	4979
	21st to end	Night	25% 9% 2 6% 4 4 4 4 6% 6% 31%	5466
April	1st to 10th	Night	23% 10% 3 5% 4 4 4 3 4 6% 33%	2005
	11th to 20th	Night	19% 8% 2 6% 5% 4 4 3 6% 9% 35%	1819
	21st to end	Night	23% 9% 3 6% 4 4 4 3 4 6% 35%	1800
May	1st to 10th	Night	30% 10% 3 7% 4 3 3 3 4 6% 26%	4054
	11th to 20th	Night	21% 10% 3 7% 4 5% 4 4 5% 7% 30%	4033
	21st to end	Night	17% 9% 3 8% 5% 5% 5% 4 5% 7% 33%	3986
June	1st to 10th	Night	22% 8% 3 6% 4 4 5% 4 6% 7% 30%	1400
	11th to 20th	Night	16% 8% 2 6% 4 3 4 5% 6% 7% 38%	1400
	21st to end	Night	23% 9% 3 7% 4 4 4 4 5% 7% 30%	1400
July	1st to 10th	Night	15% 9% 2 6% 5% 5% 6% 5% 7% 8% 33%	3599
	11th to 20th	Night	16% 11% 2 6% 4 5% 5% 4 6% 8% 35%	3600
	21st to end	Night	11% 6% 2 5% 4 4 5% 4 6% 9% 43%	3971
August	1st to 10th	Night	22% 8% 3 7% 5% 5% 5% 3 5% 7% 31%	2915
	11th to 20th	Night	16% 10% 3 7% 5% 4 5% 3 5% 7% 34%	2872
	21st to end	Night	10% 5% 2 5% 4 4 4 4 5% 7% 49%	3281
September	1st to 10th	Night	12% 6% 2 5% 3 3 4 3 5% 7% 50%	2090
	11th to 20th	Night	14% 7% 1 4 2 2 3 2 4 7% 53%	2200
	21st to end	Night	16% 6% 2 5% 3 4 4 3 5% 7% 46%	2200
October	1st to 10th	Night	18% 6% 3 5% 3 4 4 3 4 6% 43%	2239
	11th to 20th	Night	17% 6% 2 6% 3 3 4 3 5% 6% 44%	2420
	21st to end	Night	23% 8% 2 5% 4 4 3 3 4 6% 37%	2860
November	1st to 10th	Night	18% 6% 2 6% 4 3 3 4 5% 6% 44%	2667
	11th to 20th	Night	17% 6% 2 5% 4 4 4 3 4 6% 44%	2692
	21st to end	Night	19% 7% 2 5% 4 3 4 3 5% 6% 41%	2775
December	1st to 10th	Night	17% 9% 3 6% 3 3 4 3 6% 7% 39%	4762
	11th to 20th	Night	23% 8% 2 4 3 3 3 3 3 5% 44%	5591
	21st to end	Night	21% 11% 3 6% 3 3 3 3 4 5% 39%	7290

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	46% 5% 10% 27% 11% 1	3598
	11th to 20th	Day	41% 4 12% 28% 13% 3	3600
	21st to end	Day	42% 4 10% 20% 18% 7%	4029
February	1st to 10th	Day	49% 4 11% 19% 15% 3	1800
	11th to 20th	Day	45% 5% 12% 20% 15% 3	1893
	21st to end	Day	47% 5% 10% 21% 13% 5%	1650
March	1st to 10th	Day	55% 5% 8% 10% 15% 7%	4494
	11th to 20th	Day	49% 4 15% 18% 11% 2	4980
	21st to end	Day	53% 3 7% 17% 16% 4	5466
April	1st to 10th	Day	51% 4 8% 17% 15% 4	2390
	11th to 20th	Day	45% 5% 10% 22% 16% 3	2528
	21st to end	Day	49% 5% 8% 19% 16% 4	2600
May	1st to 10th	Day	59% 8% 10% 15% 6% 1	5897
	11th to 20th	Day	50% 7% 12% 21% 7% 3	5865
	21st to end	Day	47% 7% 14% 20% 11% 1	6928
June	1st to 10th	Day	50% 7% 11% 21% 10% 1	3000
	11th to 20th	Day	44% 7% 11% 20% 16% 2	3000
	21st to end	Day	52% 8% 10% 19% 10% 1	2993
July	1st to 10th	Day	48% 7% 13% 21% 10%	6290
	11th to 20th	Day	43% 7% 15% 22% 13% 1	6285
	21st to end	Day	39% 6% 13% 27% 14% 1	6625
August	1st to 10th	Day	45% 8% 14% 26% 7%	4222
	11th to 20th	Day	44% 8% 17% 21% 9%	4214
	21st to end	Day	30% 8% 14% 27% 19% 1	4614
September	1st to 10th	Day	33% 7% 13% 27% 19% 1	2310
	11th to 20th	Day	32% 5% 12% 27% 21% 3	2200
	21st to end	Day	41% 5% 8% 27% 18% 1	2200
October	1st to 10th	Day	45% 8% 11% 23% 13% 1	3524
	11th to 20th	Day	32% 4 10% 31% 23%	3192
	21st to end	Day	35% 3 14% 24% 20% 4	3180
November	1st to 10th	Day	41% 4 13% 24% 17% 2	1851
	11th to 20th	Day	41% 4 10% 21% 20% 3	1863
	21st to end	Day	45% 3 15% 22% 13% 1	1622
December	1st to 10th	Day	41% 4 14% 28% 12% 1	2427
	11th to 20th	Day	42% 3 12% 17% 17% 8%	2618
	21st to end	Day	51% 6% 9% 17% 13% 3	3674
January	1st to 10th	Night	43% 4 11% 29% 12% 2	6349
	11th to 20th	Night	50% 5% 12% 21% 11% 2	6360
	21st to end	Night	46% 3 8% 20% 17% 5%	6926
February	1st to 10th	Night	50% 4 11% 18% 14% 3	2600
	11th to 20th	Night	46% 4 10% 20% 17% 3	2399
	21st to end	Night	45% 4 10% 21% 15% 5%	1980
March	1st to 10th	Night	56% 3 7% 13% 13% 8%	5357
	11th to 20th	Night	48% 6% 18% 18% 9% 2	4980
	21st to end	Night	53% 3 7% 15% 19% 4	5466
April	1st to 10th	Night	52% 4 8% 15% 17% 4	2005
	11th to 20th	Night	47% 5% 8% 22% 16% 1	1819
	21st to end	Night	51% 5% 10% 17% 15% 3	1800
May	1st to 10th	Night	59% 7% 12% 14% 7% 1	4060
	11th to 20th	Night	53% 7% 12% 19% 8% 1	4034
	21st to end	Night	50% 8% 12% 20% 10% 1	3987
June	1st to 10th	Night	51% 8% 9% 21% 9% 1	1400
	11th to 20th	Night	46% 6% 15% 19% 13% 2	1400
	21st to end	Night	54% 5% 9% 19% 11% 2	1400
July	1st to 10th	Night	48% 7% 13% 21% 10%	3559
	11th to 20th	Night	48% 7% 14% 20% 11%	3552
	21st to end	Night	36% 7% 17% 29% 11% 1	3853
August	1st to 10th	Night	54% 7% 12% 20% 7%	2903
	11th to 20th	Night	48% 8% 13% 20% 10%	2899
	21st to end	Night	32% 7% 13% 26% 20% 1	3281
September	1st to 10th	Night	35% 5% 12% 28% 18% 1	2090
	11th to 20th	Night	34% 4 11% 28% 21% 2	2200
	21st to end	Night	38% 5% 9% 29% 17% 2	2200
October	1st to 10th	Night	40% 5% 14% 24% 15% 1	3655
	11th to 20th	Night	31% 4 10% 29% 24% 2	3931
	21st to end	Night	38% 4 10% 28% 17% 3	4610
November	1st to 10th	Night	40% 5% 11% 25% 17% 2	2667
	11th to 20th	Night	42% 4 10% 23% 18% 3	2692
	21st to end	Night	45% 4 14% 20% 15% 2	2775
December	1st to 10th	Night	45% 4 9% 29% 13%	4762
	11th to 20th	Night	45% 3 11% 19% 19% 3	5592
	21st to end	Night	49% 5% 9% 18% 18% 1	7290

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	26% 23% 30% 17% 5%	200
	11th to 20th	Day	25% 26% 29% 16% 4 1	200
	21st to end	Day	22% 23% 34% 18% 4	250
February	1st to 10th	Day	28% 22% 32% 16% 3	400
	11th to 20th	Day	26% 26% 33% 13% 2	463
	21st to end	Day	23% 23% 35% 17% 3	414
March	1st to 10th	Day	26% 23% 34% 15% 2	500
	11th to 20th	Day	22% 25% 36% 15% 3 1	500
	21st to end	Day	29% 24% 29% 12% 5% 1	550
April	1st to 10th	Day	32% 22% 29% 12% 4 1	500
	11th to 20th	Day	27% 23% 30% 15% 4 1	492
	21st to end	Day	26% 18% 38% 12% 5% 1	500
May	1st to 10th	Day	29% 20% 30% 16% 4 1	503
	11th to 20th	Day	17% 16% 39% 22% 5% 1	527
	21st to end	Day	20% 16% 37% 21% 5% 1	583
June	1st to 10th	Day	22% 12% 31% 24% 9% 1	730
	11th to 20th	Day	20% 10% 34% 22% 11% 2	730
	21st to end	Day	27% 9% 29% 25% 10% 1	723
July	1st to 10th	Day	21% 8% 35% 26% 9% 2	525
	11th to 20th	Day	17% 7% 35% 28% 10% 3	524
	21st to end	Day	18% 6% 36% 28% 10% 2	576
August	1st to 10th	Day	14% 6% 31% 34% 13% 2	526
	11th to 20th	Day	18% 7% 27% 32% 12% 4	519
	21st to end	Day	15% 11% 32% 27% 12% 3	583
September	1st to 10th	Day	14% 9% 32% 29% 14% 2	530
	11th to 20th	Day	15% 9% 33% 22% 14% 7%	530
	21st to end	Day	18% 12% 32% 23% 10% 5%	530
October	1st to 10th	Day	19% 14% 25% 28% 11% 3	508
	11th to 20th	Day	21% 16% 31% 22% 8% 2	420
	21st to end	Day	30% 14% 31% 20% 5%	462
November	1st to 10th	Day	22% 20% 28% 22% 6% 2	425
	11th to 20th	Day	26% 20% 31% 18% 4 1	421
	21st to end	Day	26% 23% 28% 17% 6%	400
December	1st to 10th	Day	23% 18% 36% 17% 5% 1	295
	11th to 20th	Day	33% 25% 30% 11% 1 1	200
	21st to end	Day	26% 23% 32% 13% 5%	220
January	1st to 10th	Night	21% 22% 35% 19% 3	800
	11th to 20th	Night	26% 20% 34% 16% 4	800
	21st to end	Night	18% 22% 40% 18% 3	880
February	1st to 10th	Night	24% 20% 34% 19% 3	800
	11th to 20th	Night	21% 22% 38% 16% 3	783
	21st to end	Night	22% 16% 37% 21% 4	660
March	1st to 10th	Night	26% 18% 37% 18% 2	800
	11th to 20th	Night	22% 16% 35% 22% 6%	800
	21st to end	Night	24% 16% 33% 21% 5%	880
April	1st to 10th	Night	29% 15% 32% 19% 3 1	800
	11th to 20th	Night	24% 12% 33% 27% 5%	635
	21st to end	Night	30% 12% 30% 24% 5% 1	600
May	1st to 10th	Night	26% 8% 31% 27% 7% 1	600
	11th to 20th	Night	24% 7% 35% 27% 6% 1	592
	21st to end	Night	22% 8% 28% 33% 8% 1	480
June	1st to 10th	Night	26% 6% 26% 32% 10% 1	400
	11th to 20th	Night	18% 7% 26% 36% 13% 1	400
	21st to end	Night	25% 7% 26% 34% 9%	400
July	1st to 10th	Night	21% 4 21% 41% 14%	390
	11th to 20th	Night	20% 4 20% 39% 16% 1	388
	21st to end	Night	17% 3 25% 39% 15% 1	458
August	1st to 10th	Night	17% 3 23% 41% 15% 1	598
	11th to 20th	Night	17% 5% 23% 39% 15% 1	592
	21st to end	Night	15% 5% 23% 38% 17% 1	692
September	1st to 10th	Night	15% 5% 28% 35% 17% 1	800
	11th to 20th	Night	18% 7% 26% 29% 16% 5%	800
	21st to end	Night	18% 8% 29% 29% 14% 2	800
October	1st to 10th	Night	22% 8% 26% 29% 15% 1	800
	11th to 20th	Night	20% 12% 31% 24% 10% 2	800
	21st to end	Night	28% 13% 30% 24% 5%	880
November	1st to 10th	Night	25% 13% 30% 25% 6% 1	820
	11th to 20th	Night	22% 16% 33% 21% 6% 1	829
	21st to end	Night	23% 20% 32% 19% 5%	887
December	1st to 10th	Night	26% 16% 37% 16% 6%	900
	11th to 20th	Night	25% 22% 32% 17% 3	900
	21st to end	Night	27% 19% 33% 18% 3	943

Page generated at 2025-11-15 00:55:54. Version ac07

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