Kile Knob Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kile Knob Observatory clear sky chart from 2005-11-06 to 2026-05-02.

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	11% 7% 3 8% 5% 5% 5% 4 6% 8% 37%	131404
	Night	10% 7% 3 7% 5% 5% 5% 4 6% 8% 39%	131061
Transparency	Day	27% 38% 8% 15% 10% 3	135010
	Night	26% 37% 9% 16% 10% 2	135525
Seeing	Day	23% 16% 26% 20% 11% 4	16828
	Night	20% 15% 25% 27% 12% 1	26789

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	9% 8% 4 10% 6% 5% 4 3 5% 7% 40%	5258
	11th to 20th	Day	6% 10% 5% 10% 7% 5% 5% 3 4 5% 39%	5280
	21st to end	Day	9% 7% 3 8% 5% 5% 5% 4 5% 5% 42%	5780
February	1st to 10th	Day	8% 10% 3 8% 6% 5% 6% 4 5% 8% 37%	1890
	11th to 20th	Day	11% 9% 4 10% 5% 5% 4 4 6% 7% 36%	1843
	21st to end	Day	9% 11% 4 8% 5% 5% 4 3 6% 6% 38%	1795
March	1st to 10th	Day	12% 6% 4 8% 5% 5% 5% 4 6% 7% 39%	5045
	11th to 20th	Day	9% 7% 2 7% 5% 4 3 4 5% 7% 47%	5090
	21st to end	Day	10% 9% 3 8% 6% 6% 5% 4 5% 6% 37%	5586
April	1st to 10th	Day	10% 8% 4 8% 6% 5% 5% 3 6% 7% 38%	2431
	11th to 20th	Day	11% 8% 2 7% 4 4 4 4 6% 7% 43%	2494
	21st to end	Day	15% 9% 3 7% 5% 5% 4 4 5% 6% 37%	2657
May	1st to 10th	Day	14% 8% 3 8% 6% 6% 7% 5% 7% 8% 27%	5875
	11th to 20th	Day	21% 8% 3 7% 5% 5% 5% 4 6% 8% 29%	5861
	21st to end	Day	15% 6% 3 8% 6% 6% 6% 5% 7% 8% 30%	6561
June	1st to 10th	Day	13% 6% 2 6% 5% 5% 6% 5% 7% 7% 38%	2800
	11th to 20th	Day	11% 7% 3 7% 6% 6% 6% 5% 7% 9% 34%	2800
	21st to end	Day	8% 5% 2 7% 6% 6% 7% 6% 7% 9% 38%	2779
July	1st to 10th	Day	6% 6% 2 8% 6% 7% 6% 5% 7% 9% 37%	5900
	11th to 20th	Day	8% 5% 3 8% 7% 7% 7% 6% 9% 11% 30%	5900
	21st to end	Day	10% 8% 3 9% 7% 7% 6% 5% 7% 9% 29%	6424
August	1st to 10th	Day	13% 6% 3 8% 6% 6% 7% 6% 7% 10% 28%	4234
	11th to 20th	Day	8% 6% 3 8% 7% 8% 8% 5% 8% 9% 31%	4174
	21st to end	Day	7% 5% 2 6% 5% 6% 6% 5% 6% 9% 42%	4345
September	1st to 10th	Day	13% 6% 2 6% 5% 6% 5% 4 5% 6% 42%	2400
	11th to 20th	Day	13% 6% 2 7% 4 5% 5% 4 6% 7% 41%	2233
	21st to end	Day	21% 7% 3 6% 5% 4 5% 3 5% 6% 34%	2178
October	1st to 10th	Day	14% 5% 2 5% 4 5% 5% 3 5% 7% 45%	2000
	11th to 20th	Day	14% 10% 3 6% 5% 4 3 3 4 5% 45%	2000
	21st to end	Day	12% 7% 3 6% 4 4 4 4 5% 8% 45%	2200
November	1st to 10th	Day	8% 7% 2 5% 4 4 5% 4 6% 6% 50%	2057
	11th to 20th	Day	12% 7% 3 6% 4 4 5% 3 6% 7% 43%	1842
	21st to end	Day	11% 9% 3 7% 5% 4 5% 4 5% 6% 42%	1680
December	1st to 10th	Day	7% 7% 3 7% 5% 6% 4 4 5% 8% 44%	2680
	11th to 20th	Day	13% 8% 3 7% 4 6% 4 4 5% 7% 38%	3070
	21st to end	Day	14% 9% 3 9% 5% 5% 6% 4 7% 8% 31%	4262
January	1st to 10th	Night	7% 9% 5% 10% 8% 7% 6% 4 6% 6% 33%	7635
	11th to 20th	Night	7% 8% 3 9% 8% 5% 5% 4 5% 6% 42%	7680
	21st to end	Night	9% 8% 3 6% 5% 5% 5% 3 5% 6% 45%	8401
February	1st to 10th	Night	8% 7% 3 8% 6% 5% 5% 5% 7% 8% 38%	2730
	11th to 20th	Night	12% 9% 3 9% 6% 5% 6% 5% 6% 6% 34%	2663
	21st to end	Night	10% 8% 3 9% 5% 5% 4 4 6% 7% 37%	2006
March	1st to 10th	Night	14% 8% 2 6% 4 5% 5% 4 6% 6% 40%	5028
	11th to 20th	Night	8% 6% 4 7% 4 4 3 3 6% 8% 46%	5090
	21st to end	Night	8% 9% 2 7% 5% 4 5% 4 6% 8% 42%	5588
April	1st to 10th	Night	10% 8% 3 7% 5% 5% 4 5% 5% 7% 40%	2187
	11th to 20th	Night	10% 7% 2 5% 5% 5% 5% 4 6% 9% 42%	2075
	21st to end	Night	13% 6% 2 6% 5% 4 4 4 7% 7% 42%	1979
May	1st to 10th	Night	16% 9% 3 9% 5% 5% 5% 5% 6% 8% 30%	4042
	11th to 20th	Night	22% 9% 2 7% 5% 4 4 4 6% 7% 29%	4032
	21st to end	Night	13% 7% 3 9% 6% 6% 6% 5% 7% 8% 30%	4286
June	1st to 10th	Night	10% 5% 2 5% 5% 5% 6% 5% 7% 9% 43%	1600
	11th to 20th	Night	10% 5% 2 6% 5% 5% 5% 5% 7% 10% 41%	1600
	21st to end	Night	7% 4 2 5% 4 4 5% 4 8% 10% 46%	1612
July	1st to 10th	Night	6% 4 2 7% 4 5% 6% 5% 8% 10% 43%	4058
	11th to 20th	Night	8% 7% 3 9% 6% 6% 7% 5% 7% 10% 32%	4057
	21st to end	Night	8% 7% 3 9% 6% 6% 7% 5% 8% 10% 31%	4427
August	1st to 10th	Night	15% 5% 2 7% 5% 5% 6% 5% 7% 9% 36%	2915
	11th to 20th	Night	9% 7% 3 7% 6% 7% 6% 4 7% 8% 38%	2875
	21st to end	Night	7% 5% 2 6% 5% 5% 5% 4 6% 10% 47%	3519
September	1st to 10th	Night	12% 5% 2 6% 4 4 5% 4 5% 7% 47%	2000
	11th to 20th	Night	12% 6% 3 6% 5% 4 4 3 5% 6% 46%	2163
	21st to end	Night	20% 7% 2 5% 5% 4 5% 4 5% 6% 36%	2220
October	1st to 10th	Night	14% 6% 2 5% 3 3 5% 4 5% 7% 46%	2400
	11th to 20th	Night	12% 8% 2 6% 4 4 4 3 5% 7% 46%	2400
	21st to end	Night	13% 7% 2 5% 4 4 4 4 5% 7% 45%	2640
November	1st to 10th	Night	7% 8% 2 6% 5% 5% 5% 4 5% 7% 46%	2461
	11th to 20th	Night	10% 7% 3 6% 6% 4 5% 4 6% 7% 42%	2770
	21st to end	Night	10% 8% 3 8% 5% 5% 6% 4 6% 6% 39%	2940
December	1st to 10th	Night	7% 7% 3 8% 5% 5% 5% 4 6% 9% 41%	4720
	11th to 20th	Night	12% 9% 4 9% 5% 4 5% 4 6% 6% 36%	5345
	21st to end	Night	11% 6% 6% 9% 6% 6% 6% 5% 7% 9% 31%	6917

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	34% 21% 6% 19% 16% 4	5259
	11th to 20th	Day	34% 21% 6% 12% 18% 9%	5280
	21st to end	Day	33% 22% 6% 22% 13% 3	5780
February	1st to 10th	Day	19% 60% 4 8% 8% 1	1890
	11th to 20th	Day	21% 59% 3 8% 8% 1	1852
	21st to end	Day	19% 59% 4 10% 7% 2	1795
March	1st to 10th	Day	34% 29% 5% 14% 12% 6%	5045
	11th to 20th	Day	24% 28% 6% 22% 16% 4	5090
	21st to end	Day	33% 29% 6% 13% 15% 4	5586
April	1st to 10th	Day	20% 60% 5% 10% 6% 1	2431
	11th to 20th	Day	15% 60% 6% 11% 7% 1	2494
	21st to end	Day	20% 59% 5% 12% 4 1	2657
May	1st to 10th	Day	37% 31% 9% 16% 5% 2	5910
	11th to 20th	Day	37% 30% 8% 18% 7%	5865
	21st to end	Day	36% 30% 10% 14% 8% 2	6576
June	1st to 10th	Day	17% 63% 5% 10% 6%	2800
	11th to 20th	Day	17% 64% 6% 9% 4	2800
	21st to end	Day	16% 62% 6% 10% 5% 1	2779
July	1st to 10th	Day	28% 31% 12% 18% 9% 3	5835
	11th to 20th	Day	32% 33% 14% 17% 3	5831
	21st to end	Day	34% 29% 10% 18% 9%	6240
August	1st to 10th	Day	31% 40% 11% 14% 4	4221
	11th to 20th	Day	23% 39% 9% 19% 8%	4213
	21st to end	Day	18% 39% 12% 21% 10%	4345
September	1st to 10th	Day	16% 58% 7% 8% 9% 2	2400
	11th to 20th	Day	18% 58% 4 10% 9% 1	2233
	21st to end	Day	25% 57% 5% 8% 5% 1	2178
October	1st to 10th	Day	15% 37% 6% 15% 23% 5%	3260
	11th to 20th	Day	16% 36% 5% 19% 12% 12%	3240
	21st to end	Day	14% 35% 6% 21% 14% 9%	3538
November	1st to 10th	Day	18% 54% 5% 11% 10% 2	2057
	11th to 20th	Day	15% 54% 4 10% 14% 3	1842
	21st to end	Day	19% 54% 5% 14% 7% 1	1680
December	1st to 10th	Day	22% 37% 7% 16% 15% 3	2680
	11th to 20th	Day	29% 31% 11% 14% 14% 2	3066
	21st to end	Day	36% 28% 11% 13% 11% 1	4262
January	1st to 10th	Night	35% 21% 7% 19% 15% 3	7636
	11th to 20th	Night	30% 21% 7% 18% 16% 8%	7680
	21st to end	Night	29% 22% 8% 22% 17% 2	8401
February	1st to 10th	Night	16% 60% 7% 9% 6% 1	2730
	11th to 20th	Night	22% 59% 3 10% 5% 1	2665
	21st to end	Night	18% 59% 5% 9% 7% 3	2006
March	1st to 10th	Night	33% 29% 6% 15% 10% 6%	5028
	11th to 20th	Night	22% 28% 7% 24% 16% 4	5090
	21st to end	Night	27% 29% 12% 16% 14% 3	5588
April	1st to 10th	Night	18% 60% 7% 9% 6%	2187
	11th to 20th	Night	15% 61% 8% 12% 4 1	2075
	21st to end	Night	17% 59% 6% 13% 5%	1979
May	1st to 10th	Night	37% 32% 12% 13% 5% 1	4069
	11th to 20th	Night	39% 30% 9% 19% 4	4033
	21st to end	Night	37% 31% 13% 15% 2 2	4293
June	1st to 10th	Night	14% 64% 7% 10% 5%	1600
	11th to 20th	Night	14% 64% 7% 10% 5%	1600
	21st to end	Night	13% 63% 8% 10% 6%	1612
July	1st to 10th	Night	25% 32% 16% 19% 6% 1	4015
	11th to 20th	Night	36% 33% 15% 13% 3	4006
	21st to end	Night	33% 32% 14% 14% 6%	4297
August	1st to 10th	Night	30% 40% 13% 15% 2	2904
	11th to 20th	Night	24% 40% 13% 14% 8%	2902
	21st to end	Night	18% 37% 13% 24% 7%	3519
September	1st to 10th	Night	15% 58% 9% 10% 6% 2	2000
	11th to 20th	Night	19% 57% 4 12% 8%	2163
	21st to end	Night	24% 57% 6% 9% 4	2220
October	1st to 10th	Night	20% 37% 6% 17% 16% 3	3920
	11th to 20th	Night	17% 36% 7% 12% 18% 9%	3899
	21st to end	Night	12% 36% 8% 21% 16% 7%	4252
November	1st to 10th	Night	19% 54% 7% 11% 8% 2	2461
	11th to 20th	Night	16% 54% 4 11% 13% 3	2770
	21st to end	Night	19% 55% 6% 12% 7% 1	2940
December	1st to 10th	Night	21% 36% 10% 20% 12% 1	4720
	11th to 20th	Night	33% 32% 10% 11% 12% 2	5348
	21st to end	Night	35% 27% 10% 16% 10%	6917

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	38% 26% 23% 9% 3	330
	11th to 20th	Day	37% 27% 26% 8% 2	330
	21st to end	Day	37% 30% 25% 6% 1	363
February	1st to 10th	Day	35% 29% 28% 7% 1	330
	11th to 20th	Day	49% 25% 20% 5% 1	330
	21st to end	Day	38% 25% 27% 10%	367
March	1st to 10th	Day	31% 22% 28% 15% 4	540
	11th to 20th	Day	34% 23% 22% 16% 4 1	540
	21st to end	Day	29% 24% 29% 14% 4 1	594
April	1st to 10th	Day	27% 30% 23% 16% 4 1	540
	11th to 20th	Day	26% 21% 27% 16% 8% 2	532
	21st to end	Day	28% 19% 30% 14% 7% 2	540
May	1st to 10th	Day	28% 21% 25% 14% 10% 3	507
	11th to 20th	Day	27% 15% 28% 18% 9% 3	527
	21st to end	Day	21% 11% 23% 26% 13% 6%	573
June	1st to 10th	Day	16% 13% 28% 24% 15% 5%	530
	11th to 20th	Day	17% 10% 30% 20% 17% 6%	530
	21st to end	Day	10% 11% 29% 31% 13% 5%	530
July	1st to 10th	Day	9% 8% 26% 28% 22% 8%	525
	11th to 20th	Day	6% 6% 26% 34% 18% 10%	524
	21st to end	Day	13% 5% 24% 28% 20% 9%	576
August	1st to 10th	Day	14% 7% 23% 26% 19% 10%	526
	11th to 20th	Day	11% 5% 24% 28% 20% 11%	519
	21st to end	Day	10% 6% 23% 26% 22% 12%	583
September	1st to 10th	Day	15% 10% 19% 26% 20% 10%	530
	11th to 20th	Day	15% 5% 21% 29% 20% 11%	530
	21st to end	Day	28% 12% 21% 24% 13% 3	530
October	1st to 10th	Day	18% 9% 23% 26% 19% 4	530
	11th to 20th	Day	21% 19% 24% 24% 10% 3	530
	21st to end	Day	23% 17% 31% 20% 7% 1	583
November	1st to 10th	Day	19% 19% 31% 20% 10% 1	535
	11th to 20th	Day	28% 19% 28% 19% 6%	320
	21st to end	Day	36% 16% 30% 14% 3	220
December	1st to 10th	Day	30% 24% 33% 10% 3	220
	11th to 20th	Day	34% 20% 26% 15% 5%	220
	21st to end	Day	33% 22% 30% 10% 4	294
January	1st to 10th	Night	28% 26% 29% 14% 2	840
	11th to 20th	Night	28% 22% 29% 20% 1	840
	21st to end	Night	25% 23% 36% 14% 2	924
February	1st to 10th	Night	24% 24% 32% 19% 1	840
	11th to 20th	Night	30% 27% 30% 13% 1	823
	21st to end	Night	28% 24% 34% 14% 1	692
March	1st to 10th	Night	24% 22% 33% 19% 3	840
	11th to 20th	Night	29% 21% 26% 21% 4 1	840
	21st to end	Night	23% 21% 31% 20% 4 1	924
April	1st to 10th	Night	22% 22% 30% 23% 3	840
	11th to 20th	Night	18% 18% 30% 26% 8% 1	831
	21st to end	Night	19% 15% 29% 29% 8%	719
May	1st to 10th	Night	20% 10% 26% 30% 13% 2	603
	11th to 20th	Night	20% 8% 24% 34% 13% 1	591
	21st to end	Night	15% 5% 25% 32% 20% 3	592
June	1st to 10th	Night	11% 4 27% 36% 21% 2	400
	11th to 20th	Night	11% 5% 19% 46% 18% 1	400
	21st to end	Night	7% 5% 25% 45% 17% 1	412
July	1st to 10th	Night	11% 2 14% 43% 26% 5%	585
	11th to 20th	Night	6% 2 16% 41% 30% 4	582
	21st to end	Night	9% 4 16% 38% 31% 3	657
August	1st to 10th	Night	9% 2 14% 42% 29% 3	597
	11th to 20th	Night	11% 3 12% 41% 30% 3	594
	21st to end	Night	11% 4 16% 38% 28% 3	839
September	1st to 10th	Night	13% 4 15% 37% 25% 6%	800
	11th to 20th	Night	13% 7% 15% 33% 29% 3	800
	21st to end	Night	24% 7% 21% 29% 18% 2	800
October	1st to 10th	Night	19% 9% 18% 29% 22% 3	800
	11th to 20th	Night	19% 16% 25% 27% 12% 1	800
	21st to end	Night	22% 13% 27% 29% 8% 1	880
November	1st to 10th	Night	17% 14% 30% 29% 10% 1	820
	11th to 20th	Night	24% 16% 28% 23% 7% 1	840
	21st to end	Night	22% 20% 29% 23% 5% 1	840
December	1st to 10th	Night	25% 23% 28% 21% 4	840
	11th to 20th	Night	22% 22% 30% 23% 3	840
	21st to end	Night	23% 20% 30% 26% 2	924

Page generated at 2026-04-29 02:21:45. Version ac07

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