Wahnsiedler Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wahnsiedler Observatory clear sky chart from 2005-11-06 to 2025-02-06.

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	13% 8% 3 7% 4 4 4 4 5% 7% 40%	108352
	Night	15% 8% 3 6% 4 4 4 3 5% 6% 42%	110022
Transparency	Day	41% 5% 11% 24% 16% 2	112013
	Night	41% 5% 10% 23% 18% 3	114501
Seeing	Day	16% 9% 23% 25% 18% 9%	15769
	Night	17% 7% 25% 31% 17% 2	25693

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	15% 12% 7% 11% 4 5% 4 3 4 5% 28%	3617
	11th to 20th	Day	14% 10% 5% 12% 7% 5% 4 3 4 6% 30%	3620
	21st to end	Day	21% 12% 6% 8% 4 3 3 2 4 6% 32%	4418
February	1st to 10th	Day	18% 11% 4 7% 4 4 3 3 5% 5% 35%	1950
	11th to 20th	Day	16% 10% 3 8% 4 4 4 3 5% 6% 36%	1848
	21st to end	Day	17% 11% 4 9% 5% 4 4 3 6% 6% 32%	1570
March	1st to 10th	Day	22% 14% 3 7% 3 3 3 2 3 4 35%	3120
	11th to 20th	Day	14% 7% 3 6% 3 3 4 3 5% 6% 46%	3275
	21st to end	Day	13% 8% 3 8% 5% 4 5% 4 6% 7% 38%	4123
April	1st to 10th	Day	14% 7% 2 6% 4 4 4 5% 5% 8% 40%	2280
	11th to 20th	Day	16% 8% 2 6% 4 4 4 4 5% 6% 40%	2254
	21st to end	Day	18% 6% 2 6% 4 4 4 4 5% 6% 41%	2337
May	1st to 10th	Day	16% 8% 3 7% 6% 5% 5% 4 8% 9% 30%	4082
	11th to 20th	Day	18% 7% 3 7% 4 4 4 4 5% 7% 38%	4081
	21st to end	Day	11% 7% 3 7% 4 4 5% 5% 7% 8% 39%	4588
June	1st to 10th	Day	11% 5% 3 5% 5% 4 4 3 6% 8% 46%	2660
	11th to 20th	Day	5% 5% 2 6% 4 5% 6% 4 7% 8% 48%	2660
	21st to end	Day	8% 5% 2 5% 4 4 5% 5% 8% 10% 45%	2660
July	1st to 10th	Day	13% 6% 2 6% 4 5% 5% 4 6% 9% 41%	4440
	11th to 20th	Day	6% 4 2 6% 4 4 5% 4 7% 11% 48%	4440
	21st to end	Day	10% 7% 3 9% 6% 7% 7% 6% 8% 8% 29%	4698
August	1st to 10th	Day	6% 4 1 5% 3 4 4 4 7% 9% 53%	3980
	11th to 20th	Day	8% 4 2 7% 6% 5% 5% 4 8% 10% 41%	3729
	21st to end	Day	5% 4 2 5% 3 4 4 4 6% 9% 55%	4180
September	1st to 10th	Day	9% 6% 2 6% 5% 4 4 4 6% 6% 48%	2280
	11th to 20th	Day	8% 5% 2 6% 5% 4 3 4 6% 8% 49%	2104
	21st to end	Day	13% 5% 2 5% 4 3 4 3 5% 6% 52%	2090
October	1st to 10th	Day	10% 4 2 4 3 3 3 3 5% 6% 57%	2090
	11th to 20th	Day	13% 5% 2 5% 4 3 4 3 5% 7% 49%	1963
	21st to end	Day	18% 7% 3 6% 3 3 4 3 3 5% 45%	1891
November	1st to 10th	Day	10% 5% 2 4 4 4 4 3 5% 7% 52%	1762
	11th to 20th	Day	15% 8% 3 6% 4 3 3 3 4 6% 44%	1800
	21st to end	Day	19% 10% 3 6% 3 4 4 3 4 5% 40%	1800
December	1st to 10th	Day	15% 10% 3 6% 3 3 3 2 4 5% 46%	2930
	11th to 20th	Day	16% 12% 5% 10% 4 5% 4 3 5% 6% 31%	3050
	21st to end	Day	27% 16% 5% 8% 5% 4 4 3 4 5% 20%	3982
January	1st to 10th	Night	18% 13% 5% 9% 4 4 4 4 5% 5% 30%	6348
	11th to 20th	Night	16% 13% 4 9% 5% 6% 5% 3 4 4 32%	6360
	21st to end	Night	20% 11% 4 6% 3 3 3 3 4 6% 37%	6521
February	1st to 10th	Night	21% 11% 3 7% 4 4 4 4 5% 5% 31%	2341
	11th to 20th	Night	16% 9% 3 8% 5% 4 4 3 4 5% 39%	2218
	21st to end	Night	20% 11% 3 8% 3 3 3 4 6% 5% 35%	1884
March	1st to 10th	Night	23% 11% 3 6% 4 3 3 3 4 4 33%	3733
	11th to 20th	Night	12% 7% 2 6% 3 3 3 3 5% 6% 49%	3683
	21st to end	Night	17% 8% 2 8% 5% 4 3 4 4 6% 40%	3535
April	1st to 10th	Night	12% 8% 2 6% 4 3 4 4 5% 6% 46%	1900
	11th to 20th	Night	17% 7% 2 6% 4 3 3 4 4 6% 44%	1875
	21st to end	Night	18% 7% 3 6% 5% 4 4 4 5% 8% 37%	1842
May	1st to 10th	Night	16% 8% 3 7% 5% 4 4 4 6% 8% 34%	2813
	11th to 20th	Night	16% 7% 2 5% 5% 4 4 4 5% 7% 42%	2812
	21st to end	Night	9% 6% 2 7% 4 5% 5% 4 7% 10% 41%	2967
June	1st to 10th	Night	10% 5% 2 5% 4 4 4 4 7% 7% 48%	1520
	11th to 20th	Night	6% 4 1 5% 4 4 4 5% 7% 9% 50%	1520
	21st to end	Night	4 4 1 4 4 3 4 5% 7% 11% 53%	1520
July	1st to 10th	Night	9% 5% 2 6% 4 4 3 4 5% 8% 49%	2530
	11th to 20th	Night	5% 4 1 5% 3 3 4 3 5% 8% 57%	2530
	21st to end	Night	8% 7% 4 8% 6% 5% 6% 6% 8% 9% 33%	2859
August	1st to 10th	Night	5% 4 1 5% 3 3 3 3 6% 9% 59%	2945
	11th to 20th	Night	5% 5% 2 6% 4 4 5% 4 6% 9% 51%	3100
	21st to end	Night	4 3 1 4 3 3 4 3 6% 9% 60%	3476
September	1st to 10th	Night	10% 4 2 6% 3 4 3 3 5% 7% 54%	1900
	11th to 20th	Night	8% 4 1 5% 3 4 4 4 6% 7% 54%	2057
	21st to end	Night	12% 5% 2 5% 3 3 4 3 5% 7% 51%	2090
October	1st to 10th	Night	8% 4 2 5% 3 3 3 2 4 6% 59%	2090
	11th to 20th	Night	14% 5% 2 5% 3 3 3 3 4 5% 53%	2213
	21st to end	Night	17% 7% 2 5% 3 4 4 2 4 5% 46%	2707
November	1st to 10th	Night	12% 6% 2 5% 4 3 3 3 4 5% 52%	2536
	11th to 20th	Night	14% 6% 3 6% 3 4 4 3 4 6% 47%	2600
	21st to end	Night	19% 8% 3 5% 3 4 4 3 4 5% 43%	2600
December	1st to 10th	Night	18% 9% 2 6% 3 3 3 3 3 5% 43%	4250
	11th to 20th	Night	19% 9% 3 6% 4 4 4 3 5% 6% 38%	5151
	21st to end	Night	27% 15% 4 7% 5% 4 4 3 4 4 23%	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	58% 3 10% 21% 7% 1	3618
	11th to 20th	Day	57% 3 10% 19% 11% 1	3620
	21st to end	Day	55% 3 10% 18% 10% 4	4418
February	1st to 10th	Day	51% 3 11% 22% 11% 2	1950
	11th to 20th	Day	49% 5% 9% 22% 13% 2	1858
	21st to end	Day	52% 4 9% 19% 12% 3	1570
March	1st to 10th	Day	55% 3 5% 19% 14% 3	3120
	11th to 20th	Day	38% 5% 11% 28% 16% 3	3275
	21st to end	Day	44% 6% 12% 24% 13% 1	4123
April	1st to 10th	Day	40% 7% 13% 23% 16% 1	2280
	11th to 20th	Day	44% 5% 9% 23% 16% 3	2254
	21st to end	Day	43% 6% 12% 25% 12% 2	2337
May	1st to 10th	Day	47% 9% 15% 21% 8%	4120
	11th to 20th	Day	45% 7% 10% 26% 11% 1	4085
	21st to end	Day	40% 7% 12% 18% 21% 2	4601
June	1st to 10th	Day	35% 7% 11% 24% 19% 3	2660
	11th to 20th	Day	31% 9% 12% 25% 20% 3	2660
	21st to end	Day	32% 9% 13% 23% 17% 5%	2660
July	1st to 10th	Day	39% 6% 11% 25% 16% 2	4371
	11th to 20th	Day	29% 7% 14% 32% 17% 2	4365
	21st to end	Day	49% 8% 15% 18% 9% 1	4549
August	1st to 10th	Day	26% 7% 15% 35% 16% 1	3967
	11th to 20th	Day	36% 7% 13% 25% 18% 1	3765
	21st to end	Day	26% 5% 14% 35% 17% 4	4179
September	1st to 10th	Day	35% 5% 10% 24% 20% 5%	2280
	11th to 20th	Day	32% 6% 11% 26% 22% 3	2104
	21st to end	Day	34% 5% 8% 24% 26% 4	2090
October	1st to 10th	Day	19% 3 6% 25% 43% 4	3480
	11th to 20th	Day	24% 3 8% 26% 34% 5%	3242
	21st to end	Day	33% 3 7% 25% 26% 5%	3091
November	1st to 10th	Day	32% 6% 10% 30% 17% 6%	1762
	11th to 20th	Day	41% 5% 8% 23% 19% 5%	1800
	21st to end	Day	47% 4 8% 22% 16% 2	1800
December	1st to 10th	Day	42% 3 12% 26% 16%	2930
	11th to 20th	Day	55% 3 10% 21% 10% 1	3047
	21st to end	Day	67% 4 11% 12% 5%	3982
January	1st to 10th	Night	56% 4 11% 21% 8% 1	6348
	11th to 20th	Night	56% 3 8% 19% 12% 3	6360
	21st to end	Night	50% 3 8% 20% 17% 1	6521
February	1st to 10th	Night	54% 5% 11% 20% 9% 1	2341
	11th to 20th	Night	48% 4 9% 23% 15% 2	2219
	21st to end	Night	50% 4 10% 19% 13% 3	1884
March	1st to 10th	Night	54% 5% 7% 18% 14% 2	3733
	11th to 20th	Night	36% 6% 12% 23% 19% 4	3683
	21st to end	Night	46% 6% 10% 26% 12% 1	3535
April	1st to 10th	Night	38% 5% 11% 27% 16% 3	1900
	11th to 20th	Night	41% 4 9% 21% 20% 5%	1875
	21st to end	Night	46% 6% 9% 21% 16% 2	1842
May	1st to 10th	Night	45% 10% 14% 23% 7% 1	2840
	11th to 20th	Night	41% 7% 12% 26% 13% 1	2813
	21st to end	Night	35% 9% 14% 22% 17% 3	2975
June	1st to 10th	Night	33% 6% 11% 25% 21% 4	1520
	11th to 20th	Night	28% 7% 13% 22% 24% 6%	1520
	21st to end	Night	23% 8% 17% 25% 19% 8%	1520
July	1st to 10th	Night	34% 7% 10% 25% 20% 4	2490
	11th to 20th	Night	24% 7% 11% 36% 19% 3	2482
	21st to end	Night	44% 7% 15% 21% 11% 1	2768
August	1st to 10th	Night	23% 6% 16% 39% 15% 2	2934
	11th to 20th	Night	29% 6% 13% 28% 21% 2	3130
	21st to end	Night	21% 6% 13% 33% 25% 4	3476
September	1st to 10th	Night	30% 6% 8% 26% 23% 6%	1900
	11th to 20th	Night	28% 6% 10% 26% 25% 5%	2057
	21st to end	Night	33% 5% 8% 23% 24% 7%	2090
October	1st to 10th	Night	18% 4 6% 15% 52% 6%	3480
	11th to 20th	Night	24% 2 6% 26% 38% 4	3673
	21st to end	Night	31% 3 8% 23% 27% 8%	4457
November	1st to 10th	Night	34% 4 10% 24% 23% 5%	2536
	11th to 20th	Night	38% 4 8% 22% 22% 6%	2600
	21st to end	Night	44% 4 9% 24% 17% 2	2600
December	1st to 10th	Night	44% 4 11% 24% 17%	4250
	11th to 20th	Night	47% 3 13% 21% 15% 1	5153
	21st to end	Night	65% 4 9% 16% 6% 1	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	26% 18% 29% 20% 6% 1	300
	11th to 20th	Day	28% 20% 32% 17% 3	300
	21st to end	Day	24% 21% 35% 15% 5%	330
February	1st to 10th	Day	24% 16% 38% 18% 3 1	285
	11th to 20th	Day	26% 19% 37% 15% 4 1	270
	21st to end	Day	28% 16% 34% 18% 4	225
March	1st to 10th	Day	22% 14% 40% 18% 5%	270
	11th to 20th	Day	25% 15% 37% 17% 6% 1	333
	21st to end	Day	27% 13% 35% 17% 8% 1	506
April	1st to 10th	Day	17% 15% 31% 27% 9% 2	460
	11th to 20th	Day	21% 14% 26% 22% 14% 2	452
	21st to end	Day	21% 12% 32% 23% 9% 4	460
May	1st to 10th	Day	18% 13% 27% 28% 9% 4	463
	11th to 20th	Day	20% 7% 21% 29% 14% 8%	487
	21st to end	Day	12% 4 23% 29% 20% 12%	589
June	1st to 10th	Day	13% 5% 17% 25% 28% 11%	680
	11th to 20th	Day	7% 4 18% 33% 26% 13%	680
	21st to end	Day	11% 4 21% 33% 21% 11%	680
July	1st to 10th	Day	12% 3 13% 23% 26% 22%	671
	11th to 20th	Day	6% 4 14% 31% 30% 16%	668
	21st to end	Day	8% 2 13% 30% 33% 14%	673
August	1st to 10th	Day	11% 3 11% 27% 29% 18%	486
	11th to 20th	Day	13% 2 14% 28% 31% 12%	479
	21st to end	Day	8% 2 10% 24% 36% 21%	539
September	1st to 10th	Day	10% 3 14% 24% 34% 15%	490
	11th to 20th	Day	7% 3 9% 31% 32% 17%	490
	21st to end	Day	15% 6% 20% 22% 24% 14%	490
October	1st to 10th	Day	11% 3 20% 34% 24% 8%	490
	11th to 20th	Day	13% 10% 33% 25% 13% 6%	363
	21st to end	Day	25% 12% 29% 25% 10%	330
November	1st to 10th	Day	15% 7% 33% 26% 13% 6%	300
	11th to 20th	Day	17% 21% 28% 23% 9% 2	300
	21st to end	Day	27% 9% 31% 24% 8% 1	300
December	1st to 10th	Day	21% 22% 30% 17% 7% 3	300
	11th to 20th	Day	27% 13% 32% 20% 8% 1	300
	21st to end	Day	30% 18% 29% 18% 4	330
January	1st to 10th	Night	23% 12% 32% 28% 4	1000
	11th to 20th	Night	26% 13% 35% 22% 4	1000
	21st to end	Night	21% 11% 39% 27% 2	1043
February	1st to 10th	Night	26% 10% 35% 27% 2	781
	11th to 20th	Night	22% 12% 37% 26% 2	743
	21st to end	Night	26% 13% 37% 22% 2	628
March	1st to 10th	Night	22% 11% 33% 29% 5%	760
	11th to 20th	Night	21% 10% 35% 26% 7% 1	760
	21st to end	Night	24% 8% 28% 32% 7%	670
April	1st to 10th	Night	14% 11% 31% 35% 8%	570
	11th to 20th	Night	20% 8% 29% 29% 13% 1	563
	21st to end	Night	21% 6% 31% 31% 9% 2	570
May	1st to 10th	Night	17% 7% 26% 35% 13% 1	570
	11th to 20th	Night	14% 5% 19% 37% 22% 2	561
	21st to end	Night	8% 2 19% 39% 28% 4	617
June	1st to 10th	Night	12% 1 16% 40% 28% 3	570
	11th to 20th	Night	6% 2 17% 42% 32% 2	570
	21st to end	Night	5% 1 18% 41% 33% 2	570
July	1st to 10th	Night	11% 1 10% 33% 37% 9%	555
	11th to 20th	Night	5% 2 10% 33% 44% 5%	552
	21st to end	Night	8% 2 9% 37% 36% 7%	624
August	1st to 10th	Night	7% 2 7% 37% 41% 7%	567
	11th to 20th	Night	6% 2 9% 38% 40% 6%	564
	21st to end	Night	6% 1 7% 35% 44% 8%	627
September	1st to 10th	Night	11% 2 10% 33% 39% 5%	570
	11th to 20th	Night	8% 2 12% 36% 37% 5%	727
	21st to end	Night	14% 4 19% 30% 28% 6%	760
October	1st to 10th	Night	9% 5% 17% 37% 27% 5%	760
	11th to 20th	Night	17% 6% 25% 33% 17% 2	760
	21st to end	Night	20% 9% 31% 29% 11%	836
November	1st to 10th	Night	15% 7% 27% 37% 13% 1	780
	11th to 20th	Night	17% 9% 33% 29% 11%	800
	21st to end	Night	22% 10% 27% 31% 10%	800
December	1st to 10th	Night	23% 8% 32% 30% 6%	800
	11th to 20th	Night	26% 7% 31% 30% 6% 1	965
	21st to end	Night	29% 12% 32% 24% 4	1100

Page generated at 2025-02-03 03:05:54. Version ac07

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