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 2025-05-26.

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	18% 8% 3 8% 5% 4 4 3 5% 6% 37%	118272
	Night	20% 9% 3 8% 5% 4 4 3 5% 5% 34%	119825
Transparency	Day	47% 8% 12% 17% 12% 4	118017
	Night	49% 8% 12% 17% 10% 3	119669
Seeing	Day	17% 9% 20% 27% 21% 6%	15354
	Night	20% 6% 18% 33% 21% 2	24415

By Month

Percentage Cloud Cover SW (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	37% 15% 5% 13% 6% 5% 4 3 3 3 7%	3639
	11th to 20th	Day	29% 10% 3 11% 8% 5% 5% 3 4 4 18%	3655
	21st to end	Day	24% 9% 3 9% 5% 5% 5% 3 5% 5% 26%	4510
February	1st to 10th	Day	27% 14% 5% 10% 7% 5% 6% 4 5% 5% 14%	1800
	11th to 20th	Day	27% 13% 4 9% 7% 5% 4 3 4 5% 18%	1755
	21st to end	Day	28% 15% 4 11% 5% 5% 4 3 3 4 18%	1560
March	1st to 10th	Day	19% 11% 4 11% 8% 6% 6% 5% 6% 6% 18%	4798
	11th to 20th	Day	26% 11% 4 9% 5% 5% 4 3 4 5% 25%	5000
	21st to end	Day	23% 12% 4 11% 7% 7% 6% 5% 5% 6% 15%	5563
April	1st to 10th	Day	25% 12% 4 9% 7% 5% 5% 3 5% 6% 18%	2400
	11th to 20th	Day	22% 10% 3 7% 5% 4 5% 3 5% 6% 28%	2369
	21st to end	Day	20% 9% 3 8% 6% 5% 5% 4 6% 7% 29%	2594
May	1st to 10th	Day	19% 7% 3 8% 5% 4 5% 4 5% 6% 35%	4418
	11th to 20th	Day	11% 5% 1 5% 4 3 3 3 5% 6% 53%	4517
	21st to end	Day	15% 7% 2 7% 6% 6% 6% 6% 7% 8% 31%	4886
June	1st to 10th	Day	19% 8% 3 7% 4 4 4 3 5% 6% 36%	2660
	11th to 20th	Day	16% 7% 3 7% 6% 4 4 5% 6% 7% 34%	2660
	21st to end	Day	9% 4 2 5% 3 3 4 3 4 6% 57%	2660
July	1st to 10th	Day	3 2 1 2 2 2 2 2 3 3 79%	4420
	11th to 20th	Day	4 2 1 2 2 2 2 2 2 3 78%	4420
	21st to end	Day	4 2 1 2 2 1 2 2 3 4 78%	4731
August	1st to 10th	Day	2 3 1 3 2 3 3 2 4 6% 72%	4091
	11th to 20th	Day	5% 3 1 5% 3 3 4 4 4 8% 60%	4026
	21st to end	Day	6% 6% 2 4 3 3 3 3 4 6% 59%	4306
September	1st to 10th	Day	6% 3 1 3 2 2 3 2 3 6% 67%	2280
	11th to 20th	Day	11% 7% 2 6% 5% 3 4 4 5% 7% 45%	2260
	21st to end	Day	15% 6% 3 6% 4 4 3 3 4 5% 48%	2009
October	1st to 10th	Day	13% 6% 3 7% 4 4 4 2 4 6% 48%	3180
	11th to 20th	Day	16% 7% 3 9% 6% 6% 6% 4 5% 8% 29%	3161
	21st to end	Day	22% 10% 4 10% 6% 5% 5% 4 5% 7% 22%	3430
November	1st to 10th	Day	29% 12% 5% 10% 6% 5% 5% 3 4 4 16%	1662
	11th to 20th	Day	30% 12% 5% 9% 5% 5% 4 4 5% 5% 16%	1600
	21st to end	Day	27% 11% 4 12% 7% 6% 4 3 5% 5% 18%	1600
December	1st to 10th	Day	21% 7% 4 13% 8% 4 4 4 5% 6% 24%	2620
	11th to 20th	Day	29% 14% 6% 14% 7% 6% 4 4 5% 4 7%	3028
	21st to end	Day	34% 15% 6% 16% 7% 5% 3 2 3 3 5%	4004
January	1st to 10th	Night	35% 15% 5% 10% 6% 5% 4 3 4 4 9%	6306
	11th to 20th	Night	28% 11% 3 10% 7% 5% 5% 3 4 4 20%	6303
	21st to end	Night	27% 10% 3 8% 3 4 4 2 5% 5% 29%	6468
February	1st to 10th	Night	27% 13% 4 10% 7% 5% 4 4 5% 5% 16%	2600
	11th to 20th	Night	28% 11% 4 8% 5% 5% 4 3 4 5% 24%	2532
	21st to end	Night	29% 11% 3 8% 5% 4 4 4 4 6% 22%	2070
March	1st to 10th	Night	18% 12% 4 10% 6% 7% 7% 5% 7% 6% 19%	5079
	11th to 20th	Night	23% 12% 3 9% 5% 5% 4 3 5% 5% 27%	5000
	21st to end	Night	23% 12% 4 12% 7% 6% 5% 4 5% 6% 16%	5412
April	1st to 10th	Night	27% 11% 4 8% 6% 4 4 3 5% 5% 24%	2000
	11th to 20th	Night	20% 9% 3 6% 4 4 4 3 5% 6% 35%	1979
	21st to end	Night	20% 8% 2 7% 5% 5% 4 3 5% 8% 33%	1803
May	1st to 10th	Night	22% 7% 3 7% 4 3 3 3 4 5% 38%	2763
	11th to 20th	Night	9% 5% 3 5% 4 3 3 2 4 5% 57%	2596
	21st to end	Night	14% 6% 3 5% 4 4 5% 4 7% 9% 39%	2805
June	1st to 10th	Night	17% 7% 2 6% 4 3 4 4 6% 7% 41%	1520
	11th to 20th	Night	12% 6% 2 6% 5% 4 4 3 5% 8% 43%	1520
	21st to end	Night	6% 5% 2 4 3 3 3 3 4 5% 62%	1520
July	1st to 10th	Night	3 2 1 2 2 1 2 1 2 3 82%	2540
	11th to 20th	Night	4 3 1 2 2 1 1 2 2 3 80%	2540
	21st to end	Night	3 2 1 2 1 1 1 1 2 3 81%	2818
August	1st to 10th	Night	2 2 2 1 2 2 2 4 5% 77%	2848
	11th to 20th	Night	5% 3 2 3 3 3 4 3 4 6% 63%	2812
	21st to end	Night	8% 3 2 4 3 2 2 2 3 5% 66%	3366
September	1st to 10th	Night	6% 3 1 3 2 3 3 2 4 5% 69%	1900
	11th to 20th	Night	8% 4 2 5% 3 5% 5% 4 5% 5% 54%	1917
	21st to end	Night	10% 5% 2 5% 4 4 3 3 5% 7% 53%	2171
October	1st to 10th	Night	11% 5% 2 6% 4 5% 4 3 4 6% 50%	3800
	11th to 20th	Night	13% 6% 2 6% 5% 6% 5% 5% 6% 8% 37%	3777
	21st to end	Night	21% 9% 4 9% 6% 6% 5% 4 5% 5% 27%	4137
November	1st to 10th	Night	26% 10% 3 8% 5% 5% 5% 4 5% 6% 23%	2635
	11th to 20th	Night	32% 9% 3 8% 5% 4 5% 3 4 5% 21%	2800
	21st to end	Night	23% 9% 3 10% 6% 5% 4 4 5% 5% 26%	2800
December	1st to 10th	Night	19% 7% 3 9% 6% 5% 6% 5% 6% 7% 27%	4560
	11th to 20th	Night	33% 12% 5% 13% 6% 6% 4 3 4 3 10%	5176
	21st to end	Night	31% 12% 6% 14% 7% 6% 5% 3 4 4 9%	6952

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	78% 9% 6% 5% 2	3639
	11th to 20th	Day	68% 7% 7% 12% 6% 1	3655
	21st to end	Day	56% 9% 7% 10% 15% 3	4510
February	1st to 10th	Day	70% 9% 9% 8% 4	1800
	11th to 20th	Day	68% 8% 9% 9% 4 2	1764
	21st to end	Day	70% 7% 8% 9% 5% 2	1560
March	1st to 10th	Day	58% 11% 12% 14% 4	4798
	11th to 20th	Day	58% 8% 9% 17% 7%	5000
	21st to end	Day	66% 11% 13% 7% 3	5563
April	1st to 10th	Day	65% 9% 12% 11% 4	2400
	11th to 20th	Day	56% 9% 11% 14% 8% 2	2372
	21st to end	Day	54% 10% 14% 14% 7% 1	2594
May	1st to 10th	Day	46% 10% 13% 18% 12%	4418
	11th to 20th	Day	30% 7% 18% 31% 12% 1	4520
	21st to end	Day	45% 15% 23% 16% 2	4887
June	1st to 10th	Day	49% 6% 18% 20% 6% 1	2660
	11th to 20th	Day	46% 9% 21% 18% 6%	2660
	21st to end	Day	28% 6% 18% 30% 13% 4	2660
July	1st to 10th	Day	12% 4 9% 18% 25% 32%	4351
	11th to 20th	Day	14% 3 6% 18% 37% 23%	4345
	21st to end	Day	12% 3 10% 28% 38% 9%	4581
August	1st to 10th	Day	15% 4 10% 30% 28% 11%	4076
	11th to 20th	Day	22% 7% 18% 33% 17% 3	4065
	21st to end	Day	24% 7% 13% 24% 25% 6%	4305
September	1st to 10th	Day	19% 4 13% 31% 21% 12%	2280
	11th to 20th	Day	37% 9% 13% 21% 15% 7%	2260
	21st to end	Day	38% 7% 14% 20% 16% 6%	2009
October	1st to 10th	Day	37% 6% 8% 22% 23% 4	3180
	11th to 20th	Day	50% 10% 15% 15% 10% 1	3161
	21st to end	Day	58% 8% 9% 15% 9% 1	3430
November	1st to 10th	Day	69% 8% 10% 9% 4	1662
	11th to 20th	Day	69% 8% 10% 7% 6% 2	1600
	21st to end	Day	67% 7% 8% 7% 11% 1	1600
December	1st to 10th	Day	58% 8% 10% 11% 12% 1	2620
	11th to 20th	Day	77% 9% 7% 6% 1	3028
	21st to end	Day	81% 9% 5% 3 1	4004
January	1st to 10th	Night	76% 8% 8% 4 3 1	6306
	11th to 20th	Night	64% 8% 7% 13% 6% 1	6303
	21st to end	Night	56% 6% 7% 12% 15% 4	6468
February	1st to 10th	Night	66% 10% 10% 10% 4 1	2600
	11th to 20th	Night	60% 8% 13% 10% 6% 2	2534
	21st to end	Night	61% 8% 12% 12% 6% 2	2070
March	1st to 10th	Night	57% 11% 14% 13% 5%	5079
	11th to 20th	Night	54% 9% 11% 18% 7% 1	5000
	21st to end	Night	65% 11% 14% 9% 1	5412
April	1st to 10th	Night	62% 7% 14% 12% 5%	2000
	11th to 20th	Night	49% 9% 17% 15% 7% 3	1979
	21st to end	Night	50% 8% 17% 18% 6% 2	1803
May	1st to 10th	Night	45% 8% 15% 21% 10% 1	2763
	11th to 20th	Night	28% 6% 18% 34% 12% 2	2596
	21st to end	Night	36% 15% 32% 14% 3	2805
June	1st to 10th	Night	41% 9% 18% 26% 5% 1	1520
	11th to 20th	Night	38% 7% 23% 24% 8%	1520
	21st to end	Night	24% 5% 20% 34% 14% 4	1520
July	1st to 10th	Night	10% 3 9% 20% 25% 33%	2500
	11th to 20th	Night	13% 3 7% 19% 31% 28%	2492
	21st to end	Night	10% 3 11% 30% 38% 9%	2730
August	1st to 10th	Night	10% 3 10% 38% 28% 10%	2839
	11th to 20th	Night	20% 6% 21% 36% 14% 4	2839
	21st to end	Night	22% 5% 12% 30% 25% 6%	3366
September	1st to 10th	Night	18% 5% 12% 31% 23% 11%	1900
	11th to 20th	Night	30% 7% 14% 26% 14% 9%	1917
	21st to end	Night	31% 6% 16% 23% 16% 8%	2171
October	1st to 10th	Night	32% 7% 9% 27% 23% 3	3800
	11th to 20th	Night	41% 10% 20% 18% 9% 2	3777
	21st to end	Night	55% 9% 13% 12% 9% 1	4137
November	1st to 10th	Night	58% 10% 11% 15% 6%	2635
	11th to 20th	Night	65% 8% 10% 9% 7% 2	2800
	21st to end	Night	57% 9% 10% 11% 11% 2	2800
December	1st to 10th	Night	52% 8% 12% 17% 11% 1	4560
	11th to 20th	Night	75% 9% 7% 7% 3	5176
	21st to end	Night	73% 12% 8% 5% 1	6952

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	41% 14% 18% 14% 12% 2	200
	11th to 20th	Day	29% 12% 15% 26% 12% 5%	202
	21st to end	Day	29% 12% 18% 19% 15% 6%	440
February	1st to 10th	Day	29% 10% 22% 21% 14% 5%	400
	11th to 20th	Day	30% 11% 24% 22% 9% 4	395
	21st to end	Day	24% 17% 23% 20% 12% 3	369
March	1st to 10th	Day	27% 13% 24% 24% 10% 1	500
	11th to 20th	Day	27% 11% 21% 23% 15% 3	500
	21st to end	Day	25% 15% 24% 23% 10% 2	550
April	1st to 10th	Day	27% 14% 20% 21% 14% 4	500
	11th to 20th	Day	22% 14% 23% 23% 12% 5%	492
	21st to end	Day	19% 12% 24% 25% 17% 3	500
May	1st to 10th	Day	14% 12% 24% 28% 17% 5%	503
	11th to 20th	Day	22% 9% 19% 24% 19% 7%	528
	21st to end	Day	13% 8% 21% 26% 22% 10%	550
June	1st to 10th	Day	18% 8% 18% 28% 23% 4	490
	11th to 20th	Day	14% 9% 24% 33% 18% 2	490
	21st to end	Day	5% 4 16% 38% 30% 8%	490
July	1st to 10th	Day	6% 2 16% 37% 30% 9%	486
	11th to 20th	Day	2 2 20% 36% 31% 9%	484
	21st to end	Day	3 2 12% 38% 34% 11%	531
August	1st to 10th	Day	2 1 13% 32% 39% 13%	487
	11th to 20th	Day	3 2 9% 36% 36% 15%	477
	21st to end	Day	4 3 18% 35% 31% 9%	539
September	1st to 10th	Day	6% 3 19% 32% 31% 9%	490
	11th to 20th	Day	11% 4 17% 30% 28% 9%	490
	21st to end	Day	14% 6% 19% 31% 22% 7%	490
October	1st to 10th	Day	16% 7% 21% 25% 22% 9%	490
	11th to 20th	Day	18% 7% 18% 25% 24% 8%	490
	21st to end	Day	25% 12% 22% 22% 14% 6%	533
November	1st to 10th	Day	25% 12% 26% 20% 12% 5%	248
	11th to 20th	Day	25% 14% 24% 19% 14% 6%	200
	21st to end	Day	28% 12% 19% 18% 18% 6%	200
December	1st to 10th	Day	26% 16% 13% 23% 14% 9%	200
	11th to 20th	Day	37% 7% 23% 22% 10% 3	200
	21st to end	Day	33% 16% 18% 19% 13% 1	220
January	1st to 10th	Night	35% 10% 19% 21% 12% 2	800
	11th to 20th	Night	31% 9% 18% 21% 17% 3	800
	21st to end	Night	28% 5% 16% 31% 16% 4	880
February	1st to 10th	Night	28% 8% 19% 27% 17% 2	800
	11th to 20th	Night	28% 8% 21% 28% 15% 1	784
	21st to end	Night	28% 9% 21% 27% 14%	660
March	1st to 10th	Night	26% 7% 22% 31% 13%	800
	11th to 20th	Night	24% 9% 18% 32% 16% 1	800
	21st to end	Night	27% 9% 22% 28% 13% 1	880
April	1st to 10th	Night	28% 7% 20% 27% 17% 1	800
	11th to 20th	Night	20% 7% 23% 32% 17% 1	791
	21st to end	Night	20% 5% 21% 35% 17% 1	603
May	1st to 10th	Night	12% 6% 24% 37% 19% 1	491
	11th to 20th	Night	16% 3 18% 37% 26% 1	394
	21st to end	Night	15% 5% 19% 37% 23% 1	422
June	1st to 10th	Night	17% 5% 16% 41% 21%	380
	11th to 20th	Night	12% 4 21% 47% 15% 1	380
	21st to end	Night	6% 2 18% 53% 21%	380
July	1st to 10th	Night	5% 1 11% 55% 28% 1	370
	11th to 20th	Night	4 2 22% 49% 23% 1	368
	21st to end	Night	2 2 12% 52% 31% 2	449
August	1st to 10th	Night	3 1 7% 43% 41% 5%	567
	11th to 20th	Night	4 1 5% 41% 46% 2	564
	21st to end	Night	6% 2 15% 43% 32% 2	756
September	1st to 10th	Night	6% 1 14% 44% 33% 1	760
	11th to 20th	Night	9% 3 12% 38% 32% 6%	760
	21st to end	Night	11% 3 15% 40% 29% 3	760
October	1st to 10th	Night	14% 3 21% 33% 27% 3	760
	11th to 20th	Night	17% 5% 14% 35% 26% 4	760
	21st to end	Night	24% 6% 21% 29% 17% 4	836
November	1st to 10th	Night	25% 7% 19% 31% 17% 1	780
	11th to 20th	Night	32% 8% 20% 24% 15% 1	800
	21st to end	Night	23% 8% 19% 30% 19% 3	800
December	1st to 10th	Night	25% 7% 18% 29% 19% 3	800
	11th to 20th	Night	31% 10% 21% 22% 16% 1	800
	21st to end	Night	36% 9% 21% 24% 10% 1	880

Page generated at 2025-05-23 06:20:57. Version ac07

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