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 2026-10-14.

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	6% 4 2 4 3 3 3 3 5% 7% 59%	157515
	Night	6% 5% 2 5% 3 3 4 3 5% 7% 55%	151699
Transparency	Day	24% 4 11% 26% 26% 9%	152441
	Night	27% 5% 11% 24% 24% 9%	147784
Seeing	Day	9% 8% 29% 33% 17% 3	18258
	Night	9% 8% 36% 36% 10% 1	28079

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	6% 10% 3 6% 3 3 4 3 4 6% 52%	4720
	11th to 20th	Day	4 5% 2 6% 4 3 4 3 3 6% 61%	4740
	21st to end	Day	5% 6% 3 6% 3 3 3 3 4 5% 59%	5814
February	1st to 10th	Day	5% 8% 3 6% 4 3 3 3 4 7% 53%	2100
	11th to 20th	Day	4 6% 2 6% 5% 5% 4 4 4 7% 53%	2049
	21st to end	Day	3 5% 3 5% 4 4 3 3 4 5% 62%	1730
March	1st to 10th	Day	3 6% 2 4 3 3 3 3 4 5% 63%	4600
	11th to 20th	Day	5% 4 2 5% 3 3 3 2 5% 7% 61%	4927
	21st to end	Day	4 5% 2 5% 3 3 4 3 5% 7% 59%	5772
April	1st to 10th	Day	8% 5% 1 4 3 3 3 3 5% 7% 59%	2520
	11th to 20th	Day	10% 4 1 4 3 4 3 4 6% 8% 53%	2491
	21st to end	Day	11% 5% 2 5% 4 3 5% 4 6% 7% 49%	2665
May	1st to 10th	Day	12% 6% 2 5% 3 3 3 3 5% 6% 52%	7655
	11th to 20th	Day	4 3 1 4 3 3 3 3 5% 7% 63%	7627
	21st to end	Day	16% 6% 2 4 3 3 3 3 4 6% 51%	8404
June	1st to 10th	Day	5% 3 1 4 3 3 4 3 7% 9% 58%	2898
	11th to 20th	Day	5% 4 1 3 3 2 3 2 5% 7% 63%	2940
	21st to end	Day	5% 3 1 4 4 3 3 4 6% 9% 57%	2940
July	1st to 10th	Day	4 3 1 4 3 3 4 3 6% 8% 59%	8249
	11th to 20th	Day	4 2 1 2 2 2 3 3 5% 7% 71%	8250
	21st to end	Day	3 2 1 4 3 3 4 4 7% 10% 59%	8492
August	1st to 10th	Day	9% 4 2 4 3 3 3 3 5% 7% 57%	7581
	11th to 20th	Day	4 3 1 4 3 4 4 4 6% 9% 57%	7102
	21st to end	Day	9% 4 2 4 3 3 4 3 5% 8% 54%	7751
September	1st to 10th	Day	7% 4 1 4 2 3 3 3 5% 8% 60%	2498
	11th to 20th	Day	7% 4 2 3 3 2 3 3 5% 6% 62%	2310
	21st to end	Day	7% 4 1 4 2 3 3 3 5% 6% 62%	2310
October	1st to 10th	Day	7% 2 1 2 2 1 2 2 2 5% 74%	3700
	11th to 20th	Day	5% 3 1 3 2 3 3 3 4 6% 66%	3406
	21st to end	Day	5% 4 1 3 2 2 2 2 3 4 71%	3190
November	1st to 10th	Day	7% 4 1 2 2 3 3 3 4 6% 65%	1853
	11th to 20th	Day	4 4 1 4 3 3 2 2 4 5% 67%	1890
	21st to end	Day	7% 5% 2 4 3 3 3 2 4 5% 62%	1890
December	1st to 10th	Day	3 4 1 3 2 2 2 2 4 5% 70%	3030
	11th to 20th	Day	4 4 2 4 2 3 2 2 5% 6% 67%	3329
	21st to end	Day	6% 11% 4 8% 4 4 4 3 3 6% 48%	4092
January	1st to 10th	Night	6% 7% 3 7% 4 4 4 3 4 6% 51%	8201
	11th to 20th	Night	3 5% 2 5% 3 3 3 3 4 5% 64%	8250
	21st to end	Night	5% 7% 3 6% 3 3 3 2 4 5% 57%	8454
February	1st to 10th	Night	6% 8% 3 7% 4 4 3 3 5% 6% 52%	2520
	11th to 20th	Night	5% 7% 3 6% 4 4 5% 4 6% 6% 49%	2458
	21st to end	Night	4 6% 3 5% 3 2 2 2 5% 6% 62%	2076
March	1st to 10th	Night	4 6% 2 3 2 2 3 2 4 6% 65%	5494
	11th to 20th	Night	6% 4 1 5% 3 3 3 3 5% 7% 59%	5246
	21st to end	Night	6% 5% 2 6% 4 4 4 4 6% 9% 50%	5392
April	1st to 10th	Night	7% 6% 2 5% 4 3 4 3 6% 8% 54%	2100
	11th to 20th	Night	10% 6% 2 4 4 3 4 3 6% 8% 51%	2077
	21st to end	Night	11% 6% 2 4 3 3 3 3 5% 7% 51%	1953
May	1st to 10th	Night	11% 5% 2 6% 4 4 5% 3 5% 7% 48%	5292
	11th to 20th	Night	5% 4 2 4 3 4 4 4 5% 8% 58%	5265
	21st to end	Night	17% 7% 2 4 3 3 3 3 5% 6% 47%	5803
June	1st to 10th	Night	6% 3 1 4 3 4 4 4 9% 11% 50%	1716
	11th to 20th	Night	5% 4 2 5% 3 4 4 4 5% 9% 56%	1680
	21st to end	Night	5% 4 2 5% 5% 4 4 4 6% 8% 53%	1680
July	1st to 10th	Night	5% 4 2 6% 4 5% 4 4 7% 10% 48%	4740
	11th to 20th	Night	5% 3 1 4 3 4 5% 3 7% 9% 54%	4740
	21st to end	Night	4 3 2 5% 4 4 5% 5% 9% 14% 44%	5603
August	1st to 10th	Night	9% 5% 2 6% 4 4 4 5% 7% 9% 45%	5241
	11th to 20th	Night	7% 4 2 5% 4 5% 6% 5% 9% 11% 42%	5737
	21st to end	Night	10% 4 2 6% 5% 6% 6% 5% 8% 10% 38%	6465
September	1st to 10th	Night	6% 4 1 3 3 3 4 4 5% 7% 60%	2121
	11th to 20th	Night	7% 3 1 4 3 3 4 4 5% 9% 58%	2310
	21st to end	Night	8% 4 1 4 2 3 3 2 5% 6% 62%	2310
October	1st to 10th	Night	7% 2 1 3 2 1 2 2 3 5% 72%	3700
	11th to 20th	Night	6% 3 1 2 2 3 3 2 4 6% 68%	3752
	21st to end	Night	7% 4 1 4 2 2 3 2 3 5% 67%	4610
November	1st to 10th	Night	5% 3 1 4 3 3 3 3 5% 6% 66%	2665
	11th to 20th	Night	4 4 1 3 2 2 3 2 4 5% 69%	2730
	21st to end	Night	6% 4 1 3 3 3 4 3 5% 6% 61%	2730
December	1st to 10th	Night	2 4 2 4 3 3 3 3 3 5% 67%	4380
	11th to 20th	Night	3 4 2 4 2 3 3 2 4 7% 66%	5080
	21st to end	Night	7% 10% 3 6% 3 3 3 3 4 6% 51%	7128

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% 3 9% 28% 21% 6%	4723
	11th to 20th	Day	27% 4 9% 23% 27% 11%	4740
	21st to end	Day	29% 3 8% 24% 28% 8%	5814
February	1st to 10th	Day	32% 3 11% 28% 18% 8%	2100
	11th to 20th	Day	32% 4 11% 25% 20% 7%	2059
	21st to end	Day	25% 3 8% 21% 29% 14%	1730
March	1st to 10th	Day	25% 3 6% 15% 31% 19%	4600
	11th to 20th	Day	23% 4 8% 19% 33% 14%	4927
	21st to end	Day	23% 5% 11% 40% 16% 4	5772
April	1st to 10th	Day	25% 4 11% 25% 25% 10%	2520
	11th to 20th	Day	28% 5% 13% 23% 21% 10%	2494
	21st to end	Day	33% 6% 12% 24% 20% 5%	2665
May	1st to 10th	Day	32% 5% 10% 25% 22% 7%	7655
	11th to 20th	Day	20% 5% 10% 24% 28% 13%	7631
	21st to end	Day	35% 6% 12% 22% 19% 7%	8405
June	1st to 10th	Day	21% 7% 18% 33% 17% 5%	2898
	11th to 20th	Day	21% 4 11% 28% 25% 12%	2940
	21st to end	Day	24% 5% 10% 25% 26% 10%	2940
July	1st to 10th	Day	22% 4 9% 26% 31% 6%	8181
	11th to 20th	Day	14% 4 15% 28% 29% 10%	8175
	21st to end	Day	21% 5% 15% 31% 22% 7%	8305
August	1st to 10th	Day	26% 4 12% 26% 25% 7%	6000
	11th to 20th	Day	25% 6% 18% 25% 22% 4	5593
	21st to end	Day	20% 5% 20% 32% 18% 6%	6078
September	1st to 10th	Day	24% 5% 10% 27% 23% 12%	2498
	11th to 20th	Day	23% 4 8% 27% 27% 10%	2310
	21st to end	Day	23% 4 9% 25% 27% 12%	2310
October	1st to 10th	Day	17% 2 5% 19% 42% 15%	3700
	11th to 20th	Day	20% 3 9% 27% 30% 11%	3406
	21st to end	Day	18% 3 7% 21% 38% 13%	3190
November	1st to 10th	Day	21% 4 9% 25% 30% 12%	1853
	11th to 20th	Day	20% 3 8% 27% 31% 11%	1890
	21st to end	Day	26% 3 8% 22% 27% 13%	1890
December	1st to 10th	Day	18% 3 9% 29% 32% 10%	3030
	11th to 20th	Day	19% 2 6% 36% 32% 4	3327
	21st to end	Day	39% 4 7% 22% 22% 7%	4092
January	1st to 10th	Night	34% 4 9% 28% 21% 5%	8202
	11th to 20th	Night	23% 4 9% 25% 28% 12%	8250
	21st to end	Night	31% 3 8% 23% 25% 10%	8454
February	1st to 10th	Night	34% 4 11% 23% 21% 8%	2520
	11th to 20th	Night	33% 5% 12% 23% 21% 6%	2458
	21st to end	Night	24% 3 6% 23% 29% 15%	2076
March	1st to 10th	Night	21% 3 6% 17% 32% 20%	5494
	11th to 20th	Night	24% 5% 8% 17% 29% 17%	5246
	21st to end	Night	30% 5% 13% 35% 14% 3	5392
April	1st to 10th	Night	28% 5% 11% 23% 24% 10%	2100
	11th to 20th	Night	31% 5% 12% 24% 18% 10%	2077
	21st to end	Night	31% 5% 12% 26% 22% 3	1953
May	1st to 10th	Night	34% 7% 13% 22% 19% 5%	5293
	11th to 20th	Night	23% 6% 10% 25% 25% 11%	5266
	21st to end	Night	37% 6% 17% 19% 13% 8%	5805
June	1st to 10th	Night	23% 9% 21% 27% 15% 4	1716
	11th to 20th	Night	25% 6% 15% 24% 22% 8%	1680
	21st to end	Night	28% 8% 10% 24% 22% 8%	1680
July	1st to 10th	Night	30% 6% 17% 23% 22% 2	4700
	11th to 20th	Night	25% 5% 14% 24% 24% 8%	4692
	21st to end	Night	28% 6% 15% 28% 18% 5%	5477
August	1st to 10th	Night	33% 5% 11% 23% 21% 7%	4146
	11th to 20th	Night	36% 6% 14% 26% 15% 3	4521
	21st to end	Night	31% 6% 20% 22% 15% 6%	5069
September	1st to 10th	Night	23% 6% 12% 25% 23% 12%	2121
	11th to 20th	Night	24% 6% 11% 23% 26% 11%	2310
	21st to end	Night	23% 3 10% 21% 30% 12%	2310
October	1st to 10th	Night	18% 3 6% 17% 41% 16%	3700
	11th to 20th	Night	19% 3 11% 23% 32% 12%	3752
	21st to end	Night	23% 2 6% 22% 36% 12%	4610
November	1st to 10th	Night	20% 3 9% 26% 26% 16%	2665
	11th to 20th	Night	18% 2 7% 26% 34% 12%	2730
	21st to end	Night	23% 4 9% 25% 26% 12%	2730
December	1st to 10th	Night	21% 3 8% 35% 26% 8%	4380
	11th to 20th	Night	20% 2 6% 32% 33% 7%	5081
	21st to end	Night	35% 5% 8% 25% 23% 4	7128

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% 40% 27% 15% 2	330
	11th to 20th	Day	13% 10% 35% 31% 10% 2	330
	21st to end	Day	8% 10% 38% 34% 10% 1	363
February	1st to 10th	Day	9% 8% 46% 29% 7% 1	330
	11th to 20th	Day	7% 10% 47% 25% 10% 1	330
	21st to end	Day	5% 15% 44% 30% 4	273
March	1st to 10th	Day	8% 12% 38% 31% 11% 2	330
	11th to 20th	Day	11% 13% 38% 27% 11% 1	330
	21st to end	Day	12% 15% 38% 28% 7%	447
April	1st to 10th	Day	11% 17% 41% 23% 6% 1	540
	11th to 20th	Day	11% 17% 42% 24% 5% 1	532
	21st to end	Day	16% 16% 35% 24% 7% 1	685
May	1st to 10th	Day	13% 8% 33% 32% 12% 2	753
	11th to 20th	Day	14% 8% 30% 33% 12% 3	775
	21st to end	Day	15% 9% 31% 32% 11% 2	844
June	1st to 10th	Day	7% 5% 25% 38% 20% 5%	780
	11th to 20th	Day	7% 7% 32% 35% 17% 2	780
	21st to end	Day	6% 4 30% 39% 18% 2	780
July	1st to 10th	Day	6% 3 21% 38% 27% 4	771
	11th to 20th	Day	3 1 16% 42% 29% 8%	768
	21st to end	Day	5% 2 12% 39% 34% 8%	849
August	1st to 10th	Day	7% 2 17% 37% 33% 4	776
	11th to 20th	Day	5% 2 17% 43% 30% 4	592
	21st to end	Day	7% 2 16% 42% 27% 7%	627
September	1st to 10th	Day	9% 2 18% 43% 22% 6%	548
	11th to 20th	Day	5% 4 27% 35% 19% 11%	360
	21st to end	Day	13% 6% 21% 28% 26% 6%	360
October	1st to 10th	Day	15% 6% 19% 28% 23% 9%	360
	11th to 20th	Day	6% 8% 37% 33% 13% 4	339
	21st to end	Day	15% 10% 30% 26% 16% 2	363
November	1st to 10th	Day	12% 11% 29% 32% 12% 5%	330
	11th to 20th	Day	8% 10% 35% 31% 14% 2	330
	21st to end	Day	13% 13% 31% 27% 12% 3	330
December	1st to 10th	Day	5% 7% 39% 34% 12% 2	330
	11th to 20th	Day	10% 10% 39% 30% 10%	330
	21st to end	Day	14% 11% 35% 30% 10%	363
January	1st to 10th	Night	8% 7% 39% 35% 10% 1	1050
	11th to 20th	Night	9% 9% 38% 33% 10% 1	1050
	21st to end	Night	6% 8% 44% 35% 7% 1	1118
February	1st to 10th	Night	10% 11% 40% 33% 6%	840
	11th to 20th	Night	10% 10% 46% 28% 6%	824
	21st to end	Night	7% 10% 45% 33% 5%	692
March	1st to 10th	Night	8% 13% 40% 34% 6%	840
	11th to 20th	Night	10% 10% 38% 32% 9% 1	708
	21st to end	Night	13% 11% 46% 25% 5%	693
April	1st to 10th	Night	9% 16% 43% 28% 3	630
	11th to 20th	Night	12% 16% 43% 24% 4	623
	21st to end	Night	17% 13% 35% 27% 7% 1	630
May	1st to 10th	Night	12% 11% 39% 30% 8% 1	630
	11th to 20th	Night	12% 9% 36% 32% 11% 1	621
	21st to end	Night	14% 9% 41% 28% 8%	683
June	1st to 10th	Night	7% 5% 38% 39% 10%	630
	11th to 20th	Night	7% 10% 42% 35% 5%	630
	21st to end	Night	7% 6% 39% 40% 9%	630
July	1st to 10th	Night	7% 4 29% 44% 15%	615
	11th to 20th	Night	5% 1 23% 52% 18% 2	612
	21st to end	Night	7% 2 18% 51% 22% 1	690
August	1st to 10th	Night	8% 2 21% 47% 21% 1	627
	11th to 20th	Night	8% 1 29% 48% 14%	624
	21st to end	Night	7% 2 24% 48% 18% 1	693
September	1st to 10th	Night	7% 2 29% 48% 14% 1	630
	11th to 20th	Night	9% 4 32% 41% 12% 2	630
	21st to end	Night	10% 7% 28% 40% 16%	630
October	1st to 10th	Night	12% 8% 32% 35% 14%	630
	11th to 20th	Night	8% 9% 37% 35% 11% 1	696
	21st to end	Night	11% 9% 32% 34% 14%	1100
November	1st to 10th	Night	7% 7% 35% 40% 11% 1	1025
	11th to 20th	Night	6% 9% 37% 37% 10% 1	1050
	21st to end	Night	8% 9% 34% 36% 12% 2	1050
December	1st to 10th	Night	8% 8% 38% 36% 9% 1	1050
	11th to 20th	Night	9% 10% 37% 35% 9% 1	1050
	21st to end	Night	11% 10% 35% 34% 9%	1155

Page generated at 2026-10-11 04:06:31. Version ac07

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