Adirondack Astronomy Retreat
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Adirondack Astronomy Retreat clear sky chart from 2005-11-06 to 2024-08-30.

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	14% 9% 3 9% 6% 5% 5% 4 6% 7% 32%	95756
	Night	15% 10% 4 9% 6% 5% 5% 4 5% 6% 32%	93306
Transparency	Day	48% 10% 12% 19% 9% 1	95475
	Night	50% 10% 12% 18% 9% 1	93141
Seeing	Day	21% 21% 31% 18% 7% 2	14451
	Night	18% 18% 31% 23% 8% 1	23406

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	11% 15% 4 12% 7% 6% 6% 5% 5% 5% 23%	2517
	11th to 20th	Day	12% 14% 8% 18% 6% 5% 4 3 4 5% 20%	2520
	21st to end	Day	12% 13% 4 12% 7% 6% 6% 4 6% 7% 22%	2772
February	1st to 10th	Day	11% 14% 4 12% 7% 6% 5% 3 6% 7% 24%	1695
	11th to 20th	Day	8% 12% 5% 12% 8% 5% 5% 4 5% 6% 29%	1800
	21st to end	Day	13% 13% 4 11% 7% 5% 4 3 4 7% 29%	1570
March	1st to 10th	Day	19% 13% 4 11% 7% 5% 4 4 5% 4 23%	3116
	11th to 20th	Day	10% 16% 5% 10% 6% 6% 5% 5% 5% 5% 26%	3274
	21st to end	Day	13% 10% 3 8% 6% 4 5% 3 4 6% 37%	4166
April	1st to 10th	Day	17% 12% 3 8% 6% 4 4 3 5% 5% 32%	2280
	11th to 20th	Day	17% 8% 3 9% 5% 4 4 3 5% 6% 36%	2254
	21st to end	Day	19% 9% 3 8% 6% 5% 5% 4 4 6% 33%	2418
May	1st to 10th	Day	18% 9% 3 9% 5% 5% 5% 4 5% 7% 29%	4257
	11th to 20th	Day	14% 9% 3 8% 6% 5% 4 4 7% 9% 31%	4398
	21st to end	Day	12% 5% 2 6% 6% 6% 5% 5% 7% 9% 38%	4837
June	1st to 10th	Day	18% 8% 3 8% 5% 5% 5% 4 6% 8% 29%	2660
	11th to 20th	Day	13% 6% 2 7% 5% 6% 5% 4 7% 8% 37%	2660
	21st to end	Day	16% 8% 3 8% 5% 5% 6% 5% 7% 8% 29%	2660
July	1st to 10th	Day	10% 6% 2 6% 6% 6% 6% 5% 7% 9% 38%	4440
	11th to 20th	Day	10% 6% 3 7% 5% 5% 6% 5% 9% 11% 36%	4440
	21st to end	Day	11% 5% 3 7% 5% 5% 6% 5% 6% 8% 39%	4814
August	1st to 10th	Day	10% 5% 2 7% 6% 5% 6% 5% 8% 8% 37%	2646
	11th to 20th	Day	9% 5% 2 8% 5% 5% 6% 5% 8% 10% 37%	2340
	21st to end	Day	10% 6% 2 7% 5% 5% 6% 4 6% 8% 41%	2486
September	1st to 10th	Day	12% 6% 2 5% 3 4 5% 4 6% 8% 46%	2160
	11th to 20th	Day	11% 7% 1 5% 4 4 3 4 5% 7% 49%	2070
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 7% 8% 40%	1980
October	1st to 10th	Day	19% 10% 3 7% 5% 4 5% 4 6% 6% 32%	1885
	11th to 20th	Day	14% 9% 3 8% 6% 5% 5% 5% 6% 7% 33%	1769
	21st to end	Day	20% 9% 3 10% 5% 5% 4 4 5% 5% 29%	1782
November	1st to 10th	Day	12% 11% 3 8% 5% 6% 5% 4 5% 7% 34%	1671
	11th to 20th	Day	16% 10% 3 8% 5% 6% 6% 4 5% 6% 31%	1701
	21st to end	Day	14% 12% 4 8% 6% 5% 5% 4 6% 6% 30%	1520
December	1st to 10th	Day	17% 20% 5% 11% 6% 5% 5% 3 5% 5% 20%	1520
	11th to 20th	Day	19% 15% 4 7% 5% 4 5% 4 6% 7% 24%	1906
	21st to end	Day	22% 14% 4 11% 6% 5% 5% 3 5% 6% 20%	2772
January	1st to 10th	Night	14% 15% 6% 13% 6% 5% 5% 3 4 6% 23%	4429
	11th to 20th	Night	10% 15% 7% 18% 7% 6% 4 4 5% 5% 20%	4440
	21st to end	Night	17% 15% 5% 11% 6% 5% 4 3 5% 6% 23%	4884
February	1st to 10th	Night	10% 12% 5% 14% 7% 6% 6% 4 6% 6% 24%	2481
	11th to 20th	Night	8% 12% 5% 13% 8% 5% 5% 4 5% 6% 30%	2266
	21st to end	Night	13% 11% 5% 10% 6% 6% 4 4 5% 5% 31%	1884
March	1st to 10th	Night	20% 12% 3 9% 6% 4 4 3 4 5% 29%	3724
	11th to 20th	Night	13% 15% 4 10% 6% 5% 5% 3 5% 5% 30%	3682
	21st to end	Night	12% 11% 3 10% 5% 5% 4 3 4 5% 37%	3466
April	1st to 10th	Night	15% 10% 3 9% 6% 6% 4 3 6% 6% 31%	1900
	11th to 20th	Night	19% 8% 3 9% 6% 5% 4 4 4 6% 33%	1875
	21st to end	Night	19% 8% 3 8% 4 4 5% 3 4 6% 36%	1762
May	1st to 10th	Night	19% 10% 3 9% 6% 5% 5% 4 6% 8% 26%	2711
	11th to 20th	Night	17% 10% 4 10% 5% 4 4 3 4 6% 34%	2495
	21st to end	Night	11% 6% 2 7% 5% 5% 6% 4 7% 9% 39%	2738
June	1st to 10th	Night	18% 7% 3 7% 6% 4 5% 4 5% 7% 34%	1520
	11th to 20th	Night	15% 6% 2 5% 4 5% 4 4 5% 9% 39%	1520
	21st to end	Night	15% 7% 2 7% 5% 5% 5% 4 6% 8% 36%	1520
July	1st to 10th	Night	10% 5% 2 7% 5% 6% 5% 5% 7% 8% 39%	2520
	11th to 20th	Night	12% 5% 2 6% 4 4 4 4 6% 9% 44%	2520
	21st to end	Night	8% 6% 3 7% 5% 5% 5% 4 6% 7% 42%	2739
August	1st to 10th	Night	10% 4 2 5% 5% 5% 6% 3 6% 9% 45%	1512
	11th to 20th	Night	8% 5% 2 8% 5% 5% 5% 4 5% 9% 43%	1758
	21st to end	Night	10% 6% 3 6% 5% 4 4 4 6% 8% 44%	2080
September	1st to 10th	Night	11% 5% 2 4 5% 5% 4 4 6% 7% 48%	1800
	11th to 20th	Night	12% 6% 2 6% 4 4 3 3 5% 7% 50%	1890
	21st to end	Night	13% 5% 2 5% 5% 5% 4 3 5% 7% 45%	1980
October	1st to 10th	Night	18% 8% 2 7% 6% 5% 5% 5% 5% 6% 34%	2073
	11th to 20th	Night	16% 8% 3 7% 5% 5% 5% 4 6% 7% 34%	2190
	21st to end	Night	21% 11% 2 9% 5% 4 4 3 5% 7% 29%	2574
November	1st to 10th	Night	15% 10% 4 8% 5% 4 4 4 5% 6% 35%	2407
	11th to 20th	Night	16% 9% 3 8% 5% 5% 5% 4 5% 7% 34%	2474
	21st to end	Night	15% 13% 4 8% 5% 6% 5% 4 5% 7% 28%	2660
December	1st to 10th	Night	16% 16% 4 11% 7% 6% 5% 4 5% 5% 20%	2660
	11th to 20th	Night	19% 13% 5% 10% 6% 5% 5% 4 5% 5% 26%	3288
	21st to end	Night	22% 14% 6% 11% 6% 5% 4 3 4 5% 20%	4884

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	54% 11% 13% 17% 4 1	2518
	11th to 20th	Day	63% 10% 10% 10% 5% 1	2520
	21st to end	Day	60% 11% 12% 11% 5% 1	2772
February	1st to 10th	Day	58% 10% 9% 15% 5% 2	1695
	11th to 20th	Day	54% 10% 12% 15% 9% 1	1809
	21st to end	Day	54% 8% 12% 13% 10% 2	1570
March	1st to 10th	Day	60% 11% 9% 12% 7% 1	3119
	11th to 20th	Day	53% 15% 10% 12% 8% 2	3274
	21st to end	Day	46% 9% 8% 16% 17% 3	4166
April	1st to 10th	Day	52% 7% 10% 17% 11% 2	2280
	11th to 20th	Day	48% 9% 9% 18% 14% 2	2254
	21st to end	Day	53% 8% 10% 16% 11% 3	2418
May	1st to 10th	Day	53% 10% 11% 18% 8% 1	4271
	11th to 20th	Day	46% 13% 15% 15% 9% 1	4402
	21st to end	Day	39% 11% 13% 25% 10% 1	4837
June	1st to 10th	Day	51% 9% 14% 16% 9% 1	2660
	11th to 20th	Day	43% 10% 13% 20% 12% 2	2660
	21st to end	Day	50% 10% 12% 18% 9% 1	2660
July	1st to 10th	Day	39% 10% 15% 24% 11%	4370
	11th to 20th	Day	39% 11% 15% 28% 7%	4365
	21st to end	Day	41% 10% 13% 27% 9%	4661
August	1st to 10th	Day	41% 14% 16% 20% 10%	2632
	11th to 20th	Day	39% 13% 17% 22% 8%	2340
	21st to end	Day	40% 9% 15% 24% 11% 1	2486
September	1st to 10th	Day	35% 11% 13% 29% 12% 1	2160
	11th to 20th	Day	35% 7% 13% 29% 15% 1	2070
	21st to end	Day	40% 10% 16% 22% 10% 2	1980
October	1st to 10th	Day	50% 9% 11% 18% 11%	1885
	11th to 20th	Day	46% 12% 14% 21% 7%	1769
	21st to end	Day	55% 9% 12% 16% 7% 1	1782
November	1st to 10th	Day	48% 10% 14% 17% 10%	1671
	11th to 20th	Day	51% 9% 12% 15% 10% 2	1701
	21st to end	Day	52% 10% 14% 19% 5% 1	1520
December	1st to 10th	Day	66% 9% 10% 11% 4	1520
	11th to 20th	Day	57% 10% 13% 15% 5%	1906
	21st to end	Day	61% 9% 10% 16% 3	2772
January	1st to 10th	Night	58% 10% 15% 13% 5%	4429
	11th to 20th	Night	62% 13% 9% 11% 4	4440
	21st to end	Night	61% 10% 10% 12% 7% 1	4884
February	1st to 10th	Night	57% 10% 12% 11% 8% 1	2481
	11th to 20th	Night	53% 10% 10% 16% 10% 1	2268
	21st to end	Night	52% 11% 10% 17% 9% 2	1884
March	1st to 10th	Night	55% 10% 10% 14% 9% 1	3734
	11th to 20th	Night	52% 9% 12% 16% 9% 1	3683
	21st to end	Night	47% 9% 9% 18% 14% 4	3466
April	1st to 10th	Night	50% 9% 10% 17% 12% 1	1900
	11th to 20th	Night	50% 9% 12% 17% 11% 1	1875
	21st to end	Night	47% 10% 10% 17% 12% 3	1762
May	1st to 10th	Night	54% 11% 9% 16% 9% 1	2717
	11th to 20th	Night	47% 11% 12% 19% 10% 1	2496
	21st to end	Night	38% 12% 14% 20% 15% 1	2739
June	1st to 10th	Night	45% 11% 13% 19% 10% 1	1520
	11th to 20th	Night	40% 9% 14% 22% 13% 2	1520
	21st to end	Night	43% 11% 15% 21% 10% 1	1520
July	1st to 10th	Night	40% 8% 16% 23% 13% 1	2480
	11th to 20th	Night	34% 11% 14% 30% 11%	2472
	21st to end	Night	35% 11% 16% 26% 11% 1	2651
August	1st to 10th	Night	32% 12% 19% 27% 10%	1502
	11th to 20th	Night	35% 11% 16% 27% 11%	1758
	21st to end	Night	35% 9% 18% 25% 12%	2080
September	1st to 10th	Night	34% 12% 16% 27% 12% 1	1800
	11th to 20th	Night	33% 8% 15% 29% 14%	1890
	21st to end	Night	37% 11% 13% 25% 12% 2	1980
October	1st to 10th	Night	47% 10% 12% 19% 11% 1	2073
	11th to 20th	Night	46% 10% 14% 22% 7%	2190
	21st to end	Night	54% 10% 13% 14% 8% 1	2574
November	1st to 10th	Night	48% 10% 12% 17% 10% 2	2407
	11th to 20th	Night	49% 10% 11% 18% 8% 3	2474
	21st to end	Night	53% 11% 15% 16% 5%	2660
December	1st to 10th	Night	63% 10% 13% 12% 2	2660
	11th to 20th	Night	58% 9% 11% 14% 8%	3288
	21st to end	Night	64% 9% 10% 15% 3	4884

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	17% 30% 29% 18% 6% 1	180
	11th to 20th	Day	21% 33% 34% 10% 2 1	180
	21st to end	Day	18% 27% 40% 12% 3 1	198
February	1st to 10th	Day	31% 38% 26% 3 1	263
	11th to 20th	Day	25% 31% 33% 9% 1	408
	21st to end	Day	30% 22% 34% 12% 2	382
March	1st to 10th	Day	27% 25% 31% 15% 3	460
	11th to 20th	Day	25% 32% 26% 14% 3 1	460
	21st to end	Day	27% 28% 26% 12% 5% 2	506
April	1st to 10th	Day	29% 24% 27% 15% 4 1	460
	11th to 20th	Day	30% 26% 25% 13% 4 2	452
	21st to end	Day	30% 26% 25% 12% 5% 2	460
May	1st to 10th	Day	24% 25% 32% 10% 7% 1	463
	11th to 20th	Day	20% 20% 34% 19% 5% 2	487
	21st to end	Day	17% 21% 33% 22% 6% 1	529
June	1st to 10th	Day	24% 18% 34% 18% 6% 1	490
	11th to 20th	Day	16% 19% 36% 20% 8% 1	490
	21st to end	Day	19% 21% 32% 20% 7% 1	490
July	1st to 10th	Day	14% 13% 33% 28% 11% 1	485
	11th to 20th	Day	11% 13% 37% 28% 10% 1	484
	21st to end	Day	14% 11% 36% 29% 7% 2	532
August	1st to 10th	Day	10% 11% 35% 28% 12% 3	486
	11th to 20th	Day	12% 9% 36% 27% 12% 5%	479
	21st to end	Day	11% 17% 30% 25% 11% 6%	532
September	1st to 10th	Day	15% 13% 32% 22% 10% 7%	450
	11th to 20th	Day	15% 15% 25% 21% 16% 8%	450
	21st to end	Day	14% 16% 33% 21% 12% 4	450
October	1st to 10th	Day	23% 19% 25% 18% 12% 2	450
	11th to 20th	Day	20% 23% 29% 21% 6% 1	435
	21st to end	Day	27% 20% 30% 19% 3	396
November	1st to 10th	Day	23% 21% 28% 21% 6%	365
	11th to 20th	Day	24% 29% 27% 15% 4 1	361
	21st to end	Day	26% 28% 31% 13% 2	180
December	1st to 10th	Day	22% 33% 26% 14% 3 1	180
	11th to 20th	Day	28% 28% 34% 9% 1	180
	21st to end	Day	29% 28% 32% 9% 3	198
January	1st to 10th	Night	19% 23% 39% 17% 2	760
	11th to 20th	Night	21% 24% 35% 16% 3	760
	21st to end	Night	12% 22% 40% 21% 4	836
February	1st to 10th	Night	16% 24% 40% 18% 2	760
	11th to 20th	Night	17% 27% 37% 17% 2	743
	21st to end	Night	20% 24% 34% 19% 3	628
March	1st to 10th	Night	23% 21% 33% 21% 3	760
	11th to 20th	Night	23% 26% 29% 17% 4	760
	21st to end	Night	21% 23% 30% 19% 5% 1	836
April	1st to 10th	Night	21% 24% 29% 22% 3	760
	11th to 20th	Night	23% 24% 28% 19% 6%	751
	21st to end	Night	23% 21% 29% 22% 6%	622
May	1st to 10th	Night	25% 15% 32% 21% 7%	499
	11th to 20th	Night	15% 18% 36% 24% 6% 1	374
	21st to end	Night	13% 16% 34% 27% 10%	411
June	1st to 10th	Night	19% 10% 32% 26% 12%	380
	11th to 20th	Night	16% 9% 28% 36% 11% 1	380
	21st to end	Night	16% 8% 32% 33% 9% 1	380
July	1st to 10th	Night	12% 6% 29% 37% 15% 1	370
	11th to 20th	Night	11% 4 27% 40% 17% 2	368
	21st to end	Night	10% 7% 26% 43% 13%	416
August	1st to 10th	Night	11% 6% 22% 43% 17% 1	378
	11th to 20th	Night	9% 7% 24% 39% 18% 3	634
	21st to end	Night	11% 8% 26% 35% 19% 1	832
September	1st to 10th	Night	12% 9% 28% 34% 15% 3	720
	11th to 20th	Night	13% 11% 26% 28% 18% 3	720
	21st to end	Night	13% 13% 30% 26% 16% 2	720
October	1st to 10th	Night	22% 15% 24% 24% 13% 1	720
	11th to 20th	Night	19% 18% 27% 28% 8% 1	720
	21st to end	Night	26% 18% 30% 21% 4	792
November	1st to 10th	Night	20% 19% 33% 20% 7% 1	740
	11th to 20th	Night	21% 23% 32% 16% 8% 1	760
	21st to end	Night	21% 25% 30% 17% 6% 1	760
December	1st to 10th	Night	22% 27% 32% 15% 4	760
	11th to 20th	Night	22% 23% 33% 19% 4	760
	21st to end	Night	25% 23% 34% 15% 3	836

Page generated at 2024-08-27 09:49:40. Version ac07

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