Koppany observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Koppany observing Site clear sky chart from 2005-11-06 to 2026-01-17.

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	12% 7% 3 7% 4 4 4 3 5% 7% 44%	127078
	Night	11% 7% 3 7% 4 4 4 3 5% 7% 47%	124858
Transparency	Day	38% 4 13% 26% 16% 2	130716
	Night	36% 4 12% 26% 19% 3	129283
Seeing	Day	15% 10% 31% 28% 14% 3	17412
	Night	13% 9% 33% 34% 10% 1	27373

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% 12% 6% 15% 6% 5% 4 3 5% 7% 27%	4167
	11th to 20th	Day	7% 9% 3 11% 4 5% 6% 4 5% 6% 39%	4134
	21st to end	Day	7% 11% 5% 11% 5% 5% 5% 3 5% 6% 37%	4488
February	1st to 10th	Day	10% 12% 5% 9% 6% 6% 4 3 5% 7% 32%	1800
	11th to 20th	Day	10% 12% 3 10% 4 4 5% 4 5% 6% 38%	1784
	21st to end	Day	10% 8% 3 7% 4 5% 4 4 5% 7% 42%	1650
March	1st to 10th	Day	15% 8% 3 6% 3 2 2 2 3 4 52%	4881
	11th to 20th	Day	12% 7% 2 5% 4 3 3 3 4 7% 50%	4980
	21st to end	Day	19% 11% 4 8% 4 4 5% 4 5% 7% 29%	5462
April	1st to 10th	Day	16% 8% 3 6% 3 4 3 3 4 6% 43%	2260
	11th to 20th	Day	16% 8% 2 6% 4 4 4 4 5% 7% 40%	2488
	21st to end	Day	20% 8% 2 6% 4 4 4 3 5% 7% 38%	2600
May	1st to 10th	Day	14% 7% 3 6% 4 4 3 3 5% 6% 45%	5862
	11th to 20th	Day	14% 6% 2 6% 3 3 3 2 4 5% 50%	5862
	21st to end	Day	17% 7% 2 7% 4 5% 5% 4 6% 7% 36%	6635
June	1st to 10th	Day	7% 4 2 6% 5% 4 4 4 7% 9% 48%	2800
	11th to 20th	Day	8% 6% 2 5% 5% 4 4 4 7% 8% 47%	2800
	21st to end	Day	8% 5% 2 6% 4 4 5% 3 5% 8% 50%	2800
July	1st to 10th	Day	11% 5% 2 5% 4 4 4 4 6% 8% 46%	5994
	11th to 20th	Day	8% 5% 2 6% 4 4 5% 4 6% 8% 48%	5900
	21st to end	Day	7% 4 2 5% 4 4 4 4 7% 9% 51%	6422
August	1st to 10th	Day	6% 4 2 5% 5% 4 6% 5% 7% 10% 46%	4234
	11th to 20th	Day	13% 6% 2 6% 5% 4 4 4 6% 7% 42%	4171
	21st to end	Day	7% 4 2 6% 4 4 5% 4 5% 8% 50%	4590
September	1st to 10th	Day	12% 5% 2 5% 3 3 3 3 4 6% 53%	2325
	11th to 20th	Day	9% 6% 2 5% 3 3 4 3 5% 6% 53%	2200
	21st to end	Day	10% 4 2 5% 3 3 4 3 5% 5% 57%	2200
October	1st to 10th	Day	14% 5% 2 4 3 3 3 3 4 6% 52%	2046
	11th to 20th	Day	12% 5% 2 5% 3 2 3 3 4 4 56%	2000
	21st to end	Day	13% 8% 2 6% 4 4 3 3 5% 5% 46%	2200
November	1st to 10th	Day	10% 6% 3 5% 3 3 4 3 4 5% 54%	1875
	11th to 20th	Day	10% 8% 2 8% 5% 4 4 3 4 5% 48%	1818
	21st to end	Day	14% 10% 3 6% 3 3 3 3 5% 8% 43%	1680
December	1st to 10th	Day	5% 6% 2 6% 6% 4 4 4 5% 5% 52%	2690
	11th to 20th	Day	9% 10% 4 9% 6% 5% 4 3 5% 6% 40%	3088
	21st to end	Day	17% 9% 4 14% 5% 4 4 3 5% 5% 31%	4192
January	1st to 10th	Night	10% 11% 4 19% 8% 5% 4 3 4 6% 25%	6018
	11th to 20th	Night	7% 9% 3 8% 5% 5% 7% 4 7% 6% 40%	5979
	21st to end	Night	9% 10% 5% 10% 5% 5% 4 3 4 6% 39%	6490
February	1st to 10th	Night	11% 10% 4 9% 6% 4 4 3 5% 6% 38%	2600
	11th to 20th	Night	9% 10% 4 7% 5% 4 4 4 5% 7% 42%	2518
	21st to end	Night	9% 8% 3 6% 3 3 3 3 6% 5% 50%	1980
March	1st to 10th	Night	14% 6% 2 5% 3 3 3 3 4 5% 52%	4974
	11th to 20th	Night	10% 6% 2 4 2 3 3 2 4 6% 56%	4980
	21st to end	Night	15% 10% 2 7% 4 4 4 4 6% 7% 36%	5467
April	1st to 10th	Night	12% 8% 2 6% 4 3 3 3 5% 6% 47%	2140
	11th to 20th	Night	12% 7% 2 6% 4 4 4 3 5% 6% 48%	1858
	21st to end	Night	17% 7% 2 4 4 4 3 3 4 6% 45%	1800
May	1st to 10th	Night	13% 6% 2 6% 3 3 3 3 4 5% 50%	4053
	11th to 20th	Night	14% 4 2 4 2 3 4 3 5% 6% 53%	4053
	21st to end	Night	18% 7% 2 6% 4 3 4 3 4 6% 43%	4224
June	1st to 10th	Night	5% 4 1 5% 4 5% 5% 3 5% 8% 54%	1600
	11th to 20th	Night	8% 4 2 3 3 4 6% 4 6% 10% 50%	1600
	21st to end	Night	5% 2 2 5% 4 3 4 4 6% 8% 56%	1600
July	1st to 10th	Night	7% 4 2 5% 3 3 4 3 5% 8% 55%	3978
	11th to 20th	Night	7% 4 1 5% 4 3 3 4 6% 8% 55%	4077
	21st to end	Night	5% 3 1 5% 4 4 5% 3 6% 9% 55%	4449
August	1st to 10th	Night	4 2 2 4 3 3 4 4 6% 11% 56%	2926
	11th to 20th	Night	11% 5% 2 4 4 3 4 3 5% 8% 50%	2888
	21st to end	Night	7% 4 2 4 4 3 4 3 5% 8% 55%	3315
September	1st to 10th	Night	9% 4 1 4 3 3 3 3 5% 6% 60%	2071
	11th to 20th	Night	9% 3 1 3 3 3 3 3 6% 8% 58%	2200
	21st to end	Night	10% 4 1 4 2 2 3 3 4 6% 60%	2200
October	1st to 10th	Night	14% 5% 2 4 3 3 5% 3 5% 6% 52%	2333
	11th to 20th	Night	13% 5% 2 4 3 3 3 2 4 5% 55%	2400
	21st to end	Night	15% 6% 2 5% 3 3 2 3 4 5% 51%	2640
November	1st to 10th	Night	9% 4 2 4 3 3 4 3 5% 7% 55%	2640
	11th to 20th	Night	10% 7% 2 6% 3 3 3 3 5% 6% 53%	2798
	21st to end	Night	12% 7% 3 6% 3 3 2 3 5% 6% 49%	2940
December	1st to 10th	Night	6% 6% 2 6% 5% 4 4 3 5% 6% 52%	4720
	11th to 20th	Night	10% 8% 3 8% 4 3 4 3 5% 7% 44%	5339
	21st to end	Night	17% 13% 5% 10% 4 3 3 3 4 5% 33%	7010

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	57% 3 12% 20% 7%	4168
	11th to 20th	Day	45% 3 14% 20% 16% 2	4134
	21st to end	Day	47% 5% 13% 23% 12%	4488
February	1st to 10th	Day	51% 5% 15% 18% 11% 1	1800
	11th to 20th	Day	46% 5% 11% 22% 14% 3	1793
	21st to end	Day	39% 4 13% 24% 16% 3	1650
March	1st to 10th	Day	39% 2 7% 28% 18% 6%	4881
	11th to 20th	Day	35% 3 8% 27% 23% 4	4980
	21st to end	Day	54% 5% 20% 16% 4 2	5464
April	1st to 10th	Day	42% 4 12% 27% 13% 2	2260
	11th to 20th	Day	43% 5% 13% 23% 13% 3	2488
	21st to end	Day	47% 5% 10% 25% 13% 1	2600
May	1st to 10th	Day	40% 4 10% 27% 17% 2	5900
	11th to 20th	Day	37% 3 8% 23% 24% 4	5866
	21st to end	Day	45% 5% 11% 23% 15% 1	6649
June	1st to 10th	Day	32% 6% 17% 29% 15% 2	2800
	11th to 20th	Day	33% 6% 13% 31% 16% 1	2800
	21st to end	Day	33% 5% 14% 29% 15% 4	2800
July	1st to 10th	Day	34% 5% 14% 32% 14% 1	5930
	11th to 20th	Day	34% 6% 13% 29% 16% 2	5831
	21st to end	Day	27% 7% 19% 29% 16% 1	6240
August	1st to 10th	Day	30% 7% 16% 28% 16% 3	4220
	11th to 20th	Day	40% 5% 14% 27% 15% 1	4210
	21st to end	Day	32% 6% 14% 26% 17% 5%	4589
September	1st to 10th	Day	32% 4 11% 30% 18% 5%	2325
	11th to 20th	Day	31% 5% 12% 33% 18% 1	2200
	21st to end	Day	30% 3 9% 32% 25% 1	2200
October	1st to 10th	Day	21% 2 7% 21% 46% 3	3332
	11th to 20th	Day	22% 2 12% 31% 26% 7%	3240
	21st to end	Day	36% 3 10% 26% 21% 3	3538
November	1st to 10th	Day	33% 3 14% 28% 20% 2	1875
	11th to 20th	Day	39% 4 12% 25% 19% 1	1818
	21st to end	Day	41% 3 13% 30% 12% 1	1680
December	1st to 10th	Day	33% 5% 18% 28% 16% 1	2690
	11th to 20th	Day	44% 4 17% 25% 10%	3085
	21st to end	Day	57% 4 12% 21% 6% 1	4192
January	1st to 10th	Night	60% 4 10% 16% 10%	6018
	11th to 20th	Night	41% 4 14% 23% 16% 1	5979
	21st to end	Night	46% 4 12% 20% 16% 2	6490
February	1st to 10th	Night	47% 4 13% 20% 13% 2	2600
	11th to 20th	Night	41% 4 14% 23% 15% 3	2519
	21st to end	Night	35% 4 10% 26% 21% 4	1980
March	1st to 10th	Night	36% 3 7% 29% 22% 3	4974
	11th to 20th	Night	30% 3 7% 26% 27% 7%	4980
	21st to end	Night	46% 5% 18% 24% 6% 1	5467
April	1st to 10th	Night	37% 5% 11% 27% 18% 3	2140
	11th to 20th	Night	37% 4 11% 26% 18% 3	1858
	21st to end	Night	41% 4 13% 24% 17% 1	1800
May	1st to 10th	Night	36% 4 9% 27% 22% 2	4080
	11th to 20th	Night	31% 4 12% 20% 27% 5%	4054
	21st to end	Night	42% 5% 12% 23% 16% 2	4232
June	1st to 10th	Night	27% 6% 14% 33% 16% 4	1600
	11th to 20th	Night	26% 6% 14% 28% 20% 5%	1600
	21st to end	Night	24% 5% 15% 32% 21% 3	1600
July	1st to 10th	Night	28% 5% 14% 33% 17% 3	3935
	11th to 20th	Night	27% 5% 14% 32% 19% 2	4026
	21st to end	Night	25% 7% 17% 29% 21% 1	4320
August	1st to 10th	Night	22% 5% 16% 35% 19% 2	2916
	11th to 20th	Night	32% 5% 14% 28% 19% 2	2915
	21st to end	Night	27% 5% 15% 27% 17% 8%	3315
September	1st to 10th	Night	25% 4 11% 30% 23% 6%	2071
	11th to 20th	Night	25% 5% 13% 35% 20% 3	2200
	21st to end	Night	27% 3 8% 28% 29% 4	2200
October	1st to 10th	Night	21% 3 7% 17% 48% 5%	3814
	11th to 20th	Night	23% 2 8% 29% 30% 8%	3899
	21st to end	Night	34% 3 9% 30% 22% 2	4252
November	1st to 10th	Night	28% 4 15% 26% 23% 4	2640
	11th to 20th	Night	33% 3 12% 31% 19% 3	2798
	21st to end	Night	37% 3 12% 29% 18% 2	2940
December	1st to 10th	Night	31% 3 15% 34% 16% 1	4720
	11th to 20th	Night	39% 4 15% 29% 12%	5341
	21st to end	Night	55% 3 11% 23% 8% 1	7010

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	18% 14% 38% 22% 7% 2	330
	11th to 20th	Day	20% 14% 38% 20% 7% 1	318
	21st to end	Day	14% 14% 43% 21% 7% 2	330
February	1st to 10th	Day	17% 16% 45% 18% 3	300
	11th to 20th	Day	17% 18% 38% 20% 5% 1	300
	21st to end	Day	16% 19% 38% 22% 5%	249
March	1st to 10th	Day	18% 14% 43% 19% 5%	300
	11th to 20th	Day	26% 12% 36% 19% 7% 1	300
	21st to end	Day	32% 17% 33% 15% 2 1	330
April	1st to 10th	Day	24% 17% 36% 19% 3	360
	11th to 20th	Day	22% 14% 37% 20% 6%	606
	21st to end	Day	23% 17% 31% 20% 7% 2	700
May	1st to 10th	Day	19% 12% 32% 25% 9% 2	703
	11th to 20th	Day	19% 9% 32% 26% 13% 2	725
	21st to end	Day	20% 8% 30% 26% 15% 2	789
June	1st to 10th	Day	7% 6% 23% 36% 23% 5%	730
	11th to 20th	Day	10% 6% 31% 34% 16% 3	730
	21st to end	Day	9% 8% 33% 35% 13% 2	730
July	1st to 10th	Day	10% 4 16% 33% 28% 9%	721
	11th to 20th	Day	7% 4 27% 34% 22% 6%	718
	21st to end	Day	7% 3 20% 42% 25% 3	794
August	1st to 10th	Day	8% 3 22% 44% 21% 3	726
	11th to 20th	Day	8% 3 20% 40% 26% 3	715
	21st to end	Day	10% 2 23% 39% 21% 5%	757
September	1st to 10th	Day	13% 5% 28% 33% 18% 4	455
	11th to 20th	Day	8% 5% 33% 32% 17% 5%	330
	21st to end	Day	14% 8% 30% 30% 15% 3	330
October	1st to 10th	Day	18% 6% 30% 27% 12% 5%	330
	11th to 20th	Day	13% 17% 41% 20% 7% 2	330
	21st to end	Day	21% 15% 37% 17% 9% 1	363
November	1st to 10th	Day	18% 12% 38% 23% 8% 2	330
	11th to 20th	Day	16% 15% 39% 22% 7%	330
	21st to end	Day	23% 15% 33% 22% 7% 1	330
December	1st to 10th	Day	9% 14% 43% 27% 5% 2	330
	11th to 20th	Day	17% 16% 34% 24% 8% 1	330
	21st to end	Day	20% 15% 40% 21% 4	363
January	1st to 10th	Night	12% 12% 37% 33% 7%	1050
	11th to 20th	Night	15% 13% 36% 29% 7%	1031
	21st to end	Night	16% 9% 40% 30% 6%	1100
February	1st to 10th	Night	15% 12% 40% 29% 4	1000
	11th to 20th	Night	13% 11% 42% 29% 5%	964
	21st to end	Night	14% 11% 43% 26% 5%	660
March	1st to 10th	Night	16% 12% 38% 28% 6%	631
	11th to 20th	Night	20% 9% 37% 28% 7%	600
	21st to end	Night	21% 14% 38% 22% 5%	660
April	1st to 10th	Night	17% 15% 40% 23% 4	600
	11th to 20th	Night	15% 15% 38% 29% 4 1	593
	21st to end	Night	19% 11% 34% 28% 7% 1	600
May	1st to 10th	Night	18% 10% 31% 32% 9%	600
	11th to 20th	Night	15% 10% 31% 33% 11% 1	591
	21st to end	Night	17% 6% 31% 32% 13%	650
June	1st to 10th	Night	7% 4 27% 46% 16%	600
	11th to 20th	Night	9% 3 33% 42% 13% 1	600
	21st to end	Night	6% 4 33% 45% 13% 1	600
July	1st to 10th	Night	7% 2 17% 44% 27% 2	585
	11th to 20th	Night	4 2 20% 49% 23% 1	582
	21st to end	Night	4 2 18% 52% 24% 1	657
August	1st to 10th	Night	5% 3 20% 49% 22% 2	597
	11th to 20th	Night	7% 2 19% 47% 24% 1	594
	21st to end	Night	8% 3 22% 42% 22% 3	660
September	1st to 10th	Night	10% 4 23% 42% 20% 2	600
	11th to 20th	Night	11% 2 31% 40% 16% 1	600
	21st to end	Night	12% 5% 30% 36% 16% 1	600
October	1st to 10th	Night	15% 8% 32% 33% 11% 2	733
	11th to 20th	Night	15% 10% 36% 32% 7%	800
	21st to end	Night	20% 10% 31% 30% 9%	880
November	1st to 10th	Night	11% 11% 34% 35% 9% 1	1000
	11th to 20th	Night	13% 13% 39% 30% 6%	1050
	21st to end	Night	17% 11% 34% 29% 9%	1050
December	1st to 10th	Night	13% 11% 39% 30% 6%	1050
	11th to 20th	Night	16% 10% 36% 32% 6%	1050
	21st to end	Night	20% 12% 35% 29% 4	1155

Page generated at 2026-01-14 00:14:25. Version ac07

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