Marienthal
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Marienthal clear sky chart from 2005-11-06 to 2025-06-10.

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	6% 5% 2 4 3 3 3 3 5% 7% 59%	123202
	Night	6% 5% 2 5% 3 3 4 3 5% 7% 57%	123806
Transparency	Day	25% 5% 10% 25% 26% 9%	122954
	Night	27% 5% 11% 24% 25% 9%	123644
Seeing	Day	9% 7% 29% 33% 17% 3	16353
	Night	9% 8% 36% 36% 11% 1	26357

By Month

Percentage Cloud Cover SW (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	7% 10% 3 6% 3 2 3 3 4 6% 53%	3638
	11th to 20th	Day	4 6% 2 8% 5% 4 5% 4 4 6% 53%	3640
	21st to end	Day	4 6% 3 6% 4 3 3 2 4 5% 61%	4487
February	1st to 10th	Day	5% 9% 3 6% 4 3 3 3 4 7% 52%	2000
	11th to 20th	Day	4 6% 2 7% 6% 5% 3 3 4 7% 53%	1949
	21st to end	Day	3 5% 3 5% 4 4 3 3 4 5% 61%	1650
March	1st to 10th	Day	4 6% 2 4 3 3 3 2 4 5% 63%	4500
	11th to 20th	Day	6% 4 2 5% 3 3 3 2 5% 7% 61%	4821
	21st to end	Day	5% 5% 2 5% 3 3 4 3 5% 7% 59%	5647
April	1st to 10th	Day	8% 5% 1 4 3 3 3 3 5% 7% 58%	2400
	11th to 20th	Day	10% 4 1 4 3 4 3 4 5% 9% 53%	2371
	21st to end	Day	11% 5% 2 5% 4 3 5% 4 6% 7% 49%	2538
May	1st to 10th	Day	11% 6% 2 5% 3 3 3 3 5% 7% 52%	5900
	11th to 20th	Day	5% 3 1 4 3 3 3 3 5% 8% 62%	5862
	21st to end	Day	15% 5% 1 4 3 2 3 3 5% 7% 52%	6446
June	1st to 10th	Day	5% 2 1 3 3 3 4 3 7% 10% 58%	2748
	11th to 20th	Day	6% 4 1 3 3 3 3 2 5% 7% 63%	2660
	21st to end	Day	4 3 1 4 4 3 3 4 6% 9% 58%	2660
July	1st to 10th	Day	6% 5% 2 5% 4 4 4 3 6% 8% 53%	4430
	11th to 20th	Day	2 2 1 3 2 2 4 4 7% 9% 64%	4430
	21st to end	Day	2 2 1 4 3 3 4 4 6% 9% 61%	4543
August	1st to 10th	Day	13% 4 2 4 3 3 3 4 6% 8% 51%	4103
	11th to 20th	Day	6% 4 1 4 3 4 4 4 6% 8% 57%	3769
	21st to end	Day	3 3 1 4 3 3 4 4 6% 8% 60%	4180
September	1st to 10th	Day	8% 4 1 4 2 3 3 3 5% 7% 60%	2260
	11th to 20th	Day	7% 4 2 3 3 2 2 3 5% 6% 64%	2090
	21st to end	Day	6% 3 1 4 2 2 3 2 5% 6% 65%	2090
October	1st to 10th	Day	7% 2 1 2 2 1 2 2 3 5% 73%	3480
	11th to 20th	Day	5% 3 1 3 2 3 3 3 4 6% 66%	3269
	21st to end	Day	5% 4 1 3 2 2 2 2 3 4 72%	3091
November	1st to 10th	Day	7% 4 1 2 2 3 3 4 4 6% 64%	1763
	11th to 20th	Day	4 4 1 4 3 3 3 2 5% 5% 67%	1800
	21st to end	Day	7% 5% 2 3 3 3 3 2 4 5% 64%	1800
December	1st to 10th	Day	4 4 1 3 2 2 2 2 4 5% 71%	2940
	11th to 20th	Day	4 4 2 4 2 3 2 2 5% 6% 67%	3243
	21st to end	Day	6% 11% 4 8% 4 4 4 3 3 6% 47%	4004
January	1st to 10th	Night	6% 7% 3 6% 4 4 4 3 4 7% 52%	6327
	11th to 20th	Night	2 4 2 6% 4 4 3 3 4 6% 62%	6340
	21st to end	Night	4 6% 3 5% 3 3 3 2 4 6% 60%	6531
February	1st to 10th	Night	7% 8% 3 7% 4 4 3 3 5% 6% 51%	2400
	11th to 20th	Night	5% 7% 3 7% 4 4 5% 4 6% 6% 49%	2338
	21st to end	Night	4 6% 3 6% 3 2 3 2 5% 6% 61%	1980
March	1st to 10th	Night	4 6% 2 3 2 2 3 2 4 5% 64%	5374
	11th to 20th	Night	6% 4 2 5% 3 3 3 3 5% 7% 59%	5132
	21st to end	Night	7% 5% 2 6% 4 4 4 4 6% 9% 50%	5275
April	1st to 10th	Night	7% 6% 2 5% 3 3 3 3 5% 8% 54%	2000
	11th to 20th	Night	10% 6% 2 4 4 3 4 3 6% 8% 51%	1977
	21st to end	Night	11% 6% 2 4 3 4 3 3 6% 8% 51%	1860
May	1st to 10th	Night	11% 5% 2 6% 4 3 5% 3 5% 7% 48%	4080
	11th to 20th	Night	6% 5% 2 5% 3 4 4 3 5% 7% 57%	4053
	21st to end	Night	16% 7% 2 4 3 3 3 3 5% 6% 48%	4451
June	1st to 10th	Night	6% 3 1 4 3 4 4 4 9% 12% 50%	1630
	11th to 20th	Night	5% 4 2 5% 3 4 4 4 6% 9% 55%	1520
	21st to end	Night	4 4 2 5% 4 4 4 4 6% 8% 54%	1520
July	1st to 10th	Night	7% 5% 2 6% 4 4 3 3 6% 8% 51%	2540
	11th to 20th	Night	3 3 2 5% 4 4 5% 4 8% 12% 50%	2540
	21st to end	Night	3 2 1 5% 3 3 4 5% 8% 11% 53%	3006
August	1st to 10th	Night	9% 5% 2 6% 5% 4 5% 5% 7% 10% 42%	2836
	11th to 20th	Night	9% 5% 2 6% 4 4 5% 4 7% 9% 44%	3053
	21st to end	Night	3 3 2 6% 5% 6% 6% 4 8% 11% 46%	3487
September	1st to 10th	Night	6% 3 1 3 3 3 4 4 5% 6% 61%	1919
	11th to 20th	Night	7% 2 1 4 3 3 4 3 5% 9% 60%	2090
	21st to end	Night	7% 3 1 4 2 3 3 2 5% 6% 65%	2090
October	1st to 10th	Night	6% 3 1 3 2 1 2 2 3 5% 72%	3480
	11th to 20th	Night	6% 3 1 2 2 3 3 2 4 6% 68%	3604
	21st to end	Night	7% 3 1 4 3 2 3 2 3 5% 67%	4467
November	1st to 10th	Night	5% 3 1 4 3 3 3 3 5% 6% 65%	2535
	11th to 20th	Night	4 4 2 3 2 2 3 2 4 5% 69%	2600
	21st to end	Night	5% 5% 1 4 3 3 4 3 5% 6% 62%	2600
December	1st to 10th	Night	2 4 2 4 3 3 3 3 3 5% 68%	4250
	11th to 20th	Night	3 4 2 4 2 3 3 2 4 7% 66%	4947
	21st to end	Night	7% 10% 3 6% 3 3 3 3 4 6% 50%	6974

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% 4 10% 28% 19% 5%	3639
	11th to 20th	Day	33% 5% 9% 18% 28% 7%	3640
	21st to end	Day	27% 4 9% 24% 28% 9%	4487
February	1st to 10th	Day	33% 3 11% 28% 18% 8%	2000
	11th to 20th	Day	32% 4 11% 25% 20% 7%	1959
	21st to end	Day	26% 3 9% 21% 28% 13%	1650
March	1st to 10th	Day	25% 3 6% 15% 31% 19%	4500
	11th to 20th	Day	23% 4 8% 18% 33% 14%	4821
	21st to end	Day	24% 5% 12% 40% 16% 3	5647
April	1st to 10th	Day	25% 5% 11% 25% 25% 10%	2400
	11th to 20th	Day	29% 5% 14% 24% 21% 8%	2374
	21st to end	Day	33% 6% 12% 25% 20% 5%	2538
May	1st to 10th	Day	31% 6% 12% 24% 19% 8%	5900
	11th to 20th	Day	20% 7% 12% 23% 24% 14%	5866
	21st to end	Day	32% 6% 11% 22% 23% 5%	6447
June	1st to 10th	Day	20% 7% 19% 34% 16% 5%	2748
	11th to 20th	Day	21% 4 11% 27% 25% 11%	2660
	21st to end	Day	22% 5% 10% 26% 26% 10%	2660
July	1st to 10th	Day	29% 6% 8% 22% 27% 7%	4361
	11th to 20th	Day	14% 5% 15% 28% 30% 8%	4355
	21st to end	Day	19% 6% 14% 27% 24% 11%	4399
August	1st to 10th	Day	32% 5% 15% 27% 18% 3	4090
	11th to 20th	Day	26% 6% 15% 23% 26% 5%	3806
	21st to end	Day	21% 5% 13% 29% 23% 9%	4179
September	1st to 10th	Day	24% 5% 9% 26% 23% 13%	2260
	11th to 20th	Day	22% 4 8% 26% 29% 11%	2090
	21st to end	Day	21% 4 8% 26% 28% 13%	2090
October	1st to 10th	Day	16% 2 6% 19% 41% 15%	3480
	11th to 20th	Day	20% 3 9% 27% 30% 11%	3269
	21st to end	Day	17% 3 7% 22% 38% 13%	3091
November	1st to 10th	Day	22% 4 9% 24% 30% 12%	1763
	11th to 20th	Day	20% 3 8% 27% 32% 11%	1800
	21st to end	Day	25% 3 8% 22% 29% 14%	1800
December	1st to 10th	Day	18% 3 9% 29% 32% 10%	2940
	11th to 20th	Day	20% 3 6% 37% 32% 3	3241
	21st to end	Day	39% 4 7% 22% 22% 6%	4004
January	1st to 10th	Night	33% 4 11% 29% 18% 4	6327
	11th to 20th	Night	24% 5% 10% 21% 29% 12%	6340
	21st to end	Night	26% 4 10% 22% 26% 11%	6531
February	1st to 10th	Night	35% 4 12% 22% 20% 8%	2400
	11th to 20th	Night	33% 5% 11% 24% 21% 5%	2338
	21st to end	Night	25% 4 6% 22% 29% 14%	1980
March	1st to 10th	Night	22% 3 6% 17% 32% 20%	5374
	11th to 20th	Night	24% 5% 8% 16% 29% 17%	5132
	21st to end	Night	30% 6% 13% 35% 14% 3	5275
April	1st to 10th	Night	27% 5% 11% 23% 24% 10%	2000
	11th to 20th	Night	31% 5% 12% 25% 18% 8%	1977
	21st to end	Night	31% 6% 12% 27% 22% 3	1860
May	1st to 10th	Night	32% 8% 16% 19% 17% 6%	4080
	11th to 20th	Night	26% 7% 10% 20% 25% 12%	4054
	21st to end	Night	36% 7% 14% 19% 16% 7%	4452
June	1st to 10th	Night	23% 9% 22% 27% 15% 3	1630
	11th to 20th	Night	26% 6% 13% 24% 22% 8%	1520
	21st to end	Night	26% 8% 10% 25% 24% 8%	1520
July	1st to 10th	Night	31% 6% 15% 18% 27% 4	2500
	11th to 20th	Night	25% 7% 17% 21% 25% 6%	2492
	21st to end	Night	21% 6% 17% 24% 23% 8%	2911
August	1st to 10th	Night	35% 6% 13% 26% 17% 3	2826
	11th to 20th	Night	35% 6% 13% 27% 16% 4	3081
	21st to end	Night	29% 7% 14% 23% 19% 8%	3487
September	1st to 10th	Night	23% 5% 11% 24% 24% 13%	1919
	11th to 20th	Night	22% 6% 10% 23% 27% 12%	2090
	21st to end	Night	21% 3 9% 22% 32% 13%	2090
October	1st to 10th	Night	17% 3 6% 17% 40% 17%	3480
	11th to 20th	Night	19% 3 11% 23% 31% 12%	3604
	21st to end	Night	22% 2 6% 22% 36% 12%	4467
November	1st to 10th	Night	20% 3 9% 25% 26% 16%	2535
	11th to 20th	Night	19% 3 7% 25% 34% 13%	2600
	21st to end	Night	23% 4 9% 24% 27% 13%	2600
December	1st to 10th	Night	21% 3 8% 35% 26% 8%	4250
	11th to 20th	Night	21% 2 5% 32% 33% 6%	4948
	21st to end	Night	35% 5% 8% 25% 22% 4	6974

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	10% 5% 41% 27% 15% 3	300
	11th to 20th	Day	13% 8% 35% 32% 10% 2	300
	21st to end	Day	7% 10% 37% 34% 10% 2	330
February	1st to 10th	Day	10% 9% 46% 28% 6% 1	300
	11th to 20th	Day	6% 10% 47% 25% 10% 1	300
	21st to end	Day	6% 16% 42% 31% 4	249
March	1st to 10th	Day	8% 12% 37% 31% 10% 1	300
	11th to 20th	Day	12% 11% 38% 27% 11% 1	300
	21st to end	Day	12% 15% 39% 27% 7%	410
April	1st to 10th	Day	11% 17% 42% 24% 6% 1	500
	11th to 20th	Day	12% 16% 42% 25% 5% 1	492
	21st to end	Day	16% 15% 35% 25% 7% 1	638
May	1st to 10th	Day	13% 9% 33% 32% 11% 2	703
	11th to 20th	Day	15% 8% 29% 32% 12% 3	725
	21st to end	Day	14% 10% 31% 32% 11% 2	789
June	1st to 10th	Day	7% 5% 25% 38% 20% 5%	726
	11th to 20th	Day	7% 6% 31% 36% 18% 2	680
	21st to end	Day	6% 3 29% 40% 19% 3	680
July	1st to 10th	Day	7% 2 21% 37% 27% 5%	671
	11th to 20th	Day	3 1 17% 44% 28% 7%	668
	21st to end	Day	5% 2 12% 39% 35% 8%	739
August	1st to 10th	Day	8% 2 14% 36% 36% 4	676
	11th to 20th	Day	6% 2 18% 42% 30% 3	508
	21st to end	Day	5% 1 17% 42% 28% 6%	539
September	1st to 10th	Day	9% 2 16% 43% 24% 7%	470
	11th to 20th	Day	4 3 26% 33% 20% 13%	300
	21st to end	Day	12% 7% 20% 27% 27% 7%	300
October	1st to 10th	Day	15% 5% 21% 28% 23% 8%	300
	11th to 20th	Day	5% 7% 35% 35% 15% 4	300
	21st to end	Day	15% 10% 29% 27% 17% 3	330
November	1st to 10th	Day	13% 10% 29% 32% 11% 5%	300
	11th to 20th	Day	8% 10% 34% 31% 14% 2	300
	21st to end	Day	14% 12% 30% 28% 13% 4	300
December	1st to 10th	Day	6% 7% 36% 35% 13% 3	300
	11th to 20th	Day	10% 11% 40% 29% 10%	300
	21st to end	Day	15% 12% 33% 30% 10%	330
January	1st to 10th	Night	8% 7% 38% 36% 10% 1	1000
	11th to 20th	Night	9% 9% 38% 33% 11% 1	1000
	21st to end	Night	5% 8% 43% 36% 8% 1	1065
February	1st to 10th	Night	10% 11% 40% 33% 7%	800
	11th to 20th	Night	9% 10% 46% 28% 6% 1	784
	21st to end	Night	7% 10% 45% 32% 5%	660
March	1st to 10th	Night	8% 13% 40% 33% 6%	800
	11th to 20th	Night	11% 10% 36% 34% 9% 1	674
	21st to end	Night	13% 12% 46% 24% 5%	660
April	1st to 10th	Night	10% 15% 43% 29% 3	600
	11th to 20th	Night	13% 16% 42% 25% 5%	593
	21st to end	Night	17% 12% 35% 28% 8% 1	600
May	1st to 10th	Night	12% 10% 40% 29% 8% 1	600
	11th to 20th	Night	12% 8% 36% 32% 11% 1	591
	21st to end	Night	14% 9% 40% 28% 9%	650
June	1st to 10th	Night	7% 6% 38% 38% 11% 1	599
	11th to 20th	Night	8% 10% 43% 34% 5%	570
	21st to end	Night	6% 5% 37% 43% 10%	570
July	1st to 10th	Night	8% 3 28% 45% 16%	555
	11th to 20th	Night	4 1 24% 51% 18% 2	552
	21st to end	Night	7% 2 18% 51% 21% 1	624
August	1st to 10th	Night	8% 2 18% 49% 23% 1	567
	11th to 20th	Night	9% 1 27% 49% 14%	564
	21st to end	Night	5% 3 24% 48% 19% 2	627
September	1st to 10th	Night	7% 2 27% 48% 15% 1	570
	11th to 20th	Night	9% 3 32% 42% 13% 2	570
	21st to end	Night	9% 6% 28% 41% 16%	570
October	1st to 10th	Night	12% 8% 33% 35% 12%	570
	11th to 20th	Night	8% 8% 36% 36% 11% 1	652
	21st to end	Night	10% 9% 33% 34% 14%	1045
November	1st to 10th	Night	7% 6% 35% 40% 11% 1	975
	11th to 20th	Night	6% 10% 37% 37% 9% 1	1000
	21st to end	Night	7% 9% 33% 36% 12% 2	1000
December	1st to 10th	Night	8% 8% 38% 36% 10% 1	1000
	11th to 20th	Night	9% 10% 37% 35% 9% 1	1000
	21st to end	Night	12% 10% 34% 34% 9%	1100

Page generated at 2025-06-07 09:28:20. Version ac07

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