Albany
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Albany clear sky chart from 2005-11-06 to 2025-05-11.

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	11% 6% 2 6% 5% 5% 5% 4 6% 8% 43%	114215
	Night	11% 6% 2 6% 4 4 4 4 6% 8% 45%	114729
Transparency	Day	37% 6% 12% 18% 18% 8%	118058
	Night	36% 6% 11% 17% 20% 10%	119012
Seeing	Day	12% 6% 20% 25% 23% 14%	15629
	Night	13% 5% 22% 33% 23% 4	25709

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	13% 5% 2 6% 4 4 3 3 4 5% 53%	4056
	11th to 20th	Day	16% 5% 2 3 3 3 3 3 6% 7% 50%	4060
	21st to end	Day	14% 7% 3 6% 4 4 4 3 5% 8% 44%	4853
February	1st to 10th	Day	15% 7% 2 7% 5% 5% 4 4 5% 6% 41%	2000
	11th to 20th	Day	17% 7% 2 5% 4 3 3 3 5% 5% 45%	1948
	21st to end	Day	15% 7% 2 5% 3 4 4 4 6% 6% 44%	1650
March	1st to 10th	Day	18% 7% 2 6% 4 4 4 3 6% 7% 39%	4682
	11th to 20th	Day	8% 5% 2 5% 3 4 4 3 5% 7% 54%	4980
	21st to end	Day	14% 7% 2 5% 4 4 4 3 5% 6% 46%	5465
April	1st to 10th	Day	11% 6% 2 5% 5% 5% 4 4 6% 6% 46%	2200
	11th to 20th	Day	11% 5% 2 4 5% 3 5% 4 5% 8% 49%	2362
	21st to end	Day	7% 4 1 5% 5% 4 4 4 6% 7% 53%	2510
May	1st to 10th	Day	8% 4 2 6% 5% 5% 5% 4 6% 8% 46%	4212
	11th to 20th	Day	13% 7% 3 7% 4 5% 6% 4 7% 7% 37%	4081
	21st to end	Day	4 3 2 6% 5% 5% 5% 5% 7% 10% 47%	4476
June	1st to 10th	Day	9% 6% 3 8% 7% 5% 7% 6% 7% 9% 33%	2470
	11th to 20th	Day	5% 4 2 7% 6% 6% 7% 7% 8% 11% 38%	2470
	21st to end	Day	6% 5% 2 8% 6% 7% 7% 6% 10% 11% 31%	2470
July	1st to 10th	Day	10% 7% 3 9% 8% 7% 8% 7% 10% 11% 20%	4120
	11th to 20th	Day	6% 4 2 6% 7% 7% 6% 6% 8% 12% 35%	4120
	21st to end	Day	6% 6% 3 9% 7% 8% 8% 7% 10% 13% 22%	4466
August	1st to 10th	Day	11% 5% 2 7% 6% 6% 7% 6% 10% 11% 29%	4011
	11th to 20th	Day	6% 3 2 6% 5% 5% 5% 5% 7% 10% 46%	3729
	21st to end	Day	8% 7% 2 7% 6% 6% 5% 5% 7% 11% 36%	4122
September	1st to 10th	Day	10% 6% 3 8% 5% 6% 7% 6% 7% 9% 34%	2090
	11th to 20th	Day	11% 7% 2 8% 6% 6% 5% 4 7% 8% 35%	2090
	21st to end	Day	11% 4 2 6% 5% 4 5% 3 6% 7% 46%	2090
October	1st to 10th	Day	12% 5% 2 5% 3 4 4 3 5% 5% 51%	2090
	11th to 20th	Day	9% 4 1 4 3 3 4 3 3 7% 59%	2011
	21st to end	Day	9% 4 1 5% 4 4 3 3 4 6% 57%	2090
November	1st to 10th	Day	10% 6% 2 4 4 4 4 3 5% 6% 53%	1872
	11th to 20th	Day	11% 5% 2 5% 4 3 3 3 4 5% 56%	1800
	21st to end	Day	13% 6% 2 6% 5% 3 4 3 5% 6% 49%	1800
December	1st to 10th	Day	13% 5% 3 5% 4 3 3 3 4 6% 51%	2930
	11th to 20th	Day	15% 7% 2 5% 4 4 3 3 5% 6% 47%	3373
	21st to end	Day	19% 9% 3 6% 3 3 3 3 4 5% 41%	4466
January	1st to 10th	Night	11% 5% 2 5% 3 4 4 3 4 6% 53%	5889
	11th to 20th	Night	13% 6% 3 7% 4 5% 4 3 5% 6% 44%	5900
	21st to end	Night	16% 9% 2 6% 4 3 4 3 5% 8% 41%	6099
February	1st to 10th	Night	14% 8% 2 5% 4 4 4 3 6% 5% 45%	2400
	11th to 20th	Night	17% 7% 2 5% 4 4 3 3 5% 6% 46%	2338
	21st to end	Night	14% 6% 2 5% 3 3 5% 3 5% 6% 47%	1980
March	1st to 10th	Night	19% 9% 3 6% 4 4 3 3 4 6% 39%	5157
	11th to 20th	Night	9% 5% 2 5% 3 3 4 4 6% 8% 50%	4980
	21st to end	Night	13% 5% 2 5% 4 4 4 3 6% 6% 48%	5467
April	1st to 10th	Night	10% 5% 2 5% 5% 4 4 4 6% 7% 49%	2200
	11th to 20th	Night	10% 5% 2 5% 4 4 4 3 6% 8% 51%	2003
	21st to end	Night	6% 3 1 4 4 4 4 4 6% 7% 56%	1890
May	1st to 10th	Night	7% 6% 3 7% 5% 4 5% 4 6% 10% 45%	2903
	11th to 20th	Night	13% 7% 2 6% 4 4 5% 4 5% 7% 43%	2818
	21st to end	Night	5% 4 2 5% 4 4 4 3 6% 10% 53%	3079
June	1st to 10th	Night	8% 6% 3 8% 6% 6% 6% 6% 7% 11% 33%	1710
	11th to 20th	Night	5% 5% 2 7% 5% 5% 6% 4 9% 11% 42%	1710
	21st to end	Night	6% 5% 2 8% 6% 5% 7% 6% 8% 11% 36%	1710
July	1st to 10th	Night	14% 8% 3 10% 7% 7% 8% 6% 8% 9% 20%	2840
	11th to 20th	Night	4 4 2 7% 5% 6% 6% 7% 10% 14% 35%	2840
	21st to end	Night	7% 7% 3 9% 7% 6% 7% 6% 11% 11% 25%	3087
August	1st to 10th	Night	11% 6% 2 7% 6% 6% 6% 5% 9% 12% 31%	2912
	11th to 20th	Night	6% 4 2 6% 5% 6% 6% 5% 7% 11% 42%	3100
	21st to end	Night	6% 5% 2 6% 5% 5% 5% 6% 8% 12% 40%	3499
September	1st to 10th	Night	10% 7% 3 7% 7% 6% 7% 4 8% 10% 32%	2090
	11th to 20th	Night	12% 7% 3 7% 6% 5% 5% 4 7% 9% 36%	2090
	21st to end	Night	9% 6% 2 6% 5% 5% 6% 5% 6% 8% 43%	2090
October	1st to 10th	Night	10% 6% 1 5% 3 3 4 3 5% 8% 52%	2090
	11th to 20th	Night	9% 6% 1 4 3 3 3 2 4 6% 60%	2166
	21st to end	Night	9% 4 3 5% 3 4 4 3 4 5% 57%	2508
November	1st to 10th	Night	11% 4 2 5% 3 4 4 3 4 6% 54%	2422
	11th to 20th	Night	13% 5% 2 4 3 3 3 3 4 7% 53%	2600
	21st to end	Night	13% 5% 2 5% 4 3 4 3 5% 7% 48%	2600
December	1st to 10th	Night	12% 5% 2 5% 3 3 3 2 4 6% 55%	4250
	11th to 20th	Night	15% 7% 2 5% 3 3 3 3 4 5% 51%	4822
	21st to end	Night	17% 9% 3 6% 4 3 3 3 4 5% 43%	6490

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	34% 4 5% 15% 34% 8%	4057
	11th to 20th	Day	34% 3 5% 17% 27% 15%	4060
	21st to end	Day	40% 4 7% 18% 18% 13%	4853
February	1st to 10th	Day	43% 4 8% 15% 20% 10%	2000
	11th to 20th	Day	41% 3 5% 15% 27% 10%	1958
	21st to end	Day	38% 5% 8% 18% 18% 12%	1650
March	1st to 10th	Day	44% 4 8% 16% 17% 10%	4682
	11th to 20th	Day	29% 4 9% 13% 21% 24%	4980
	21st to end	Day	39% 4 8% 20% 17% 11%	5465
April	1st to 10th	Day	38% 5% 9% 20% 16% 12%	2200
	11th to 20th	Day	34% 5% 7% 18% 25% 11%	2362
	21st to end	Day	29% 5% 11% 24% 23% 8%	2510
May	1st to 10th	Day	32% 7% 13% 23% 19% 5%	4250
	11th to 20th	Day	43% 8% 11% 21% 15% 2	4085
	21st to end	Day	28% 9% 16% 26% 19% 2	4489
June	1st to 10th	Day	43% 10% 16% 20% 10% 1	2470
	11th to 20th	Day	34% 11% 17% 22% 14% 2	2470
	21st to end	Day	41% 11% 21% 15% 10% 2	2470
July	1st to 10th	Day	51% 11% 26% 8% 3	4055
	11th to 20th	Day	35% 13% 29% 19% 3	4051
	21st to end	Day	46% 15% 24% 12% 3	4324
August	1st to 10th	Day	43% 10% 21% 21% 6%	3998
	11th to 20th	Day	30% 9% 16% 28% 15% 1	3765
	21st to end	Day	40% 8% 19% 26% 7% 1	4122
September	1st to 10th	Day	44% 10% 18% 13% 13% 3	2090
	11th to 20th	Day	44% 8% 13% 16% 15% 4	2090
	21st to end	Day	36% 6% 11% 21% 19% 7%	2090
October	1st to 10th	Day	38% 4 6% 11% 20% 21%	3480
	11th to 20th	Day	16% 3 5% 18% 25% 33%	3316
	21st to end	Day	20% 3 4 20% 38% 16%	3428
November	1st to 10th	Day	32% 4 9% 16% 24% 15%	1872
	11th to 20th	Day	31% 4 6% 16% 27% 15%	1800
	21st to end	Day	36% 4 8% 19% 23% 11%	1800
December	1st to 10th	Day	35% 4 8% 14% 29% 10%	2930
	11th to 20th	Day	39% 3 6% 23% 23% 7%	3370
	21st to end	Day	46% 3 5% 18% 25% 4	4466
January	1st to 10th	Night	33% 3 7% 12% 32% 12%	5889
	11th to 20th	Night	41% 3 4 15% 27% 10%	5900
	21st to end	Night	42% 4 7% 17% 22% 9%	6099
February	1st to 10th	Night	40% 4 7% 16% 21% 12%	2400
	11th to 20th	Night	40% 4 7% 13% 21% 14%	2339
	21st to end	Night	37% 6% 7% 18% 17% 16%	1980
March	1st to 10th	Night	46% 5% 7% 14% 17% 11%	5157
	11th to 20th	Night	31% 4 8% 16% 22% 19%	4980
	21st to end	Night	36% 4 8% 17% 22% 14%	5467
April	1st to 10th	Night	33% 6% 10% 18% 19% 14%	2200
	11th to 20th	Night	32% 4 10% 17% 26% 12%	2003
	21st to end	Night	25% 5% 12% 26% 24% 8%	1890
May	1st to 10th	Night	32% 9% 14% 22% 17% 6%	2930
	11th to 20th	Night	38% 8% 12% 24% 13% 4	2819
	21st to end	Night	25% 8% 16% 28% 20% 3	3087
June	1st to 10th	Night	39% 12% 16% 20% 11% 2	1710
	11th to 20th	Night	31% 11% 20% 24% 12% 2	1710
	21st to end	Night	37% 12% 22% 16% 11% 2	1710
July	1st to 10th	Night	56% 13% 20% 8% 3 1	2795
	11th to 20th	Night	34% 14% 31% 17% 4	2786
	21st to end	Night	46% 15% 22% 13% 3 1	2988
August	1st to 10th	Night	43% 9% 24% 20% 4	2901
	11th to 20th	Night	34% 10% 19% 26% 10% 1	3130
	21st to end	Night	33% 9% 25% 25% 6% 1	3499
September	1st to 10th	Night	43% 12% 18% 13% 11% 3	2090
	11th to 20th	Night	42% 9% 14% 14% 16% 4	2090
	21st to end	Night	35% 8% 13% 17% 20% 7%	2090
October	1st to 10th	Night	36% 4 9% 12% 20% 19%	3480
	11th to 20th	Night	16% 2 4 13% 29% 35%	3587
	21st to end	Night	20% 2 4 16% 39% 19%	4120
November	1st to 10th	Night	30% 4 9% 16% 24% 16%	2422
	11th to 20th	Night	32% 4 6% 15% 27% 16%	2600
	21st to end	Night	35% 5% 8% 18% 20% 14%	2600
December	1st to 10th	Night	32% 4 8% 19% 28% 10%	4250
	11th to 20th	Night	36% 3 7% 20% 24% 9%	4824
	21st to end	Night	44% 4 6% 17% 27% 3	6490

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	13% 17% 44% 20% 6% 1	300
	11th to 20th	Day	13% 18% 32% 24% 9% 3	300
	21st to end	Day	21% 19% 42% 13% 5%	330
February	1st to 10th	Day	16% 14% 35% 24% 10% 1	300
	11th to 20th	Day	26% 13% 37% 19% 5%	300
	21st to end	Day	15% 16% 39% 25% 4	249
March	1st to 10th	Day	16% 14% 32% 27% 11% 1	385
	11th to 20th	Day	13% 10% 36% 28% 12% 1	500
	21st to end	Day	15% 12% 32% 29% 12% 1	550
April	1st to 10th	Day	16% 12% 26% 28% 15% 2	500
	11th to 20th	Day	13% 9% 27% 27% 20% 3	492
	21st to end	Day	8% 6% 20% 36% 24% 6%	500
May	1st to 10th	Day	8% 7% 24% 29% 24% 8%	503
	11th to 20th	Day	9% 3 17% 29% 29% 13%	487
	21st to end	Day	9% 2 13% 27% 29% 21%	529
June	1st to 10th	Day	11% 2 10% 27% 32% 18%	490
	11th to 20th	Day	8% 1 11% 21% 29% 30%	490
	21st to end	Day	9% 1 6% 24% 34% 25%	490
July	1st to 10th	Day	8% 1 4 13% 35% 39%	485
	11th to 20th	Day	8% 2 2 11% 33% 44%	484
	21st to end	Day	6% 1 4 16% 35% 37%	532
August	1st to 10th	Day	10% 2 6% 18% 34% 30%	486
	11th to 20th	Day	8% 2 3 14% 36% 38%	479
	21st to end	Day	10% 3 8% 18% 36% 25%	539
September	1st to 10th	Day	13% 3 8% 21% 30% 26%	490
	11th to 20th	Day	16% 1 9% 27% 32% 15%	490
	21st to end	Day	13% 1 12% 23% 31% 20%	490
October	1st to 10th	Day	12% 3 23% 31% 22% 9%	490
	11th to 20th	Day	9% 5% 18% 32% 26% 9%	490
	21st to end	Day	10% 5% 22% 33% 25% 5%	539
November	1st to 10th	Day	15% 4 21% 32% 23% 5%	410
	11th to 20th	Day	12% 9% 37% 28% 10% 4	300
	21st to end	Day	12% 15% 27% 30% 14% 2	300
December	1st to 10th	Day	20% 10% 30% 26% 12% 2	300
	11th to 20th	Day	24% 11% 32% 23% 9% 1	300
	21st to end	Day	20% 12% 27% 28% 12% 1	330
January	1st to 10th	Night	15% 10% 37% 32% 6% 1	800
	11th to 20th	Night	14% 10% 31% 34% 11% 1	800
	21st to end	Night	20% 10% 36% 29% 5%	880
February	1st to 10th	Night	17% 10% 29% 37% 8%	800
	11th to 20th	Night	19% 10% 32% 33% 6%	783
	21st to end	Night	16% 9% 36% 35% 4	660
March	1st to 10th	Night	16% 9% 30% 37% 9%	800
	11th to 20th	Night	13% 8% 34% 32% 11% 1	800
	21st to end	Night	12% 10% 31% 36% 11% 1	880
April	1st to 10th	Night	14% 7% 29% 36% 15%	800
	11th to 20th	Night	11% 7% 28% 38% 16% 1	621
	21st to end	Night	7% 3 26% 40% 24% 1	600
May	1st to 10th	Night	9% 5% 23% 40% 22% 2	600
	11th to 20th	Night	9% 2 21% 37% 27% 4	563
	21st to end	Night	8% 1 11% 40% 35% 6%	617
June	1st to 10th	Night	8% 2 9% 37% 37% 6%	570
	11th to 20th	Night	6% 1 8% 31% 41% 12%	570
	21st to end	Night	7% 2 5% 31% 45% 10%	570
July	1st to 10th	Night	10% 2 4 23% 45% 16%	555
	11th to 20th	Night	7% 1 3 19% 48% 21%	552
	21st to end	Night	6% 4 25% 49% 16%	624
August	1st to 10th	Night	9% 2 6% 23% 45% 16%	567
	11th to 20th	Night	9% 2 3 18% 55% 13%	564
	21st to end	Night	11% 2 6% 26% 40% 15%	637
September	1st to 10th	Night	12% 3 7% 27% 41% 11%	760
	11th to 20th	Night	14% 4 9% 33% 35% 5%	760
	21st to end	Night	10% 2 13% 32% 37% 5%	760
October	1st to 10th	Night	13% 2 17% 38% 27% 4	760
	11th to 20th	Night	12% 4 20% 34% 27% 3	760
	21st to end	Night	11% 3 21% 38% 25% 2	836
November	1st to 10th	Night	12% 5% 21% 38% 22% 2	780
	11th to 20th	Night	14% 7% 29% 34% 16% 1	800
	21st to end	Night	14% 7% 29% 33% 18% 1	800
December	1st to 10th	Night	15% 6% 30% 35% 12% 2	800
	11th to 20th	Night	17% 6% 31% 32% 13% 2	800
	21st to end	Night	21% 8% 26% 34% 11%	880

Page generated at 2025-05-08 09:33:57. Version ac07

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