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 2024-01-12.

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 7% 6% 3 5% 5% 5% 7% 32%	74745
	Night	15% 10% 4 7% 6% 3 5% 5% 5% 7% 33%	74962
Transparency	Day	51% 7% 12% 19% 10% 1	74450
	Night	50% 7% 13% 19% 10% 1	74791
Seeing	Day	25% 18% 28% 18% 9% 3	13659
	Night	23% 18% 27% 23% 8% 1	22886

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	10% 13% 8% 11% 7% 3 5% 5% 7% 6% 25%	1517
	11th to 20th	Day	13% 15% 5% 10% 9% 3 6% 5% 6% 5% 22%	1448
	21st to end	Day	10% 12% 6% 12% 8% 4 6% 5% 6% 6% 25%	1678
February	1st to 10th	Day	16% 14% 6% 11% 10% 4 5% 5% 5% 6% 19%	1620
	11th to 20th	Day	10% 12% 7% 13% 9% 3 6% 5% 5% 5% 25%	1689
	21st to end	Day	17% 14% 5% 10% 8% 4 4 5% 4 5% 24%	1480
March	1st to 10th	Day	12% 11% 6% 11% 6% 4 4 4 5% 8% 28%	1797
	11th to 20th	Day	15% 13% 5% 9% 6% 3 5% 4 4 5% 29%	1916
	21st to end	Day	18% 11% 4 7% 6% 3 4 3 4 5% 34%	2340
April	1st to 10th	Day	15% 11% 6% 7% 6% 4 5% 4 5% 5% 33%	2160
	11th to 20th	Day	16% 9% 4 6% 6% 4 4 4 4 6% 36%	2134
	21st to end	Day	21% 11% 4 7% 5% 3 4 4 4 6% 31%	2204
May	1st to 10th	Day	21% 11% 5% 6% 5% 3 4 4 4 5% 31%	2425
	11th to 20th	Day	18% 7% 3 5% 6% 3 5% 5% 5% 6% 37%	2478
	21st to end	Day	14% 6% 2 6% 7% 4 5% 5% 6% 8% 38%	2725
June	1st to 10th	Day	18% 6% 3 7% 6% 3 5% 5% 6% 7% 33%	2520
	11th to 20th	Day	17% 7% 2 6% 6% 4 5% 6% 6% 11% 31%	2520
	21st to end	Day	16% 6% 3 7% 7% 4 5% 5% 6% 8% 33%	2520
July	1st to 10th	Day	12% 6% 3 6% 7% 4 6% 6% 6% 9% 35%	2520
	11th to 20th	Day	11% 5% 2 6% 7% 5% 6% 6% 7% 10% 36%	2520
	21st to end	Day	13% 6% 2 7% 7% 4 7% 5% 7% 8% 35%	2744
August	1st to 10th	Day	11% 5% 2 6% 7% 4 6% 7% 6% 10% 36%	2453
	11th to 20th	Day	13% 7% 3 7% 7% 4 6% 6% 7% 9% 32%	2156
	21st to end	Day	13% 6% 3 6% 5% 4 6% 5% 6% 8% 37%	2376
September	1st to 10th	Day	15% 6% 2 5% 5% 3 6% 6% 6% 7% 40%	2160
	11th to 20th	Day	14% 6% 3 5% 5% 3 3 5% 4 7% 45%	2106
	21st to end	Day	14% 7% 2 5% 5% 3 5% 5% 6% 8% 39%	1980
October	1st to 10th	Day	20% 9% 3 7% 5% 3 5% 4 5% 5% 33%	1836
	11th to 20th	Day	14% 9% 2 6% 7% 4 4 5% 6% 8% 36%	1800
	21st to end	Day	22% 13% 3 6% 6% 2 5% 5% 6% 6% 26%	1824
November	1st to 10th	Day	14% 11% 4 6% 4 3 4 4 5% 7% 39%	1671
	11th to 20th	Day	14% 14% 4 7% 6% 4 5% 5% 5% 6% 31%	1710
	21st to end	Day	14% 13% 4 8% 6% 4 5% 5% 5% 6% 28%	1520
December	1st to 10th	Day	15% 16% 7% 11% 8% 5% 4 5% 6% 5% 20%	1520
	11th to 20th	Day	18% 15% 7% 8% 6% 2 4 4 4 6% 26%	1906
	21st to end	Day	20% 18% 9% 7% 6% 3 5% 4 5% 6% 18%	2772
January	1st to 10th	Night	12% 13% 6% 9% 6% 3 5% 6% 6% 7% 26%	2649
	11th to 20th	Night	14% 13% 5% 11% 9% 4 5% 6% 6% 6% 21%	2541
	21st to end	Night	10% 10% 6% 10% 8% 6% 6% 5% 6% 9% 24%	2677
February	1st to 10th	Night	14% 12% 6% 10% 9% 3 6% 6% 6% 6% 21%	2340
	11th to 20th	Night	11% 10% 6% 12% 8% 5% 6% 6% 6% 7% 23%	2155
	21st to end	Night	16% 11% 5% 11% 8% 4 6% 5% 5% 5% 24%	1776
March	1st to 10th	Night	14% 12% 6% 10% 6% 4 4 4 5% 7% 29%	2150
	11th to 20th	Night	14% 11% 5% 9% 7% 4 4 5% 5% 5% 30%	2041
	21st to end	Night	17% 11% 4 8% 4 3 4 4 5% 6% 35%	2015
April	1st to 10th	Night	16% 12% 5% 7% 6% 4 6% 5% 5% 6% 30%	1800
	11th to 20th	Night	19% 9% 4 6% 5% 3 4 4 5% 6% 36%	1775
	21st to end	Night	19% 11% 3 5% 5% 3 4 4 4 6% 35%	1755
May	1st to 10th	Night	23% 13% 3 6% 5% 3 4 4 4 5% 30%	1549
	11th to 20th	Night	16% 7% 4 5% 5% 3 5% 6% 6% 7% 36%	1415
	21st to end	Night	13% 4 3 6% 5% 3 5% 6% 5% 9% 41%	1550
June	1st to 10th	Night	14% 7% 3 6% 5% 3 4 5% 6% 8% 40%	1440
	11th to 20th	Night	16% 5% 2 5% 5% 2 4 5% 5% 10% 40%	1440
	21st to end	Night	11% 4 2 5% 5% 4 5% 5% 7% 9% 43%	1440
July	1st to 10th	Night	10% 5% 2 5% 5% 3 5% 5% 6% 9% 46%	1440
	11th to 20th	Night	11% 4 2 5% 5% 3 6% 5% 6% 9% 44%	1440
	21st to end	Night	11% 5% 2 5% 4 3 4 6% 6% 9% 44%	1574
August	1st to 10th	Night	9% 5% 2 4 5% 4 4 6% 7% 10% 44%	1481
	11th to 20th	Night	11% 6% 3 7% 6% 4 5% 6% 6% 7% 40%	1727
	21st to end	Night	14% 5% 2 5% 5% 3 4 4 6% 8% 44%	1980
September	1st to 10th	Night	14% 5% 2 4 4 3 4 5% 5% 9% 46%	1800
	11th to 20th	Night	15% 5% 2 3 3 2 4 3 4 7% 52%	1854
	21st to end	Night	14% 6% 1 5% 5% 3 5% 4 5% 8% 44%	1980
October	1st to 10th	Night	18% 7% 3 6% 6% 3 4 4 6% 6% 37%	2121
	11th to 20th	Night	17% 8% 3 6% 5% 3 4 5% 5% 7% 37%	2160
	21st to end	Night	23% 11% 3 6% 5% 3 5% 4 6% 6% 29%	2531
November	1st to 10th	Night	14% 10% 3 7% 5% 3 5% 4 5% 6% 39%	2407
	11th to 20th	Night	15% 12% 4 7% 5% 3 5% 5% 5% 7% 31%	2470
	21st to end	Night	13% 12% 6% 7% 7% 3 6% 5% 5% 6% 30%	2657
December	1st to 10th	Night	14% 14% 7% 11% 6% 3 5% 7% 5% 7% 21%	2660
	11th to 20th	Night	18% 12% 5% 9% 6% 3 5% 5% 5% 6% 24%	3288
	21st to end	Night	23% 14% 9% 7% 5% 3 4 4 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	57% 7% 13% 16% 8%	1518
	11th to 20th	Day	63% 7% 10% 12% 6% 2	1448
	21st to end	Day	59% 5% 13% 13% 7% 2	1678
February	1st to 10th	Day	66% 5% 11% 12% 5% 1	1620
	11th to 20th	Day	60% 6% 9% 16% 7% 1	1698
	21st to end	Day	61% 6% 10% 13% 10%	1480
March	1st to 10th	Day	54% 6% 13% 18% 8% 2	1800
	11th to 20th	Day	57% 4 10% 16% 11% 3	1916
	21st to end	Day	53% 4 9% 16% 15% 3	2340
April	1st to 10th	Day	53% 5% 9% 21% 10% 2	2160
	11th to 20th	Day	49% 6% 12% 19% 13% 1	2134
	21st to end	Day	54% 5% 9% 18% 11% 3	2204
May	1st to 10th	Day	55% 6% 8% 19% 10% 2	2425
	11th to 20th	Day	45% 7% 10% 23% 13% 2	2482
	21st to end	Day	44% 8% 15% 22% 9% 1	2725
June	1st to 10th	Day	48% 9% 13% 19% 11% 1	2520
	11th to 20th	Day	47% 8% 14% 20% 10% 1	2520
	21st to end	Day	48% 8% 14% 19% 10% 1	2520
July	1st to 10th	Day	43% 10% 13% 22% 12% 1	2450
	11th to 20th	Day	41% 8% 18% 23% 9%	2445
	21st to end	Day	45% 8% 15% 22% 11% 1	2591
August	1st to 10th	Day	41% 10% 15% 22% 11% 1	2439
	11th to 20th	Day	46% 9% 16% 22% 6%	2156
	21st to end	Day	42% 8% 14% 24% 11% 1	2376
September	1st to 10th	Day	42% 7% 12% 26% 12% 1	2160
	11th to 20th	Day	39% 5% 11% 25% 18% 1	2106
	21st to end	Day	40% 8% 14% 24% 13% 2	1980
October	1st to 10th	Day	51% 6% 11% 18% 12% 2	1836
	11th to 20th	Day	46% 6% 16% 23% 9% 1	1800
	21st to end	Day	57% 7% 12% 14% 8% 1	1824
November	1st to 10th	Day	44% 6% 14% 22% 12% 2	1671
	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	56% 7% 12% 15% 9% 1	2649
	11th to 20th	Night	62% 7% 12% 11% 6% 1	2541
	21st to end	Night	57% 6% 13% 15% 7% 2	2677
February	1st to 10th	Night	62% 7% 12% 12% 6% 1	2340
	11th to 20th	Night	59% 7% 12% 15% 6% 1	2157
	21st to end	Night	58% 7% 13% 13% 7% 1	1776
March	1st to 10th	Night	56% 6% 12% 18% 8% 1	2160
	11th to 20th	Night	55% 5% 12% 18% 9% 1	2042
	21st to end	Night	50% 5% 10% 18% 14% 3	2015
April	1st to 10th	Night	54% 6% 11% 18% 9% 1	1800
	11th to 20th	Night	49% 6% 11% 19% 14% 1	1775
	21st to end	Night	51% 6% 11% 18% 12% 3	1755
May	1st to 10th	Night	56% 6% 8% 14% 13% 2	1549
	11th to 20th	Night	45% 7% 12% 21% 14% 1	1416
	21st to end	Night	39% 10% 15% 23% 11% 2	1551
June	1st to 10th	Night	42% 7% 11% 25% 12% 2	1440
	11th to 20th	Night	40% 7% 16% 25% 11% 1	1440
	21st to end	Night	37% 8% 16% 27% 12% 1	1440
July	1st to 10th	Night	34% 10% 16% 25% 14% 2	1400
	11th to 20th	Night	36% 8% 18% 28% 10%	1392
	21st to end	Night	35% 9% 15% 26% 13% 2	1486
August	1st to 10th	Night	33% 11% 17% 29% 10% 1	1471
	11th to 20th	Night	40% 9% 17% 24% 9%	1727
	21st to end	Night	37% 8% 14% 27% 13% 1	1980
September	1st to 10th	Night	36% 7% 16% 28% 12% 1	1800
	11th to 20th	Night	34% 6% 12% 26% 21% 1	1854
	21st to end	Night	40% 6% 13% 25% 15% 2	1980
October	1st to 10th	Night	48% 6% 13% 20% 12% 1	2121
	11th to 20th	Night	46% 7% 16% 20% 10% 1	2160
	21st to end	Night	55% 6% 13% 16% 9% 1	2531
November	1st to 10th	Night	46% 6% 12% 19% 14% 2	2407
	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	29% 26% 31% 10% 3 1	180
	11th to 20th	Day	40% 23% 28% 6% 2 1	162
	21st to end	Day	27% 26% 36% 6% 4	218
February	1st to 10th	Day	38% 31% 25% 5%	240
	11th to 20th	Day	35% 31% 23% 10% 1	357
	21st to end	Day	36% 25% 27% 10% 2	346
March	1st to 10th	Day	31% 26% 30% 10% 2	420
	11th to 20th	Day	33% 23% 27% 12% 3 1	420
	21st to end	Day	35% 23% 22% 13% 5% 2	462
April	1st to 10th	Day	32% 26% 22% 12% 6% 1	420
	11th to 20th	Day	28% 24% 25% 13% 7% 3	412
	21st to end	Day	35% 17% 28% 12% 4 3	420
May	1st to 10th	Day	34% 18% 26% 11% 7% 3	423
	11th to 20th	Day	23% 19% 32% 17% 7% 2	447
	21st to end	Day	20% 12% 31% 21% 12% 4	485
June	1st to 10th	Day	19% 17% 34% 20% 9% 2	450
	11th to 20th	Day	20% 15% 30% 23% 10% 2	450
	21st to end	Day	20% 16% 30% 23% 10% 2	450
July	1st to 10th	Day	14% 9% 31% 27% 14% 4	445
	11th to 20th	Day	11% 7% 35% 30% 13% 4	444
	21st to end	Day	14% 10% 37% 27% 10% 3	488
August	1st to 10th	Day	11% 9% 29% 27% 19% 5%	446
	11th to 20th	Day	16% 9% 27% 27% 13% 8%	439
	21st to end	Day	14% 14% 28% 23% 14% 7%	495
September	1st to 10th	Day	17% 11% 26% 22% 16% 8%	450
	11th to 20th	Day	15% 10% 27% 20% 18% 9%	450
	21st to end	Day	17% 13% 30% 20% 14% 6%	450
October	1st to 10th	Day	24% 12% 27% 19% 14% 4	450
	11th to 20th	Day	24% 18% 28% 20% 10% 1	450
	21st to end	Day	30% 18% 28% 17% 6%	417
November	1st to 10th	Day	26% 19% 21% 19% 13% 1	365
	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	26% 26% 29% 16% 2 1	727
	21st to end	Night	20% 29% 31% 17% 2	792
February	1st to 10th	Night	29% 23% 32% 15% 2	720
	11th to 20th	Night	26% 27% 31% 14% 2	703
	21st to end	Night	31% 25% 28% 14% 2	592
March	1st to 10th	Night	28% 23% 31% 16% 3	720
	11th to 20th	Night	28% 24% 29% 16% 3	720
	21st to end	Night	26% 22% 26% 19% 6% 1	792
April	1st to 10th	Night	28% 22% 28% 19% 3	720
	11th to 20th	Night	25% 20% 28% 20% 6%	711
	21st to end	Night	28% 18% 26% 21% 6%	675
May	1st to 10th	Night	29% 14% 26% 22% 8% 1	469
	11th to 20th	Night	19% 16% 28% 30% 7% 1	354
	21st to end	Night	16% 7% 30% 33% 13% 1	389
June	1st to 10th	Night	17% 11% 23% 35% 12% 1	360
	11th to 20th	Night	18% 11% 21% 35% 15%	360
	21st to end	Night	13% 7% 26% 40% 13% 1	360
July	1st to 10th	Night	10% 6% 23% 41% 18% 2	350
	11th to 20th	Night	12% 5% 24% 41% 16% 2	348
	21st to end	Night	10% 6% 26% 43% 13% 2	394
August	1st to 10th	Night	10% 2 29% 36% 21% 1	407
	11th to 20th	Night	14% 5% 19% 37% 20% 4	663
	21st to end	Night	16% 7% 21% 35% 20% 2	792
September	1st to 10th	Night	15% 7% 25% 33% 18% 2	720
	11th to 20th	Night	16% 8% 23% 28% 18% 5%	720
	21st to end	Night	17% 10% 24% 30% 17% 2	720
October	1st to 10th	Night	24% 14% 21% 24% 15% 3	720
	11th to 20th	Night	21% 15% 26% 29% 9% 1	720
	21st to end	Night	29% 19% 26% 22% 5%	792
November	1st to 10th	Night	22% 17% 27% 26% 7%	740
	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 2024-01-09 07:14:40. Version ac07

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