Branson Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Branson Observatory clear sky chart from 2005-11-06 to 2026-02-16.

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	12% 7% 2 6% 4 4 4 4 5% 7% 46%	130535
	Night	12% 7% 2 6% 4 3 4 3 5% 6% 49%	130523
Transparency	Day	36% 6% 11% 25% 18% 4	134145
	Night	35% 5% 10% 25% 20% 5%	134990
Seeing	Day	16% 11% 25% 26% 17% 5%	17181
	Night	16% 10% 27% 31% 15% 1	27128

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% 10% 3 5% 4 4 3 3 4 5% 45%	5289
	11th to 20th	Day	7% 8% 3 8% 4 4 4 3 5% 5% 52%	5310
	21st to end	Day	17% 8% 2 6% 3 3 3 3 4 5% 46%	5812
February	1st to 10th	Day	17% 10% 3 6% 4 4 4 3 4 5% 40%	1890
	11th to 20th	Day	17% 8% 3 6% 5% 3 3 4 4 5% 43%	1839
	21st to end	Day	16% 9% 3 6% 4 4 5% 3 5% 7% 39%	1730
March	1st to 10th	Day	14% 10% 2 4 3 3 3 3 4 5% 48%	4936
	11th to 20th	Day	10% 5% 2 4 3 3 4 3 5% 7% 54%	4980
	21st to end	Day	13% 8% 3 8% 5% 5% 6% 4 6% 7% 35%	5462
April	1st to 10th	Day	14% 6% 2 6% 4 5% 4 3 6% 6% 45%	2369
	11th to 20th	Day	16% 7% 3 6% 4 5% 5% 3 5% 5% 41%	2374
	21st to end	Day	20% 8% 3 7% 5% 5% 4 3 4 5% 38%	2400
May	1st to 10th	Day	16% 7% 2 7% 5% 5% 6% 4 6% 7% 34%	5713
	11th to 20th	Day	11% 6% 3 8% 5% 5% 5% 4 6% 7% 40%	5862
	21st to end	Day	19% 7% 2 6% 4 4 4 4 5% 7% 37%	6525
June	1st to 10th	Day	8% 5% 1 6% 4 5% 5% 4 7% 10% 45%	2800
	11th to 20th	Day	7% 4 1 5% 5% 5% 5% 6% 7% 9% 46%	2800
	21st to end	Day	5% 3 1 4 4 5% 5% 5% 7% 10% 52%	2743
July	1st to 10th	Day	8% 4 2 6% 5% 5% 5% 4 7% 10% 43%	5900
	11th to 20th	Day	5% 5% 2 6% 5% 5% 5% 5% 7% 10% 46%	5900
	21st to end	Day	6% 4 2 5% 5% 5% 5% 4 8% 11% 46%	6422
August	1st to 10th	Day	5% 3 1 4 3 4 5% 3 6% 8% 57%	4234
	11th to 20th	Day	10% 5% 2 6% 4 4 4 4 7% 9% 46%	4026
	21st to end	Day	5% 4 2 4 4 4 4 4 6% 9% 54%	4312
September	1st to 10th	Day	10% 5% 2 5% 5% 5% 4 4 5% 7% 49%	2400
	11th to 20th	Day	10% 6% 2 7% 4 4 5% 4 5% 7% 46%	2336
	21st to end	Day	7% 5% 2 5% 4 4 4 4 6% 7% 53%	2117
October	1st to 10th	Day	9% 3 2 4 3 3 4 3 4 6% 59%	2000
	11th to 20th	Day	13% 5% 2 4 3 3 3 2 3 5% 57%	2000
	21st to end	Day	18% 7% 2 5% 3 2 2 2 4 5% 49%	2200
November	1st to 10th	Day	13% 6% 2 4 3 2 3 2 4 4 57%	2058
	11th to 20th	Day	13% 7% 2 5% 3 3 3 3 5% 6% 51%	2001
	21st to end	Day	17% 8% 2 5% 3 4 2 3 4 5% 47%	1685
December	1st to 10th	Day	12% 8% 2 6% 3 3 3 2 3 5% 53%	2690
	11th to 20th	Day	13% 8% 3 6% 4 4 4 2 4 4 47%	3088
	21st to end	Day	18% 19% 4 7% 4 3 4 3 4 4 30%	4332
January	1st to 10th	Night	13% 9% 4 7% 4 4 4 3 4 5% 43%	7634
	11th to 20th	Night	8% 6% 2 8% 4 3 3 3 3 5% 55%	7680
	21st to end	Night	17% 9% 3 6% 4 4 3 2 3 5% 43%	8402
February	1st to 10th	Night	16% 9% 3 6% 3 3 3 3 5% 6% 43%	2730
	11th to 20th	Night	17% 7% 3 7% 4 3 3 2 4 4 45%	2557
	21st to end	Night	16% 8% 2 5% 3 3 4 3 5% 6% 46%	1915
March	1st to 10th	Night	16% 10% 3 5% 4 3 4 2 3 4 45%	4919
	11th to 20th	Night	10% 8% 2 5% 3 3 3 2 5% 6% 53%	4980
	21st to end	Night	12% 7% 2 7% 4 4 4 4 5% 7% 43%	5467
April	1st to 10th	Night	12% 6% 2 4 3 3 4 3 5% 7% 51%	2030
	11th to 20th	Night	14% 5% 2 5% 3 3 4 4 6% 7% 48%	1975
	21st to end	Night	18% 6% 2 6% 3 4 4 4 5% 7% 41%	2000
May	1st to 10th	Night	15% 8% 2 6% 4 3 4 2 6% 6% 45%	4193
	11th to 20th	Night	12% 7% 2 6% 5% 4 5% 5% 6% 8% 41%	4053
	21st to end	Night	20% 7% 2 6% 4 4 4 3 5% 7% 38%	4316
June	1st to 10th	Night	7% 3 2 4 3 4 3 3 7% 10% 53%	1600
	11th to 20th	Night	5% 3 1 4 3 3 5% 4 8% 11% 55%	1600
	21st to end	Night	2 2 1 4 4 3 4 4 6% 7% 63%	1648
July	1st to 10th	Night	7% 5% 2 7% 5% 4 4 4 6% 10% 46%	4078
	11th to 20th	Night	5% 3 1 5% 3 4 4 4 6% 9% 57%	4077
	21st to end	Night	4 4 2 6% 4 3 5% 4 6% 10% 53%	4449
August	1st to 10th	Night	4 2 1 4 3 3 4 3 5% 9% 61%	2926
	11th to 20th	Night	8% 4 2 6% 4 5% 4 4 6% 8% 50%	3015
	21st to end	Night	5% 3 1 4 3 3 4 3 6% 7% 62%	3586
September	1st to 10th	Night	9% 4 1 5% 3 3 3 3 6% 7% 55%	2000
	11th to 20th	Night	10% 4 2 7% 4 4 3 3 4 7% 52%	2060
	21st to end	Night	8% 5% 2 5% 3 3 4 2 4 7% 57%	2261
October	1st to 10th	Night	6% 3 1 5% 3 3 3 3 4 6% 62%	2400
	11th to 20th	Night	13% 5% 1 3 3 3 3 3 5% 5% 57%	2400
	21st to end	Night	17% 7% 2 4 3 3 3 2 3 4 52%	2640
November	1st to 10th	Night	13% 5% 1 4 3 3 2 2 4 5% 59%	2460
	11th to 20th	Night	11% 5% 2 5% 2 3 3 3 5% 5% 56%	2615
	21st to end	Night	16% 8% 2 5% 4 3 3 2 4 5% 49%	2930
December	1st to 10th	Night	13% 8% 2 5% 2 3 3 3 4 6% 51%	4720
	11th to 20th	Night	17% 7% 3 6% 3 3 3 2 3 4 48%	5339
	21st to end	Night	22% 15% 3 7% 4 3 3 3 3 4 32%	6868

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	43% 3 9% 26% 17% 3	5290
	11th to 20th	Day	35% 3 8% 29% 21% 5%	5310
	21st to end	Day	42% 3 7% 21% 20% 7%	5812
February	1st to 10th	Day	48% 5% 10% 22% 13% 3	1890
	11th to 20th	Day	45% 5% 9% 21% 16% 3	1848
	21st to end	Day	44% 6% 7% 20% 15% 8%	1730
March	1st to 10th	Day	38% 5% 7% 21% 16% 14%	4936
	11th to 20th	Day	30% 5% 7% 21% 25% 13%	4980
	21st to end	Day	46% 6% 9% 28% 10% 1	5464
April	1st to 10th	Day	39% 6% 11% 22% 20% 2	2369
	11th to 20th	Day	43% 7% 10% 19% 17% 3	2374
	21st to end	Day	49% 6% 9% 22% 14% 1	2400
May	1st to 10th	Day	45% 9% 10% 21% 15% 1	5749
	11th to 20th	Day	40% 9% 12% 24% 14% 2	5866
	21st to end	Day	44% 8% 11% 19% 17% 1	6539
June	1st to 10th	Day	32% 10% 15% 26% 15% 1	2800
	11th to 20th	Day	30% 9% 14% 29% 15% 2	2800
	21st to end	Day	24% 9% 18% 29% 16% 4	2743
July	1st to 10th	Day	33% 8% 15% 26% 15% 2	5836
	11th to 20th	Day	31% 8% 16% 31% 14% 1	5831
	21st to end	Day	29% 8% 18% 32% 13%	6240
August	1st to 10th	Day	23% 7% 17% 30% 21% 2	4220
	11th to 20th	Day	34% 7% 16% 29% 13% 1	4065
	21st to end	Day	26% 7% 13% 35% 16% 3	4311
September	1st to 10th	Day	34% 7% 11% 24% 16% 8%	2400
	11th to 20th	Day	36% 7% 9% 23% 22% 2	2336
	21st to end	Day	29% 7% 9% 25% 26% 4	2117
October	1st to 10th	Day	17% 4 6% 17% 42% 15%	3260
	11th to 20th	Day	20% 3 5% 21% 38% 12%	3240
	21st to end	Day	30% 4 8% 31% 24% 4	3538
November	1st to 10th	Day	32% 4 8% 28% 23% 6%	2058
	11th to 20th	Day	34% 4 8% 24% 22% 8%	2001
	21st to end	Day	41% 4 9% 21% 22% 3	1685
December	1st to 10th	Day	36% 4 8% 31% 20% 1	2690
	11th to 20th	Day	40% 4 6% 25% 23% 2	3085
	21st to end	Day	57% 5% 6% 21% 10% 1	4332
January	1st to 10th	Night	43% 4 10% 27% 14% 2	7635
	11th to 20th	Night	34% 5% 6% 20% 31% 4	7680
	21st to end	Night	46% 3 8% 19% 22% 3	8402
February	1st to 10th	Night	43% 5% 10% 25% 15% 3	2730
	11th to 20th	Night	44% 3 9% 22% 18% 3	2558
	21st to end	Night	39% 5% 9% 20% 21% 6%	1915
March	1st to 10th	Night	44% 5% 6% 17% 20% 9%	4919
	11th to 20th	Night	32% 5% 7% 24% 21% 11%	4980
	21st to end	Night	39% 7% 10% 28% 15% 1	5467
April	1st to 10th	Night	33% 5% 12% 24% 20% 5%	2030
	11th to 20th	Night	35% 6% 10% 24% 19% 6%	1975
	21st to end	Night	42% 7% 10% 23% 15% 2	2000
May	1st to 10th	Night	40% 7% 12% 27% 12% 2	4222
	11th to 20th	Night	38% 10% 13% 23% 13% 4	4054
	21st to end	Night	44% 8% 12% 22% 11% 3	4324
June	1st to 10th	Night	25% 8% 15% 31% 18% 4	1600
	11th to 20th	Night	20% 9% 14% 34% 19% 3	1600
	21st to end	Night	19% 7% 16% 31% 20% 7%	1648
July	1st to 10th	Night	32% 7% 15% 24% 18% 3	4035
	11th to 20th	Night	23% 9% 13% 36% 18% 1	4026
	21st to end	Night	26% 7% 18% 33% 16% 1	4320
August	1st to 10th	Night	20% 6% 16% 34% 23% 1	2916
	11th to 20th	Night	31% 7% 16% 29% 15% 2	3042
	21st to end	Night	20% 6% 13% 36% 21% 3	3586
September	1st to 10th	Night	26% 7% 12% 30% 17% 8%	2000
	11th to 20th	Night	33% 6% 10% 23% 23% 5%	2060
	21st to end	Night	28% 4 10% 22% 31% 4	2261
October	1st to 10th	Night	14% 3 7% 15% 41% 20%	3920
	11th to 20th	Night	20% 3 5% 19% 33% 19%	3899
	21st to end	Night	29% 4 6% 31% 25% 5%	4252
November	1st to 10th	Night	29% 4 9% 25% 25% 7%	2460
	11th to 20th	Night	30% 4 8% 26% 25% 7%	2615
	21st to end	Night	39% 4 7% 24% 22% 4	2930
December	1st to 10th	Night	35% 4 9% 34% 16% 1	4720
	11th to 20th	Night	42% 3 6% 23% 22% 3	5341
	21st to end	Night	55% 5% 8% 21% 8% 2	6868

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	23% 20% 34% 19% 2	330
	11th to 20th	Day	27% 24% 36% 11% 2	330
	21st to end	Day	19% 31% 33% 13% 4	363
February	1st to 10th	Day	24% 26% 34% 13% 3 1	330
	11th to 20th	Day	29% 26% 29% 13% 2	315
	21st to end	Day	31% 22% 36% 9% 2	249
March	1st to 10th	Day	23% 25% 32% 18% 2	300
	11th to 20th	Day	32% 21% 32% 14% 2	300
	21st to end	Day	28% 24% 38% 8% 2	330
April	1st to 10th	Day	25% 21% 29% 16% 8%	469
	11th to 20th	Day	25% 19% 33% 18% 5%	492
	21st to end	Day	26% 16% 31% 21% 6% 1	500
May	1st to 10th	Day	21% 15% 32% 23% 8%	630
	11th to 20th	Day	16% 11% 33% 25% 13% 3	725
	21st to end	Day	13% 9% 37% 23% 15% 4	789
June	1st to 10th	Day	9% 4 22% 33% 25% 6%	730
	11th to 20th	Day	6% 4 20% 38% 27% 6%	730
	21st to end	Day	5% 3 25% 36% 26% 5%	730
July	1st to 10th	Day	10% 2 13% 34% 31% 10%	721
	11th to 20th	Day	5% 3 14% 35% 33% 10%	718
	21st to end	Day	7% 1 10% 32% 37% 13%	794
August	1st to 10th	Day	8% 3 12% 42% 29% 7%	726
	11th to 20th	Day	11% 3 12% 34% 30% 10%	635
	21st to end	Day	9% 2 11% 30% 31% 16%	583
September	1st to 10th	Day	9% 2 12% 33% 33% 10%	530
	11th to 20th	Day	9% 2 16% 36% 26% 11%	466
	21st to end	Day	9% 5% 28% 26% 26% 6%	330
October	1st to 10th	Day	9% 8% 28% 31% 22% 4	330
	11th to 20th	Day	15% 15% 32% 25% 12% 1	330
	21st to end	Day	28% 15% 31% 21% 5% 1	363
November	1st to 10th	Day	16% 15% 32% 28% 8% 2	330
	11th to 20th	Day	17% 19% 35% 20% 8% 1	330
	21st to end	Day	27% 18% 27% 19% 7% 1	330
December	1st to 10th	Day	19% 24% 30% 19% 5% 2	330
	11th to 20th	Day	24% 20% 29% 22% 5%	330
	21st to end	Day	26% 23% 32% 18% 2	363
January	1st to 10th	Night	20% 17% 33% 26% 5%	1050
	11th to 20th	Night	21% 19% 36% 21% 3	1050
	21st to end	Night	18% 18% 39% 23% 3	1155
February	1st to 10th	Night	22% 14% 37% 23% 4	1050
	11th to 20th	Night	23% 16% 39% 20% 2	963
	21st to end	Night	23% 17% 38% 20% 2	595
March	1st to 10th	Night	21% 15% 35% 26% 4	600
	11th to 20th	Night	23% 14% 30% 28% 5%	600
	21st to end	Night	22% 12% 39% 23% 5%	660
April	1st to 10th	Night	16% 15% 36% 28% 5%	600
	11th to 20th	Night	16% 14% 34% 29% 7%	593
	21st to end	Night	20% 12% 35% 26% 8%	600
May	1st to 10th	Night	15% 8% 30% 39% 8%	600
	11th to 20th	Night	15% 7% 27% 32% 17% 1	591
	21st to end	Night	12% 4 24% 37% 20% 3	650
June	1st to 10th	Night	8% 4 15% 41% 32% 1	600
	11th to 20th	Night	5% 2 18% 44% 30% 2	600
	21st to end	Night	2 2 17% 44% 34% 2	600
July	1st to 10th	Night	6% 1 8% 41% 38% 6%	585
	11th to 20th	Night	3 1 8% 41% 40% 6%	582
	21st to end	Night	6% 2 7% 39% 39% 7%	657
August	1st to 10th	Night	5% 1 8% 44% 38% 3	597
	11th to 20th	Night	8% 2 10% 40% 36% 4	594
	21st to end	Night	7% 9% 38% 41% 5%	660
September	1st to 10th	Night	10% 2 11% 40% 36% 2	600
	11th to 20th	Night	11% 1 9% 41% 33% 5%	600
	21st to end	Night	10% 3 21% 34% 28% 4	661
October	1st to 10th	Night	7% 3 21% 38% 27% 3	800
	11th to 20th	Night	15% 9% 28% 34% 14% 1	800
	21st to end	Night	21% 11% 28% 30% 10%	880
November	1st to 10th	Night	14% 9% 31% 35% 11%	820
	11th to 20th	Night	13% 12% 34% 32% 9%	840
	21st to end	Night	20% 13% 30% 28% 9%	1040
December	1st to 10th	Night	19% 12% 35% 28% 5%	1050
	11th to 20th	Night	24% 13% 30% 29% 4	1050
	21st to end	Night	24% 16% 33% 24% 4	1155

Page generated at 2026-02-13 00:42:18. Version ac07

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