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 2024-07-03.

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	8% 4 2 4 3 3 3 3 4 6% 59%	89738
	Night	7% 4 1 4 3 3 3 3 5% 6% 61%	89594
Transparency	Day	26% 4 8% 22% 26% 13%	89466
	Night	24% 4 8% 21% 27% 16%	89389
Seeing	Day	8% 6% 26% 32% 22% 6%	14734
	Night	8% 7% 33% 38% 14% 1	24704

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	7% 6% 2 5% 3 3 3 2 4 5% 61%	2847
	11th to 20th	Day	6% 4 1 3 2 2 3 2 4 6% 66%	2850
	21st to end	Day	12% 7% 2 4 3 3 3 3 4 5% 54%	3405
February	1st to 10th	Day	8% 5% 1 5% 3 3 2 2 4 6% 61%	1900
	11th to 20th	Day	9% 4 1 4 3 3 3 3 4 6% 58%	1849
	21st to end	Day	11% 6% 2 5% 3 2 3 2 4 5% 58%	1570
March	1st to 10th	Day	10% 4 1 3 3 3 2 3 5% 7% 59%	3130
	11th to 20th	Day	11% 5% 2 5% 4 3 3 2 4 5% 57%	3470
	21st to end	Day	8% 7% 2 4 4 4 5% 4 5% 6% 53%	3814
April	1st to 10th	Day	7% 3 2 3 3 3 3 2 3 6% 64%	2237
	11th to 20th	Day	11% 4 2 4 3 2 3 3 5% 5% 57%	2251
	21st to end	Day	8% 5% 1 4 3 3 3 3 5% 5% 61%	2353
May	1st to 10th	Day	13% 4 2 4 2 3 3 3 4 6% 57%	4120
	11th to 20th	Day	13% 5% 2 4 3 3 3 2 3 6% 56%	4082
	21st to end	Day	10% 4 1 4 4 3 3 3 4 6% 58%	4489
June	1st to 10th	Day	6% 3 1 4 3 3 3 4 4 8% 60%	2470
	11th to 20th	Day	5% 3 1 3 3 3 4 4 5% 7% 61%	2470
	21st to end	Day	4 3 1 3 3 3 3 4 4 6% 64%	2470
July	1st to 10th	Day	6% 3 1 4 4 5% 4 4 8% 10% 50%	2367
	11th to 20th	Day	5% 2 1 3 3 2 3 3 5% 8% 64%	2340
	21st to end	Day	2 2 1 3 3 4 4 4 7% 10% 59%	2546
August	1st to 10th	Day	3 2 1 3 3 3 3 3 5% 8% 65%	2250
	11th to 20th	Day	7% 3 2 4 3 4 5% 4 7% 9% 52%	2123
	21st to end	Day	4 3 2 4 4 4 4 4 6% 7% 57%	2376
September	1st to 10th	Day	10% 3 2 5% 3 3 4 2 4 6% 58%	2063
	11th to 20th	Day	9% 5% 2 6% 4 4 4 3 6% 8% 50%	1980
	21st to end	Day	9% 2 1 3 2 3 4 3 4 6% 62%	1980
October	1st to 10th	Day	6% 3 1 5% 3 3 4 3 4 6% 63%	1980
	11th to 20th	Day	7% 4 1 4 2 2 3 2 3 4 68%	1949
	21st to end	Day	10% 4 1 3 2 2 2 2 3 3 67%	1908
November	1st to 10th	Day	8% 3 1 3 2 2 3 3 4 6% 66%	1673
	11th to 20th	Day	4 4 1 3 3 2 3 3 4 7% 68%	1710
	21st to end	Day	11% 5% 1 3 2 3 2 2 4 5% 61%	1710
December	1st to 10th	Day	8% 4 2 5% 2 4 3 3 3 6% 59%	1710
	11th to 20th	Day	7% 4 2 4 4 4 4 3 4 6% 58%	2161
	21st to end	Day	9% 5% 2 4 3 3 3 2 3 5% 61%	3135
January	1st to 10th	Night	7% 5% 1 5% 2 3 3 3 5% 5% 61%	4108
	11th to 20th	Night	4 4 1 4 3 3 3 3 4 6% 66%	4120
	21st to end	Night	9% 8% 2 4 3 3 3 2 5% 5% 56%	4277
February	1st to 10th	Night	8% 5% 2 5% 4 3 3 2 5% 5% 59%	2280
	11th to 20th	Night	8% 6% 2 4 3 2 3 3 5% 6% 58%	2218
	21st to end	Night	7% 5% 2 4 4 3 2 3 4 5% 60%	1884
March	1st to 10th	Night	6% 6% 2 4 3 3 2 2 3 5% 62%	3734
	11th to 20th	Night	9% 4 2 4 3 2 3 2 3 6% 61%	3489
	21st to end	Night	4 6% 3 6% 4 3 4 4 6% 6% 53%	3817
April	1st to 10th	Night	6% 3 1 4 4 3 4 2 4 5% 64%	1938
	11th to 20th	Night	10% 4 1 3 3 3 3 3 5% 7% 59%	1877
	21st to end	Night	6% 2 1 3 3 2 3 3 5% 7% 65%	1824
May	1st to 10th	Night	13% 5% 2 3 3 3 3 2 4 4 58%	2850
	11th to 20th	Night	8% 5% 1 4 4 3 4 4 5% 6% 56%	2823
	21st to end	Night	8% 3 1 3 2 2 3 3 4 6% 63%	3098
June	1st to 10th	Night	5% 3 1 4 3 3 3 3 7% 10% 57%	1710
	11th to 20th	Night	3 3 1 4 3 3 5% 3 7% 9% 60%	1710
	21st to end	Night	4 2 1 2 3 2 3 4 6% 8% 64%	1710
July	1st to 10th	Night	4 3 1 4 4 3 5% 5% 7% 10% 53%	1638
	11th to 20th	Night	3 2 1 3 3 3 4 4 5% 9% 62%	1620
	21st to end	Night	2 2 1 2 3 3 4 4 6% 10% 62%	1772
August	1st to 10th	Night	2 2 1 3 3 4 3 4 7% 10% 63%	1685
	11th to 20th	Night	5% 4 2 4 4 4 5% 5% 7% 10% 52%	1778
	21st to end	Night	4 3 1 3 3 3 3 4 6% 10% 61%	1980
September	1st to 10th	Night	7% 4 2 4 4 3 4 3 5% 6% 58%	1895
	11th to 20th	Night	10% 5% 2 4 3 3 4 5% 6% 7% 50%	1980
	21st to end	Night	7% 3 1 4 2 3 3 3 4 7% 64%	1980
October	1st to 10th	Night	7% 3 1 3 3 3 3 2 4 6% 65%	1980
	11th to 20th	Night	8% 3 1 3 2 2 2 2 3 4 71%	1993
	21st to end	Night	7% 3 1 3 3 1 2 2 3 5% 69%	2443
November	1st to 10th	Night	6% 3 1 2 2 2 2 3 4 5% 70%	2405
	11th to 20th	Night	4 3 1 3 2 2 3 2 5% 6% 70%	2470
	21st to end	Night	8% 4 1 3 3 3 3 3 4 7% 62%	2470
December	1st to 10th	Night	8% 4 1 3 3 3 3 3 3 5% 64%	2470
	11th to 20th	Night	7% 4 2 4 3 3 4 3 5% 6% 59%	3036
	21st to end	Night	6% 5% 2 5% 3 3 4 2 4 5% 61%	4532

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% 26% 16%	2848
	11th to 20th	Day	21% 2 6% 23% 35% 12%	2850
	21st to end	Day	34% 3 6% 20% 29% 8%	3405
February	1st to 10th	Day	27% 3 6% 21% 29% 14%	1900
	11th to 20th	Day	29% 3 6% 22% 25% 15%	1859
	21st to end	Day	30% 2 4 15% 29% 20%	1570
March	1st to 10th	Day	26% 4 5% 11% 29% 26%	3130
	11th to 20th	Day	32% 3 7% 23% 25% 10%	3470
	21st to end	Day	30% 5% 6% 22% 25% 11%	3814
April	1st to 10th	Day	24% 3 7% 19% 26% 21%	2237
	11th to 20th	Day	30% 4 6% 16% 24% 19%	2254
	21st to end	Day	25% 3 8% 23% 29% 11%	2353
May	1st to 10th	Day	29% 5% 6% 19% 21% 20%	4120
	11th to 20th	Day	31% 4 9% 22% 20% 14%	4086
	21st to end	Day	28% 5% 8% 19% 21% 19%	4489
June	1st to 10th	Day	23% 5% 14% 30% 20% 8%	2470
	11th to 20th	Day	22% 5% 10% 24% 28% 10%	2470
	21st to end	Day	20% 5% 11% 27% 27% 10%	2470
July	1st to 10th	Day	26% 9% 14% 26% 21% 4	2303
	11th to 20th	Day	17% 5% 8% 30% 31% 7%	2271
	21st to end	Day	17% 7% 16% 32% 26% 3	2405
August	1st to 10th	Day	17% 5% 12% 30% 26% 10%	2236
	11th to 20th	Day	26% 7% 14% 26% 20% 6%	2123
	21st to end	Day	24% 6% 13% 24% 24% 9%	2376
September	1st to 10th	Day	29% 5% 8% 22% 25% 12%	2063
	11th to 20th	Day	33% 5% 10% 20% 25% 7%	1980
	21st to end	Day	24% 4 7% 20% 32% 13%	1980
October	1st to 10th	Day	23% 5% 10% 24% 25% 13%	1980
	11th to 20th	Day	24% 3 5% 14% 31% 24%	1949
	21st to end	Day	24% 3 4 22% 30% 17%	1908
November	1st to 10th	Day	21% 3 6% 20% 30% 19%	1673
	11th to 20th	Day	19% 3 5% 22% 34% 17%	1710
	21st to end	Day	27% 2 4 18% 30% 18%	1710
December	1st to 10th	Day	27% 4 5% 25% 27% 12%	1710
	11th to 20th	Day	28% 3 11% 16% 28% 14%	2159
	21st to end	Day	28% 3 5% 20% 31% 12%	3135
January	1st to 10th	Night	26% 3 6% 25% 29% 11%	4108
	11th to 20th	Night	20% 3 10% 20% 33% 13%	4120
	21st to end	Night	31% 2 7% 18% 30% 11%	4277
February	1st to 10th	Night	27% 4 7% 17% 28% 17%	2280
	11th to 20th	Night	28% 3 6% 20% 25% 18%	2218
	21st to end	Night	27% 3 4 16% 26% 24%	1884
March	1st to 10th	Night	26% 3 4 13% 22% 31%	3734
	11th to 20th	Night	26% 3 8% 24% 22% 16%	3489
	21st to end	Night	30% 5% 7% 22% 24% 13%	3817
April	1st to 10th	Night	23% 3 7% 19% 24% 23%	1938
	11th to 20th	Night	27% 3 8% 17% 26% 20%	1877
	21st to end	Night	20% 4 10% 25% 28% 13%	1824
May	1st to 10th	Night	29% 5% 7% 20% 15% 24%	2850
	11th to 20th	Night	28% 5% 11% 21% 22% 13%	2824
	21st to end	Night	23% 5% 9% 17% 21% 25%	3099
June	1st to 10th	Night	21% 6% 15% 29% 20% 8%	1710
	11th to 20th	Night	20% 6% 11% 24% 28% 11%	1710
	21st to end	Night	18% 4 10% 27% 25% 15%	1710
July	1st to 10th	Night	23% 9% 12% 32% 19% 5%	1593
	11th to 20th	Night	17% 4 8% 24% 34% 13%	1566
	21st to end	Night	15% 5% 11% 32% 33% 5%	1673
August	1st to 10th	Night	15% 5% 9% 31% 30% 11%	1675
	11th to 20th	Night	26% 6% 13% 25% 24% 6%	1778
	21st to end	Night	18% 5% 13% 28% 25% 11%	1980
September	1st to 10th	Night	27% 5% 8% 21% 25% 14%	1895
	11th to 20th	Night	30% 6% 12% 18% 25% 9%	1980
	21st to end	Night	22% 4 7% 21% 29% 18%	1980
October	1st to 10th	Night	22% 4 10% 21% 27% 16%	1980
	11th to 20th	Night	20% 3 5% 17% 27% 28%	1993
	21st to end	Night	20% 3 6% 18% 33% 20%	2443
November	1st to 10th	Night	18% 2 7% 23% 29% 20%	2405
	11th to 20th	Night	17% 3 5% 21% 36% 18%	2470
	21st to end	Night	24% 3 5% 18% 31% 19%	2470
December	1st to 10th	Night	24% 3 6% 23% 28% 16%	2470
	11th to 20th	Night	26% 4 6% 19% 30% 15%	3037
	21st to end	Night	25% 4 4 20% 30% 17%	4532

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	7% 11% 43% 27% 11% 1	270
	11th to 20th	Day	14% 13% 30% 31% 10% 1	270
	21st to end	Day	9% 12% 39% 30% 9% 1	297
February	1st to 10th	Day	13% 12% 40% 27% 8%	270
	11th to 20th	Day	13% 9% 44% 26% 8%	270
	21st to end	Day	21% 16% 38% 23% 3	225
March	1st to 10th	Day	11% 9% 43% 31% 6%	270
	11th to 20th	Day	14% 10% 43% 23% 9% 1	270
	21st to end	Day	12% 13% 40% 26% 9%	297
April	1st to 10th	Day	10% 17% 43% 23% 8%	417
	11th to 20th	Day	13% 14% 47% 23% 3 1	452
	21st to end	Day	10% 14% 41% 27% 8% 2	533
May	1st to 10th	Day	9% 9% 41% 32% 9%	653
	11th to 20th	Day	11% 8% 31% 31% 15% 3	675
	21st to end	Day	8% 6% 35% 33% 15% 4	734
June	1st to 10th	Day	5% 3 20% 42% 25% 3	680
	11th to 20th	Day	6% 2 24% 42% 25% 2	680
	21st to end	Day	4 1 13% 41% 33% 8%	680
July	1st to 10th	Day	5% 8% 38% 35% 13%	632
	11th to 20th	Day	4 7% 34% 44% 11%	618
	21st to end	Day	2 1 4 32% 46% 16%	684
August	1st to 10th	Day	3 1 6% 33% 45% 12%	548
	11th to 20th	Day	6% 2 7% 33% 37% 16%	437
	21st to end	Day	5% 1 7% 29% 42% 16%	495
September	1st to 10th	Day	8% 1 6% 30% 38% 16%	353
	11th to 20th	Day	6% 3 7% 34% 38% 12%	270
	21st to end	Day	12% 3 9% 30% 34% 12%	270
October	1st to 10th	Day	7% 1 22% 33% 31% 5%	270
	11th to 20th	Day	7% 6% 32% 34% 19% 3	270
	21st to end	Day	17% 9% 26% 29% 16% 3	297
November	1st to 10th	Day	14% 6% 27% 35% 16% 2	270
	11th to 20th	Day	6% 11% 29% 34% 16% 4	270
	21st to end	Day	17% 13% 30% 24% 13% 3	270
December	1st to 10th	Day	10% 9% 41% 26% 12% 2	270
	11th to 20th	Day	9% 9% 36% 34% 10% 1	270
	21st to end	Day	16% 13% 42% 21% 8% 1	297
January	1st to 10th	Night	7% 9% 38% 36% 11%	950
	11th to 20th	Night	8% 11% 34% 39% 8%	950
	21st to end	Night	8% 9% 34% 42% 6%	894
February	1st to 10th	Night	9% 11% 41% 33% 6% 1	760
	11th to 20th	Night	10% 12% 42% 30% 6%	744
	21st to end	Night	10% 14% 44% 29% 3	628
March	1st to 10th	Night	9% 12% 45% 29% 5%	760
	11th to 20th	Night	13% 13% 39% 28% 7%	579
	21st to end	Night	7% 16% 43% 31% 4	627
April	1st to 10th	Night	6% 12% 52% 27% 3	570
	11th to 20th	Night	12% 11% 53% 23% 2	563
	21st to end	Night	6% 9% 49% 30% 5%	570
May	1st to 10th	Night	8% 10% 46% 31% 4	570
	11th to 20th	Night	9% 7% 40% 32% 11% 1	561
	21st to end	Night	6% 6% 40% 37% 10% 1	617
June	1st to 10th	Night	5% 3 29% 46% 17%	570
	11th to 20th	Night	3 2 38% 51% 7%	570
	21st to end	Night	5% 2 24% 45% 24% 1	570
July	1st to 10th	Night	4 13% 45% 35% 4	531
	11th to 20th	Night	4 1 9% 49% 35% 2	522
	21st to end	Night	2 5% 48% 44% 1	591
August	1st to 10th	Night	2 7% 51% 37% 2	537
	11th to 20th	Night	6% 1 10% 47% 36% 1	534
	21st to end	Night	5% 1 7% 42% 42% 3	594
September	1st to 10th	Night	9% 10% 45% 34% 2	540
	11th to 20th	Night	11% 2 15% 47% 25% 1	540
	21st to end	Night	7% 2 19% 45% 26% 1	540
October	1st to 10th	Night	7% 4 28% 41% 19% 1	540
	11th to 20th	Night	9% 5% 34% 37% 13%	553
	21st to end	Night	8% 9% 31% 36% 15% 1	859
November	1st to 10th	Night	8% 6% 31% 41% 13% 1	925
	11th to 20th	Night	5% 8% 36% 39% 12% 1	950
	21st to end	Night	10% 8% 36% 34% 11% 1	950
December	1st to 10th	Night	10% 7% 35% 40% 8%	950
	11th to 20th	Night	11% 8% 38% 36% 6% 1	950
	21st to end	Night	9% 9% 39% 35% 7%	1045

Page generated at 2024-06-29 21:08:49. Version ac07

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