KK's Hill
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the KK's Hill clear sky chart from 2005-11-06 to 2026-08-15.

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	17% 10% 3 8% 5% 4 5% 4 5% 7% 31%	142969
	Night	17% 12% 4 9% 5% 4 4 3 5% 6% 31%	138881
Transparency	Day	51% 5% 10% 20% 11% 2	146575
	Night	53% 5% 10% 19% 11% 2	143347
Seeing	Day	25% 14% 25% 20% 11% 4	17121
	Night	24% 12% 23% 27% 12% 1	26952

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	18% 20% 8% 17% 5% 3 3 2 3 4 16%	5258
	11th to 20th	Day	15% 20% 8% 16% 9% 5% 4 2 3 3 15%	5280
	21st to end	Day	18% 17% 5% 12% 8% 5% 5% 3 5% 5% 18%	5780
February	1st to 10th	Day	22% 15% 6% 8% 6% 4 3 3 4 6% 23%	1890
	11th to 20th	Day	21% 17% 5% 10% 5% 4 4 2 4 5% 23%	1844
	21st to end	Day	20% 17% 4 10% 4 3 3 3 4 5% 28%	1772
March	1st to 10th	Day	17% 17% 4 7% 4 3 3 3 4 5% 33%	5045
	11th to 20th	Day	14% 8% 3 7% 4 4 4 3 5% 7% 39%	5090
	21st to end	Day	19% 10% 4 9% 6% 5% 4 4 5% 5% 30%	5586
April	1st to 10th	Day	18% 13% 3 8% 5% 5% 4 4 5% 7% 31%	2404
	11th to 20th	Day	16% 10% 2 7% 5% 4 5% 3 5% 6% 36%	2506
	21st to end	Day	20% 8% 3 7% 5% 4 5% 4 6% 6% 33%	2730
May	1st to 10th	Day	19% 9% 3 8% 5% 5% 6% 5% 6% 7% 27%	7616
	11th to 20th	Day	17% 8% 3 7% 5% 4 5% 4 6% 8% 32%	7626
	21st to end	Day	23% 8% 3 6% 4 4 5% 4 5% 7% 32%	8510
June	1st to 10th	Day	14% 7% 2 6% 5% 4 5% 4 7% 9% 36%	2940
	11th to 20th	Day	14% 7% 2 6% 5% 6% 6% 5% 6% 8% 35%	2940
	21st to end	Day	14% 6% 3 6% 5% 4 5% 4 7% 9% 36%	2916
July	1st to 10th	Day	11% 6% 2 7% 5% 5% 5% 4 6% 8% 39%	7680
	11th to 20th	Day	13% 7% 3 7% 5% 5% 5% 4 7% 10% 33%	7680
	21st to end	Day	15% 8% 2 7% 5% 5% 6% 4 6% 8% 33%	8340
August	1st to 10th	Day	14% 8% 3 8% 5% 5% 6% 4 7% 9% 31%	4364
	11th to 20th	Day	12% 7% 3 7% 5% 5% 6% 4 6% 9% 37%	4226
	21st to end	Day	8% 3 1 5% 4 5% 5% 4 7% 10% 47%	4424
September	1st to 10th	Day	15% 5% 1 5% 3 4 4 3 5% 7% 48%	2385
	11th to 20th	Day	12% 7% 2 6% 4 5% 4 4 5% 8% 45%	2200
	21st to end	Day	19% 8% 3 7% 4 4 5% 4 5% 7% 34%	2200
October	1st to 10th	Day	16% 6% 2 6% 3 4 4 3 5% 6% 44%	2008
	11th to 20th	Day	19% 8% 2 6% 3 4 4 3 5% 7% 39%	2000
	21st to end	Day	23% 9% 3 5% 4 3 3 3 4 6% 37%	2200
November	1st to 10th	Day	13% 9% 2 6% 4 3 4 3 5% 6% 45%	2004
	11th to 20th	Day	16% 14% 4 6% 4 4 4 2 7% 6% 32%	1830
	21st to end	Day	20% 15% 5% 8% 4 3 4 3 5% 5% 27%	1680
December	1st to 10th	Day	20% 14% 6% 18% 5% 3 3 3 4 4 19%	2680
	11th to 20th	Day	23% 18% 6% 9% 4 3 3 2 4 4 24%	3070
	21st to end	Day	21% 18% 5% 10% 5% 4 4 3 5% 6% 17%	4265
January	1st to 10th	Night	18% 18% 8% 16% 5% 4 4 3 3 4 17%	7635
	11th to 20th	Night	17% 17% 9% 16% 7% 5% 3 2 3 3 19%	7680
	21st to end	Night	19% 14% 5% 10% 7% 6% 4 3 4 4 24%	8401
February	1st to 10th	Night	20% 15% 4 9% 6% 4 4 3 4 5% 26%	2730
	11th to 20th	Night	21% 15% 5% 11% 5% 5% 4 3 4 5% 24%	2658
	21st to end	Night	21% 15% 5% 8% 4 4 4 3 5% 5% 27%	2032
March	1st to 10th	Night	22% 13% 3 7% 5% 4 3 3 4 6% 32%	5028
	11th to 20th	Night	13% 12% 4 6% 4 4 3 3 5% 6% 40%	5090
	21st to end	Night	17% 11% 3 7% 5% 4 5% 4 5% 6% 34%	5588
April	1st to 10th	Night	20% 12% 3 7% 5% 4 4 2 4 6% 32%	2215
	11th to 20th	Night	18% 8% 3 5% 4 4 4 4 6% 8% 35%	2075
	21st to end	Night	15% 8% 3 8% 6% 4 3 3 5% 7% 39%	1895
May	1st to 10th	Night	23% 11% 4 9% 5% 5% 4 3 5% 7% 26%	5237
	11th to 20th	Night	15% 7% 2 7% 5% 4 5% 5% 6% 8% 35%	5234
	21st to end	Night	25% 11% 4 8% 4 4 4 3 4 6% 28%	5624
June	1st to 10th	Night	12% 6% 3 6% 5% 4 5% 4 5% 8% 42%	1680
	11th to 20th	Night	11% 7% 2 7% 6% 4 5% 5% 6% 9% 37%	1680
	21st to end	Night	12% 7% 2 6% 4 5% 5% 4 7% 9% 40%	1697
July	1st to 10th	Night	13% 8% 3 8% 5% 5% 5% 4 6% 7% 37%	5278
	11th to 20th	Night	16% 8% 3 7% 4 5% 5% 4 6% 8% 33%	5277
	21st to end	Night	15% 8% 3 7% 5% 5% 5% 4 6% 8% 35%	5736
August	1st to 10th	Night	13% 8% 3 8% 5% 5% 5% 5% 7% 10% 31%	3005
	11th to 20th	Night	15% 8% 2 7% 5% 4 4 3 6% 7% 38%	2911
	21st to end	Night	7% 5% 2 6% 4 5% 4 4 7% 9% 47%	3439
September	1st to 10th	Night	13% 6% 2 6% 4 4 5% 3 5% 7% 46%	2010
	11th to 20th	Night	12% 5% 1 4 3 3 4 5% 5% 7% 51%	2200
	21st to end	Night	16% 7% 3 8% 5% 4 5% 3 4 7% 39%	2200
October	1st to 10th	Night	16% 6% 2 4 3 4 3 3 5% 6% 47%	2391
	11th to 20th	Night	16% 6% 2 6% 3 4 4 4 5% 7% 43%	2400
	21st to end	Night	24% 8% 2 5% 3 3 4 2 4 5% 40%	2640
November	1st to 10th	Night	14% 9% 2 6% 3 4 4 3 4 6% 45%	2508
	11th to 20th	Night	20% 13% 3 7% 4 4 3 4 5% 5% 33%	2787
	21st to end	Night	20% 13% 4 9% 5% 4 4 3 4 4 29%	2940
December	1st to 10th	Night	19% 16% 6% 18% 4 3 3 2 4 5% 20%	4720
	11th to 20th	Night	23% 16% 7% 8% 4 4 4 3 4 5% 23%	5345
	21st to end	Night	20% 18% 5% 10% 6% 5% 4 3 5% 5% 21%	6915

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	73% 3 9% 10% 3	5259
	11th to 20th	Day	76% 3 6% 9% 6% 1	5280
	21st to end	Day	69% 3 8% 14% 6%	5780
February	1st to 10th	Day	62% 5% 9% 17% 7%	1890
	11th to 20th	Day	65% 4 10% 13% 8%	1853
	21st to end	Day	61% 5% 10% 14% 10% 1	1772
March	1st to 10th	Day	53% 5% 7% 21% 10% 3	5045
	11th to 20th	Day	44% 6% 9% 28% 11% 3	5090
	21st to end	Day	55% 5% 7% 19% 13% 1	5586
April	1st to 10th	Day	52% 7% 10% 17% 11% 3	2404
	11th to 20th	Day	47% 6% 11% 15% 18% 2	2506
	21st to end	Day	50% 6% 11% 21% 11% 1	2730
May	1st to 10th	Day	54% 6% 10% 21% 7% 2	7651
	11th to 20th	Day	49% 7% 12% 24% 8% 1	7630
	21st to end	Day	50% 7% 11% 16% 12% 4	8525
June	1st to 10th	Day	42% 9% 13% 21% 14% 1	2940
	11th to 20th	Day	46% 9% 12% 21% 11% 1	2940
	21st to end	Day	42% 9% 14% 22% 12% 1	2916
July	1st to 10th	Day	42% 6% 13% 22% 15% 1	7615
	11th to 20th	Day	44% 5% 12% 29% 9% 1	7611
	21st to end	Day	47% 4 10% 21% 17% 1	8156
August	1st to 10th	Day	48% 7% 15% 23% 7% 1	4351
	11th to 20th	Day	43% 6% 12% 28% 12%	4265
	21st to end	Day	32% 7% 15% 28% 17% 2	4424
September	1st to 10th	Day	36% 6% 11% 22% 22% 3	2385
	11th to 20th	Day	37% 6% 11% 27% 16% 3	2200
	21st to end	Day	49% 6% 12% 18% 15% 1	2200
October	1st to 10th	Day	32% 4 9% 27% 25% 3	3268
	11th to 20th	Day	41% 4 10% 24% 14% 7%	3240
	21st to end	Day	36% 3 9% 29% 21% 2	3538
November	1st to 10th	Day	41% 5% 9% 24% 17% 4	2004
	11th to 20th	Day	52% 5% 10% 17% 14% 3	1830
	21st to end	Day	59% 5% 10% 15% 11%	1680
December	1st to 10th	Day	70% 3 11% 12% 3 1	2680
	11th to 20th	Day	64% 3 11% 17% 4 1	3066
	21st to end	Day	67% 4 10% 13% 5%	4265
January	1st to 10th	Night	73% 3 9% 11% 4	7636
	11th to 20th	Night	72% 3 6% 10% 6% 2	7680
	21st to end	Night	65% 3 10% 15% 6% 1	8401
February	1st to 10th	Night	61% 5% 10% 15% 9%	2730
	11th to 20th	Night	64% 5% 9% 14% 8%	2660
	21st to end	Night	59% 5% 9% 15% 9% 2	2032
March	1st to 10th	Night	54% 5% 7% 22% 10% 2	5028
	11th to 20th	Night	44% 5% 8% 28% 10% 3	5090
	21st to end	Night	50% 5% 9% 20% 13% 2	5588
April	1st to 10th	Night	54% 5% 8% 18% 13% 2	2215
	11th to 20th	Night	45% 6% 13% 19% 13% 4	2075
	21st to end	Night	45% 6% 12% 22% 13% 2	1895
May	1st to 10th	Night	59% 6% 11% 14% 9% 2	5264
	11th to 20th	Night	46% 8% 13% 23% 10% 1	5235
	21st to end	Night	56% 7% 10% 15% 10% 2	5633
June	1st to 10th	Night	39% 8% 12% 24% 16% 1	1680
	11th to 20th	Night	42% 10% 13% 20% 13% 1	1680
	21st to end	Night	39% 9% 15% 20% 15% 1	1697
July	1st to 10th	Night	46% 6% 10% 22% 14% 2	5235
	11th to 20th	Night	48% 5% 14% 23% 10% 1	5226
	21st to end	Night	47% 6% 11% 18% 17% 1	5606
August	1st to 10th	Night	47% 7% 16% 22% 7% 1	2994
	11th to 20th	Night	44% 6% 10% 22% 17% 1	2938
	21st to end	Night	32% 7% 12% 33% 15% 2	3439
September	1st to 10th	Night	37% 7% 12% 20% 19% 5%	2010
	11th to 20th	Night	31% 7% 13% 26% 22% 2	2200
	21st to end	Night	44% 7% 11% 20% 17% 1	2200
October	1st to 10th	Night	34% 4 9% 26% 22% 4	3911
	11th to 20th	Night	37% 4 9% 23% 17% 8%	3899
	21st to end	Night	36% 3 6% 27% 25% 3	4252
November	1st to 10th	Night	41% 5% 11% 19% 19% 5%	2508
	11th to 20th	Night	53% 5% 8% 18% 13% 3	2787
	21st to end	Night	59% 4 8% 18% 10% 1	2940
December	1st to 10th	Night	69% 3 10% 14% 3 1	4720
	11th to 20th	Night	65% 4 12% 15% 4	5348
	21st to end	Night	66% 5% 10% 13% 6%	6915

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	33% 31% 21% 10% 4 1	330
	11th to 20th	Day	45% 23% 25% 6%	330
	21st to end	Day	40% 26% 24% 6% 3	363
February	1st to 10th	Day	36% 27% 26% 9% 2	330
	11th to 20th	Day	48% 24% 23% 4 1	330
	21st to end	Day	42% 23% 29% 6% 1	315
March	1st to 10th	Day	35% 21% 26% 15% 3	540
	11th to 20th	Day	35% 22% 26% 12% 4 1	540
	21st to end	Day	32% 20% 30% 14% 4	594
April	1st to 10th	Day	35% 19% 22% 18% 5% 1	540
	11th to 20th	Day	27% 20% 27% 17% 6% 3	532
	21st to end	Day	28% 18% 27% 18% 7% 2	540
May	1st to 10th	Day	28% 18% 28% 15% 6% 4	543
	11th to 20th	Day	24% 15% 28% 20% 11% 3	567
	21st to end	Day	20% 10% 29% 21% 14% 7%	617
June	1st to 10th	Day	15% 11% 28% 24% 16% 5%	570
	11th to 20th	Day	19% 9% 24% 27% 16% 5%	570
	21st to end	Day	15% 9% 28% 27% 16% 4	570
July	1st to 10th	Day	15% 5% 20% 27% 21% 12%	565
	11th to 20th	Day	13% 7% 22% 29% 21% 8%	564
	21st to end	Day	21% 6% 22% 25% 19% 8%	620
August	1st to 10th	Day	16% 6% 20% 32% 17% 10%	566
	11th to 20th	Day	17% 7% 20% 26% 22% 9%	535
	21st to end	Day	11% 7% 21% 28% 21% 12%	583
September	1st to 10th	Day	17% 7% 19% 26% 21% 9%	530
	11th to 20th	Day	12% 3 18% 30% 25% 12%	530
	21st to end	Day	25% 9% 24% 27% 13% 3	530
October	1st to 10th	Day	18% 9% 21% 26% 22% 5%	530
	11th to 20th	Day	25% 10% 28% 24% 10% 3	530
	21st to end	Day	30% 16% 26% 18% 10% 1	583
November	1st to 10th	Day	22% 12% 29% 24% 9% 4	482
	11th to 20th	Day	34% 18% 24% 17% 4 1	298
	21st to end	Day	34% 20% 31% 12% 2	220
December	1st to 10th	Day	33% 25% 26% 11% 3 1	220
	11th to 20th	Day	40% 22% 22% 13% 3	220
	21st to end	Day	43% 18% 22% 14% 4	294
January	1st to 10th	Night	34% 22% 25% 15% 3	840
	11th to 20th	Night	38% 18% 26% 16% 2	840
	21st to end	Night	30% 23% 29% 17% 1	924
February	1st to 10th	Night	31% 18% 27% 23% 2	840
	11th to 20th	Night	33% 22% 31% 14% 1	823
	21st to end	Night	32% 19% 30% 18% 1	692
March	1st to 10th	Night	29% 18% 27% 23% 3	840
	11th to 20th	Night	33% 17% 25% 19% 5% 1	840
	21st to end	Night	29% 17% 29% 21% 3 1	924
April	1st to 10th	Night	28% 18% 28% 21% 5%	840
	11th to 20th	Night	22% 15% 30% 24% 9%	831
	21st to end	Night	19% 12% 30% 30% 8%	635
May	1st to 10th	Night	23% 9% 29% 29% 9% 1	630
	11th to 20th	Night	21% 9% 25% 32% 12% 1	621
	21st to end	Night	18% 5% 21% 29% 24% 3	636
June	1st to 10th	Night	12% 6% 22% 39% 20%	420
	11th to 20th	Night	15% 4 24% 37% 20% 1	420
	21st to end	Night	15% 3 20% 41% 21% 1	437
July	1st to 10th	Night	13% 3 14% 37% 30% 4	615
	11th to 20th	Night	14% 3 13% 36% 31% 3	612
	21st to end	Night	16% 3 13% 36% 30% 2	690
August	1st to 10th	Night	12% 3 13% 43% 27% 3	627
	11th to 20th	Night	16% 4 12% 37% 28% 3	606
	21st to end	Night	14% 3 12% 37% 29% 4	785
September	1st to 10th	Night	15% 3 17% 36% 26% 4	800
	11th to 20th	Night	14% 4 15% 35% 29% 3	800
	21st to end	Night	20% 7% 21% 32% 19% 2	800
October	1st to 10th	Night	19% 6% 18% 34% 20% 3	800
	11th to 20th	Night	21% 10% 26% 31% 12% 1	800
	21st to end	Night	29% 11% 21% 28% 10% 1	880
November	1st to 10th	Night	19% 10% 26% 31% 12% 1	820
	11th to 20th	Night	32% 13% 23% 24% 6% 1	840
	21st to end	Night	29% 15% 27% 22% 6% 1	840
December	1st to 10th	Night	33% 18% 26% 19% 4	840
	11th to 20th	Night	32% 18% 24% 21% 4	840
	21st to end	Night	33% 14% 27% 24% 2	924

Page generated at 2026-08-12 03:37:21. Version ac07

Copyright © 2026 Attilla Danko.