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 2024-01-14.

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 6% 5% 3 4 5% 5% 7% 44%	74622
	Night	11% 7% 3 5% 4 3 4 4 5% 7% 48%	75140
Transparency	Day	40% 5% 13% 26% 14% 2	74345
	Night	36% 4 13% 27% 17% 3	74937
Seeing	Day	15% 9% 30% 29% 15% 3	14634
	Night	14% 9% 33% 34% 11% 1	24649

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% 11% 4 6% 7% 4 4 4 5% 8% 38%	1707
	11th to 20th	Day	11% 9% 4 10% 5% 3 5% 4 5% 6% 38%	1647
	21st to end	Day	10% 11% 5% 10% 7% 3 5% 4 5% 6% 33%	1782
February	1st to 10th	Day	11% 11% 5% 9% 7% 4 4 4 4 7% 33%	1620
	11th to 20th	Day	10% 10% 4 8% 5% 2 5% 5% 5% 7% 38%	1601
	21st to end	Day	11% 8% 4 7% 5% 4 5% 4 5% 7% 39%	1480
March	1st to 10th	Day	11% 10% 5% 6% 5% 3 3 4 4 6% 43%	1949
	11th to 20th	Day	15% 10% 4 6% 5% 2 4 4 5% 6% 40%	1980
	21st to end	Day	20% 13% 3 6% 4 3 4 5% 5% 6% 30%	2178
April	1st to 10th	Day	16% 7% 3 6% 4 3 4 4 4 6% 43%	2034
	11th to 20th	Day	17% 9% 3 5% 5% 3 4 5% 5% 6% 39%	2236
	21st to end	Day	20% 7% 3 5% 5% 3 4 4 4 7% 38%	2340
May	1st to 10th	Day	16% 7% 3 6% 6% 3 5% 6% 5% 6% 37%	2340
	11th to 20th	Day	14% 8% 3 6% 6% 4 3 4 5% 7% 39%	2302
	21st to end	Day	16% 6% 3 6% 6% 3 5% 6% 6% 8% 34%	2607
June	1st to 10th	Day	7% 4 2 5% 5% 2 5% 5% 6% 9% 49%	2520
	11th to 20th	Day	9% 5% 2 4 6% 3 5% 5% 6% 9% 47%	2520
	21st to end	Day	8% 5% 2 5% 5% 3 5% 4 5% 8% 50%	2520
July	1st to 10th	Day	8% 4 2 3 4 3 5% 4 7% 9% 52%	2378
	11th to 20th	Day	6% 4 2 5% 4 3 5% 5% 5% 7% 55%	2340
	21st to end	Day	6% 3 2 4 4 3 4 5% 7% 11% 51%	2546
August	1st to 10th	Day	7% 5% 3 5% 6% 4 6% 7% 7% 10% 41%	2328
	11th to 20th	Day	7% 4 2 5% 5% 4 5% 5% 6% 8% 49%	2301
	21st to end	Day	9% 4 1 4 5% 2 4 6% 5% 8% 52%	2534
September	1st to 10th	Day	13% 5% 2 4 4 2 4 4 4 7% 52%	2093
	11th to 20th	Day	10% 6% 2 5% 4 2 4 4 5% 5% 54%	1980
	21st to end	Day	11% 4 2 4 4 2 4 4 5% 6% 56%	1980
October	1st to 10th	Day	15% 5% 2 3 4 2 4 4 4 6% 50%	1842
	11th to 20th	Day	13% 5% 2 4 4 2 4 4 4 4 55%	1800
	21st to end	Day	13% 8% 2 5% 5% 2 3 4 5% 5% 47%	1980
November	1st to 10th	Day	9% 5% 3 4 3 2 4 4 4 6% 56%	1693
	11th to 20th	Day	10% 7% 3 7% 6% 3 5% 4 3 5% 46%	1646
	21st to end	Day	14% 9% 3 5% 3 2 3 4 4 8% 44%	1520
December	1st to 10th	Day	9% 8% 4 5% 6% 3 4 5% 6% 6% 45%	1520
	11th to 20th	Day	9% 10% 5% 8% 6% 3 5% 5% 6% 7% 38%	1918
	21st to end	Day	16% 10% 5% 13% 8% 3 4 5% 5% 5% 26%	2860
January	1st to 10th	Night	7% 9% 3 8% 8% 3 5% 4 4 7% 41%	2458
	11th to 20th	Night	10% 11% 5% 7% 6% 3 5% 3 5% 7% 38%	2392
	21st to end	Night	12% 10% 4 7% 5% 3 3 4 4 6% 41%	2574
February	1st to 10th	Night	12% 10% 4 8% 6% 3 4 4 5% 6% 38%	2340
	11th to 20th	Night	9% 8% 4 6% 4 3 4 5% 6% 8% 42%	2259
	21st to end	Night	10% 8% 4 6% 4 3 4 4 5% 5% 47%	1776
March	1st to 10th	Night	11% 8% 3 6% 4 3 4 4 4 5% 49%	2009
	11th to 20th	Night	15% 10% 3 5% 3 2 3 3 4 7% 45%	1980
	21st to end	Night	17% 10% 4 6% 5% 3 4 4 5% 7% 33%	2178
April	1st to 10th	Night	12% 7% 3 5% 5% 3 4 4 4 6% 47%	1926
	11th to 20th	Night	13% 7% 3 5% 4 3 5% 3 4 6% 47%	1670
	21st to end	Night	17% 7% 3 4 5% 3 3 4 3 7% 45%	1620
May	1st to 10th	Night	15% 7% 2 6% 4 3 4 5% 6% 8% 39%	1620
	11th to 20th	Night	13% 7% 3 5% 5% 3 4 4 4 7% 46%	1593
	21st to end	Night	14% 7% 3 6% 5% 2 5% 5% 5% 9% 40%	1665
June	1st to 10th	Night	5% 4 2 3 5% 3 5% 5% 5% 9% 55%	1440
	11th to 20th	Night	9% 4 2 3 4 3 5% 5% 6% 10% 51%	1440
	21st to end	Night	5% 2 2 4 4 2 4 5% 6% 10% 56%	1440
July	1st to 10th	Night	5% 4 2 4 3 1 4 4 5% 9% 57%	1576
	11th to 20th	Night	3 2 1 3 3 3 3 5% 7% 9% 62%	1620
	21st to end	Night	4 2 1 3 4 3 4 4 5% 9% 60%	1772
August	1st to 10th	Night	6% 3 2 5% 5% 3 5% 5% 6% 10% 51%	1611
	11th to 20th	Night	6% 4 1 4 4 2 4 4 5% 8% 58%	1600
	21st to end	Night	8% 4 1 4 4 3 3 3 5% 8% 58%	1822
September	1st to 10th	Night	9% 4 1 3 4 2 4 3 5% 6% 60%	1863
	11th to 20th	Night	10% 3 1 3 3 2 3 4 6% 8% 58%	1980
	21st to end	Night	10% 4 2 4 2 2 3 4 4 6% 60%	1980
October	1st to 10th	Night	14% 5% 2 3 3 2 5% 4 5% 6% 50%	2099
	11th to 20th	Night	14% 5% 2 3 4 2 3 3 4 5% 55%	2160
	21st to end	Night	14% 6% 2 4 4 2 3 3 4 5% 52%	2376
November	1st to 10th	Night	8% 4 2 4 3 2 4 4 4 7% 57%	2382
	11th to 20th	Night	10% 6% 3 5% 4 2 4 3 4 6% 53%	2531
	21st to end	Night	12% 7% 3 4 4 2 3 3 4 7% 51%	2660
December	1st to 10th	Night	10% 7% 3 5% 6% 3 5% 4 5% 6% 45%	2660
	11th to 20th	Night	10% 8% 4 6% 5% 2 4 3 4 7% 47%	3279
	21st to end	Night	18% 13% 6% 11% 5% 2 3 3 3 4 31%	4789

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	46% 3 17% 22% 10% 1	1708
	11th to 20th	Day	46% 4 14% 23% 12%	1647
	21st to end	Day	52% 4 15% 20% 8%	1782
February	1st to 10th	Day	50% 5% 15% 19% 10% 1	1620
	11th to 20th	Day	45% 5% 12% 23% 13% 3	1610
	21st to end	Day	43% 5% 14% 23% 14% 2	1480
March	1st to 10th	Day	43% 4 13% 26% 13% 2	1949
	11th to 20th	Day	47% 4 11% 23% 14% 1	1980
	21st to end	Day	54% 6% 14% 18% 7% 1	2178
April	1st to 10th	Day	43% 4 12% 26% 13% 1	2034
	11th to 20th	Day	45% 5% 12% 23% 12% 2	2236
	21st to end	Day	47% 5% 10% 25% 13% 1	2340
May	1st to 10th	Day	47% 5% 13% 19% 14% 1	2340
	11th to 20th	Day	43% 5% 14% 26% 12%	2306
	21st to end	Day	46% 6% 16% 20% 10% 1	2607
June	1st to 10th	Day	31% 6% 17% 28% 15% 2	2520
	11th to 20th	Day	33% 6% 13% 30% 16% 1	2520
	21st to end	Day	32% 6% 15% 29% 15% 4	2520
July	1st to 10th	Day	28% 5% 17% 32% 15% 2	2314
	11th to 20th	Day	29% 6% 13% 28% 20% 5%	2271
	21st to end	Day	26% 7% 18% 31% 17% 1	2405
August	1st to 10th	Day	34% 9% 18% 26% 11% 2	2314
	11th to 20th	Day	31% 5% 14% 32% 16% 1	2301
	21st to end	Day	31% 5% 11% 28% 20% 6%	2534
September	1st to 10th	Day	32% 4 11% 30% 18% 5%	2093
	11th to 20th	Day	31% 4 10% 34% 18% 1	1980
	21st to end	Day	30% 3 9% 33% 23% 1	1980
October	1st to 10th	Day	36% 4 12% 26% 20% 1	1842
	11th to 20th	Day	32% 3 9% 27% 24% 5%	1800
	21st to end	Day	40% 4 13% 21% 19% 4	1980
November	1st to 10th	Day	31% 3 15% 29% 20% 3	1693
	11th to 20th	Day	40% 4 12% 24% 19% 1	1646
	21st to end	Day	40% 3 12% 30% 13% 1	1520
December	1st to 10th	Day	39% 5% 16% 26% 13% 2	1520
	11th to 20th	Day	46% 3 17% 28% 6%	1915
	21st to end	Day	60% 5% 10% 18% 6%	2860
January	1st to 10th	Night	42% 5% 14% 23% 16% 1	2458
	11th to 20th	Night	46% 4 14% 27% 9%	2392
	21st to end	Night	44% 3 15% 25% 11% 2	2574
February	1st to 10th	Night	48% 4 13% 20% 13% 2	2340
	11th to 20th	Night	40% 5% 15% 23% 15% 3	2260
	21st to end	Night	37% 4 11% 25% 19% 3	1776
March	1st to 10th	Night	38% 4 12% 29% 14% 3	2009
	11th to 20th	Night	42% 4 10% 25% 17% 3	1980
	21st to end	Night	51% 5% 13% 21% 9% 1	2178
April	1st to 10th	Night	38% 5% 11% 26% 17% 3	1926
	11th to 20th	Night	38% 4 12% 26% 18% 2	1670
	21st to end	Night	41% 4 13% 23% 18% 1	1620
May	1st to 10th	Night	43% 5% 13% 23% 13% 2	1620
	11th to 20th	Night	38% 5% 15% 24% 17% 1	1594
	21st to end	Night	41% 6% 18% 20% 12% 3	1666
June	1st to 10th	Night	26% 6% 14% 35% 16% 3	1440
	11th to 20th	Night	27% 6% 15% 28% 20% 5%	1440
	21st to end	Night	23% 5% 15% 33% 20% 3	1440
July	1st to 10th	Night	25% 5% 16% 31% 20% 4	1531
	11th to 20th	Night	19% 5% 18% 32% 20% 6%	1566
	21st to end	Night	19% 5% 16% 37% 21% 2	1673
August	1st to 10th	Night	28% 7% 18% 32% 14% 1	1601
	11th to 20th	Night	24% 6% 13% 34% 20% 3	1600
	21st to end	Night	25% 6% 12% 26% 21% 10%	1822
September	1st to 10th	Night	27% 4 11% 29% 23% 7%	1863
	11th to 20th	Night	25% 4 11% 36% 20% 4	1980
	21st to end	Night	28% 3 9% 29% 28% 4	1980
October	1st to 10th	Night	34% 4 12% 25% 23% 3	2099
	11th to 20th	Night	32% 2 8% 25% 27% 6%	2160
	21st to end	Night	35% 4 11% 23% 24% 2	2376
November	1st to 10th	Night	26% 4 15% 26% 25% 4	2382
	11th to 20th	Night	33% 3 12% 31% 18% 3	2531
	21st to end	Night	36% 3 11% 29% 19% 2	2660
December	1st to 10th	Night	39% 3 15% 29% 13% 1	2660
	11th to 20th	Night	37% 4 14% 35% 9%	3281
	21st to end	Night	58% 3 9% 21% 7% 1	4789

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	19% 13% 36% 22% 8% 2	270
	11th to 20th	Day	23% 11% 37% 20% 7% 2	249
	21st to end	Day	15% 14% 44% 21% 5% 1	264
February	1st to 10th	Day	16% 16% 46% 20% 3	240
	11th to 20th	Day	19% 16% 40% 19% 5% 1	240
	21st to end	Day	17% 20% 37% 23% 4	198
March	1st to 10th	Day	16% 15% 45% 18% 5%	240
	11th to 20th	Day	28% 10% 37% 18% 7% 1	240
	21st to end	Day	33% 17% 32% 15% 2 1	264
April	1st to 10th	Day	23% 16% 37% 21% 3	294
	11th to 20th	Day	21% 13% 37% 21% 7%	514
	21st to end	Day	23% 16% 31% 21% 8% 2	600
May	1st to 10th	Day	21% 12% 33% 24% 9% 1	603
	11th to 20th	Day	19% 9% 34% 25% 12% 2	625
	21st to end	Day	20% 6% 29% 26% 16% 2	679
June	1st to 10th	Day	6% 6% 22% 35% 25% 5%	630
	11th to 20th	Day	10% 5% 30% 35% 17% 3	630
	21st to end	Day	9% 7% 31% 35% 15% 3	630
July	1st to 10th	Day	10% 3 14% 33% 30% 9%	621
	11th to 20th	Day	7% 4 26% 35% 22% 7%	618
	21st to end	Day	7% 2 19% 43% 26% 3	684
August	1st to 10th	Day	8% 2 20% 43% 23% 4	626
	11th to 20th	Day	7% 3 18% 40% 27% 4	615
	21st to end	Day	11% 2 21% 37% 23% 5%	653
September	1st to 10th	Day	14% 4 28% 33% 19% 4	383
	11th to 20th	Day	7% 4 32% 32% 20% 5%	270
	21st to end	Day	14% 9% 33% 30% 13% 2	270
October	1st to 10th	Day	20% 7% 30% 25% 12% 6%	270
	11th to 20th	Day	13% 18% 39% 21% 7% 2	270
	21st to end	Day	21% 14% 36% 18% 10% 2	297
November	1st to 10th	Day	16% 11% 37% 25% 9% 2	270
	11th to 20th	Day	15% 15% 40% 22% 8%	270
	21st to end	Day	23% 11% 33% 24% 7% 1	270
December	1st to 10th	Day	9% 11% 42% 30% 5% 2	270
	11th to 20th	Day	17% 13% 33% 27% 10% 1	270
	21st to end	Day	20% 15% 40% 22% 3	297
January	1st to 10th	Night	11% 12% 36% 33% 7% 1	950
	11th to 20th	Night	16% 12% 35% 30% 7%	920
	21st to end	Night	17% 8% 39% 30% 6%	990
February	1st to 10th	Night	16% 11% 40% 29% 5%	900
	11th to 20th	Night	13% 11% 42% 29% 5%	865
	21st to end	Night	16% 11% 42% 26% 5%	592
March	1st to 10th	Night	16% 12% 38% 27% 6%	569
	11th to 20th	Night	21% 8% 35% 29% 7%	540
	21st to end	Night	21% 14% 36% 23% 5%	594
April	1st to 10th	Night	17% 14% 41% 23% 5%	540
	11th to 20th	Night	15% 12% 39% 29% 4 1	533
	21st to end	Night	19% 11% 34% 28% 8% 1	540
May	1st to 10th	Night	18% 11% 32% 32% 8%	540
	11th to 20th	Night	15% 10% 33% 31% 11% 1	531
	21st to end	Night	17% 6% 31% 32% 14% 1	584
June	1st to 10th	Night	6% 4 26% 46% 17%	540
	11th to 20th	Night	9% 3 33% 42% 13% 1	540
	21st to end	Night	5% 3 32% 45% 14% 1	540
July	1st to 10th	Night	7% 2 17% 44% 28% 2	525
	11th to 20th	Night	4 2 20% 49% 24% 2	522
	21st to end	Night	4 2 18% 53% 24%	591
August	1st to 10th	Night	5% 2 19% 48% 24% 2	537
	11th to 20th	Night	7% 2 19% 47% 25%	534
	21st to end	Night	9% 3 22% 41% 23% 3	594
September	1st to 10th	Night	10% 3 23% 41% 20% 2	540
	11th to 20th	Night	11% 1 29% 39% 18% 1	540
	21st to end	Night	13% 5% 32% 35% 14% 1	540
October	1st to 10th	Night	15% 7% 33% 33% 10% 2	659
	11th to 20th	Night	17% 9% 35% 32% 7%	720
	21st to end	Night	19% 9% 31% 31% 9%	792
November	1st to 10th	Night	9% 11% 34% 35% 9% 1	902
	11th to 20th	Night	13% 12% 39% 30% 6%	950
	21st to end	Night	16% 11% 34% 30% 9%	950
December	1st to 10th	Night	13% 11% 39% 31% 6%	950
	11th to 20th	Night	16% 9% 35% 33% 6%	950
	21st to end	Night	20% 12% 34% 29% 4	1045

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