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 2026-09-29.

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	15% 7% 3 7% 5% 4 4 3 5% 6% 42%	158678
	Night	18% 8% 3 8% 5% 4 4 3 5% 5% 38%	150147
Transparency	Day	42% 7% 13% 20% 14% 4	153462
	Night	46% 8% 13% 19% 12% 4	146362
Seeing	Day	17% 9% 19% 27% 21% 7%	17125
	Night	20% 6% 18% 33% 21% 2	26011

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	35% 15% 6% 13% 6% 5% 5% 3 4 3 6%	4722
	11th to 20th	Day	22% 8% 3 10% 7% 4 5% 3 5% 5% 28%	4755
	21st to end	Day	22% 9% 4 10% 6% 6% 5% 4 6% 5% 24%	5843
February	1st to 10th	Day	27% 13% 4 10% 7% 5% 5% 4 5% 6% 14%	1890
	11th to 20th	Day	27% 13% 5% 9% 7% 5% 4 3 4 5% 18%	1845
	21st to end	Day	29% 15% 4 11% 5% 4 4 3 4 4 18%	1636
March	1st to 10th	Day	19% 11% 4 11% 8% 6% 6% 5% 6% 6% 18%	4904
	11th to 20th	Day	26% 11% 4 9% 5% 5% 4 3 4 5% 24%	5110
	21st to end	Day	22% 12% 4 11% 7% 7% 6% 5% 5% 6% 15%	5685
April	1st to 10th	Day	24% 12% 4 9% 7% 5% 5% 3 5% 7% 18%	2520
	11th to 20th	Day	22% 11% 4 7% 5% 4 5% 4 5% 6% 28%	2489
	21st to end	Day	20% 9% 2 8% 6% 5% 5% 4 6% 7% 29%	2724
May	1st to 10th	Day	11% 5% 2 6% 4 5% 5% 4 5% 7% 45%	7940
	11th to 20th	Day	10% 6% 2 7% 5% 5% 5% 4 6% 8% 41%	8160
	21st to end	Day	11% 5% 2 6% 5% 5% 5% 5% 7% 8% 42%	8992
June	1st to 10th	Day	18% 8% 3 7% 4 4 4 3 5% 6% 38%	2940
	11th to 20th	Day	15% 6% 3 7% 6% 4 4 5% 6% 7% 37%	2940
	21st to end	Day	9% 4 2 5% 3 4 4 4 5% 6% 55%	2940
July	1st to 10th	Day	2 2 1 2 2 2 2 2 3 4 79%	8219
	11th to 20th	Day	3 2 1 2 2 2 2 2 2 3 79%	8220
	21st to end	Day	3 2 1 2 2 1 2 2 3 4 77%	8811
August	1st to 10th	Day	2 2 1 3 2 2 2 2 3 5% 75%	7547
	11th to 20th	Day	4 3 1 4 3 3 4 3 5% 8% 62%	7563
	21st to end	Day	5% 5% 2 4 3 3 3 3 5% 8% 59%	7976
September	1st to 10th	Day	7% 4 1 4 2 2 3 2 4 7% 64%	2520
	11th to 20th	Day	10% 7% 3 6% 5% 3 4 4 5% 7% 46%	2498
	21st to end	Day	14% 5% 3 6% 4 4 3 3 4 6% 48%	2202
October	1st to 10th	Day	13% 6% 3 7% 4 4 4 2 4 6% 47%	3280
	11th to 20th	Day	16% 7% 3 9% 6% 6% 6% 4 5% 8% 30%	3261
	21st to end	Day	22% 10% 4 10% 6% 5% 5% 4 5% 7% 22%	3539
November	1st to 10th	Day	29% 12% 5% 10% 6% 5% 5% 4 5% 4 16%	1747
	11th to 20th	Day	29% 12% 5% 10% 6% 5% 4 4 5% 5% 15%	1680
	21st to end	Day	27% 10% 4 12% 7% 6% 4 4 5% 5% 17%	1680
December	1st to 10th	Day	22% 7% 4 13% 8% 5% 4 4 5% 6% 23%	2700
	11th to 20th	Day	29% 14% 6% 14% 7% 6% 4 4 5% 4 7%	3108
	21st to end	Day	34% 14% 6% 16% 7% 5% 4 2 3 3 6%	4092
January	1st to 10th	Night	33% 14% 6% 12% 6% 5% 4 3 4 4 9%	8172
	11th to 20th	Night	22% 8% 3 9% 7% 5% 5% 3 4 5% 28%	8203
	21st to end	Night	23% 10% 4 10% 4 4 4 2 5% 5% 28%	8371
February	1st to 10th	Night	26% 12% 4 10% 7% 6% 5% 4 4 5% 17%	2730
	11th to 20th	Night	28% 11% 4 8% 5% 5% 4 3 4 5% 24%	2662
	21st to end	Night	29% 11% 3 8% 5% 5% 4 4 4 6% 22%	2170
March	1st to 10th	Night	18% 12% 4 10% 6% 7% 7% 5% 7% 6% 19%	5193
	11th to 20th	Night	23% 11% 3 9% 5% 5% 4 3 5% 5% 27%	5110
	21st to end	Night	23% 12% 4 12% 7% 6% 5% 4 5% 6% 16%	5531
April	1st to 10th	Night	26% 11% 4 8% 6% 4 4 3 5% 5% 24%	2100
	11th to 20th	Night	20% 9% 3 7% 4 4 4 4 5% 6% 34%	2079
	21st to end	Night	20% 8% 2 6% 5% 4 4 3 5% 8% 34%	1893
May	1st to 10th	Night	15% 5% 2 5% 3 3 3 3 5% 8% 49%	4988
	11th to 20th	Night	12% 6% 3 7% 4 4 4 3 5% 7% 45%	4700
	21st to end	Night	11% 5% 2 6% 4 4 4 3 7% 9% 45%	5181
June	1st to 10th	Night	16% 7% 2 6% 4 3 4 4 5% 7% 43%	1680
	11th to 20th	Night	11% 6% 2 6% 5% 4 4 3 5% 8% 46%	1680
	21st to end	Night	7% 5% 2 4 2 3 3 3 5% 5% 61%	1680
July	1st to 10th	Night	2 2 2 1 2 2 2 4 5% 78%	4740
	11th to 20th	Night	2 2 1 2 2 1 2 2 2 3 81%	4740
	21st to end	Night	3 2 1 2 2 2 2 2 2 4 79%	5266
August	1st to 10th	Night	3 2 1 2 2 2 2 2 4 5% 74%	5275
	11th to 20th	Night	6% 3 2 3 3 3 4 3 4 6% 63%	5292
	21st to end	Night	6% 3 1 4 3 2 3 2 4 6% 67%	6259
September	1st to 10th	Night	7% 4 1 3 2 3 3 3 4 5% 66%	2100
	11th to 20th	Night	8% 4 2 5% 3 5% 4 4 5% 5% 55%	2119
	21st to end	Night	9% 5% 2 5% 4 4 3 3 5% 7% 54%	2375
October	1st to 10th	Night	11% 5% 2 7% 4 5% 4 3 4 6% 50%	3920
	11th to 20th	Night	13% 6% 2 6% 5% 5% 5% 5% 6% 8% 37%	3897
	21st to end	Night	20% 9% 4 9% 6% 6% 5% 4 5% 5% 27%	4269
November	1st to 10th	Night	26% 10% 3 8% 5% 6% 5% 4 5% 6% 22%	2770
	11th to 20th	Night	32% 10% 4 8% 5% 4 5% 3 4 5% 20%	2940
	21st to end	Night	23% 9% 3 11% 6% 5% 5% 4 5% 5% 25%	2940
December	1st to 10th	Night	19% 7% 3 10% 6% 5% 6% 5% 6% 7% 26%	4700
	11th to 20th	Night	33% 12% 5% 13% 6% 6% 4 3 4 3 10%	5316
	21st to end	Night	31% 12% 6% 13% 7% 6% 5% 3 4 4 9%	7106

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	79% 9% 6% 4 1	4723
	11th to 20th	Day	56% 6% 8% 12% 13% 6%	4755
	21st to end	Day	58% 8% 7% 11% 14% 2	5843
February	1st to 10th	Day	69% 9% 9% 9% 4	1890
	11th to 20th	Day	68% 8% 9% 9% 4 2	1854
	21st to end	Day	70% 7% 7% 9% 6% 2	1636
March	1st to 10th	Day	59% 11% 12% 14% 4	4904
	11th to 20th	Day	58% 8% 9% 17% 7%	5110
	21st to end	Day	66% 11% 13% 7% 3	5685
April	1st to 10th	Day	64% 9% 12% 12% 3	2520
	11th to 20th	Day	56% 9% 11% 14% 8% 2	2492
	21st to end	Day	53% 10% 14% 14% 7% 1	2724
May	1st to 10th	Day	35% 8% 13% 29% 14%	7940
	11th to 20th	Day	36% 10% 21% 26% 7% 1	8163
	21st to end	Day	36% 11% 25% 23% 6%	8994
June	1st to 10th	Day	47% 6% 18% 21% 8% 1	2940
	11th to 20th	Day	44% 8% 19% 20% 8% 1	2940
	21st to end	Day	30% 7% 17% 30% 13% 4	2940
July	1st to 10th	Day	10% 4 12% 34% 22% 18%	8151
	11th to 20th	Day	13% 2 6% 16% 41% 21%	8145
	21st to end	Day	12% 3 14% 37% 28% 5%	8613
August	1st to 10th	Day	12% 3 8% 25% 34% 17%	5976
	11th to 20th	Day	19% 6% 18% 36% 17% 3	5962
	21st to end	Day	22% 6% 15% 32% 21% 5%	6255
September	1st to 10th	Day	21% 4 14% 29% 20% 11%	2520
	11th to 20th	Day	36% 9% 12% 23% 15% 6%	2498
	21st to end	Day	37% 7% 14% 20% 16% 5%	2202
October	1st to 10th	Day	38% 6% 8% 21% 23% 4	3280
	11th to 20th	Day	50% 10% 15% 15% 10% 1	3261
	21st to end	Day	58% 8% 9% 15% 8% 1	3539
November	1st to 10th	Day	69% 8% 10% 9% 3	1747
	11th to 20th	Day	69% 8% 9% 7% 5% 1	1680
	21st to end	Day	67% 7% 8% 7% 10% 1	1680
December	1st to 10th	Day	59% 8% 10% 11% 12% 1	2700
	11th to 20th	Day	76% 10% 7% 6% 1	3108
	21st to end	Day	80% 9% 6% 4 1	4092
January	1st to 10th	Night	77% 8% 8% 5% 2 1	8172
	11th to 20th	Night	55% 7% 8% 12% 13% 5%	8203
	21st to end	Night	57% 6% 7% 12% 15% 3	8371
February	1st to 10th	Night	66% 9% 10% 10% 4 1	2730
	11th to 20th	Night	61% 8% 13% 10% 6% 2	2664
	21st to end	Night	62% 8% 11% 11% 6% 2	2170
March	1st to 10th	Night	57% 11% 14% 13% 5%	5193
	11th to 20th	Night	55% 9% 11% 18% 7% 1	5110
	21st to end	Night	65% 11% 14% 9% 1	5531
April	1st to 10th	Night	60% 8% 15% 12% 5%	2100
	11th to 20th	Night	50% 9% 17% 15% 7% 3	2079
	21st to end	Night	49% 8% 17% 19% 6% 2	1893
May	1st to 10th	Night	32% 6% 15% 34% 11% 1	4986
	11th to 20th	Night	36% 8% 20% 28% 7% 1	4700
	21st to end	Night	32% 11% 29% 24% 4	5182
June	1st to 10th	Night	40% 8% 17% 28% 6% 1	1680
	11th to 20th	Night	35% 6% 22% 26% 9% 1	1680
	21st to end	Night	25% 5% 20% 33% 14% 4	1680
July	1st to 10th	Night	9% 4 13% 36% 21% 18%	4700
	11th to 20th	Night	11% 3 8% 17% 39% 22%	4692
	21st to end	Night	12% 3 17% 37% 26% 5%	5152
August	1st to 10th	Night	8% 3 8% 31% 35% 16%	4169
	11th to 20th	Night	18% 6% 19% 40% 14% 3	4169
	21st to end	Night	18% 5% 14% 40% 19% 5%	4904
September	1st to 10th	Night	20% 6% 13% 29% 22% 11%	2100
	11th to 20th	Night	29% 7% 14% 27% 14% 8%	2119
	21st to end	Night	30% 6% 16% 24% 16% 7%	2375
October	1st to 10th	Night	32% 7% 9% 27% 22% 3	3920
	11th to 20th	Night	41% 10% 20% 18% 9% 2	3897
	21st to end	Night	55% 9% 13% 13% 9% 1	4269
November	1st to 10th	Night	58% 9% 11% 14% 6%	2770
	11th to 20th	Night	66% 8% 9% 9% 7% 2	2940
	21st to end	Night	58% 9% 10% 11% 11% 2	2940
December	1st to 10th	Night	53% 8% 12% 16% 10% 1	4700
	11th to 20th	Night	75% 9% 7% 7% 3	5316
	21st to end	Night	73% 12% 8% 5% 1	7106

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% 13% 17% 14% 13% 2	220
	11th to 20th	Day	26% 11% 15% 27% 15% 5%	222
	21st to end	Day	29% 12% 18% 20% 16% 6%	473
February	1st to 10th	Day	28% 10% 21% 22% 14% 4	430
	11th to 20th	Day	29% 10% 25% 23% 9% 4	425
	21st to end	Day	25% 17% 24% 21% 12% 3	397
March	1st to 10th	Day	27% 14% 25% 23% 10% 1	540
	11th to 20th	Day	28% 11% 22% 23% 14% 3	540
	21st to end	Day	25% 15% 25% 24% 10% 2	594
April	1st to 10th	Day	26% 13% 20% 21% 15% 6%	540
	11th to 20th	Day	21% 15% 23% 23% 12% 6%	532
	21st to end	Day	19% 12% 23% 25% 16% 4	540
May	1st to 10th	Day	13% 11% 23% 29% 18% 6%	543
	11th to 20th	Day	20% 11% 20% 24% 18% 7%	568
	21st to end	Day	13% 7% 20% 27% 22% 10%	617
June	1st to 10th	Day	16% 8% 20% 27% 22% 6%	570
	11th to 20th	Day	13% 8% 24% 34% 19% 2	570
	21st to end	Day	5% 5% 16% 37% 30% 8%	570
July	1st to 10th	Day	5% 2 15% 36% 31% 11%	566
	11th to 20th	Day	3 3 20% 36% 30% 9%	564
	21st to end	Day	3 2 12% 36% 33% 14%	619
August	1st to 10th	Day	2 1 14% 32% 36% 14%	567
	11th to 20th	Day	3 2 9% 35% 36% 16%	557
	21st to end	Day	5% 3 17% 33% 32% 10%	627
September	1st to 10th	Day	6% 4 18% 31% 29% 12%	570
	11th to 20th	Day	11% 5% 17% 29% 28% 11%	570
	21st to end	Day	14% 6% 19% 31% 23% 7%	563
October	1st to 10th	Day	16% 7% 21% 26% 22% 8%	530
	11th to 20th	Day	18% 8% 18% 24% 24% 7%	530
	21st to end	Day	25% 11% 23% 22% 14% 5%	576
November	1st to 10th	Day	26% 12% 25% 19% 12% 4	273
	11th to 20th	Day	25% 14% 23% 20% 13% 5%	220
	21st to end	Day	28% 12% 18% 20% 17% 6%	220
December	1st to 10th	Day	28% 16% 13% 23% 13% 8%	220
	11th to 20th	Day	35% 8% 24% 20% 10% 3	220
	21st to end	Day	31% 17% 19% 18% 14% 2	242
January	1st to 10th	Night	35% 10% 19% 22% 12% 2	840
	11th to 20th	Night	30% 9% 17% 23% 18% 3	840
	21st to end	Night	27% 5% 16% 32% 16% 3	924
February	1st to 10th	Night	27% 8% 19% 28% 17% 1	840
	11th to 20th	Night	28% 8% 20% 29% 14% 1	824
	21st to end	Night	28% 9% 21% 28% 14%	692
March	1st to 10th	Night	26% 7% 22% 31% 13%	840
	11th to 20th	Night	24% 9% 19% 32% 15% 1	840
	21st to end	Night	27% 9% 23% 28% 13% 1	924
April	1st to 10th	Night	28% 7% 19% 27% 19% 1	840
	11th to 20th	Night	20% 7% 23% 32% 17% 1	831
	21st to end	Night	20% 6% 21% 35% 17% 1	633
May	1st to 10th	Night	12% 6% 24% 37% 20% 2	516
	11th to 20th	Night	15% 3 18% 38% 25%	414
	21st to end	Night	14% 5% 18% 39% 22% 1	455
June	1st to 10th	Night	16% 5% 17% 42% 20% 1	420
	11th to 20th	Night	11% 4 20% 48% 16% 1	420
	21st to end	Night	7% 1 17% 53% 21%	420
July	1st to 10th	Night	4 1 10% 54% 29% 1	410
	11th to 20th	Night	3 1 22% 51% 22% 1	408
	21st to end	Night	1 2 11% 51% 32% 2	497
August	1st to 10th	Night	3 1 9% 43% 40% 5%	627
	11th to 20th	Night	5% 1 5% 42% 45% 2	624
	21st to end	Night	5% 2 15% 44% 31% 2	836
September	1st to 10th	Night	7% 2 15% 43% 32% 1	840
	11th to 20th	Night	8% 3 12% 39% 32% 6%	840
	21st to end	Night	10% 3 15% 41% 28% 3	832
October	1st to 10th	Night	14% 3 20% 34% 27% 3	800
	11th to 20th	Night	16% 6% 14% 35% 25% 4	800
	21st to end	Night	23% 6% 21% 28% 17% 4	880
November	1st to 10th	Night	25% 8% 19% 30% 17% 1	820
	11th to 20th	Night	33% 8% 20% 24% 14% 1	840
	21st to end	Night	23% 8% 18% 30% 18% 3	840
December	1st to 10th	Night	25% 8% 17% 28% 18% 3	840
	11th to 20th	Night	31% 10% 20% 22% 16% 1	840
	21st to end	Night	35% 9% 21% 24% 11% 1	924

Page generated at 2026-09-26 01:18:45. Version ac07

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