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 2025-09-04.

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% 8% 3 8% 5% 5% 5% 4 6% 7% 33%	126156
	Night	17% 10% 3 8% 5% 5% 5% 4 5% 6% 32%	122541
Transparency	Day	47% 8% 13% 20% 11% 1	129645
	Night	49% 8% 13% 18% 11% 1	127139
Seeing	Day	21% 17% 29% 21% 9% 3	15884
	Night	21% 15% 31% 25% 7% 1	24887

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	12% 10% 6% 18% 6% 5% 4 4 5% 5% 25%	3597
	11th to 20th	Day	14% 12% 4 11% 6% 5% 4 4 5% 7% 27%	3570
	21st to end	Day	16% 9% 4 8% 6% 5% 5% 3 5% 7% 32%	4098
February	1st to 10th	Day	16% 11% 3 8% 6% 6% 5% 5% 7% 8% 25%	1800
	11th to 20th	Day	12% 13% 4 11% 6% 5% 6% 4 5% 6% 28%	1924
	21st to end	Day	17% 11% 4 9% 6% 5% 4 4 5% 6% 29%	1650
March	1st to 10th	Day	21% 12% 5% 9% 5% 4 4 4 4 5% 29%	4476
	11th to 20th	Day	15% 12% 3 7% 5% 4 4 3 4 6% 38%	4704
	21st to end	Day	19% 9% 2 8% 5% 5% 5% 3 4 5% 33%	5965
April	1st to 10th	Day	18% 10% 4 8% 5% 4 4 4 5% 5% 33%	2400
	11th to 20th	Day	16% 8% 3 7% 5% 4 5% 4 5% 6% 36%	2374
	21st to end	Day	19% 8% 2 7% 4 5% 5% 3 6% 7% 34%	2490
May	1st to 10th	Day	28% 9% 3 8% 4 4 5% 3 5% 6% 25%	5978
	11th to 20th	Day	16% 8% 3 9% 5% 5% 5% 4 6% 7% 32%	6318
	21st to end	Day	18% 7% 3 7% 5% 5% 5% 4 6% 8% 32%	6949
June	1st to 10th	Day	15% 6% 2 8% 6% 6% 5% 5% 7% 8% 33%	2800
	11th to 20th	Day	15% 6% 3 6% 4 5% 5% 6% 7% 9% 34%	2800
	21st to end	Day	15% 7% 3 7% 5% 5% 5% 5% 6% 8% 36%	2800
July	1st to 10th	Day	9% 6% 2 8% 6% 6% 6% 5% 7% 10% 35%	6360
	11th to 20th	Day	8% 6% 2 7% 6% 6% 6% 5% 8% 10% 36%	6360
	21st to end	Day	12% 5% 2 6% 5% 4 5% 4 6% 9% 41%	6926
August	1st to 10th	Day	15% 6% 3 8% 6% 5% 6% 4 6% 8% 33%	4525
	11th to 20th	Day	12% 7% 2 8% 5% 6% 6% 4 8% 9% 34%	3850
	21st to end	Day	10% 5% 2 7% 4 5% 5% 5% 7% 10% 39%	4312
September	1st to 10th	Day	12% 5% 2 6% 4 4 5% 4 6% 8% 44%	2316
	11th to 20th	Day	12% 6% 2 5% 4 4 4 3 5% 8% 48%	2191
	21st to end	Day	16% 5% 2 6% 4 4 6% 4 6% 7% 41%	2090
October	1st to 10th	Day	18% 8% 3 8% 5% 5% 4 3 4 5% 35%	1986
	11th to 20th	Day	16% 7% 2 8% 4 4 4 4 6% 6% 40%	1900
	21st to end	Day	24% 8% 3 7% 5% 4 4 4 5% 6% 31%	1890
November	1st to 10th	Day	13% 8% 3 6% 4 4 4 4 6% 7% 42%	1761
	11th to 20th	Day	15% 8% 3 8% 5% 5% 5% 3 6% 6% 37%	1800
	21st to end	Day	18% 10% 3 6% 4 6% 5% 4 6% 6% 32%	1650
December	1st to 10th	Day	16% 13% 4 10% 6% 6% 5% 4 5% 6% 24%	2600
	11th to 20th	Day	21% 11% 3 7% 5% 5% 4 3 5% 5% 31%	2986
	21st to end	Day	21% 15% 4 8% 5% 4 4 3 5% 6% 25%	3960
January	1st to 10th	Night	15% 12% 6% 16% 5% 5% 4 3 4 5% 25%	6349
	11th to 20th	Night	11% 14% 4 15% 7% 5% 5% 4 5% 6% 25%	6315
	21st to end	Night	16% 9% 4 9% 6% 5% 5% 4 5% 6% 30%	6840
February	1st to 10th	Night	16% 12% 5% 9% 7% 5% 4 4 5% 6% 27%	2600
	11th to 20th	Night	12% 12% 4 11% 7% 6% 5% 4 6% 6% 28%	2360
	21st to end	Night	16% 11% 4 10% 6% 5% 5% 4 5% 6% 28%	1980
March	1st to 10th	Night	20% 10% 4 9% 6% 5% 5% 4 5% 6% 27%	5364
	11th to 20th	Night	17% 11% 3 7% 5% 4 4 3 4 6% 35%	5239
	21st to end	Night	21% 10% 3 9% 5% 4 4 4 4 5% 30%	4967
April	1st to 10th	Night	19% 11% 3 8% 5% 4 5% 3 5% 6% 31%	2000
	11th to 20th	Night	20% 9% 2 7% 5% 4 4 3 5% 5% 35%	1975
	21st to end	Night	19% 7% 3 7% 4 4 4 3 6% 6% 38%	1909
May	1st to 10th	Night	29% 9% 3 8% 5% 4 4 3 5% 5% 25%	3990
	11th to 20th	Night	15% 10% 4 10% 6% 6% 5% 4 6% 7% 28%	3575
	21st to end	Night	20% 9% 3 9% 5% 4 4 4 5% 7% 31%	3926
June	1st to 10th	Night	17% 6% 2 5% 6% 5% 4 4 5% 7% 39%	1600
	11th to 20th	Night	14% 6% 2 6% 4 4 5% 5% 7% 9% 38%	1600
	21st to end	Night	13% 4 2 6% 4 5% 5% 4 6% 9% 42%	1600
July	1st to 10th	Night	8% 7% 3 8% 6% 5% 5% 5% 6% 8% 40%	3600
	11th to 20th	Night	11% 7% 3 8% 6% 5% 6% 5% 7% 8% 35%	3600
	21st to end	Night	10% 7% 3 7% 5% 4 4 3 5% 8% 46%	3926
August	1st to 10th	Night	19% 7% 3 7% 5% 4 4 4 5% 8% 33%	2601
	11th to 20th	Night	14% 8% 3 7% 5% 5% 5% 4 6% 7% 37%	3184
	21st to end	Night	11% 6% 2 6% 4 4 4 4 6% 8% 43%	3586
September	1st to 10th	Night	14% 8% 3 7% 4 3 3 4 6% 7% 42%	1931
	11th to 20th	Night	14% 5% 2 4 3 3 3 2 5% 8% 51%	1988
	21st to end	Night	15% 6% 2 6% 5% 5% 4 4 5% 7% 41%	2090
October	1st to 10th	Night	18% 8% 3 7% 5% 5% 4 4 5% 5% 36%	2190
	11th to 20th	Night	16% 6% 2 7% 4 5% 4 4 5% 6% 40%	2280
	21st to end	Night	23% 8% 2 7% 5% 4 4 3 5% 7% 31%	2707
November	1st to 10th	Night	15% 8% 2 7% 4 3 4 3 4 7% 42%	2537
	11th to 20th	Night	16% 9% 3 7% 4 5% 5% 4 5% 6% 37%	2600
	21st to end	Night	16% 9% 3 7% 6% 5% 4 4 6% 7% 34%	2748
December	1st to 10th	Night	17% 12% 6% 10% 6% 5% 5% 4 5% 7% 24%	4580
	11th to 20th	Night	25% 11% 4 6% 4 4 4 3 5% 5% 29%	5208
	21st to end	Night	24% 14% 4 7% 4 4 4 3 4 5% 25%	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	58% 9% 11% 18% 4	3598
	11th to 20th	Day	54% 8% 11% 15% 10% 2	3600
	21st to end	Day	51% 8% 9% 20% 11% 1	4098
February	1st to 10th	Day	55% 10% 13% 15% 7% 1	1800
	11th to 20th	Day	54% 8% 12% 17% 8% 1	1933
	21st to end	Day	54% 8% 11% 16% 10% 1	1650
March	1st to 10th	Day	56% 6% 11% 14% 9% 4	4479
	11th to 20th	Day	43% 10% 18% 19% 7% 3	4704
	21st to end	Day	51% 7% 8% 13% 18% 2	5965
April	1st to 10th	Day	52% 7% 8% 20% 11% 2	2400
	11th to 20th	Day	47% 8% 10% 19% 14% 2	2374
	21st to end	Day	49% 8% 10% 17% 13% 3	2490
May	1st to 10th	Day	59% 8% 10% 14% 7% 1	5989
	11th to 20th	Day	49% 8% 15% 19% 9% 1	6322
	21st to end	Day	47% 9% 13% 21% 10% 1	6949
June	1st to 10th	Day	45% 11% 14% 19% 10% 1	2800
	11th to 20th	Day	44% 10% 16% 19% 12% 1	2800
	21st to end	Day	45% 9% 15% 20% 10% 1	2800
July	1st to 10th	Day	43% 8% 13% 22% 12% 1	6290
	11th to 20th	Day	41% 8% 17% 22% 12%	6285
	21st to end	Day	39% 6% 14% 27% 13%	6728
August	1st to 10th	Day	47% 9% 15% 19% 9% 1	4511
	11th to 20th	Day	43% 8% 17% 25% 6% 1	3886
	21st to end	Day	36% 9% 16% 28% 10% 1	4312
September	1st to 10th	Day	37% 9% 14% 26% 14% 1	2316
	11th to 20th	Day	34% 8% 13% 24% 20% 1	2191
	21st to end	Day	39% 9% 13% 24% 13% 2	2090
October	1st to 10th	Day	45% 7% 8% 22% 17% 1	3298
	11th to 20th	Day	37% 7% 13% 27% 16%	3140
	21st to end	Day	38% 7% 15% 26% 13% 1	3090
November	1st to 10th	Day	40% 8% 15% 25% 11% 1	1761
	11th to 20th	Day	46% 9% 11% 19% 14% 2	1800
	21st to end	Day	50% 9% 15% 18% 6% 1	1650
December	1st to 10th	Day	60% 6% 13% 17% 3	2600
	11th to 20th	Day	53% 6% 13% 17% 10% 1	2986
	21st to end	Day	58% 8% 8% 16% 9% 1	3960
January	1st to 10th	Night	58% 9% 11% 14% 7% 1	6349
	11th to 20th	Night	57% 8% 13% 13% 8% 1	6360
	21st to end	Night	52% 7% 12% 13% 12% 4	6840
February	1st to 10th	Night	56% 8% 13% 15% 7% 1	2600
	11th to 20th	Night	54% 7% 14% 15% 8% 1	2362
	21st to end	Night	52% 9% 13% 16% 8% 2	1980
March	1st to 10th	Night	54% 8% 12% 14% 11% 2	5374
	11th to 20th	Night	48% 8% 18% 17% 7% 2	5240
	21st to end	Night	54% 7% 7% 15% 15% 2	4967
April	1st to 10th	Night	53% 7% 12% 17% 10% 1	2000
	11th to 20th	Night	49% 8% 10% 18% 14% 1	1975
	21st to end	Night	46% 8% 11% 17% 14% 3	1909
May	1st to 10th	Night	60% 7% 12% 11% 9% 1	3996
	11th to 20th	Night	53% 9% 13% 17% 8% 1	3576
	21st to end	Night	50% 9% 12% 17% 10% 1	3927
June	1st to 10th	Night	43% 7% 14% 22% 12% 1	1600
	11th to 20th	Night	40% 11% 16% 22% 11% 1	1600
	21st to end	Night	38% 9% 16% 23% 13% 1	1600
July	1st to 10th	Night	42% 6% 16% 21% 15% 1	3560
	11th to 20th	Night	44% 9% 14% 20% 13%	3552
	21st to end	Night	36% 6% 14% 30% 13% 1	3809
August	1st to 10th	Night	48% 8% 15% 20% 8% 1	2591
	11th to 20th	Night	43% 8% 18% 22% 9%	3214
	21st to end	Night	36% 8% 15% 31% 10% 1	3586
September	1st to 10th	Night	40% 7% 13% 26% 14% 1	1931
	11th to 20th	Night	31% 7% 13% 27% 21% 1	1988
	21st to end	Night	40% 9% 12% 22% 16% 1	2090
October	1st to 10th	Night	49% 6% 12% 21% 11% 1	3658
	11th to 20th	Night	35% 7% 13% 26% 19% 1	3779
	21st to end	Night	41% 7% 14% 28% 10% 1	4457
November	1st to 10th	Night	42% 8% 12% 20% 16% 2	2537
	11th to 20th	Night	47% 8% 13% 19% 12% 2	2600
	21st to end	Night	48% 8% 17% 19% 7%	2748
December	1st to 10th	Night	59% 7% 14% 17% 3	4580
	11th to 20th	Night	55% 8% 12% 13% 12% 1	5208
	21st to end	Night	59% 9% 9% 13% 9% 1	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	26% 30% 28% 12% 4 1	200
	11th to 20th	Day	34% 26% 25% 14% 2 1	200
	21st to end	Day	25% 24% 32% 14% 4 1	250
February	1st to 10th	Day	31% 29% 31% 8% 1	300
	11th to 20th	Day	31% 28% 30% 10% 1	472
	21st to end	Day	28% 23% 33% 14% 2	414
March	1st to 10th	Day	28% 22% 32% 15% 3	500
	11th to 20th	Day	28% 25% 29% 15% 3 1	500
	21st to end	Day	32% 24% 24% 13% 5% 1	550
April	1st to 10th	Day	31% 26% 22% 15% 5% 1	500
	11th to 20th	Day	28% 25% 26% 14% 5% 1	492
	21st to end	Day	26% 20% 31% 16% 5% 2	500
May	1st to 10th	Day	29% 17% 30% 15% 7% 2	503
	11th to 20th	Day	20% 16% 34% 21% 7% 2	527
	21st to end	Day	18% 12% 32% 26% 10% 3	573
June	1st to 10th	Day	17% 14% 34% 22% 12% 1	530
	11th to 20th	Day	17% 13% 31% 26% 12% 2	530
	21st to end	Day	17% 12% 32% 25% 11% 2	530
July	1st to 10th	Day	12% 10% 30% 30% 14% 4	525
	11th to 20th	Day	11% 7% 32% 30% 17% 2	524
	21st to end	Day	12% 7% 33% 30% 16% 2	576
August	1st to 10th	Day	12% 6% 27% 32% 18% 6%	526
	11th to 20th	Day	14% 5% 28% 30% 17% 7%	519
	21st to end	Day	10% 11% 31% 26% 17% 5%	583
September	1st to 10th	Day	16% 11% 23% 25% 18% 7%	502
	11th to 20th	Day	13% 11% 24% 22% 16% 13%	490
	21st to end	Day	18% 11% 26% 26% 15% 5%	490
October	1st to 10th	Day	22% 14% 26% 21% 12% 4	490
	11th to 20th	Day	19% 17% 30% 23% 10% 2	490
	21st to end	Day	28% 16% 27% 22% 5% 1	433
November	1st to 10th	Day	23% 19% 25% 20% 11% 2	395
	11th to 20th	Day	23% 24% 30% 17% 6% 1	400
	21st to end	Day	30% 22% 26% 19% 2	250
December	1st to 10th	Day	23% 27% 31% 13% 5% 1	200
	11th to 20th	Day	28% 26% 32% 12% 3	200
	21st to end	Day	24% 24% 35% 14% 3	220
January	1st to 10th	Night	22% 20% 38% 17% 2	800
	11th to 20th	Night	26% 22% 31% 19% 2	800
	21st to end	Night	20% 21% 39% 19% 2	880
February	1st to 10th	Night	24% 19% 38% 17% 1	800
	11th to 20th	Night	22% 24% 37% 17% 1	783
	21st to end	Night	26% 22% 33% 17% 3	660
March	1st to 10th	Night	24% 23% 35% 16% 2	800
	11th to 20th	Night	25% 23% 34% 18% 2	800
	21st to end	Night	25% 21% 32% 18% 4	880
April	1st to 10th	Night	26% 21% 31% 20% 2	800
	11th to 20th	Night	26% 19% 32% 18% 5%	791
	21st to end	Night	22% 20% 31% 22% 4	709
May	1st to 10th	Night	24% 18% 30% 22% 6%	575
	11th to 20th	Night	19% 14% 35% 27% 5% 1	394
	21st to end	Night	13% 10% 32% 36% 8%	433
June	1st to 10th	Night	19% 7% 32% 32% 10% 1	400
	11th to 20th	Night	15% 9% 31% 36% 10%	400
	21st to end	Night	13% 6% 30% 41% 11% 1	400
July	1st to 10th	Night	13% 5% 24% 44% 14% 1	390
	11th to 20th	Night	12% 6% 22% 43% 16% 1	388
	21st to end	Night	11% 4 24% 50% 10% 1	438
August	1st to 10th	Night	14% 2 22% 47% 15% 1	400
	11th to 20th	Night	13% 6% 23% 36% 19% 3	777
	21st to end	Night	15% 6% 25% 35% 18% 1	880
September	1st to 10th	Night	18% 5% 28% 32% 15% 2	773
	11th to 20th	Night	17% 7% 25% 28% 19% 4	760
	21st to end	Night	16% 7% 30% 32% 13% 2	760
October	1st to 10th	Night	22% 11% 25% 28% 13% 2	760
	11th to 20th	Night	18% 12% 32% 30% 8%	760
	21st to end	Night	28% 15% 31% 22% 4	836
November	1st to 10th	Night	20% 16% 34% 23% 7%	780
	11th to 20th	Night	21% 18% 34% 20% 7% 1	800
	21st to end	Night	22% 19% 32% 22% 5%	800
December	1st to 10th	Night	26% 20% 35% 15% 4	800
	11th to 20th	Night	27% 18% 30% 23% 2	800
	21st to end	Night	29% 19% 32% 17% 3	880

Page generated at 2025-09-01 01:51:02. Version ac07

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