Cobleskill
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cobleskill clear sky chart from 2005-11-06 to 2024-11-05.

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% 10% 4 8% 5% 5% 5% 4 6% 7% 31%	101447
	Night	15% 11% 4 8% 5% 4 5% 4 5% 6% 32%	97613
Transparency	Day	50% 7% 13% 20% 10% 1	104954
	Night	50% 7% 13% 19% 9% 1	102195
Seeing	Day	25% 17% 28% 18% 9% 3	14790
	Night	23% 18% 27% 23% 8% 1	23879

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% 10% 13% 6% 5% 4 4 5% 4 24%	2517
	11th to 20th	Day	13% 18% 6% 12% 8% 4 5% 3 5% 4 22%	2520
	21st to end	Day	17% 19% 7% 11% 6% 6% 4 3 4 5% 18%	2936
February	1st to 10th	Day	15% 15% 5% 11% 8% 5% 5% 4 5% 6% 21%	1710
	11th to 20th	Day	9% 13% 6% 14% 7% 5% 5% 4 5% 5% 26%	1785
	21st to end	Day	16% 15% 4 10% 8% 4 4 4 4 5% 26%	1570
March	1st to 10th	Day	22% 15% 5% 10% 4 3 3 3 4 5% 26%	3116
	11th to 20th	Day	12% 17% 7% 10% 5% 5% 5% 4 4 6% 28%	3374
	21st to end	Day	18% 11% 4 10% 5% 4 3 2 4 5% 33%	4116
April	1st to 10th	Day	16% 15% 3 8% 5% 5% 5% 3 5% 5% 32%	2280
	11th to 20th	Day	16% 11% 4 7% 5% 5% 4 3 4 6% 35%	2254
	21st to end	Day	20% 12% 4 8% 4 4 4 4 4 6% 32%	2327
May	1st to 10th	Day	24% 10% 4 7% 4 4 3 3 5% 6% 30%	4261
	11th to 20th	Day	18% 9% 2 7% 6% 5% 6% 4 6% 7% 31%	4398
	21st to end	Day	11% 6% 2 7% 5% 5% 4 4 7% 9% 38%	4837
June	1st to 10th	Day	17% 7% 2 8% 5% 5% 5% 5% 6% 7% 32%	2660
	11th to 20th	Day	16% 7% 2 7% 5% 5% 5% 5% 7% 11% 31%	2660
	21st to end	Day	16% 7% 3 8% 6% 5% 5% 5% 6% 8% 32%	2660
July	1st to 10th	Day	10% 6% 3 7% 6% 5% 6% 5% 7% 10% 35%	4440
	11th to 20th	Day	8% 6% 2 7% 6% 6% 7% 5% 8% 11% 35%	4440
	21st to end	Day	12% 6% 2 8% 6% 6% 6% 4 7% 7% 35%	4814
August	1st to 10th	Day	18% 6% 3 7% 5% 5% 5% 4 5% 8% 33%	4328
	11th to 20th	Day	13% 7% 3 8% 5% 6% 6% 4 8% 9% 31%	3773
	21st to end	Day	12% 7% 2 8% 4 5% 5% 4 7% 9% 37%	4180
September	1st to 10th	Day	15% 6% 2 5% 4 4 5% 4 6% 7% 41%	2280
	11th to 20th	Day	13% 6% 2 6% 4 4 4 3 4 7% 46%	2222
	21st to end	Day	14% 8% 2 5% 4 5% 4 5% 7% 8% 38%	2090
October	1st to 10th	Day	19% 9% 3 7% 5% 5% 5% 4 6% 5% 33%	1938
	11th to 20th	Day	14% 9% 2 7% 5% 4 4 4 6% 7% 37%	1900
	21st to end	Day	21% 13% 2 7% 5% 3 5% 4 6% 6% 28%	1925
November	1st to 10th	Day	13% 12% 3 6% 4 4 4 3 5% 6% 39%	1708
	11th to 20th	Day	14% 15% 3 7% 5% 5% 5% 4 5% 6% 31%	1710
	21st to end	Day	14% 14% 4 8% 6% 4 5% 4 5% 6% 28%	1520
December	1st to 10th	Day	15% 18% 6% 12% 7% 5% 4 4 6% 5% 20%	1520
	11th to 20th	Day	18% 16% 6% 9% 5% 4 3 3 4 6% 26%	1906
	21st to end	Day	20% 19% 8% 8% 5% 4 4 3 5% 6% 18%	2772
January	1st to 10th	Night	14% 14% 6% 12% 5% 4 5% 4 6% 6% 24%	4429
	11th to 20th	Night	11% 15% 5% 14% 9% 6% 4 4 5% 5% 21%	4440
	21st to end	Night	19% 17% 6% 12% 7% 5% 4 3 4 6% 17%	4719
February	1st to 10th	Night	13% 13% 5% 11% 7% 5% 5% 5% 6% 6% 23%	2470
	11th to 20th	Night	11% 11% 6% 12% 8% 6% 5% 5% 6% 7% 23%	2279
	21st to end	Night	16% 12% 5% 12% 6% 5% 5% 4 5% 6% 25%	1884
March	1st to 10th	Night	20% 10% 4 9% 5% 4 4 4 6% 6% 27%	3724
	11th to 20th	Night	12% 16% 6% 8% 6% 5% 4 3 5% 5% 30%	3583
	21st to end	Night	14% 15% 4 11% 5% 4 4 3 4 4 32%	3515
April	1st to 10th	Night	16% 13% 4 7% 6% 5% 5% 4 5% 6% 29%	1900
	11th to 20th	Night	19% 10% 3 6% 4 4 4 3 5% 6% 36%	1875
	21st to end	Night	18% 12% 3 6% 4 4 4 3 4 5% 36%	1852
May	1st to 10th	Night	26% 12% 3 6% 4 3 4 3 4 6% 30%	2707
	11th to 20th	Night	15% 10% 4 8% 5% 5% 5% 4 5% 6% 32%	2495
	21st to end	Night	12% 6% 3 7% 5% 4 5% 5% 7% 8% 37%	2738
June	1st to 10th	Night	14% 7% 2 7% 4 5% 4 4 7% 8% 39%	1520
	11th to 20th	Night	16% 5% 2 6% 4 3 4 4 6% 9% 41%	1520
	21st to end	Night	11% 4 2 6% 5% 5% 6% 4 7% 8% 42%	1520
July	1st to 10th	Night	9% 6% 3 7% 6% 6% 6% 4 7% 7% 40%	2520
	11th to 20th	Night	12% 5% 2 6% 4 4 5% 4 6% 8% 43%	2520
	21st to end	Night	12% 6% 2 6% 5% 5% 5% 4 6% 7% 41%	2739
August	1st to 10th	Night	18% 6% 2 6% 4 5% 4 4 6% 8% 37%	2597
	11th to 20th	Night	13% 7% 3 7% 5% 4 4 4 5% 7% 41%	3024
	21st to end	Night	13% 6% 2 5% 4 4 4 4 6% 8% 46%	3476
September	1st to 10th	Night	14% 6% 2 5% 4 4 4 3 5% 8% 46%	1900
	11th to 20th	Night	14% 5% 2 4 3 3 4 3 4 6% 53%	1957
	21st to end	Night	14% 6% 1 7% 4 4 4 3 6% 7% 42%	2090
October	1st to 10th	Night	18% 8% 3 7% 5% 4 4 4 6% 6% 36%	2239
	11th to 20th	Night	16% 8% 3 7% 4 4 4 4 5% 7% 39%	2280
	21st to end	Night	21% 11% 3 7% 4 4 4 3 6% 6% 30%	2672
November	1st to 10th	Night	13% 10% 3 7% 4 4 5% 3 5% 6% 39%	2470
	11th to 20th	Night	14% 13% 4 7% 5% 4 5% 4 6% 7% 31%	2470
	21st to end	Night	13% 12% 5% 8% 6% 5% 5% 4 5% 6% 30%	2657
December	1st to 10th	Night	14% 16% 6% 12% 6% 5% 5% 5% 5% 7% 20%	2660
	11th to 20th	Night	18% 13% 5% 10% 6% 5% 5% 4 5% 5% 24%	3288
	21st to end	Night	23% 15% 9% 8% 4 4 4 3 4 5% 21%	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	61% 7% 13% 14% 5% 1	2518
	11th to 20th	Day	64% 7% 11% 13% 4 1	2520
	21st to end	Day	69% 6% 11% 9% 4 1	2936
February	1st to 10th	Day	64% 5% 11% 14% 5% 1	1710
	11th to 20th	Day	60% 6% 9% 16% 8% 1	1794
	21st to end	Day	60% 6% 10% 14% 9%	1570
March	1st to 10th	Day	60% 5% 12% 14% 8% 1	3119
	11th to 20th	Day	56% 6% 15% 14% 7% 2	3374
	21st to end	Day	53% 5% 7% 16% 16% 2	4116
April	1st to 10th	Day	54% 5% 8% 21% 10% 2	2280
	11th to 20th	Day	50% 6% 12% 18% 13% 1	2254
	21st to end	Day	53% 6% 9% 18% 12% 3	2327
May	1st to 10th	Day	54% 7% 9% 18% 10% 1	4275
	11th to 20th	Day	49% 9% 13% 21% 8% 1	4402
	21st to end	Day	38% 9% 14% 26% 11% 1	4837
June	1st to 10th	Day	48% 9% 13% 19% 11% 1	2660
	11th to 20th	Day	47% 8% 14% 20% 10% 1	2660
	21st to end	Day	48% 8% 14% 19% 10% 1	2660
July	1st to 10th	Day	41% 10% 14% 24% 11%	4370
	11th to 20th	Day	38% 10% 17% 25% 10%	4365
	21st to end	Day	45% 7% 15% 22% 10%	4661
August	1st to 10th	Day	48% 8% 13% 20% 10%	4314
	11th to 20th	Day	46% 8% 17% 24% 5%	3810
	21st to end	Day	40% 8% 13% 31% 8%	4180
September	1st to 10th	Day	40% 7% 12% 26% 14% 1	2280
	11th to 20th	Day	38% 5% 12% 26% 18% 1	2222
	21st to end	Day	41% 8% 13% 23% 12% 2	2090
October	1st to 10th	Day	46% 7% 9% 23% 14% 1	3224
	11th to 20th	Day	41% 4 12% 23% 17% 2	3140
	21st to end	Day	40% 6% 14% 26% 11% 2	3150
November	1st to 10th	Day	44% 6% 14% 22% 13% 2	1708
	11th to 20th	Day	54% 5% 13% 17% 10% 2	1710
	21st to end	Day	54% 7% 16% 16% 6% 1	1520
December	1st to 10th	Day	66% 7% 11% 12% 5% 1	1520
	11th to 20th	Day	62% 5% 16% 12% 4 1	1906
	21st to end	Day	68% 6% 10% 13% 4	2772
January	1st to 10th	Night	58% 7% 14% 13% 7%	4429
	11th to 20th	Night	63% 7% 10% 13% 6% 1	4440
	21st to end	Night	68% 5% 11% 10% 4 1	4719
February	1st to 10th	Night	60% 7% 12% 14% 6% 1	2470
	11th to 20th	Night	59% 7% 12% 15% 6% 1	2281
	21st to end	Night	58% 7% 13% 14% 8% 1	1884
March	1st to 10th	Night	55% 7% 13% 15% 8% 1	3734
	11th to 20th	Night	55% 6% 14% 19% 6% 1	3584
	21st to end	Night	53% 7% 7% 17% 14% 2	3515
April	1st to 10th	Night	54% 7% 11% 18% 9% 1	1900
	11th to 20th	Night	49% 6% 11% 19% 14% 1	1875
	21st to end	Night	50% 6% 11% 18% 13% 3	1852
May	1st to 10th	Night	55% 7% 10% 15% 11% 2	2713
	11th to 20th	Night	49% 9% 15% 18% 8% 1	2496
	21st to end	Night	41% 10% 14% 20% 14% 1	2739
June	1st to 10th	Night	42% 8% 12% 25% 12% 2	1520
	11th to 20th	Night	39% 7% 17% 25% 11% 1	1520
	21st to end	Night	38% 8% 16% 26% 12% 1	1520
July	1st to 10th	Night	40% 9% 14% 22% 14% 1	2480
	11th to 20th	Night	37% 8% 16% 26% 13%	2472
	21st to end	Night	41% 8% 12% 28% 11% 1	2651
August	1st to 10th	Night	44% 9% 15% 24% 8%	2587
	11th to 20th	Night	42% 7% 17% 25% 8%	3053
	21st to end	Night	36% 6% 14% 33% 10% 1	3476
September	1st to 10th	Night	36% 7% 15% 28% 13% 1	1900
	11th to 20th	Night	33% 6% 12% 28% 20% 1	1957
	21st to end	Night	41% 6% 13% 24% 14% 2	2090
October	1st to 10th	Night	49% 6% 12% 23% 10% 1	3733
	11th to 20th	Night	38% 5% 14% 23% 17% 3	3779
	21st to end	Night	43% 6% 14% 27% 9% 1	4397
November	1st to 10th	Night	46% 6% 12% 19% 14% 2	2470
	11th to 20th	Night	52% 7% 12% 18% 10% 2	2470
	21st to end	Night	53% 7% 16% 18% 5% 1	2657
December	1st to 10th	Night	61% 7% 14% 14% 3	2660
	11th to 20th	Night	60% 8% 12% 13% 7%	3288
	21st to end	Night	66% 6% 12% 12% 4	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	31% 26% 30% 10% 3 1	180
	11th to 20th	Day	41% 21% 29% 6% 2 1	180
	21st to end	Day	28% 25% 36% 7% 4	245
February	1st to 10th	Day	36% 30% 27% 7% 1	270
	11th to 20th	Day	37% 31% 22% 10% 1	393
	21st to end	Day	35% 24% 28% 11% 2	382
March	1st to 10th	Day	32% 25% 30% 11% 3	460
	11th to 20th	Day	34% 22% 28% 12% 3 1	460
	21st to end	Day	36% 23% 23% 12% 5% 2	506
April	1st to 10th	Day	34% 25% 22% 12% 6% 1	460
	11th to 20th	Day	30% 25% 24% 12% 7% 2	452
	21st to end	Day	34% 18% 28% 13% 4 3	460
May	1st to 10th	Day	35% 18% 26% 11% 7% 3	463
	11th to 20th	Day	22% 18% 31% 18% 8% 3	487
	21st to end	Day	20% 12% 32% 22% 12% 3	529
June	1st to 10th	Day	19% 17% 34% 19% 9% 2	490
	11th to 20th	Day	19% 15% 29% 23% 12% 2	490
	21st to end	Day	21% 17% 30% 22% 9% 1	490
July	1st to 10th	Day	13% 9% 33% 27% 14% 4	485
	11th to 20th	Day	11% 7% 36% 30% 13% 4	484
	21st to end	Day	14% 10% 37% 27% 10% 3	532
August	1st to 10th	Day	13% 10% 29% 26% 18% 5%	486
	11th to 20th	Day	16% 10% 28% 27% 13% 7%	479
	21st to end	Day	14% 14% 28% 23% 14% 6%	539
September	1st to 10th	Day	17% 12% 25% 23% 16% 8%	490
	11th to 20th	Day	14% 10% 26% 21% 19% 11%	490
	21st to end	Day	17% 13% 30% 21% 14% 5%	490
October	1st to 10th	Day	23% 13% 27% 19% 14% 4	490
	11th to 20th	Day	24% 18% 27% 20% 10% 2	490
	21st to end	Day	29% 18% 29% 17% 7%	452
November	1st to 10th	Day	27% 19% 22% 19% 12% 1	378
	11th to 20th	Day	32% 24% 22% 15% 6% 1	370
	21st to end	Day	33% 24% 28% 13% 1 1	180
December	1st to 10th	Day	35% 25% 22% 13% 4	180
	11th to 20th	Day	41% 22% 26% 11% 1	180
	21st to end	Day	34% 20% 33% 10% 3 1	198
January	1st to 10th	Night	27% 26% 32% 13% 2	760
	11th to 20th	Night	27% 25% 29% 16% 2 1	760
	21st to end	Night	21% 29% 31% 17% 2	836
February	1st to 10th	Night	28% 22% 33% 16% 2	760
	11th to 20th	Night	26% 27% 31% 14% 2	743
	21st to end	Night	31% 25% 28% 15% 2	628
March	1st to 10th	Night	28% 23% 31% 16% 3	760
	11th to 20th	Night	28% 24% 29% 16% 3	760
	21st to end	Night	26% 22% 26% 19% 6%	836
April	1st to 10th	Night	28% 21% 29% 18% 3	760
	11th to 20th	Night	25% 21% 28% 19% 6%	751
	21st to end	Night	27% 18% 25% 22% 6%	712
May	1st to 10th	Night	30% 13% 27% 21% 8% 1	495
	11th to 20th	Night	19% 15% 27% 31% 7% 1	374
	21st to end	Night	16% 8% 30% 32% 13% 1	411
June	1st to 10th	Night	16% 12% 24% 35% 11% 1	380
	11th to 20th	Night	17% 11% 21% 36% 15%	380
	21st to end	Night	14% 8% 26% 39% 12% 1	380
July	1st to 10th	Night	10% 6% 24% 42% 17% 2	370
	11th to 20th	Night	13% 5% 23% 41% 15% 2	368
	21st to end	Night	10% 6% 26% 43% 13% 2	416
August	1st to 10th	Night	11% 3 29% 35% 21% 1	430
	11th to 20th	Night	14% 5% 20% 37% 20% 4	701
	21st to end	Night	16% 7% 21% 35% 20% 1	836
September	1st to 10th	Night	15% 8% 25% 32% 19% 2	760
	11th to 20th	Night	15% 8% 22% 28% 21% 6%	760
	21st to end	Night	18% 10% 24% 29% 17% 2	760
October	1st to 10th	Night	24% 15% 20% 24% 15% 3	760
	11th to 20th	Night	21% 15% 26% 28% 9% 1	760
	21st to end	Night	28% 18% 27% 22% 5%	836
November	1st to 10th	Night	22% 18% 27% 26% 7%	760
	11th to 20th	Night	28% 19% 26% 18% 7% 2	760
	21st to end	Night	24% 24% 26% 21% 5% 1	760
December	1st to 10th	Night	26% 28% 27% 15% 4	760
	11th to 20th	Night	33% 20% 28% 16% 3	760
	21st to end	Night	31% 27% 26% 14% 2	836

Page generated at 2024-11-03 02:11:21. Version ac07

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