Insel Haus
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Insel Haus clear sky chart from 2005-11-06 to 2026-07-16.

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% 10% 4 9% 5% 5% 5% 4 5% 7% 34%	137586
	Night	14% 12% 5% 11% 6% 5% 5% 3 5% 6% 28%	135348
Transparency	Day	32% 36% 8% 16% 7% 1	141076
	Night	37% 36% 8% 13% 6% 1	139945
Seeing	Day	17% 6% 21% 32% 19% 5%	17837
	Night	20% 8% 25% 30% 14% 2	27291

By Month

Percentage Cloud Cover NE (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	11% 17% 8% 22% 9% 7% 5% 3 4 5% 9%	4668
	11th to 20th	Day	10% 19% 7% 21% 14% 7% 5% 3 4 3 7%	4679
	21st to end	Day	9% 14% 6% 16% 9% 8% 7% 4 6% 6% 15%	5156
February	1st to 10th	Day	9% 14% 5% 12% 8% 6% 5% 3 5% 7% 24%	1827
	11th to 20th	Day	12% 13% 5% 12% 7% 6% 5% 4 6% 6% 24%	1966
	21st to end	Day	11% 14% 5% 11% 7% 5% 5% 4 5% 7% 26%	1730
March	1st to 10th	Day	13% 9% 2 10% 5% 5% 4 3 6% 8% 35%	4578
	11th to 20th	Day	12% 12% 4 10% 7% 6% 5% 4 5% 6% 29%	5042
	21st to end	Day	18% 11% 7% 9% 5% 5% 5% 4 5% 6% 26%	5667
April	1st to 10th	Day	17% 11% 3 8% 5% 5% 5% 4 5% 7% 30%	2520
	11th to 20th	Day	17% 10% 3 7% 4 4 4 3 5% 6% 36%	2664
	21st to end	Day	14% 9% 3 9% 5% 5% 4 4 6% 7% 35%	2730
May	1st to 10th	Day	12% 7% 2 6% 4 5% 5% 4 5% 7% 43%	7642
	11th to 20th	Day	13% 8% 3 7% 5% 5% 5% 3 5% 6% 39%	7823
	21st to end	Day	10% 7% 2 6% 4 4 4 3 4 7% 48%	9436
June	1st to 10th	Day	13% 5% 2 5% 4 4 4 4 6% 8% 43%	3150
	11th to 20th	Day	11% 6% 3 7% 4 5% 5% 5% 7% 9% 39%	3150
	21st to end	Day	15% 7% 3 6% 4 4 3 4 5% 9% 42%	3150
July	1st to 10th	Day	14% 6% 2 5% 3 3 3 3 5% 8% 47%	6790
	11th to 20th	Day	8% 4 2 5% 4 4 4 3 6% 9% 52%	6431
	21st to end	Day	9% 5% 2 5% 3 4 4 3 6% 8% 51%	6926
August	1st to 10th	Day	7% 6% 2 6% 5% 5% 5% 5% 6% 9% 45%	4339
	11th to 20th	Day	11% 5% 2 6% 4 4 4 4 6% 7% 47%	4174
	21st to end	Day	11% 6% 2 7% 4 4 4 3 5% 7% 48%	4620
September	1st to 10th	Day	14% 6% 2 6% 4 4 4 3 5% 7% 43%	2337
	11th to 20th	Day	11% 5% 2 6% 4 5% 4 5% 5% 8% 44%	2200
	21st to end	Day	15% 9% 3 7% 5% 4 3 3 5% 7% 39%	2200
October	1st to 10th	Day	18% 9% 3 7% 3 3 5% 4 5% 9% 35%	2161
	11th to 20th	Day	20% 15% 4 10% 5% 5% 5% 4 5% 7% 21%	1922
	21st to end	Day	22% 14% 3 8% 5% 5% 5% 4 5% 7% 20%	1980
November	1st to 10th	Day	17% 14% 4 10% 5% 5% 6% 4 5% 8% 22%	1852
	11th to 20th	Day	14% 18% 6% 12% 7% 6% 5% 4 5% 5% 18%	1833
	21st to end	Day	19% 20% 9% 13% 6% 5% 5% 3 4 4 12%	1649
December	1st to 10th	Day	13% 25% 8% 15% 8% 5% 5% 4 4 4 9%	2350
	11th to 20th	Day	13% 19% 7% 19% 10% 7% 5% 3 4 4 9%	2691
	21st to end	Day	23% 20% 9% 16% 6% 4 5% 3 3 3 8%	3553
January	1st to 10th	Night	12% 15% 7% 21% 9% 6% 5% 4 4 5% 11%	8253
	11th to 20th	Night	10% 19% 8% 20% 12% 7% 6% 4 4 4 8%	8236
	21st to end	Night	8% 14% 6% 15% 8% 8% 7% 5% 6% 7% 17%	9058
February	1st to 10th	Night	10% 16% 5% 11% 9% 7% 5% 5% 5% 5% 22%	2791
	11th to 20th	Night	10% 14% 5% 14% 7% 6% 5% 3 6% 6% 24%	2539
	21st to end	Night	13% 14% 5% 9% 7% 6% 5% 4 6% 6% 25%	2076
March	1st to 10th	Night	16% 10% 3 7% 5% 4 4 3 5% 7% 36%	5482
	11th to 20th	Night	11% 12% 4 10% 5% 5% 5% 4 5% 7% 32%	5136
	21st to end	Night	20% 11% 5% 8% 5% 4 4 3 5% 5% 30%	5548
April	1st to 10th	Night	19% 11% 3 7% 6% 5% 5% 4 5% 5% 29%	2100
	11th to 20th	Night	19% 10% 3 7% 4 4 5% 3 4 5% 36%	1904
	21st to end	Night	17% 9% 3 8% 5% 4 5% 3 6% 6% 34%	1890
May	1st to 10th	Night	13% 6% 3 7% 5% 5% 5% 4 6% 6% 40%	5257
	11th to 20th	Night	14% 8% 3 8% 4 4 3 3 5% 6% 42%	5032
	21st to end	Night	14% 8% 3 6% 4 3 3 3 5% 7% 45%	4771
June	1st to 10th	Night	13% 7% 2 6% 5% 4 4 4 6% 9% 40%	1470
	11th to 20th	Night	12% 5% 2 6% 6% 4 5% 4 7% 8% 41%	1470
	21st to end	Night	14% 7% 2 6% 5% 4 5% 4 6% 6% 43%	1470
July	1st to 10th	Night	12% 6% 2 7% 5% 4 4 4 5% 8% 44%	3404
	11th to 20th	Night	8% 5% 2 6% 4 4 4 3 5% 7% 52%	3660
	21st to end	Night	8% 5% 2 4 4 3 4 4 6% 8% 52%	3948
August	1st to 10th	Night	9% 6% 3 6% 5% 5% 4 4 5% 8% 44%	2811
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 5% 9% 49%	2875
	21st to end	Night	10% 5% 2 4 4 3 4 3 5% 6% 52%	3274
September	1st to 10th	Night	12% 7% 2 6% 4 4 4 4 5% 7% 46%	2041
	11th to 20th	Night	14% 5% 2 5% 4 4 4 3 6% 8% 44%	2200
	21st to end	Night	17% 8% 3 7% 4 4 4 4 5% 7% 38%	2200
October	1st to 10th	Night	18% 8% 2 7% 4 4 4 3 4 6% 39%	2238
	11th to 20th	Night	22% 12% 4 8% 5% 5% 4 4 5% 6% 25%	2475
	21st to end	Night	24% 14% 3 9% 6% 5% 4 4 4 5% 23%	2860
November	1st to 10th	Night	17% 15% 4 9% 5% 4 4 3 5% 8% 26%	2666
	11th to 20th	Night	15% 18% 5% 13% 7% 5% 5% 4 4 6% 19%	2784
	21st to end	Night	20% 21% 8% 12% 6% 4 4 3 4 4 13%	2966
December	1st to 10th	Night	12% 21% 8% 17% 9% 5% 4 3 4 5% 10%	5060
	11th to 20th	Night	13% 19% 7% 20% 9% 5% 5% 3 3 4 11%	5736
	21st to end	Night	24% 21% 10% 13% 6% 5% 4 2 3 3 8%	7667

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	60% 26% 7% 4 2 1	4669
	11th to 20th	Day	66% 23% 6% 5% 1	4710
	21st to end	Day	54% 25% 9% 9% 3	5156
February	1st to 10th	Day	24% 59% 6% 8% 3	1827
	11th to 20th	Day	27% 59% 5% 6% 4	1975
	21st to end	Day	24% 60% 4 9% 4	1730
March	1st to 10th	Day	34% 29% 13% 12% 10% 2	4580
	11th to 20th	Day	43% 28% 10% 14% 5% 1	5042
	21st to end	Day	45% 28% 7% 13% 7%	5667
April	1st to 10th	Day	23% 60% 4 9% 4 1	2520
	11th to 20th	Day	20% 59% 4 9% 7% 1	2664
	21st to end	Day	19% 60% 5% 10% 6% 1	2730
May	1st to 10th	Day	31% 24% 7% 22% 14% 2	7651
	11th to 20th	Day	38% 23% 5% 21% 12% 1	7827
	21st to end	Day	29% 23% 8% 21% 16% 3	9436
June	1st to 10th	Day	16% 59% 4 12% 8% 2	3150
	11th to 20th	Day	19% 60% 6% 9% 5% 1	3150
	21st to end	Day	17% 58% 6% 13% 5% 1	3150
July	1st to 10th	Day	29% 27% 12% 23% 9% 1	6720
	11th to 20th	Day	20% 28% 14% 31% 6%	6356
	21st to end	Day	21% 27% 11% 29% 12%	6728
August	1st to 10th	Day	20% 39% 11% 23% 8%	4324
	11th to 20th	Day	25% 38% 10% 21% 6%	4213
	21st to end	Day	25% 38% 12% 21% 4	4619
September	1st to 10th	Day	18% 59% 7% 12% 4	2337
	11th to 20th	Day	14% 58% 6% 15% 6%	2200
	21st to end	Day	19% 57% 8% 11% 5%	2200
October	1st to 10th	Day	19% 37% 9% 23% 12%	3525
	11th to 20th	Day	31% 37% 7% 18% 6%	3112
	21st to end	Day	37% 38% 8% 13% 4	3180
November	1st to 10th	Day	29% 54% 5% 10% 2	1852
	11th to 20th	Day	32% 54% 7% 6% 2	1833
	21st to end	Day	36% 55% 4 3 1	1649
December	1st to 10th	Day	48% 38% 9% 4 1	2350
	11th to 20th	Day	53% 33% 7% 5% 1	2691
	21st to end	Day	63% 26% 3 5% 3	3553
January	1st to 10th	Night	58% 24% 8% 6% 4	8253
	11th to 20th	Night	64% 23% 7% 4 2	8280
	21st to end	Night	50% 26% 11% 10% 4	9058
February	1st to 10th	Night	24% 60% 5% 7% 4	2791
	11th to 20th	Night	25% 59% 5% 9% 2	2541
	21st to end	Night	23% 59% 6% 7% 5%	2076
March	1st to 10th	Night	35% 29% 14% 14% 8% 1	5493
	11th to 20th	Night	39% 28% 15% 12% 5% 1	5137
	21st to end	Night	44% 28% 7% 13% 8%	5548
April	1st to 10th	Night	25% 59% 3 8% 5%	2100
	11th to 20th	Night	23% 59% 2 10% 5% 2	1904
	21st to end	Night	22% 59% 4 8% 6% 1	1890
May	1st to 10th	Night	33% 25% 7% 21% 12% 2	5264
	11th to 20th	Night	34% 23% 4 25% 13%	5033
	21st to end	Night	33% 23% 7% 19% 13% 5%	4772
June	1st to 10th	Night	17% 59% 4 10% 10% 1	1470
	11th to 20th	Night	19% 60% 4 11% 5% 2	1470
	21st to end	Night	17% 58% 5% 13% 5% 1	1470
July	1st to 10th	Night	31% 27% 12% 18% 11% 1	3366
	11th to 20th	Night	22% 27% 13% 26% 12%	3612
	21st to end	Night	20% 27% 12% 26% 15%	3832
August	1st to 10th	Night	25% 39% 9% 18% 9%	2802
	11th to 20th	Night	24% 37% 9% 21% 7% 1	2902
	21st to end	Night	20% 37% 10% 23% 9%	3274
September	1st to 10th	Night	16% 59% 7% 12% 6%	2041
	11th to 20th	Night	15% 58% 7% 14% 7%	2200
	21st to end	Night	18% 57% 7% 13% 5%	2200
October	1st to 10th	Night	23% 38% 8% 22% 9%	3654
	11th to 20th	Night	25% 36% 13% 16% 10%	4024
	21st to end	Night	33% 38% 10% 16% 3	4610
November	1st to 10th	Night	30% 53% 5% 8% 3	2666
	11th to 20th	Night	29% 55% 6% 6% 3	2784
	21st to end	Night	36% 54% 4 4 2	2966
December	1st to 10th	Night	47% 39% 8% 5% 1	5060
	11th to 20th	Night	53% 33% 7% 5% 2	5735
	21st to end	Night	63% 27% 4 5% 1	7667

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% 11% 33% 28% 8% 1	325
	11th to 20th	Day	21% 10% 31% 28% 8% 1	330
	21st to end	Day	21% 7% 26% 30% 14% 1	363
February	1st to 10th	Day	16% 12% 35% 26% 10% 1	330
	11th to 20th	Day	17% 8% 39% 25% 9% 2	330
	21st to end	Day	19% 12% 33% 29% 7%	273
March	1st to 10th	Day	15% 8% 32% 31% 14%	330
	11th to 20th	Day	18% 9% 29% 32% 11% 2	518
	21st to end	Day	24% 8% 26% 30% 10% 2	594
April	1st to 10th	Day	22% 8% 26% 34% 9% 2	540
	11th to 20th	Day	22% 7% 27% 29% 13% 2	532
	21st to end	Day	19% 5% 29% 30% 14% 3	540
May	1st to 10th	Day	20% 2 25% 32% 17% 3	543
	11th to 20th	Day	17% 4 17% 40% 18% 5%	634
	21st to end	Day	13% 2 18% 39% 22% 5%	844
June	1st to 10th	Day	12% 2 21% 37% 23% 4	780
	11th to 20th	Day	13% 2 18% 41% 22% 4	780
	21st to end	Day	18% 4 13% 39% 22% 3	780
July	1st to 10th	Day	9% 1 12% 41% 30% 8%	771
	11th to 20th	Day	10% 2 13% 37% 30% 7%	744
	21st to end	Day	11% 2 13% 34% 31% 9%	794
August	1st to 10th	Day	11% 1 11% 34% 32% 10%	593
	11th to 20th	Day	10% 4 9% 30% 32% 14%	519
	21st to end	Day	13% 4 13% 35% 27% 9%	583
September	1st to 10th	Day	16% 4 15% 30% 25% 10%	530
	11th to 20th	Day	12% 2 14% 28% 29% 15%	530
	21st to end	Day	18% 5% 16% 30% 25% 6%	530
October	1st to 10th	Day	20% 7% 24% 25% 18% 6%	530
	11th to 20th	Day	23% 8% 24% 31% 12% 1	452
	21st to end	Day	29% 6% 21% 30% 11% 2	363
November	1st to 10th	Day	20% 12% 26% 28% 12% 2	330
	11th to 20th	Day	21% 14% 32% 23% 8% 1	300
	21st to end	Day	25% 17% 35% 20% 4	220
December	1st to 10th	Day	21% 15% 36% 19% 8% 1	220
	11th to 20th	Day	20% 18% 35% 20% 7%	220
	21st to end	Day	27% 15% 34% 18% 4 1	242
January	1st to 10th	Night	22% 13% 32% 26% 6% 1	1050
	11th to 20th	Night	22% 12% 33% 25% 8%	1050
	21st to end	Night	17% 10% 33% 31% 8% 1	1155
February	1st to 10th	Night	16% 10% 36% 29% 9% 1	901
	11th to 20th	Night	18% 9% 34% 28% 10%	823
	21st to end	Night	19% 9% 33% 31% 8%	692
March	1st to 10th	Night	18% 7% 33% 32% 10% 1	840
	11th to 20th	Night	18% 8% 32% 32% 9% 1	840
	21st to end	Night	19% 7% 27% 34% 12% 1	909
April	1st to 10th	Night	23% 6% 27% 33% 10% 1	630
	11th to 20th	Night	24% 6% 22% 33% 13% 2	623
	21st to end	Night	22% 4 25% 34% 14% 1	630
May	1st to 10th	Night	17% 3 20% 39% 20% 2	630
	11th to 20th	Night	19% 4 15% 39% 20% 2	621
	21st to end	Night	14% 2 19% 37% 25% 4	553
June	1st to 10th	Night	14% 3 18% 38% 25% 2	420
	11th to 20th	Night	13% 2 17% 38% 25% 4	420
	21st to end	Night	17% 3 13% 40% 24% 3	420
July	1st to 10th	Night	11% 2 12% 40% 31% 5%	477
	11th to 20th	Night	7% 3 12% 38% 30% 9%	597
	21st to end	Night	11% 2 12% 40% 30% 5%	657
August	1st to 10th	Night	12% 3 12% 39% 29% 6%	597
	11th to 20th	Night	11% 2 16% 32% 31% 9%	594
	21st to end	Night	14% 3 13% 39% 28% 4	660
September	1st to 10th	Night	15% 3 18% 29% 27% 7%	641
	11th to 20th	Night	15% 4 16% 31% 26% 10%	800
	21st to end	Night	21% 4 17% 28% 24% 7%	800
October	1st to 10th	Night	22% 5% 21% 32% 19% 2	800
	11th to 20th	Night	28% 9% 24% 30% 8% 1	800
	21st to end	Night	31% 9% 22% 29% 7% 1	880
November	1st to 10th	Night	24% 12% 28% 26% 10% 1	820
	11th to 20th	Night	25% 15% 31% 22% 7% 1	840
	21st to end	Night	32% 14% 30% 19% 5%	866
December	1st to 10th	Night	21% 16% 36% 20% 6% 1	1050
	11th to 20th	Night	24% 16% 35% 17% 6% 1	1050
	21st to end	Night	33% 11% 31% 19% 6% 1	1155

Page generated at 2026-07-13 03:14:47. Version ac07

Copyright © 2026 Attilla Danko.