The Kiski School Astronomy Club
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the The Kiski School Astronomy Club clear sky chart from 2005-11-06 to 2025-10-19.

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	16% 11% 4 9% 5% 5% 4 4 5% 7% 30%	126419
	Night	17% 12% 4 9% 5% 4 4 3 5% 6% 31%	123283
Transparency	Day	52% 6% 11% 20% 10% 1	130020
	Night	54% 5% 11% 19% 10% 1	127751
Seeing	Day	25% 13% 26% 20% 11% 4	15967
	Night	24% 11% 24% 27% 12% 1	25567

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	17% 20% 8% 23% 5% 3 2 2 3 4 14%	3936
	11th to 20th	Day	13% 23% 10% 18% 10% 6% 2 2 2 2 13%	4060
	21st to end	Day	20% 20% 6% 12% 7% 5% 4 2 3 4 17%	4466
February	1st to 10th	Day	19% 18% 6% 12% 8% 5% 3 3 3 4 20%	1800
	11th to 20th	Day	17% 17% 7% 14% 5% 5% 3 3 5% 5% 20%	1753
	21st to end	Day	21% 16% 5% 12% 5% 3 4 3 4 5% 23%	1647
March	1st to 10th	Day	16% 14% 5% 9% 4 4 3 3 5% 5% 32%	4935
	11th to 20th	Day	13% 10% 5% 9% 5% 5% 5% 4 6% 6% 34%	4980
	21st to end	Day	16% 11% 3 10% 6% 5% 5% 4 5% 5% 31%	5465
April	1st to 10th	Day	16% 13% 3 8% 5% 4 5% 4 6% 6% 29%	2335
	11th to 20th	Day	16% 11% 3 8% 4 5% 4 4 5% 6% 33%	2374
	21st to end	Day	20% 10% 2 7% 5% 4 4 3 4 6% 34%	2589
May	1st to 10th	Day	20% 9% 3 8% 5% 5% 5% 5% 6% 7% 26%	5862
	11th to 20th	Day	18% 9% 3 7% 5% 5% 5% 4 7% 9% 28%	5861
	21st to end	Day	19% 8% 3 7% 4 5% 5% 4 7% 8% 30%	6934
June	1st to 10th	Day	15% 7% 3 6% 5% 6% 6% 5% 7% 7% 34%	2800
	11th to 20th	Day	14% 7% 2 7% 5% 5% 5% 5% 7% 9% 32%	2800
	21st to end	Day	13% 7% 2 7% 5% 5% 6% 4 6% 10% 36%	2800
July	1st to 10th	Day	10% 6% 3 7% 5% 5% 5% 4 6% 9% 40%	6320
	11th to 20th	Day	11% 8% 3 8% 6% 5% 5% 5% 8% 11% 31%	5900
	21st to end	Day	12% 7% 3 8% 5% 5% 5% 4 6% 8% 38%	6424
August	1st to 10th	Day	14% 8% 4 8% 5% 6% 6% 5% 7% 8% 30%	4234
	11th to 20th	Day	12% 7% 3 7% 5% 5% 7% 4 7% 8% 36%	4174
	21st to end	Day	9% 5% 2 6% 5% 6% 6% 4 8% 10% 40%	4393
September	1st to 10th	Day	16% 7% 2 5% 4 3 4 3 6% 7% 44%	2400
	11th to 20th	Day	12% 6% 2 5% 5% 4 4 4 5% 7% 46%	2254
	21st to end	Day	20% 9% 3 7% 4 4 3 4 5% 7% 34%	2170
October	1st to 10th	Day	16% 6% 2 5% 4 4 4 4 6% 8% 41%	2000
	11th to 20th	Day	18% 9% 3 7% 4 4 5% 3 5% 7% 35%	1980
	21st to end	Day	23% 11% 2 6% 4 3 4 3 5% 6% 33%	2090
November	1st to 10th	Day	12% 10% 3 7% 5% 4 4 3 5% 7% 41%	1917
	11th to 20th	Day	17% 15% 3 7% 4 4 4 4 5% 6% 30%	1616
	21st to end	Day	19% 18% 5% 8% 5% 4 4 3 5% 5% 24%	1600
December	1st to 10th	Day	18% 15% 8% 21% 6% 4 4 2 3 4 17%	2600
	11th to 20th	Day	23% 19% 7% 10% 4 3 2 3 3 5% 21%	2990
	21st to end	Day	22% 21% 6% 11% 5% 4 4 3 4 5% 15%	3960
January	1st to 10th	Night	14% 18% 8% 24% 5% 4 3 3 3 4 15%	6004
	11th to 20th	Night	14% 19% 8% 16% 9% 5% 4 3 4 4 14%	5900
	21st to end	Night	22% 17% 6% 12% 6% 5% 4 3 3 3 19%	6490
February	1st to 10th	Night	19% 15% 6% 11% 5% 4 4 3 4 5% 23%	2600
	11th to 20th	Night	18% 15% 5% 12% 6% 5% 4 3 4 5% 24%	2533
	21st to end	Night	19% 14% 4 12% 5% 4 4 3 4 5% 25%	1980
March	1st to 10th	Night	21% 12% 5% 8% 5% 3 3 3 4 5% 31%	4918
	11th to 20th	Night	13% 12% 4 6% 4 3 3 3 4 6% 41%	4980
	21st to end	Night	16% 10% 4 9% 5% 4 5% 3 5% 5% 34%	5467
April	1st to 10th	Night	19% 13% 3 7% 3 4 3 4 4 5% 34%	2065
	11th to 20th	Night	17% 9% 2 7% 4 4 4 3 6% 7% 37%	1975
	21st to end	Night	16% 8% 3 8% 5% 4 4 3 5% 8% 35%	1829
May	1st to 10th	Night	25% 13% 3 8% 4 3 4 3 6% 6% 25%	4033
	11th to 20th	Night	19% 9% 3 8% 4 4 4 4 5% 7% 34%	4016
	21st to end	Night	20% 8% 3 7% 5% 3 4 3 6% 8% 32%	3920
June	1st to 10th	Night	12% 5% 3 5% 5% 5% 4 4 6% 9% 42%	1600
	11th to 20th	Night	11% 7% 3 7% 5% 4 4 5% 7% 9% 39%	1600
	21st to end	Night	12% 7% 2 5% 3 5% 5% 4 7% 10% 40%	1600
July	1st to 10th	Night	11% 8% 4 8% 4 5% 4 3 5% 8% 40%	3634
	11th to 20th	Night	12% 7% 3 8% 5% 5% 6% 5% 7% 9% 33%	4057
	21st to end	Night	11% 7% 3 8% 5% 5% 4 4 6% 8% 41%	4427
August	1st to 10th	Night	15% 8% 2 8% 5% 4 5% 4 6% 8% 35%	2915
	11th to 20th	Night	13% 7% 3 7% 5% 4 4 4 5% 7% 41%	2875
	21st to end	Night	8% 5% 2 6% 4 5% 4 5% 7% 10% 44%	3471
September	1st to 10th	Night	12% 6% 1 5% 4 3 5% 4 6% 7% 48%	2000
	11th to 20th	Night	10% 5% 2 4 3 3 3 3 5% 8% 52%	2142
	21st to end	Night	18% 8% 3 7% 4 4 4 3 4 6% 38%	2230
October	1st to 10th	Night	15% 7% 2 6% 4 3 4 4 5% 6% 45%	2400
	11th to 20th	Night	17% 7% 3 7% 5% 5% 4 3 5% 7% 39%	2377
	21st to end	Night	24% 9% 2 6% 3 3 4 2 5% 6% 36%	2508
November	1st to 10th	Night	13% 10% 3 6% 4 3 4 3 5% 6% 44%	2376
	11th to 20th	Night	19% 14% 3 7% 5% 5% 4 3 5% 5% 30%	2780
	21st to end	Night	19% 15% 5% 7% 5% 4 4 3 5% 5% 29%	2800
December	1st to 10th	Night	17% 17% 11% 14% 5% 4 3 2 4 5% 18%	4580
	11th to 20th	Night	23% 17% 6% 10% 4 4 3 3 4 4 22%	5205
	21st to end	Night	21% 19% 5% 11% 5% 5% 5% 3 5% 5% 17%	6996

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	77% 3 7% 8% 5%	3937
	11th to 20th	Day	80% 3 5% 8% 3 1	4060
	21st to end	Day	73% 3 8% 11% 5%	4466
February	1st to 10th	Day	70% 4 8% 13% 5% 1	1800
	11th to 20th	Day	67% 5% 9% 13% 6%	1762
	21st to end	Day	63% 5% 11% 14% 6% 1	1647
March	1st to 10th	Day	53% 5% 10% 23% 7% 2	4935
	11th to 20th	Day	49% 5% 13% 23% 8% 1	4980
	21st to end	Day	53% 5% 9% 20% 12% 1	5465
April	1st to 10th	Day	55% 6% 10% 17% 10% 2	2335
	11th to 20th	Day	51% 6% 11% 17% 14% 2	2374
	21st to end	Day	51% 6% 11% 20% 11% 2	2589
May	1st to 10th	Day	56% 7% 11% 16% 8% 3	5897
	11th to 20th	Day	51% 8% 11% 20% 9% 1	5865
	21st to end	Day	49% 9% 13% 19% 9% 2	6949
June	1st to 10th	Day	45% 11% 12% 21% 11% 1	2800
	11th to 20th	Day	45% 9% 14% 20% 11% 1	2800
	21st to end	Day	44% 8% 12% 25% 12% 1	2800
July	1st to 10th	Day	41% 6% 10% 26% 15% 2	6250
	11th to 20th	Day	45% 7% 15% 22% 10%	5831
	21st to end	Day	43% 5% 9% 21% 20% 1	6240
August	1st to 10th	Day	50% 9% 13% 20% 8%	4221
	11th to 20th	Day	43% 7% 12% 27% 11%	4213
	21st to end	Day	37% 7% 13% 28% 13% 2	4393
September	1st to 10th	Day	39% 7% 10% 22% 18% 3	2400
	11th to 20th	Day	37% 6% 13% 26% 16% 1	2254
	21st to end	Day	49% 6% 12% 20% 12% 1	2170
October	1st to 10th	Day	35% 5% 9% 30% 20% 1	3260
	11th to 20th	Day	44% 6% 11% 21% 14% 5%	3220
	21st to end	Day	38% 4 10% 28% 19% 1	3428
November	1st to 10th	Day	44% 5% 12% 19% 17% 3	1917
	11th to 20th	Day	54% 6% 11% 18% 10% 2	1616
	21st to end	Day	63% 5% 11% 16% 5% 1	1600
December	1st to 10th	Day	74% 4 10% 8% 4	2600
	11th to 20th	Day	67% 3 12% 14% 3	2986
	21st to end	Day	72% 4 8% 12% 5%	3960
January	1st to 10th	Night	75% 4 7% 10% 4	6004
	11th to 20th	Night	76% 4 7% 10% 2 1	5900
	21st to end	Night	72% 4 7% 11% 5% 1	6490
February	1st to 10th	Night	64% 5% 9% 16% 6%	2600
	11th to 20th	Night	65% 4 10% 14% 7%	2535
	21st to end	Night	62% 5% 9% 14% 9% 1	1980
March	1st to 10th	Night	57% 4 9% 22% 8% 1	4918
	11th to 20th	Night	45% 5% 14% 26% 8% 3	4980
	21st to end	Night	51% 5% 10% 18% 15% 1	5467
April	1st to 10th	Night	53% 6% 10% 18% 12% 1	2065
	11th to 20th	Night	47% 6% 11% 19% 15% 3	1975
	21st to end	Night	47% 6% 10% 23% 11% 3	1829
May	1st to 10th	Night	59% 6% 10% 13% 9% 3	4060
	11th to 20th	Night	50% 6% 10% 23% 9% 1	4017
	21st to end	Night	48% 8% 12% 21% 9% 3	3927
June	1st to 10th	Night	40% 8% 12% 25% 14% 2	1600
	11th to 20th	Night	40% 9% 14% 24% 12% 1	1600
	21st to end	Night	38% 9% 13% 24% 16% 1	1600
July	1st to 10th	Night	43% 6% 10% 23% 16% 2	3596
	11th to 20th	Night	45% 6% 17% 20% 11% 1	4006
	21st to end	Night	41% 6% 10% 19% 23% 1	4297
August	1st to 10th	Night	47% 7% 14% 22% 9% 1	2904
	11th to 20th	Night	42% 5% 10% 29% 13% 1	2902
	21st to end	Night	34% 6% 15% 31% 12% 2	3471
September	1st to 10th	Night	35% 7% 12% 23% 19% 4	2000
	11th to 20th	Night	29% 6% 14% 28% 22% 1	2142
	21st to end	Night	47% 6% 11% 20% 15% 1	2230
October	1st to 10th	Night	37% 5% 8% 25% 23% 1	3920
	11th to 20th	Night	39% 4 10% 25% 15% 7%	3876
	21st to end	Night	38% 3 10% 27% 20% 1	4120
November	1st to 10th	Night	42% 5% 11% 21% 17% 3	2376
	11th to 20th	Night	56% 4 10% 17% 10% 2	2780
	21st to end	Night	57% 6% 11% 19% 7% 1	2800
December	1st to 10th	Night	71% 4 11% 11% 3	4580
	11th to 20th	Night	67% 3 13% 14% 3	5208
	21st to end	Night	70% 5% 10% 12% 2	6996

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	35% 26% 22% 11% 5% 2	273
	11th to 20th	Day	41% 26% 26% 5% 1 1	300
	21st to end	Day	37% 23% 28% 8% 3 1	330
February	1st to 10th	Day	36% 23% 34% 6% 2	300
	11th to 20th	Day	43% 24% 27% 6% 1	300
	21st to end	Day	41% 24% 28% 6% 1	313
March	1st to 10th	Day	31% 23% 28% 15% 4	500
	11th to 20th	Day	36% 18% 28% 11% 5% 1	500
	21st to end	Day	33% 20% 26% 16% 4 1	550
April	1st to 10th	Day	31% 21% 25% 17% 5% 1	500
	11th to 20th	Day	28% 20% 26% 15% 8% 3	492
	21st to end	Day	30% 16% 27% 19% 6% 2	500
May	1st to 10th	Day	32% 13% 27% 18% 8% 2	503
	11th to 20th	Day	23% 13% 29% 20% 12% 4	527
	21st to end	Day	22% 7% 25% 26% 13% 6%	573
June	1st to 10th	Day	18% 11% 30% 25% 13% 4	530
	11th to 20th	Day	21% 11% 24% 25% 15% 4	530
	21st to end	Day	17% 7% 28% 32% 15% 2	530
July	1st to 10th	Day	17% 5% 18% 29% 21% 10%	525
	11th to 20th	Day	14% 6% 25% 29% 18% 7%	524
	21st to end	Day	16% 4 24% 31% 18% 7%	576
August	1st to 10th	Day	13% 6% 21% 31% 19% 10%	526
	11th to 20th	Day	18% 4 19% 29% 18% 11%	519
	21st to end	Day	13% 5% 24% 25% 22% 11%	583
September	1st to 10th	Day	21% 7% 18% 25% 17% 11%	530
	11th to 20th	Day	15% 2 18% 32% 22% 12%	530
	21st to end	Day	28% 9% 22% 23% 13% 5%	530
October	1st to 10th	Day	20% 9% 25% 22% 21% 5%	530
	11th to 20th	Day	24% 15% 27% 22% 10% 2	522
	21st to end	Day	32% 12% 30% 16% 9% 1	539
November	1st to 10th	Day	20% 15% 30% 22% 10% 4	455
	11th to 20th	Day	33% 15% 32% 12% 5% 2	207
	21st to end	Day	32% 20% 37% 11% 2 1	200
December	1st to 10th	Day	36% 28% 22% 9% 5% 1	200
	11th to 20th	Day	36% 22% 28% 11% 4	200
	21st to end	Day	40% 18% 27% 11% 4	220
January	1st to 10th	Night	32% 22% 28% 15% 3	800
	11th to 20th	Night	34% 18% 28% 18% 3	800
	21st to end	Night	33% 20% 26% 19% 3	880
February	1st to 10th	Night	32% 16% 28% 22% 2	800
	11th to 20th	Night	33% 20% 30% 16% 1	783
	21st to end	Night	30% 17% 31% 20% 1	660
March	1st to 10th	Night	29% 16% 30% 22% 3	800
	11th to 20th	Night	31% 18% 24% 21% 6% 1	800
	21st to end	Night	26% 17% 31% 21% 5% 1	880
April	1st to 10th	Night	31% 15% 27% 21% 6%	800
	11th to 20th	Night	25% 13% 29% 23% 10%	791
	21st to end	Night	21% 11% 30% 31% 6%	629
May	1st to 10th	Night	24% 9% 24% 31% 11% 1	600
	11th to 20th	Night	23% 6% 25% 34% 12%	588
	21st to end	Night	12% 5% 26% 31% 23% 3	433
June	1st to 10th	Night	13% 4 25% 41% 17% 1	400
	11th to 20th	Night	14% 6% 20% 40% 19% 2	400
	21st to end	Night	14% 3 27% 36% 20% 2	400
July	1st to 10th	Night	12% 1 19% 44% 21% 4	400
	11th to 20th	Night	13% 2 13% 37% 31% 3	582
	21st to end	Night	13% 2 13% 42% 27% 2	657
August	1st to 10th	Night	11% 2 13% 44% 28% 2	597
	11th to 20th	Night	13% 3 12% 36% 32% 4	594
	21st to end	Night	13% 2 15% 36% 29% 4	804
September	1st to 10th	Night	16% 3 17% 35% 26% 3	800
	11th to 20th	Night	12% 2 15% 37% 29% 5%	800
	21st to end	Night	22% 6% 22% 28% 19% 3	800
October	1st to 10th	Night	19% 6% 21% 29% 23% 2	800
	11th to 20th	Night	23% 10% 27% 28% 10% 1	793
	21st to end	Night	29% 11% 24% 28% 8%	836
November	1st to 10th	Night	19% 11% 26% 32% 11% 1	780
	11th to 20th	Night	31% 13% 25% 24% 7% 1	800
	21st to end	Night	31% 13% 29% 21% 5%	800
December	1st to 10th	Night	34% 17% 27% 18% 5%	800
	11th to 20th	Night	32% 20% 25% 20% 3	800
	21st to end	Night	33% 16% 26% 23% 2	880

Page generated at 2025-10-16 01:50:25. Version ac07

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