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 2024-10-25.

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 6% 4 4 4 4 5% 7% 41%	100872
	Night	14% 7% 3 6% 4 4 4 3 5% 7% 44%	97931
Transparency	Day	41% 6% 11% 24% 16% 3	100667
	Night	40% 6% 10% 23% 18% 3	97807
Seeing	Day	16% 10% 23% 24% 18% 8%	15327
	Night	17% 8% 25% 30% 18% 2	25077

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	14% 12% 6% 10% 5% 5% 4 3 4 5% 32%	2527
	11th to 20th	Day	18% 10% 3 8% 6% 4 5% 3 4 5% 34%	2530
	21st to end	Day	24% 11% 5% 7% 4 4 3 3 4 6% 28%	3281
February	1st to 10th	Day	18% 11% 3 6% 5% 4 4 3 5% 6% 35%	1900
	11th to 20th	Day	19% 9% 3 7% 4 3 4 3 4 6% 36%	1848
	21st to end	Day	19% 10% 3 8% 6% 3 4 3 4 5% 36%	1570
March	1st to 10th	Day	21% 14% 3 8% 3 4 3 3 4 4 33%	3120
	11th to 20th	Day	14% 7% 3 6% 4 3 3 3 5% 6% 48%	3256
	21st to end	Day	12% 8% 3 7% 4 4 4 3 5% 7% 42%	4150
April	1st to 10th	Day	13% 6% 2 7% 5% 4 4 3 5% 7% 43%	2280
	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% 7% 2 5% 3 3 3 3 3 6% 47%	1868
November	1st to 10th	Day	11% 5% 1 6% 3 3 3 2 5% 5% 55%	1672
	11th to 20th	Day	15% 7% 2 4 3 3 4 4 5% 6% 49%	1710
	21st to end	Day	16% 8% 3 5% 4 4 3 3 5% 4 44%	1710
December	1st to 10th	Day	20% 10% 3 6% 3 4 4 4 4 5% 37%	1710
	11th to 20th	Day	16% 12% 4 6% 4 4 4 4 5% 5% 35%	2035
	21st to end	Day	16% 13% 6% 8% 5% 5% 4 3 5% 7% 29%	2783
January	1st to 10th	Night	18% 11% 4 6% 4 3 4 4 5% 6% 37%	4428
	11th to 20th	Night	17% 12% 4 9% 5% 4 4 3 4 5% 33%	4440
	21st to end	Night	24% 11% 4 6% 4 3 3 3 4 5% 33%	4361
February	1st to 10th	Night	22% 11% 3 8% 4 4 3 3 4 5% 33%	2280
	11th to 20th	Night	20% 8% 3 8% 4 4 3 3 4 5% 38%	2218
	21st to end	Night	20% 10% 4 6% 5% 4 4 3 4 5% 34%	1884
March	1st to 10th	Night	22% 11% 3 7% 4 3 3 3 4 5% 35%	3733
	11th to 20th	Night	12% 7% 3 6% 4 3 3 3 4 6% 49%	3690
	21st to end	Night	15% 7% 3 7% 4 4 4 3 5% 6% 42%	3511
April	1st to 10th	Night	12% 4 2 6% 4 3 4 3 5% 7% 48%	1900
	11th to 20th	Night	14% 6% 3 5% 4 3 4 3 4 7% 46%	1875
	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% 47%	2591
November	1st to 10th	Night	12% 5% 2 5% 4 3 3 2 4 5% 55%	2406
	11th to 20th	Night	13% 6% 2 4 4 4 4 2 5% 7% 49%	2470
	21st to end	Night	17% 7% 2 5% 3 3 4 3 5% 5% 47%	2470
December	1st to 10th	Night	20% 11% 3 7% 3 3 4 4 5% 5% 36%	2470
	11th to 20th	Night	17% 8% 3 6% 4 4 4 3 4 5% 42%	3150
	21st to end	Night	17% 12% 5% 9% 5% 5% 5% 3 4 6% 28%	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	54% 5% 7% 22% 10% 2	2528
	11th to 20th	Day	53% 4 9% 22% 12% 1	2530
	21st to end	Day	57% 4 8% 21% 9% 1	3281
February	1st to 10th	Day	50% 4 8% 23% 13% 2	1900
	11th to 20th	Day	50% 5% 7% 21% 13% 4	1858
	21st to end	Day	50% 4 8% 18% 14% 5%	1570
March	1st to 10th	Day	56% 4 5% 16% 13% 7%	3120
	11th to 20th	Day	37% 5% 9% 27% 17% 4	3256
	21st to end	Day	42% 5% 10% 24% 17% 1	4150
April	1st to 10th	Day	40% 5% 11% 22% 20% 2	2280
	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	28% 5% 9% 23% 29% 6%	2090
	11th to 20th	Day	33% 4 7% 23% 25% 8%	1974
	21st to end	Day	40% 3 7% 23% 21% 5%	1868
November	1st to 10th	Day	31% 5% 9% 24% 26% 5%	1672
	11th to 20th	Day	36% 4 8% 23% 22% 6%	1710
	21st to end	Day	43% 3 7% 25% 17% 4	1710
December	1st to 10th	Day	48% 5% 10% 22% 13% 2	1710
	11th to 20th	Day	49% 6% 10% 20% 14% 2	2032
	21st to end	Day	54% 6% 12% 17% 10%	2783
January	1st to 10th	Night	47% 4 8% 26% 13% 1	4428
	11th to 20th	Night	53% 5% 9% 18% 13% 3	4440
	21st to end	Night	54% 4 9% 22% 11% 1	4361
February	1st to 10th	Night	55% 4 9% 18% 14% 1	2280
	11th to 20th	Night	50% 4 6% 21% 14% 4	2219
	21st to end	Night	52% 5% 8% 15% 16% 4	1884
March	1st to 10th	Night	52% 5% 7% 14% 17% 5%	3733
	11th to 20th	Night	37% 5% 10% 24% 14% 10%	3690
	21st to end	Night	43% 5% 10% 23% 18% 1	3511
April	1st to 10th	Night	35% 5% 11% 26% 20% 3	1900
	11th to 20th	Night	38% 5% 9% 19% 22% 7%	1875
	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	25% 4 9% 23% 31% 8%	2090
	11th to 20th	Night	35% 3 8% 20% 27% 7%	2203
	21st to end	Night	39% 4 6% 22% 23% 5%	2591
November	1st to 10th	Night	33% 3 7% 24% 26% 6%	2406
	11th to 20th	Night	35% 4 6% 24% 23% 9%	2470
	21st to end	Night	39% 4 8% 25% 20% 4	2470
December	1st to 10th	Night	50% 5% 10% 20% 13% 2	2470
	11th to 20th	Night	44% 4 10% 22% 18% 3	3152
	21st to end	Night	56% 6% 9% 16% 11% 2	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	26% 22% 31% 16% 5%	270
	11th to 20th	Day	26% 24% 32% 15% 3	270
	21st to end	Day	21% 23% 41% 12% 3	297
February	1st to 10th	Day	27% 19% 35% 15% 3 1	270
	11th to 20th	Day	29% 23% 37% 8% 2	270
	21st to end	Day	31% 24% 31% 10% 4	225
March	1st to 10th	Day	26% 20% 36% 14% 3 1	270
	11th to 20th	Day	22% 21% 37% 14% 4 1	327
	21st to end	Day	25% 17% 33% 18% 6% 1	506
April	1st to 10th	Day	21% 17% 30% 24% 7% 1	460
	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	27% 14% 24% 25% 9% 2	311
November	1st to 10th	Day	15% 7% 39% 23% 14% 2	270
	11th to 20th	Day	16% 19% 34% 24% 7% 1	270
	21st to end	Day	23% 13% 33% 20% 10% 2	270
December	1st to 10th	Day	26% 17% 30% 18% 9%	270
	11th to 20th	Day	23% 16% 34% 21% 6%	270
	21st to end	Day	27% 19% 34% 17% 3	297
January	1st to 10th	Night	25% 14% 31% 26% 3	950
	11th to 20th	Night	27% 14% 33% 21% 4	950
	21st to end	Night	23% 13% 39% 22% 3	932
February	1st to 10th	Night	26% 14% 33% 25% 2	760
	11th to 20th	Night	25% 14% 38% 22% 2	743
	21st to end	Night	29% 14% 35% 21% 1	628
March	1st to 10th	Night	22% 14% 32% 28% 5%	760
	11th to 20th	Night	21% 13% 36% 25% 6% 1	760
	21st to end	Night	20% 12% 32% 28% 8% 1	659
April	1st to 10th	Night	15% 11% 34% 32% 8% 1	570
	11th to 20th	Night	18% 11% 30% 28% 13% 1	563
	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	19% 8% 30% 28% 15% 1	812
November	1st to 10th	Night	14% 7% 27% 35% 16% 1	740
	11th to 20th	Night	15% 10% 33% 29% 11% 1	760
	21st to end	Night	21% 11% 28% 28% 11% 1	760
December	1st to 10th	Night	25% 11% 29% 29% 6%	760
	11th to 20th	Night	24% 9% 31% 29% 6% 1	831
	21st to end	Night	28% 11% 31% 26% 4	1045

Page generated at 2024-10-22 19:21:05. Version ac07

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