Paducah Skies/Star Ranch Observatories
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Paducah Skies/Star Ranch Observatories clear sky chart from 2005-11-06 to 2026-03-03.

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	7% 4 1 4 3 3 3 3 5% 6% 61%	140064
	Night	6% 4 1 4 3 3 3 3 5% 7% 63%	138517
Transparency	Day	25% 3 8% 22% 28% 15%	135091
	Night	23% 3 7% 22% 28% 17%	134513
Seeing	Day	8% 7% 26% 32% 22% 6%	16911
	Night	8% 7% 33% 38% 14% 1	26980

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	6% 5% 2 5% 3 4 4 3 4 5% 60%	5287
	11th to 20th	Day	4 4 1 3 2 2 2 2 3 5% 73%	5310
	21st to end	Day	13% 4 2 4 3 3 3 3 4 6% 56%	6330
February	1st to 10th	Day	8% 5% 1 4 3 3 3 2 4 6% 61%	2100
	11th to 20th	Day	9% 5% 1 4 3 3 3 4 4 6% 57%	2049
	21st to end	Day	10% 6% 2 5% 2 2 3 2 4 5% 61%	1730
March	1st to 10th	Day	10% 4 1 3 3 3 2 3 4 6% 60%	4520
	11th to 20th	Day	8% 4 2 5% 3 3 3 2 4 6% 60%	4970
	21st to end	Day	6% 5% 1 3 3 3 4 3 6% 7% 58%	5464
April	1st to 10th	Day	8% 3 2 3 3 3 3 2 3 6% 63%	2355
	11th to 20th	Day	11% 5% 2 4 3 2 3 3 5% 5% 57%	2371
	21st to end	Day	8% 5% 1 4 3 3 3 3 5% 5% 61%	2477
May	1st to 10th	Day	15% 4 2 4 2 3 3 3 4 6% 54%	5900
	11th to 20th	Day	10% 4 1 4 3 3 3 2 4 6% 61%	5862
	21st to end	Day	10% 5% 2 5% 4 3 4 3 5% 6% 53%	6446
June	1st to 10th	Day	6% 3 1 4 4 4 4 4 5% 8% 59%	2600
	11th to 20th	Day	5% 3 1 3 3 3 4 4 5% 7% 62%	2600
	21st to end	Day	4 4 1 3 4 4 3 4 5% 6% 62%	2600
July	1st to 10th	Day	11% 6% 2 5% 4 4 4 3 6% 8% 45%	5899
	11th to 20th	Day	3 2 1 4 3 3 4 3 6% 9% 62%	5900
	21st to end	Day	2 2 1 2 2 3 3 3 6% 8% 68%	6424
August	1st to 10th	Day	3 2 1 3 2 3 3 3 5% 7% 68%	5586
	11th to 20th	Day	4 2 1 4 3 4 5% 5% 8% 11% 55%	5366
	21st to end	Day	6% 3 1 4 4 3 4 3 5% 7% 59%	5984
September	1st to 10th	Day	11% 3 2 5% 3 3 4 2 4 6% 57%	2291
	11th to 20th	Day	8% 5% 2 5% 4 4 4 3 5% 8% 52%	2200
	21st to end	Day	9% 2 1 3 2 3 4 4 4 6% 63%	2200
October	1st to 10th	Day	3 2 1 3 2 2 2 2 3 4 77%	3590
	11th to 20th	Day	6% 4 2 5% 3 3 3 2 3 4 66%	3509
	21st to end	Day	6% 3 1 2 1 2 2 2 3 4 74%	3413
November	1st to 10th	Day	8% 3 1 3 2 2 3 2 3 6% 67%	1853
	11th to 20th	Day	3 3 1 3 2 2 3 2 4 7% 68%	1890
	21st to end	Day	10% 5% 1 3 2 2 3 2 4 5% 62%	1890
December	1st to 10th	Day	6% 4 2 6% 3 3 3 3 4 6% 60%	3030
	11th to 20th	Day	5% 2 1 3 3 3 4 3 4 5% 67%	3481
	21st to end	Day	8% 6% 2 5% 3 3 3 2 3 4 63%	4587
January	1st to 10th	Night	6% 6% 2 5% 2 3 3 2 4 6% 60%	7634
	11th to 20th	Night	2 3 1 3 2 2 2 2 3 5% 74%	7680
	21st to end	Night	10% 7% 2 5% 3 3 3 2 4 6% 55%	7927
February	1st to 10th	Night	7% 5% 2 5% 3 2 3 2 5% 5% 61%	2520
	11th to 20th	Night	8% 6% 2 4 3 2 3 3 5% 7% 57%	2458
	21st to end	Night	6% 5% 2 4 4 2 2 3 4 5% 61%	2076
March	1st to 10th	Night	6% 6% 2 4 3 3 2 3 4 6% 62%	5398
	11th to 20th	Night	6% 3 1 4 3 3 3 2 3 6% 66%	4989
	21st to end	Night	3 5% 2 5% 3 3 4 4 6% 6% 59%	5467
April	1st to 10th	Night	6% 4 1 4 3 3 3 2 4 5% 63%	2040
	11th to 20th	Night	10% 4 1 3 2 3 3 3 4 7% 59%	1977
	21st to end	Night	7% 2 1 3 3 2 3 3 5% 7% 63%	1920
May	1st to 10th	Night	12% 5% 2 3 3 3 3 2 4 4 59%	4080
	11th to 20th	Night	6% 4 1 3 3 3 4 4 6% 7% 60%	4053
	21st to end	Night	10% 5% 2 4 3 3 4 3 4 7% 57%	4451
June	1st to 10th	Night	5% 3 1 4 3 3 3 4 7% 10% 57%	1800
	11th to 20th	Night	3 3 1 4 3 3 5% 3 7% 9% 60%	1800
	21st to end	Night	4 2 1 3 3 2 3 5% 6% 8% 63%	1800
July	1st to 10th	Night	6% 6% 2 6% 5% 4 5% 4 6% 9% 47%	4080
	11th to 20th	Night	3 2 1 3 3 3 3 4 6% 10% 62%	4080
	21st to end	Night	2 2 1 3 3 4 4 4 6% 9% 63%	4449
August	1st to 10th	Night	2 2 1 3 2 3 2 2 5% 8% 71%	4208
	11th to 20th	Night	2 2 1 3 3 4 5% 4 8% 13% 55%	4483
	21st to end	Night	5% 4 1 4 3 3 3 4 6% 9% 58%	4993
September	1st to 10th	Night	8% 4 2 4 4 3 4 3 5% 6% 57%	2107
	11th to 20th	Night	9% 4 2 4 3 3 4 5% 6% 8% 52%	2200
	21st to end	Night	7% 3 1 4 2 3 3 3 4 7% 64%	2200
October	1st to 10th	Night	4 2 1 2 2 2 2 2 3 4 79%	3590
	11th to 20th	Night	6% 3 1 3 2 3 3 2 5% 6% 65%	3597
	21st to end	Night	4 2 1 2 2 1 2 2 3 6% 75%	4376
November	1st to 10th	Night	7% 3 1 2 2 2 2 3 4 5% 70%	2665
	11th to 20th	Night	4 3 1 3 2 2 3 2 5% 6% 70%	2730
	21st to end	Night	8% 4 1 3 3 3 3 3 4 6% 62%	2730
December	1st to 10th	Night	6% 3 1 3 3 3 3 3 4 6% 64%	4380
	11th to 20th	Night	4 3 1 3 2 3 3 2 5% 6% 67%	4946
	21st to end	Night	6% 5% 2 5% 3 2 3 2 4 5% 63%	6633

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	27% 2 5% 24% 28% 15%	5290
	11th to 20th	Day	17% 1 4 19% 38% 20%	5310
	21st to end	Day	31% 2 6% 18% 29% 14%	6330
February	1st to 10th	Day	26% 3 5% 21% 31% 14%	2100
	11th to 20th	Day	29% 3 6% 23% 25% 14%	2059
	21st to end	Day	28% 2 4 16% 29% 21%	1730
March	1st to 10th	Day	26% 3 3 9% 27% 31%	4520
	11th to 20th	Day	28% 3 5% 16% 24% 25%	4970
	21st to end	Day	24% 4 7% 24% 29% 12%	5464
April	1st to 10th	Day	25% 3 7% 18% 28% 20%	2355
	11th to 20th	Day	30% 4 6% 17% 25% 19%	2374
	21st to end	Day	26% 3 8% 23% 28% 11%	2477
May	1st to 10th	Day	31% 4 8% 23% 20% 14%	5900
	11th to 20th	Day	27% 3 7% 17% 22% 24%	5866
	21st to end	Day	33% 4 9% 21% 17% 16%	6447
June	1st to 10th	Day	24% 5% 13% 30% 20% 8%	2600
	11th to 20th	Day	22% 5% 10% 24% 29% 10%	2600
	21st to end	Day	22% 4 11% 27% 26% 10%	2600
July	1st to 10th	Day	36% 5% 9% 22% 22% 5%	5836
	11th to 20th	Day	20% 4 12% 29% 29% 5%	5831
	21st to end	Day	14% 4 16% 33% 28% 6%	6240
August	1st to 10th	Day	14% 3 10% 24% 31% 16%	4067
	11th to 20th	Day	18% 5% 10% 27% 29% 11%	3882
	21st to end	Day	21% 5% 12% 25% 28% 8%	4311
September	1st to 10th	Day	29% 4 8% 22% 25% 12%	2291
	11th to 20th	Day	31% 4 9% 22% 26% 7%	2200
	21st to end	Day	24% 4 6% 20% 33% 14%	2200
October	1st to 10th	Day	13% 3 6% 14% 35% 29%	3590
	11th to 20th	Day	25% 2 4 21% 26% 21%	3509
	21st to end	Day	16% 2 3 27% 38% 13%	3413
November	1st to 10th	Day	21% 3 6% 19% 32% 19%	1853
	11th to 20th	Day	19% 2 5% 21% 35% 18%	1890
	21st to end	Day	27% 2 4 19% 31% 17%	1890
December	1st to 10th	Day	26% 3 4 30% 27% 10%	3030
	11th to 20th	Day	22% 2 7% 17% 34% 18%	3479
	21st to end	Day	28% 2 5% 23% 30% 13%	4587
January	1st to 10th	Night	27% 2 4 27% 30% 9%	7635
	11th to 20th	Night	14% 2 6% 20% 38% 19%	7680
	21st to end	Night	32% 2 5% 17% 31% 13%	7927
February	1st to 10th	Night	26% 3 6% 17% 29% 18%	2520
	11th to 20th	Night	28% 3 7% 20% 24% 17%	2458
	21st to end	Night	26% 3 4 17% 26% 25%	2076
March	1st to 10th	Night	25% 3 3 12% 21% 36%	5398
	11th to 20th	Night	22% 3 6% 17% 17% 36%	4989
	21st to end	Night	25% 4 8% 19% 30% 14%	5467
April	1st to 10th	Night	24% 3 7% 19% 25% 22%	2040
	11th to 20th	Night	27% 3 8% 16% 26% 19%	1977
	21st to end	Night	21% 4 10% 25% 27% 12%	1920
May	1st to 10th	Night	29% 4 11% 23% 16% 17%	4080
	11th to 20th	Night	23% 4 8% 15% 24% 26%	4054
	21st to end	Night	30% 5% 10% 18% 16% 22%	4452
June	1st to 10th	Night	21% 6% 15% 30% 20% 8%	1800
	11th to 20th	Night	19% 5% 11% 25% 28% 11%	1800
	21st to end	Night	19% 4 11% 27% 25% 15%	1800
July	1st to 10th	Night	34% 6% 10% 29% 19% 3	4035
	11th to 20th	Night	16% 3 11% 32% 30% 8%	4026
	21st to end	Night	18% 3 12% 30% 31% 7%	4320
August	1st to 10th	Night	12% 3 7% 27% 34% 16%	3064
	11th to 20th	Night	17% 4 11% 26% 30% 11%	3243
	21st to end	Night	18% 4 14% 27% 27% 10%	3597
September	1st to 10th	Night	27% 5% 9% 21% 25% 13%	2107
	11th to 20th	Night	28% 5% 11% 20% 26% 9%	2200
	21st to end	Night	22% 4 7% 20% 29% 18%	2200
October	1st to 10th	Night	12% 2 6% 13% 32% 34%	3590
	11th to 20th	Night	21% 2 7% 20% 27% 23%	3597
	21st to end	Night	14% 2 4 23% 38% 20%	4376
November	1st to 10th	Night	18% 2 7% 22% 30% 21%	2665
	11th to 20th	Night	17% 3 5% 20% 37% 19%	2730
	21st to end	Night	24% 3 5% 20% 31% 17%	2730
December	1st to 10th	Night	22% 3 5% 27% 32% 12%	4380
	11th to 20th	Night	19% 3 4 18% 35% 20%	4947
	21st to end	Night	25% 3 4 26% 27% 14%	6633

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	8% 11% 41% 28% 11% 1	330
	11th to 20th	Day	13% 14% 31% 32% 9% 2	330
	21st to end	Day	11% 12% 38% 30% 9% 1	363
February	1st to 10th	Day	12% 11% 40% 27% 8% 2	330
	11th to 20th	Day	12% 12% 43% 25% 8% 1	330
	21st to end	Day	18% 15% 37% 24% 5% 1	273
March	1st to 10th	Day	12% 9% 41% 30% 7%	306
	11th to 20th	Day	15% 11% 43% 22% 8% 1	300
	21st to end	Day	11% 12% 41% 26% 10% 1	330
April	1st to 10th	Day	11% 16% 41% 24% 7%	455
	11th to 20th	Day	13% 14% 47% 23% 3 1	492
	21st to end	Day	10% 13% 42% 26% 7% 2	577
May	1st to 10th	Day	9% 8% 40% 33% 9%	703
	11th to 20th	Day	11% 9% 32% 31% 15% 3	725
	21st to end	Day	8% 6% 35% 33% 15% 3	789
June	1st to 10th	Day	5% 4 21% 42% 25% 3	730
	11th to 20th	Day	6% 2 23% 42% 25% 2	730
	21st to end	Day	4 2 14% 42% 32% 8%	730
July	1st to 10th	Day	7% 1 8% 36% 34% 13%	721
	11th to 20th	Day	3 1 8% 35% 43% 10%	718
	21st to end	Day	2 1 5% 33% 45% 15%	794
August	1st to 10th	Day	3 1 6% 34% 44% 12%	638
	11th to 20th	Day	5% 1 7% 34% 38% 15%	517
	21st to end	Day	5% 1 7% 29% 42% 16%	583
September	1st to 10th	Day	9% 2 5% 32% 37% 14%	421
	11th to 20th	Day	6% 2 8% 37% 35% 12%	330
	21st to end	Day	11% 2 9% 30% 36% 12%	330
October	1st to 10th	Day	6% 2 20% 34% 32% 7%	330
	11th to 20th	Day	6% 5% 31% 35% 20% 3	330
	21st to end	Day	15% 10% 25% 28% 18% 4	363
November	1st to 10th	Day	13% 7% 28% 34% 16% 2	330
	11th to 20th	Day	5% 12% 28% 35% 15% 5%	330
	21st to end	Day	15% 12% 32% 25% 13% 3	330
December	1st to 10th	Day	9% 8% 43% 26% 12% 2	330
	11th to 20th	Day	7% 8% 36% 36% 11% 2	330
	21st to end	Day	15% 12% 39% 23% 10% 1	363
January	1st to 10th	Night	7% 10% 38% 35% 10%	1050
	11th to 20th	Night	8% 11% 35% 38% 8%	1050
	21st to end	Night	9% 9% 36% 40% 6%	988
February	1st to 10th	Night	9% 10% 42% 33% 6%	840
	11th to 20th	Night	10% 13% 42% 29% 5%	824
	21st to end	Night	9% 14% 43% 32% 3	692
March	1st to 10th	Night	9% 12% 43% 30% 4	808
	11th to 20th	Night	12% 13% 41% 27% 7%	609
	21st to end	Night	6% 15% 44% 31% 3	660
April	1st to 10th	Night	6% 13% 51% 27% 3	600
	11th to 20th	Night	12% 11% 53% 22% 2	593
	21st to end	Night	7% 9% 50% 30% 5%	600
May	1st to 10th	Night	9% 10% 45% 32% 4	600
	11th to 20th	Night	8% 8% 40% 32% 10% 1	591
	21st to end	Night	7% 6% 39% 37% 10% 1	650
June	1st to 10th	Night	5% 3 30% 46% 16%	600
	11th to 20th	Night	3 2 37% 51% 7%	600
	21st to end	Night	5% 2 24% 46% 23% 1	600
July	1st to 10th	Night	5% 1 14% 44% 34% 3	585
	11th to 20th	Night	3 1 9% 51% 34% 1	582
	21st to end	Night	2 6% 49% 42% 1	657
August	1st to 10th	Night	2 1 8% 54% 35% 2	597
	11th to 20th	Night	5% 1 10% 47% 36% 1	594
	21st to end	Night	5% 1 7% 42% 42% 3	660
September	1st to 10th	Night	9% 1 11% 46% 32% 2	600
	11th to 20th	Night	10% 2 15% 49% 24% 1	600
	21st to end	Night	7% 2 20% 44% 26% 1	600
October	1st to 10th	Night	6% 3 28% 43% 20% 1	600
	11th to 20th	Night	9% 5% 35% 38% 13%	615
	21st to end	Night	7% 10% 31% 36% 15% 1	955
November	1st to 10th	Night	8% 6% 31% 41% 12% 1	1025
	11th to 20th	Night	5% 8% 36% 39% 12% 1	1050
	21st to end	Night	10% 8% 36% 34% 11% 1	1050
December	1st to 10th	Night	9% 7% 36% 40% 7%	1050
	11th to 20th	Night	10% 8% 38% 37% 6% 1	1050
	21st to end	Night	9% 9% 40% 35% 7%	1155

Page generated at 2026-02-28 00:40:23. Version ac07

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