Hopkinsville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hopkinsville clear sky chart from 2005-11-06 to 2025-04-11.

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	13% 7% 3 7% 4 4 4 3 5% 7% 42%	113347
	Night	14% 7% 3 6% 4 4 4 3 5% 6% 43%	115032
Transparency	Day	40% 6% 10% 24% 18% 3	117038
	Night	39% 5% 9% 23% 19% 4	119470
Seeing	Day	16% 10% 24% 24% 18% 8%	15853
	Night	17% 8% 25% 30% 17% 2	25767

By Month

Percentage Cloud Cover SE (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	15% 10% 7% 10% 5% 4 4 3 5% 5% 31%	3617
	11th to 20th	Day	13% 9% 3 9% 5% 3 4 3 4 6% 41%	3620
	21st to end	Day	20% 9% 4 6% 3 4 4 3 4 6% 38%	4712
February	1st to 10th	Day	18% 11% 4 6% 5% 4 4 3 5% 6% 35%	2000
	11th to 20th	Day	20% 9% 3 8% 4 3 4 3 4 6% 35%	1948
	21st to end	Day	18% 10% 3 7% 6% 3 4 3 4 5% 37%	1650
March	1st to 10th	Day	16% 13% 3 8% 4 4 3 3 4 4 37%	4480
	11th to 20th	Day	13% 8% 3 6% 4 3 3 2 5% 6% 47%	4658
	21st to end	Day	12% 8% 3 7% 4 4 4 3 5% 6% 43%	5938
April	1st to 10th	Day	14% 6% 2 7% 5% 4 4 4 5% 7% 43%	2400
	11th to 20th	Day	15% 7% 3 7% 5% 5% 3 3 6% 6% 40%	2254
	21st to end	Day	15% 8% 2 6% 4 4 4 3 5% 7% 41%	2289
May	1st to 10th	Day	17% 7% 2 7% 5% 5% 5% 5% 7% 8% 33%	4082
	11th to 20th	Day	17% 7% 2 7% 5% 4 4 4 5% 7% 37%	4081
	21st to end	Day	11% 6% 2 7% 5% 5% 6% 4 6% 8% 39%	4476
June	1st to 10th	Day	11% 5% 2 6% 5% 4 4 4 7% 8% 46%	2640
	11th to 20th	Day	4 4 1 5% 5% 5% 6% 5% 8% 10% 47%	2660
	21st to end	Day	5% 4 2 5% 5% 6% 6% 4 7% 11% 45%	2660
July	1st to 10th	Day	8% 6% 2 7% 5% 6% 5% 5% 7% 10% 39%	4440
	11th to 20th	Day	8% 4 2 6% 4 5% 5% 4 7% 11% 45%	4440
	21st to end	Day	14% 10% 3 10% 6% 5% 5% 4 7% 7% 28%	4602
August	1st to 10th	Day	5% 4 1 4 4 4 5% 4 6% 10% 54%	3851
	11th to 20th	Day	8% 6% 2 7% 5% 5% 6% 4 7% 10% 41%	3729
	21st to end	Day	5% 4 1 4 4 4 5% 4 6% 9% 54%	4180
September	1st to 10th	Day	11% 4 2 6% 6% 5% 4 4 6% 8% 45%	2280
	11th to 20th	Day	11% 5% 3 6% 4 4 4 4 5% 7% 46%	2104
	21st to end	Day	13% 5% 1 5% 4 4 4 3 4 8% 48%	2090
October	1st to 10th	Day	10% 4 2 4 3 3 2 3 4 7% 57%	2090
	11th to 20th	Day	12% 5% 2 5% 3 4 3 3 3 7% 53%	1974
	21st to end	Day	19% 6% 2 6% 3 3 2 2 3 6% 47%	1925
November	1st to 10th	Day	12% 5% 1 6% 3 3 3 2 5% 6% 54%	1762
	11th to 20th	Day	15% 7% 2 4 3 3 4 4 5% 6% 48%	1800
	21st to end	Day	16% 9% 3 6% 4 4 3 3 5% 4 44%	1800
December	1st to 10th	Day	16% 9% 2 6% 3 4 3 3 4 5% 44%	2930
	11th to 20th	Day	18% 12% 4 7% 5% 4 4 3 5% 5% 33%	3203
	21st to end	Day	18% 12% 5% 9% 5% 5% 5% 3 5% 7% 27%	3982
January	1st to 10th	Night	16% 12% 4 9% 4 3 3 3 5% 6% 35%	6348
	11th to 20th	Night	17% 10% 3 9% 4 4 4 2 4 4 39%	6360
	21st to end	Night	20% 9% 4 6% 3 3 3 2 4 5% 40%	6235
February	1st to 10th	Night	22% 10% 3 8% 4 4 4 3 4 5% 32%	2400
	11th to 20th	Night	21% 8% 3 8% 4 4 3 2 4 5% 36%	2338
	21st to end	Night	19% 10% 4 6% 5% 4 4 3 5% 5% 36%	1980
March	1st to 10th	Night	18% 10% 4 8% 4 3 4 3 5% 5% 37%	5373
	11th to 20th	Night	11% 6% 2 6% 4 3 3 3 5% 6% 49%	5288
	21st to end	Night	15% 7% 3 8% 4 4 4 3 5% 7% 41%	5021
April	1st to 10th	Night	13% 5% 2 6% 4 4 4 3 5% 7% 47%	2000
	11th to 20th	Night	14% 6% 3 5% 4 3 4 3 4 7% 46%	1881
	21st to end	Night	14% 6% 2 6% 5% 4 4 4 5% 8% 41%	1890
May	1st to 10th	Night	17% 8% 2 6% 4 4 4 3 5% 7% 39%	2813
	11th to 20th	Night	13% 7% 2 6% 5% 5% 4 4 6% 8% 40%	2812
	21st to end	Night	8% 6% 2 7% 4 5% 5% 4 6% 10% 43%	3079
June	1st to 10th	Night	12% 6% 2 6% 4 3 4 4 4 9% 46%	1535
	11th to 20th	Night	4 3 2 5% 4 3 4 4 6% 10% 56%	1520
	21st to end	Night	3 2 1 4 4 5% 5% 4 8% 11% 52%	1520
July	1st to 10th	Night	7% 4 2 6% 4 5% 5% 4 8% 11% 45%	2530
	11th to 20th	Night	5% 4 2 5% 4 4 3 4 7% 9% 54%	2530
	21st to end	Night	10% 8% 3 10% 6% 6% 6% 5% 7% 8% 31%	2952
August	1st to 10th	Night	4 3 1 4 3 4 4 4 5% 8% 60%	3073
	11th to 20th	Night	3 4 2 5% 5% 4 5% 5% 8% 10% 50%	3100
	21st to end	Night	4 3 1 4 3 3 4 3 6% 8% 61%	3476
September	1st to 10th	Night	11% 5% 2 5% 3 3 3 3 5% 6% 52%	1900
	11th to 20th	Night	9% 5% 2 6% 4 3 4 4 5% 6% 52%	2057
	21st to end	Night	10% 5% 2 5% 3 3 3 3 4 7% 54%	2090
October	1st to 10th	Night	8% 5% 1 4 2 3 4 2 5% 6% 61%	2090
	11th to 20th	Night	15% 5% 2 5% 3 3 3 2 4 4 54%	2203
	21st to end	Night	15% 7% 2 6% 4 3 4 2 4 6% 48%	2670
November	1st to 10th	Night	12% 5% 2 5% 4 3 3 3 4 6% 53%	2536
	11th to 20th	Night	14% 6% 2 4 4 4 4 2 5% 7% 49%	2600
	21st to end	Night	17% 7% 3 5% 3 3 4 3 5% 5% 47%	2600
December	1st to 10th	Night	18% 9% 3 7% 3 3 3 3 4 4 43%	4250
	11th to 20th	Night	20% 8% 2 6% 4 3 3 3 4 5% 41%	4986
	21st to end	Night	20% 13% 5% 9% 5% 5% 5% 3 4 5% 27%	6996

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	55% 5% 10% 19% 10% 2	3618
	11th to 20th	Day	45% 3 7% 24% 19% 2	3620
	21st to end	Day	47% 4 7% 20% 16% 5%	4712
February	1st to 10th	Day	50% 4 8% 23% 13% 2	2000
	11th to 20th	Day	52% 5% 7% 20% 13% 4	1958
	21st to end	Day	49% 4 8% 19% 15% 5%	1650
March	1st to 10th	Day	51% 4 4 18% 18% 6%	4480
	11th to 20th	Day	39% 5% 7% 25% 20% 5%	4658
	21st to end	Day	42% 5% 9% 27% 16% 1	5940
April	1st to 10th	Day	40% 5% 11% 22% 20% 2	2400
	11th to 20th	Day	43% 4 9% 21% 19% 4	2254
	21st to end	Day	42% 5% 10% 27% 14% 2	2289
May	1st to 10th	Day	46% 8% 13% 21% 11% 1	4120
	11th to 20th	Day	45% 8% 9% 25% 12% 1	4085
	21st to end	Day	39% 9% 12% 19% 21% 1	4489
June	1st to 10th	Day	34% 8% 13% 23% 19% 3	2640
	11th to 20th	Day	29% 9% 15% 25% 19% 3	2660
	21st to end	Day	30% 10% 16% 23% 16% 5%	2660
July	1st to 10th	Day	38% 8% 16% 26% 10% 2	4371
	11th to 20th	Day	31% 8% 13% 35% 10% 2	4365
	21st to end	Day	52% 8% 12% 19% 7% 1	4456
August	1st to 10th	Day	23% 8% 14% 32% 22% 1	3838
	11th to 20th	Day	36% 8% 12% 25% 18% 1	3765
	21st to end	Day	25% 8% 10% 33% 22% 2	4179
September	1st to 10th	Day	36% 7% 11% 23% 19% 5%	2280
	11th to 20th	Day	37% 6% 10% 23% 22% 3	2104
	21st to end	Day	35% 6% 9% 24% 21% 6%	2090
October	1st to 10th	Day	18% 3 6% 17% 46% 9%	3480
	11th to 20th	Day	23% 3 7% 27% 30% 10%	3253
	21st to end	Day	29% 3 6% 26% 28% 7%	3150
November	1st to 10th	Day	32% 5% 9% 23% 26% 5%	1762
	11th to 20th	Day	37% 4 8% 23% 22% 6%	1800
	21st to end	Day	44% 3 7% 25% 17% 4	1800
December	1st to 10th	Day	42% 4 7% 28% 18% 1	2930
	11th to 20th	Day	52% 5% 8% 19% 14% 2	3200
	21st to end	Day	56% 5% 11% 20% 7%	3982
January	1st to 10th	Night	50% 3 10% 23% 13% 1	6348
	11th to 20th	Night	49% 4 7% 19% 18% 3	6360
	21st to end	Night	48% 3 7% 22% 16% 4	6235
February	1st to 10th	Night	55% 4 9% 17% 13% 1	2400
	11th to 20th	Night	52% 4 6% 20% 14% 4	2339
	21st to end	Night	51% 5% 8% 17% 16% 3	1980
March	1st to 10th	Night	49% 4 6% 16% 19% 6%	5373
	11th to 20th	Night	36% 4 8% 22% 19% 11%	5288
	21st to end	Night	44% 5% 10% 25% 15% 2	5021
April	1st to 10th	Night	36% 5% 11% 25% 20% 3	2000
	11th to 20th	Night	38% 5% 9% 19% 22% 6%	1881
	21st to end	Night	41% 5% 10% 25% 18% 2	1890
May	1st to 10th	Night	43% 8% 13% 22% 12% 2	2840
	11th to 20th	Night	39% 10% 14% 22% 14% 1	2813
	21st to end	Night	34% 10% 14% 23% 17% 2	3087
June	1st to 10th	Night	36% 5% 12% 23% 21% 3	1535
	11th to 20th	Night	23% 8% 16% 26% 24% 4	1520
	21st to end	Night	24% 8% 17% 28% 17% 6%	1520
July	1st to 10th	Night	31% 7% 14% 31% 13% 2	2490
	11th to 20th	Night	26% 7% 13% 36% 16% 2	2482
	21st to end	Night	48% 10% 13% 20% 9% 1	2858
August	1st to 10th	Night	21% 7% 12% 37% 22% 1	3062
	11th to 20th	Night	25% 8% 19% 28% 18% 1	3130
	21st to end	Night	21% 6% 11% 34% 25% 3	3476
September	1st to 10th	Night	32% 6% 11% 25% 21% 5%	1900
	11th to 20th	Night	32% 6% 8% 26% 25% 4	2057
	21st to end	Night	31% 5% 9% 23% 26% 7%	2090
October	1st to 10th	Night	17% 3 6% 16% 46% 11%	3480
	11th to 20th	Night	22% 2 5% 22% 38% 11%	3650
	21st to end	Night	28% 3 7% 24% 27% 11%	4395
November	1st to 10th	Night	34% 3 7% 24% 26% 6%	2536
	11th to 20th	Night	35% 4 6% 24% 22% 8%	2600
	21st to end	Night	40% 4 8% 25% 19% 4	2600
December	1st to 10th	Night	45% 4 8% 21% 20% 1	4250
	11th to 20th	Night	45% 3 9% 23% 18% 2	4988
	21st to end	Night	59% 5% 8% 18% 8% 1	6996

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	25% 23% 31% 16% 5%	300
	11th to 20th	Day	24% 26% 34% 14% 2	300
	21st to end	Day	20% 23% 42% 12% 3	330
February	1st to 10th	Day	27% 19% 35% 15% 3 1	300
	11th to 20th	Day	30% 24% 36% 8% 2	300
	21st to end	Day	28% 23% 34% 11% 3	249
March	1st to 10th	Day	25% 20% 35% 14% 4 1	300
	11th to 20th	Day	23% 21% 38% 14% 4 1	360
	21st to end	Day	25% 18% 34% 17% 5% 1	550
April	1st to 10th	Day	22% 16% 31% 23% 7% 1	500
	11th to 20th	Day	23% 15% 26% 23% 12% 1	452
	21st to end	Day	20% 15% 30% 22% 9% 3	460
May	1st to 10th	Day	20% 15% 26% 25% 9% 3	463
	11th to 20th	Day	17% 8% 23% 31% 15% 6%	487
	21st to end	Day	10% 5% 22% 29% 19% 14%	529
June	1st to 10th	Day	12% 5% 19% 27% 25% 13%	660
	11th to 20th	Day	5% 4 18% 32% 29% 12%	680
	21st to end	Day	5% 4 20% 33% 25% 13%	680
July	1st to 10th	Day	10% 2 13% 26% 28% 21%	671
	11th to 20th	Day	9% 3 13% 28% 31% 17%	668
	21st to end	Day	9% 2 15% 29% 28% 18%	616
August	1st to 10th	Day	10% 2 13% 29% 30% 16%	486
	11th to 20th	Day	13% 2 15% 32% 29% 10%	479
	21st to end	Day	10% 1 9% 21% 37% 21%	539
September	1st to 10th	Day	11% 2 14% 26% 34% 13%	490
	11th to 20th	Day	10% 2 10% 25% 36% 16%	490
	21st to end	Day	17% 6% 18% 26% 22% 10%	490
October	1st to 10th	Day	9% 5% 19% 35% 25% 8%	490
	11th to 20th	Day	13% 13% 27% 28% 13% 5%	374
	21st to end	Day	26% 14% 25% 25% 9% 2	330
November	1st to 10th	Day	17% 8% 38% 22% 13% 2	300
	11th to 20th	Day	17% 20% 32% 24% 6% 1	300
	21st to end	Day	23% 14% 33% 19% 10% 2	300
December	1st to 10th	Day	26% 16% 31% 17% 9%	300
	11th to 20th	Day	24% 16% 33% 21% 5%	300
	21st to end	Day	28% 17% 34% 18% 2	330
January	1st to 10th	Night	25% 14% 32% 26% 3	1000
	11th to 20th	Night	27% 14% 34% 21% 4	1000
	21st to end	Night	23% 13% 39% 23% 3	981
February	1st to 10th	Night	26% 14% 34% 24% 2	800
	11th to 20th	Night	26% 14% 37% 21% 2	783
	21st to end	Night	28% 13% 36% 22% 2	660
March	1st to 10th	Night	22% 15% 32% 28% 5%	800
	11th to 20th	Night	20% 13% 36% 25% 6% 1	800
	21st to end	Night	20% 12% 33% 27% 8% 1	693
April	1st to 10th	Night	17% 11% 34% 30% 8% 1	600
	11th to 20th	Night	18% 11% 30% 28% 13% 1	565
	21st to end	Night	17% 8% 32% 32% 10% 1	570
May	1st to 10th	Night	18% 8% 31% 26% 15% 2	570
	11th to 20th	Night	13% 6% 21% 37% 21% 3	561
	21st to end	Night	8% 2 17% 40% 29% 5%	617
June	1st to 10th	Night	14% 3 14% 36% 31% 3	570
	11th to 20th	Night	5% 2 12% 42% 36% 3	570
	21st to end	Night	3 1 13% 42% 35% 5%	570
July	1st to 10th	Night	8% 3 7% 30% 43% 10%	555
	11th to 20th	Night	8% 3 9% 27% 47% 6%	552
	21st to end	Night	8% 3 11% 36% 36% 8%	624
August	1st to 10th	Night	6% 2 7% 32% 45% 7%	567
	11th to 20th	Night	6% 1 10% 42% 37% 4	564
	21st to end	Night	7% 1 8% 31% 45% 8%	627
September	1st to 10th	Night	12% 2 12% 31% 37% 6%	570
	11th to 20th	Night	12% 2 10% 31% 40% 6%	727
	21st to end	Night	11% 3 20% 31% 31% 4	760
October	1st to 10th	Night	11% 4 18% 33% 29% 5%	760
	11th to 20th	Night	18% 6% 24% 34% 17% 2	760
	21st to end	Night	18% 8% 29% 29% 14% 1	836
November	1st to 10th	Night	15% 8% 27% 35% 15% 1	780
	11th to 20th	Night	16% 10% 33% 30% 11% 1	800
	21st to end	Night	21% 11% 29% 28% 11% 1	800
December	1st to 10th	Night	24% 11% 29% 29% 6%	800
	11th to 20th	Night	24% 9% 32% 28% 6% 1	875
	21st to end	Night	29% 11% 30% 26% 4	1100

Page generated at 2025-04-08 08:17:26. Version ac07

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