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 2026-07-31.

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 8% 5% 5% 5% 4 6% 7% 35%	138172
	Night	15% 9% 3 8% 5% 4 4 3 5% 7% 37%	134859
Transparency	Day	46% 5% 10% 23% 14% 2	141870
	Night	46% 5% 10% 22% 15% 2	139233
Seeing	Day	21% 13% 24% 22% 15% 6%	17229
	Night	20% 10% 22% 29% 17% 2	27266

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% 19% 7% 11% 5% 4 4 3 4 5% 24%	5258
	11th to 20th	Day	13% 14% 8% 12% 5% 4 3 2 3 3 32%	5280
	21st to end	Day	17% 13% 4 10% 6% 3 4 3 4 5% 30%	5780
February	1st to 10th	Day	18% 14% 4 8% 5% 4 4 3 5% 5% 30%	1928
	11th to 20th	Day	23% 10% 4 8% 4 4 4 3 4 5% 30%	2048
	21st to end	Day	22% 11% 5% 7% 4 5% 3 3 4 4 31%	1730
March	1st to 10th	Day	18% 14% 3 7% 5% 4 4 3 4 5% 32%	4857
	11th to 20th	Day	12% 8% 2 6% 4 4 5% 4 6% 7% 43%	5090
	21st to end	Day	16% 8% 3 6% 5% 4 5% 3 6% 7% 38%	5586
April	1st to 10th	Day	14% 9% 3 7% 5% 4 4 4 5% 7% 38%	2310
	11th to 20th	Day	14% 7% 2 7% 5% 4 4 3 5% 7% 41%	2612
	21st to end	Day	16% 7% 3 7% 5% 4 5% 4 5% 7% 37%	2730
May	1st to 10th	Day	15% 7% 3 8% 6% 5% 5% 5% 6% 8% 31%	7616
	11th to 20th	Day	13% 7% 3 8% 6% 5% 6% 5% 6% 7% 34%	7626
	21st to end	Day	17% 7% 3 8% 6% 6% 6% 5% 8% 9% 26%	8391
June	1st to 10th	Day	10% 6% 2 7% 5% 5% 5% 4 7% 8% 40%	2730
	11th to 20th	Day	8% 5% 2 7% 6% 6% 7% 5% 7% 9% 38%	2730
	21st to end	Day	9% 5% 3 6% 5% 5% 5% 5% 8% 9% 40%	2730
July	1st to 10th	Day	8% 4 2 6% 5% 5% 5% 5% 6% 9% 42%	6030
	11th to 20th	Day	11% 5% 2 7% 5% 5% 6% 5% 8% 12% 34%	6030
	21st to end	Day	14% 8% 3 9% 6% 6% 6% 5% 6% 9% 28%	6554
August	1st to 10th	Day	10% 6% 2 8% 5% 4 6% 5% 7% 10% 37%	4234
	11th to 20th	Day	10% 6% 2 7% 5% 5% 6% 4 7% 10% 39%	4174
	21st to end	Day	6% 3 1 4 4 4 5% 3 6% 9% 54%	4461
September	1st to 10th	Day	12% 6% 2 5% 4 4 4 4 7% 8% 45%	2200
	11th to 20th	Day	12% 5% 2 7% 4 5% 4 4 6% 7% 45%	2200
	21st to end	Day	18% 6% 3 6% 4 3 4 3 4 6% 43%	2200
October	1st to 10th	Day	12% 5% 2 5% 3 3 4 3 5% 7% 50%	2157
	11th to 20th	Day	15% 5% 2 6% 3 4 3 2 5% 6% 50%	2000
	21st to end	Day	20% 7% 3 6% 3 3 3 2 4 7% 42%	2200
November	1st to 10th	Day	13% 6% 2 5% 3 3 4 4 6% 5% 50%	1872
	11th to 20th	Day	14% 9% 3 7% 5% 3 4 3 4 6% 42%	1890
	21st to end	Day	16% 11% 4 8% 3 3 4 3 5% 6% 38%	1890
December	1st to 10th	Day	18% 11% 3 9% 5% 4 4 3 5% 5% 34%	3020
	11th to 20th	Day	21% 15% 4 8% 4 4 4 3 4 5% 27%	3463
	21st to end	Day	16% 13% 5% 9% 7% 6% 6% 4 5% 6% 22%	4565
January	1st to 10th	Night	15% 15% 6% 14% 5% 4 4 3 4 5% 25%	7635
	11th to 20th	Night	18% 12% 4 11% 5% 3 3 3 4 4 33%	7680
	21st to end	Night	18% 10% 4 11% 5% 4 4 2 4 4 34%	8401
February	1st to 10th	Night	18% 11% 4 9% 5% 4 3 3 4 6% 31%	2688
	11th to 20th	Night	23% 12% 4 8% 5% 3 3 3 5% 5% 29%	2458
	21st to end	Night	21% 12% 4 8% 4 4 4 3 5% 5% 28%	2076
March	1st to 10th	Night	19% 11% 3 7% 4 5% 4 3 4 6% 36%	5216
	11th to 20th	Night	12% 7% 2 5% 3 3 4 3 6% 8% 47%	5090
	21st to end	Night	13% 7% 3 7% 6% 6% 5% 4 6% 7% 36%	5588
April	1st to 10th	Night	14% 8% 3 6% 5% 4 5% 3 5% 7% 40%	2310
	11th to 20th	Night	14% 8% 2 6% 3 3 4 4 7% 8% 42%	1973
	21st to end	Night	14% 9% 3 7% 4 5% 5% 3 5% 7% 39%	1890
May	1st to 10th	Night	16% 8% 3 8% 5% 5% 5% 4 6% 9% 30%	5237
	11th to 20th	Night	12% 6% 3 7% 6% 5% 5% 4 6% 9% 37%	5234
	21st to end	Night	18% 8% 3 8% 5% 5% 5% 4 6% 8% 30%	5761
June	1st to 10th	Night	9% 6% 2 4 4 4 5% 5% 8% 10% 43%	1890
	11th to 20th	Night	6% 5% 3 6% 4 4 5% 5% 8% 10% 42%	1890
	21st to end	Night	9% 5% 1 6% 4 5% 7% 4 7% 10% 42%	1890
July	1st to 10th	Night	8% 5% 2 7% 5% 5% 6% 5% 9% 10% 40%	4148
	11th to 20th	Night	9% 5% 3 7% 5% 5% 5% 4 9% 11% 38%	4147
	21st to end	Night	13% 7% 4 9% 5% 5% 6% 5% 6% 10% 30%	4517
August	1st to 10th	Night	10% 5% 2 6% 5% 6% 5% 5% 7% 10% 39%	2915
	11th to 20th	Night	11% 5% 3 6% 5% 5% 5% 4 7% 9% 41%	2875
	21st to end	Night	6% 3 1 4 3 2 4 4 6% 8% 58%	3400
September	1st to 10th	Night	11% 5% 2 5% 4 5% 4 4 6% 8% 47%	2200
	11th to 20th	Night	11% 5% 2 7% 4 4 4 3 4 7% 49%	2200
	21st to end	Night	12% 6% 2 7% 4 3 4 4 4 6% 47%	2200
October	1st to 10th	Night	12% 5% 2 5% 3 3 3 4 4 6% 53%	2241
	11th to 20th	Night	15% 6% 2 5% 4 3 3 2 4 6% 49%	2400
	21st to end	Night	19% 7% 2 6% 3 3 3 3 5% 5% 44%	2640
November	1st to 10th	Night	13% 6% 3 5% 4 3 4 2 4 6% 51%	2644
	11th to 20th	Night	15% 8% 3 6% 4 4 4 3 4 6% 43%	2730
	21st to end	Night	15% 11% 2 6% 4 4 4 3 4 5% 41%	2730
December	1st to 10th	Night	17% 13% 4 9% 4 4 4 3 4 4 33%	4380
	11th to 20th	Night	20% 13% 5% 8% 5% 4 3 3 4 5% 30%	4952
	21st to end	Night	17% 15% 4 10% 6% 5% 5% 3 6% 6% 23%	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	64% 3 7% 17% 8%	5259
	11th to 20th	Day	59% 2 4 18% 14% 2	5280
	21st to end	Day	57% 3 6% 26% 8% 1	5780
February	1st to 10th	Day	57% 3 8% 20% 11% 1	1928
	11th to 20th	Day	58% 3 7% 19% 11% 2	2058
	21st to end	Day	56% 3 7% 18% 12% 3	1730
March	1st to 10th	Day	55% 4 6% 16% 15% 5%	4857
	11th to 20th	Day	41% 3 8% 21% 24% 4	5090
	21st to end	Day	46% 4 9% 26% 14% 1	5586
April	1st to 10th	Day	44% 5% 11% 23% 14% 3	2310
	11th to 20th	Day	42% 4 9% 22% 18% 4	2612
	21st to end	Day	46% 5% 10% 25% 12% 2	2730
May	1st to 10th	Day	49% 5% 10% 23% 11% 1	7651
	11th to 20th	Day	47% 7% 11% 23% 12% 1	7630
	21st to end	Day	51% 7% 11% 17% 11% 2	8405
June	1st to 10th	Day	39% 7% 13% 23% 17% 1	2730
	11th to 20th	Day	40% 8% 13% 20% 17% 2	2730
	21st to end	Day	37% 8% 15% 22% 15% 3	2730
July	1st to 10th	Day	37% 8% 15% 23% 16% 1	5965
	11th to 20th	Day	41% 9% 16% 26% 7% 1	5961
	21st to end	Day	52% 7% 10% 21% 9% 1	6370
August	1st to 10th	Day	40% 8% 15% 27% 10%	4221
	11th to 20th	Day	38% 7% 12% 30% 12% 1	4213
	21st to end	Day	26% 6% 14% 34% 19% 2	4461
September	1st to 10th	Day	36% 6% 11% 23% 19% 5%	2200
	11th to 20th	Day	38% 5% 10% 28% 18% 2	2200
	21st to end	Day	43% 4 10% 21% 19% 2	2200
October	1st to 10th	Day	29% 4 7% 22% 35% 3	3508
	11th to 20th	Day	26% 2 10% 28% 29% 4	3240
	21st to end	Day	31% 2 9% 31% 20% 7%	3538
November	1st to 10th	Day	35% 4 9% 24% 25% 3	1872
	11th to 20th	Day	45% 3 7% 24% 19% 4	1890
	21st to end	Day	48% 3 9% 22% 17% 2	1890
December	1st to 10th	Day	54% 4 6% 21% 15% 1	3020
	11th to 20th	Day	61% 3 8% 17% 11% 1	3460
	21st to end	Day	61% 5% 9% 19% 5%	4565
January	1st to 10th	Night	62% 3 10% 18% 6% 1	7636
	11th to 20th	Night	55% 3 4 18% 17% 3	7680
	21st to end	Night	55% 2 7% 22% 12% 2	8401
February	1st to 10th	Night	54% 3 10% 20% 11% 1	2688
	11th to 20th	Night	58% 3 8% 18% 11% 2	2459
	21st to end	Night	57% 4 8% 16% 11% 3	2076
March	1st to 10th	Night	51% 3 6% 21% 16% 4	5216
	11th to 20th	Night	35% 3 7% 28% 23% 3	5090
	21st to end	Night	47% 5% 9% 23% 15% 1	5588
April	1st to 10th	Night	43% 5% 11% 22% 17% 3	2310
	11th to 20th	Night	39% 5% 10% 24% 16% 6%	1973
	21st to end	Night	44% 6% 11% 24% 14% 2	1890
May	1st to 10th	Night	49% 6% 11% 22% 11% 1	5264
	11th to 20th	Night	44% 6% 15% 22% 13%	5235
	21st to end	Night	52% 7% 11% 16% 12% 2	5771
June	1st to 10th	Night	33% 8% 16% 22% 18% 3	1890
	11th to 20th	Night	33% 9% 17% 21% 18% 2	1890
	21st to end	Night	35% 8% 15% 22% 15% 4	1890
July	1st to 10th	Night	37% 10% 13% 24% 13% 2	4105
	11th to 20th	Night	38% 10% 18% 24% 9% 2	4096
	21st to end	Night	48% 7% 14% 19% 11% 1	4387
August	1st to 10th	Night	38% 9% 14% 26% 12% 1	2904
	11th to 20th	Night	39% 6% 12% 29% 14% 1	2902
	21st to end	Night	23% 7% 13% 33% 23% 3	3400
September	1st to 10th	Night	34% 7% 12% 22% 17% 8%	2200
	11th to 20th	Night	36% 6% 10% 23% 23% 3	2200
	21st to end	Night	37% 6% 10% 23% 22% 2	2200
October	1st to 10th	Night	28% 4 7% 23% 34% 4	3670
	11th to 20th	Night	28% 3 6% 26% 28% 9%	3899
	21st to end	Night	29% 3 7% 26% 27% 8%	4252
November	1st to 10th	Night	37% 4 7% 23% 24% 6%	2644
	11th to 20th	Night	43% 4 8% 21% 19% 5%	2730
	21st to end	Night	45% 4 8% 25% 16% 2	2730
December	1st to 10th	Night	55% 4 8% 20% 11% 1	4380
	11th to 20th	Night	58% 3 8% 20% 9% 1	4954
	21st to end	Night	59% 5% 10% 17% 8%	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	29% 25% 28% 14% 3 1	330
	11th to 20th	Day	40% 24% 24% 11% 1	330
	21st to end	Day	31% 28% 27% 12% 2 1	363
February	1st to 10th	Day	28% 22% 33% 13% 4	330
	11th to 20th	Day	45% 22% 24% 7% 1 1	330
	21st to end	Day	34% 22% 31% 12% 1	273
March	1st to 10th	Day	32% 18% 29% 15% 6%	451
	11th to 20th	Day	28% 21% 30% 16% 4 1	540
	21st to end	Day	28% 19% 30% 17% 5%	594
April	1st to 10th	Day	29% 18% 26% 18% 9% 1	540
	11th to 20th	Day	21% 22% 28% 17% 9% 2	532
	21st to end	Day	24% 14% 32% 20% 8% 2	540
May	1st to 10th	Day	22% 19% 29% 18% 9% 3	543
	11th to 20th	Day	17% 13% 27% 26% 13% 5%	567
	21st to end	Day	18% 7% 25% 22% 19% 8%	617
June	1st to 10th	Day	13% 8% 24% 26% 22% 8%	570
	11th to 20th	Day	11% 8% 21% 30% 21% 10%	570
	21st to end	Day	13% 5% 24% 26% 20% 13%	570
July	1st to 10th	Day	14% 4 16% 24% 21% 20%	565
	11th to 20th	Day	10% 5% 18% 29% 23% 15%	564
	21st to end	Day	15% 6% 17% 27% 23% 11%	616
August	1st to 10th	Day	16% 5% 17% 24% 27% 12%	526
	11th to 20th	Day	13% 6% 14% 29% 27% 12%	519
	21st to end	Day	11% 3 14% 26% 31% 15%	583
September	1st to 10th	Day	15% 4 15% 23% 31% 12%	530
	11th to 20th	Day	14% 3 13% 28% 27% 15%	530
	21st to end	Day	22% 9% 19% 26% 17% 7%	530
October	1st to 10th	Day	14% 7% 21% 27% 24% 7%	530
	11th to 20th	Day	17% 10% 25% 27% 17% 4	530
	21st to end	Day	25% 14% 23% 24% 12% 2	583
November	1st to 10th	Day	20% 13% 31% 24% 10% 3	350
	11th to 20th	Day	27% 14% 30% 18% 10% 1	330
	21st to end	Day	28% 18% 27% 19% 8% 1	330
December	1st to 10th	Day	32% 18% 30% 15% 4 1	330
	11th to 20th	Day	29% 18% 29% 18% 4 2	330
	21st to end	Day	30% 18% 31% 14% 6% 1	363
January	1st to 10th	Night	28% 18% 28% 22% 4	840
	11th to 20th	Night	32% 18% 27% 20% 4	840
	21st to end	Night	25% 17% 32% 24% 2	924
February	1st to 10th	Night	25% 15% 30% 28% 2	840
	11th to 20th	Night	33% 17% 30% 19% 1	823
	21st to end	Night	32% 17% 30% 20% 2	692
March	1st to 10th	Night	27% 15% 27% 27% 5%	840
	11th to 20th	Night	25% 15% 30% 23% 7%	840
	21st to end	Night	20% 15% 31% 26% 7%	924
April	1st to 10th	Night	20% 15% 28% 29% 8%	840
	11th to 20th	Night	20% 12% 25% 30% 12% 1	650
	21st to end	Night	17% 11% 33% 30% 9% 1	630
May	1st to 10th	Night	20% 8% 28% 32% 11% 2	630
	11th to 20th	Night	16% 8% 23% 35% 17% 2	621
	21st to end	Night	13% 5% 18% 33% 27% 5%	683
June	1st to 10th	Night	11% 3 17% 38% 27% 4	630
	11th to 20th	Night	8% 4 15% 40% 28% 5%	630
	21st to end	Night	10% 2 17% 36% 30% 5%	630
July	1st to 10th	Night	13% 2 10% 32% 37% 7%	615
	11th to 20th	Night	8% 2 10% 32% 42% 5%	612
	21st to end	Night	11% 5% 10% 33% 34% 7%	687
August	1st to 10th	Night	11% 3 9% 34% 39% 5%	597
	11th to 20th	Night	12% 2 8% 32% 38% 8%	594
	21st to end	Night	10% 2 7% 32% 41% 8%	670
September	1st to 10th	Night	12% 3 10% 31% 38% 6%	800
	11th to 20th	Night	13% 2 14% 27% 39% 5%	800
	21st to end	Night	15% 5% 19% 30% 29% 3	800
October	1st to 10th	Night	14% 4 17% 31% 31% 4	800
	11th to 20th	Night	19% 8% 20% 33% 18% 2	800
	21st to end	Night	23% 9% 23% 31% 13% 1	880
November	1st to 10th	Night	16% 9% 23% 34% 16% 2	820
	11th to 20th	Night	20% 14% 25% 30% 11% 1	840
	21st to end	Night	23% 12% 21% 33% 10%	840
December	1st to 10th	Night	30% 14% 25% 26% 5%	840
	11th to 20th	Night	26% 12% 28% 28% 5% 1	840
	21st to end	Night	31% 14% 22% 29% 4	924

Page generated at 2026-07-28 03:25:21. Version ac07

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