East Kentucky Science Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the East Kentucky Science Center clear sky chart from 2005-11-06 to 2025-03-27.

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	14% 9% 3 7% 5% 4 5% 4 6% 7% 36%	109508
	Night	15% 9% 3 7% 4 4 4 3 5% 7% 37%	109850
Transparency	Day	45% 5% 10% 23% 14% 2	113250
	Night	45% 5% 10% 22% 15% 3	114247
Seeing	Day	21% 12% 24% 22% 15% 6%	15388
	Night	20% 10% 22% 29% 17% 2	25556

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% 20% 8% 13% 5% 4 4 3 4 5% 21%	4056
	11th to 20th	Day	15% 17% 9% 10% 6% 5% 3 2 3 3 29%	4060
	21st to end	Day	18% 14% 3 8% 5% 3 4 3 4 5% 33%	4466
February	1st to 10th	Day	18% 14% 4 8% 4 4 4 3 5% 5% 30%	1836
	11th to 20th	Day	24% 11% 4 8% 5% 4 3 3 4 5% 30%	1948
	21st to end	Day	22% 11% 4 7% 4 5% 3 4 4 4 31%	1650
March	1st to 10th	Day	22% 14% 4 7% 4 3 4 3 4 6% 29%	3413
	11th to 20th	Day	13% 7% 3 7% 4 4 4 3 5% 6% 43%	3590
	21st to end	Day	17% 8% 3 5% 4 4 5% 3 6% 7% 38%	3881
April	1st to 10th	Day	14% 9% 3 7% 5% 4 4 4 5% 7% 37%	2090
	11th to 20th	Day	15% 7% 2 7% 5% 4 4 3 4 7% 42%	2361
	21st to end	Day	17% 7% 3 7% 5% 4 4 4 5% 7% 37%	2470
May	1st to 10th	Day	16% 9% 3 10% 7% 5% 5% 4 6% 6% 28%	4082
	11th to 20th	Day	16% 10% 3 8% 5% 5% 5% 4 5% 6% 32%	4081
	21st to end	Day	10% 6% 2 6% 5% 5% 6% 6% 9% 10% 36%	4476
June	1st to 10th	Day	11% 6% 2 7% 5% 5% 5% 5% 7% 8% 40%	2470
	11th to 20th	Day	7% 5% 2 7% 6% 6% 7% 5% 7% 9% 39%	2470
	21st to end	Day	9% 6% 3 6% 5% 4 5% 5% 8% 9% 40%	2470
July	1st to 10th	Day	9% 5% 2 6% 5% 5% 5% 5% 7% 9% 41%	4120
	11th to 20th	Day	9% 5% 2 6% 4 4 5% 4 7% 10% 41%	4120
	21st to end	Day	17% 10% 4 10% 7% 6% 6% 4 6% 8% 24%	4466
August	1st to 10th	Day	9% 6% 2 8% 5% 4 6% 5% 7% 10% 37%	4104
	11th to 20th	Day	10% 6% 2 7% 5% 5% 6% 4 7% 10% 39%	4044
	21st to end	Day	6% 3 1 4 4 5% 5% 3 6% 9% 54%	4325
September	1st to 10th	Day	12% 6% 2 5% 4 4 4 4 7% 7% 45%	2090
	11th to 20th	Day	13% 5% 2 7% 4 4 4 4 6% 7% 44%	2090
	21st to end	Day	19% 6% 3 6% 4 3 3 3 4 5% 44%	2090
October	1st to 10th	Day	12% 6% 2 5% 3 3 4 3 5% 7% 49%	2049
	11th to 20th	Day	15% 5% 2 6% 3 4 3 2 5% 6% 50%	1900
	21st to end	Day	20% 7% 2 5% 3 3 3 2 4 7% 43%	2090
November	1st to 10th	Day	13% 6% 2 5% 3 3 4 4 6% 5% 51%	1781
	11th to 20th	Day	14% 9% 3 7% 5% 4 4 3 5% 6% 41%	1800
	21st to end	Day	16% 11% 3 7% 3 3 4 3 5% 6% 39%	1800
December	1st to 10th	Day	18% 11% 3 9% 5% 4 4 3 4 5% 35%	2930
	11th to 20th	Day	22% 15% 4 8% 4 4 4 3 4 5% 27%	3373
	21st to end	Day	15% 13% 5% 9% 7% 6% 6% 4 5% 6% 22%	4466
January	1st to 10th	Night	16% 17% 7% 17% 5% 4 4 3 4 4 21%	5889
	11th to 20th	Night	20% 13% 4 10% 5% 3 3 3 4 4 29%	5900
	21st to end	Night	19% 9% 4 8% 5% 4 4 3 4 5% 37%	6490
February	1st to 10th	Night	18% 11% 4 9% 5% 4 3 3 4 6% 31%	2560
	11th to 20th	Night	23% 12% 4 8% 5% 3 3 3 5% 5% 29%	2338
	21st to end	Night	22% 12% 4 8% 4 4 4 4 5% 5% 29%	1980
March	1st to 10th	Night	22% 12% 3 7% 5% 5% 4 3 4 6% 31%	3660
	11th to 20th	Night	14% 8% 2 5% 4 3 4 3 5% 7% 45%	3590
	21st to end	Night	13% 6% 2 6% 6% 5% 4 4 6% 8% 40%	3890
April	1st to 10th	Night	13% 8% 3 6% 5% 4 5% 3 5% 7% 40%	2090
	11th to 20th	Night	15% 8% 2 5% 4 3 4 3 6% 7% 43%	1783
	21st to end	Night	14% 8% 3 6% 4 5% 5% 3 4 7% 40%	1710
May	1st to 10th	Night	18% 9% 3 8% 5% 5% 5% 4 6% 8% 28%	2813
	11th to 20th	Night	17% 8% 3 6% 5% 4 4 4 6% 8% 37%	2812
	21st to end	Night	9% 6% 3 7% 4 4 5% 4 6% 10% 42%	3079
June	1st to 10th	Night	9% 6% 2 4 4 5% 5% 5% 8% 10% 43%	1710
	11th to 20th	Night	5% 5% 3 6% 4 4 5% 5% 8% 10% 43%	1710
	21st to end	Night	9% 5% 1 6% 5% 4 6% 4 7% 10% 43%	1710
July	1st to 10th	Night	8% 4 2 7% 5% 5% 5% 5% 9% 10% 40%	2840
	11th to 20th	Night	8% 5% 2 5% 4 4 4 4 8% 9% 47%	2840
	21st to end	Night	14% 8% 4 9% 5% 5% 6% 4 6% 9% 31%	3087
August	1st to 10th	Night	10% 5% 2 7% 5% 6% 6% 5% 7% 10% 39%	2825
	11th to 20th	Night	11% 5% 3 6% 5% 5% 5% 4 7% 9% 41%	2785
	21st to end	Night	5% 3 1 4 3 2 4 4 6% 8% 59%	3295
September	1st to 10th	Night	11% 5% 2 6% 4 5% 4 4 6% 8% 46%	2090
	11th to 20th	Night	12% 5% 2 8% 4 4 4 3 4 7% 48%	2090
	21st to end	Night	12% 6% 2 6% 4 3 4 4 4 6% 47%	2090
October	1st to 10th	Night	12% 5% 2 5% 3 3 3 4 5% 7% 52%	2129
	11th to 20th	Night	15% 6% 2 6% 4 3 3 2 4 6% 48%	2280
	21st to end	Night	18% 7% 2 5% 3 3 3 3 5% 6% 44%	2508
November	1st to 10th	Night	14% 6% 2 5% 4 4 4 2 4 6% 50%	2515
	11th to 20th	Night	15% 8% 2 6% 4 5% 4 3 5% 6% 42%	2600
	21st to end	Night	15% 11% 2 5% 4 4 4 3 5% 5% 42%	2600
December	1st to 10th	Night	17% 13% 4 9% 4 4 4 3 4 4 34%	4250
	11th to 20th	Night	20% 14% 5% 8% 5% 4 3 3 4 5% 30%	4822
	21st to end	Night	17% 15% 4 9% 6% 5% 5% 3 6% 7% 23%	6490

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	66% 4 6% 18% 7%	4057
	11th to 20th	Day	63% 2 5% 15% 13% 1	4060
	21st to end	Day	54% 3 7% 26% 9% 1	4466
February	1st to 10th	Day	57% 3 8% 20% 11% 1	1836
	11th to 20th	Day	58% 3 7% 18% 12% 2	1958
	21st to end	Day	56% 4 7% 17% 13% 3	1650
March	1st to 10th	Day	56% 4 7% 17% 13% 2	3413
	11th to 20th	Day	41% 3 9% 24% 19% 2	3590
	21st to end	Day	45% 4 9% 28% 12% 2	3881
April	1st to 10th	Day	45% 5% 10% 23% 15% 3	2090
	11th to 20th	Day	42% 4 9% 22% 19% 5%	2361
	21st to end	Day	47% 5% 10% 24% 11% 3	2470
May	1st to 10th	Day	54% 6% 10% 19% 9% 1	4120
	11th to 20th	Day	50% 7% 10% 22% 10% 1	4085
	21st to end	Day	37% 9% 15% 21% 15% 2	4489
June	1st to 10th	Day	40% 7% 13% 24% 15% 1	2470
	11th to 20th	Day	39% 8% 13% 20% 18% 2	2470
	21st to end	Day	37% 8% 14% 21% 16% 3	2470
July	1st to 10th	Day	37% 8% 19% 22% 13% 1	4055
	11th to 20th	Day	36% 6% 13% 33% 10% 2	4051
	21st to end	Day	58% 7% 9% 16% 9% 1	4324
August	1st to 10th	Day	39% 8% 15% 26% 10%	4091
	11th to 20th	Day	39% 7% 12% 30% 12% 1	4083
	21st to end	Day	26% 6% 14% 34% 19% 2	4325
September	1st to 10th	Day	37% 6% 11% 23% 18% 6%	2090
	11th to 20th	Day	38% 5% 10% 27% 17% 2	2090
	21st to end	Day	43% 4 10% 22% 20% 2	2090
October	1st to 10th	Day	29% 4 8% 22% 34% 3	3400
	11th to 20th	Day	26% 2 10% 28% 29% 3	3140
	21st to end	Day	30% 2 9% 32% 20% 7%	3428
November	1st to 10th	Day	34% 4 9% 24% 25% 3	1781
	11th to 20th	Day	45% 3 6% 23% 19% 4	1800
	21st to end	Day	47% 3 9% 22% 17% 2	1800
December	1st to 10th	Day	53% 4 6% 21% 15% 1	2930
	11th to 20th	Day	61% 3 8% 17% 11% 1	3370
	21st to end	Day	61% 5% 9% 20% 5%	4466
January	1st to 10th	Night	67% 3 8% 14% 7% 1	5889
	11th to 20th	Night	58% 3 4 17% 14% 3	5900
	21st to end	Night	51% 3 7% 24% 14% 2	6490
February	1st to 10th	Night	55% 3 10% 19% 11% 1	2560
	11th to 20th	Night	58% 3 8% 17% 11% 2	2339
	21st to end	Night	57% 4 8% 16% 12% 3	1980
March	1st to 10th	Night	55% 4 6% 18% 14% 2	3660
	11th to 20th	Night	39% 4 8% 30% 15% 3	3590
	21st to end	Night	41% 5% 11% 24% 17% 1	3890
April	1st to 10th	Night	43% 5% 10% 22% 17% 3	2090
	11th to 20th	Night	40% 5% 10% 22% 17% 7%	1783
	21st to end	Night	44% 6% 11% 24% 13% 2	1710
May	1st to 10th	Night	52% 8% 11% 19% 8% 2	2840
	11th to 20th	Night	45% 6% 14% 25% 9% 1	2813
	21st to end	Night	36% 9% 14% 22% 17% 3	3087
June	1st to 10th	Night	34% 8% 17% 22% 17% 3	1710
	11th to 20th	Night	32% 9% 17% 21% 19% 3	1710
	21st to end	Night	34% 8% 15% 23% 15% 5%	1710
July	1st to 10th	Night	36% 9% 17% 24% 13% 2	2795
	11th to 20th	Night	32% 7% 15% 32% 13% 2	2786
	21st to end	Night	49% 7% 12% 19% 12% 1	2988
August	1st to 10th	Night	38% 9% 14% 25% 12% 1	2814
	11th to 20th	Night	39% 6% 12% 28% 14% 1	2812
	21st to end	Night	22% 7% 13% 33% 23% 3	3295
September	1st to 10th	Night	35% 7% 12% 22% 16% 8%	2090
	11th to 20th	Night	37% 6% 10% 22% 22% 3	2090
	21st to end	Night	36% 6% 10% 24% 22% 2	2090
October	1st to 10th	Night	28% 4 7% 23% 33% 4	3558
	11th to 20th	Night	29% 3 6% 26% 27% 9%	3779
	21st to end	Night	29% 3 7% 26% 27% 8%	4120
November	1st to 10th	Night	37% 4 8% 22% 24% 6%	2515
	11th to 20th	Night	43% 4 8% 20% 20% 5%	2600
	21st to end	Night	44% 4 8% 26% 16% 2	2600
December	1st to 10th	Night	55% 4 8% 20% 12% 1	4250
	11th to 20th	Night	58% 3 8% 20% 9% 1	4824
	21st to end	Night	59% 5% 10% 18% 8%	6490

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	30% 24% 29% 14% 3 1	300
	11th to 20th	Day	39% 23% 24% 12% 1	300
	21st to end	Day	29% 27% 28% 13% 2 1	330
February	1st to 10th	Day	27% 21% 34% 12% 5%	300
	11th to 20th	Day	46% 22% 24% 6% 1 1	300
	21st to end	Day	35% 21% 32% 12% 1	249
March	1st to 10th	Day	32% 18% 29% 15% 6%	415
	11th to 20th	Day	27% 21% 30% 17% 4 1	500
	21st to end	Day	30% 19% 28% 17% 6%	530
April	1st to 10th	Day	29% 18% 25% 18% 10% 1	460
	11th to 20th	Day	21% 21% 28% 17% 11% 3	452
	21st to end	Day	25% 14% 32% 20% 8% 2	460
May	1st to 10th	Day	22% 17% 29% 18% 10% 4	463
	11th to 20th	Day	17% 11% 28% 26% 13% 5%	487
	21st to end	Day	14% 6% 26% 23% 21% 9%	529
June	1st to 10th	Day	13% 7% 23% 28% 20% 8%	490
	11th to 20th	Day	11% 7% 19% 30% 22% 11%	490
	21st to end	Day	13% 5% 26% 26% 19% 12%	490
July	1st to 10th	Day	15% 4 18% 24% 20% 20%	485
	11th to 20th	Day	8% 5% 20% 29% 23% 15%	484
	21st to end	Day	15% 6% 17% 28% 23% 12%	532
August	1st to 10th	Day	15% 4 18% 24% 27% 12%	486
	11th to 20th	Day	13% 6% 14% 29% 25% 11%	479
	21st to end	Day	12% 3 13% 26% 32% 16%	539
September	1st to 10th	Day	14% 3 15% 23% 32% 13%	490
	11th to 20th	Day	15% 3 13% 28% 26% 14%	490
	21st to end	Day	22% 9% 19% 27% 17% 7%	490
October	1st to 10th	Day	14% 8% 22% 26% 22% 8%	490
	11th to 20th	Day	17% 11% 25% 26% 16% 5%	490
	21st to end	Day	25% 13% 22% 26% 13% 2	539
November	1st to 10th	Day	19% 13% 30% 25% 11% 3	319
	11th to 20th	Day	26% 15% 29% 19% 11% 1	300
	21st to end	Day	27% 17% 27% 20% 8% 1	300
December	1st to 10th	Day	32% 19% 28% 15% 5% 1	300
	11th to 20th	Day	30% 18% 28% 19% 4 2	300
	21st to end	Day	29% 18% 32% 14% 6% 1	330
January	1st to 10th	Night	28% 18% 28% 21% 5%	800
	11th to 20th	Night	32% 17% 27% 21% 4	800
	21st to end	Night	25% 17% 33% 24% 2	880
February	1st to 10th	Night	26% 15% 30% 27% 2	800
	11th to 20th	Night	34% 17% 30% 18% 2	783
	21st to end	Night	32% 17% 30% 20% 2	660
March	1st to 10th	Night	28% 15% 25% 27% 5%	800
	11th to 20th	Night	26% 15% 29% 23% 7%	800
	21st to end	Night	20% 15% 31% 27% 8%	863
April	1st to 10th	Night	20% 16% 27% 28% 8%	760
	11th to 20th	Night	21% 12% 24% 29% 13% 1	588
	21st to end	Night	18% 10% 33% 31% 8% 1	570
May	1st to 10th	Night	20% 8% 26% 31% 12% 2	570
	11th to 20th	Night	16% 7% 23% 33% 19% 2	561
	21st to end	Night	10% 4 17% 34% 29% 6%	617
June	1st to 10th	Night	11% 3 18% 37% 27% 4	570
	11th to 20th	Night	8% 3 15% 39% 30% 6%	570
	21st to end	Night	10% 2 18% 36% 29% 4	570
July	1st to 10th	Night	13% 2 11% 32% 35% 7%	555
	11th to 20th	Night	8% 2 10% 34% 40% 5%	552
	21st to end	Night	11% 4 9% 34% 34% 8%	624
August	1st to 10th	Night	10% 3 9% 33% 40% 5%	567
	11th to 20th	Night	13% 2 9% 32% 37% 8%	564
	21st to end	Night	10% 1 7% 31% 42% 8%	636
September	1st to 10th	Night	12% 3 11% 30% 38% 6%	760
	11th to 20th	Night	14% 2 14% 27% 38% 4	760
	21st to end	Night	15% 5% 19% 29% 29% 3	760
October	1st to 10th	Night	14% 4 17% 31% 30% 4	760
	11th to 20th	Night	19% 8% 20% 32% 18% 2	760
	21st to end	Night	22% 9% 23% 32% 14% 1	836
November	1st to 10th	Night	16% 9% 23% 33% 17% 2	780
	11th to 20th	Night	20% 14% 25% 30% 11% 1	800
	21st to end	Night	22% 12% 21% 34% 11% 1	800
December	1st to 10th	Night	30% 15% 25% 26% 5%	800
	11th to 20th	Night	26% 12% 28% 28% 6% 1	800
	21st to end	Night	30% 14% 22% 30% 4	880

Page generated at 2025-03-24 09:04:32. Version ac07

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