Cibolo Creek Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cibolo Creek Ranch clear sky chart from 2005-11-06 to 2026-01-02.

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	3 3 1 3 3 3 4 3 5% 7% 65%	134782
	Night	3 3 1 4 3 3 4 3 5% 7% 63%	133999
Transparency	Day	17% 4 8% 19% 26% 26%	129894
	Night	20% 5% 8% 17% 24% 26%	129890
Seeing	Day	6% 7% 23% 32% 25% 7%	15766
	Night	6% 5% 22% 42% 22% 2	26142

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	3 3 1 3 2 2 3 2 4 7% 71%	4547
	11th to 20th	Day	2 2 1 2 2 2 2 2 4 5% 75%	4540
	21st to end	Day	3 3 1 5% 4 2 3 2 3 5% 67%	4994
February	1st to 10th	Day	3 4 1 4 3 4 4 3 4 5% 65%	2000
	11th to 20th	Day	5% 4 2 3 3 3 3 3 5% 5% 65%	1949
	21st to end	Day	4 3 1 3 3 3 3 2 5% 6% 67%	1650
March	1st to 10th	Day	3 4 2 3 3 3 3 3 5% 8% 64%	4500
	11th to 20th	Day	4 3 1 3 2 2 2 3 4 6% 69%	4971
	21st to end	Day	2 3 2 5% 3 4 3 3 6% 6% 63%	5871
April	1st to 10th	Day	3 3 1 3 3 3 3 3 4 6% 67%	2400
	11th to 20th	Day	2 3 1 3 3 3 3 3 5% 5% 68%	2371
	21st to end	Day	3 3 1 3 2 2 2 2 3 5% 74%	2400
May	1st to 10th	Day	2 2 1 2 2 2 2 1 3 4 80%	5440
	11th to 20th	Day	3 3 1 3 2 3 3 3 4 7% 69%	5405
	21st to end	Day	2 1 2 2 2 3 3 5% 6% 74%	5944
June	1st to 10th	Day	1 1 1 2 2 2 4 3 6% 9% 69%	2590
	11th to 20th	Day	2 2 1 3 3 3 3 3 5% 7% 68%	2592
	21st to end	Day	2 3 1 4 4 5% 5% 5% 8% 8% 56%	2400
July	1st to 10th	Day	4 3 1 4 4 5% 5% 5% 7% 10% 53%	5439
	11th to 20th	Day	2 2 1 3 3 3 6% 5% 8% 11% 57%	5440
	21st to end	Day	2 3 1 5% 4 5% 6% 5% 7% 12% 51%	5922
August	1st to 10th	Day	1 2 1 3 3 3 4 4 7% 10% 63%	5348
	11th to 20th	Day	3 2 1 4 4 5% 7% 6% 9% 11% 47%	5366
	21st to end	Day	3 2 1 4 4 5% 6% 6% 7% 9% 54%	5984
September	1st to 10th	Day	7% 6% 2 4 4 4 5% 5% 7% 9% 46%	2400
	11th to 20th	Day	9% 4 1 5% 4 4 5% 4 6% 8% 49%	2304
	21st to end	Day	6% 4 2 4 4 3 4 4 5% 6% 59%	2200
October	1st to 10th	Day	2 1 1 1 1 2 2 3 5% 81%	3590
	11th to 20th	Day	3 2 1 3 2 2 3 2 3 4 75%	3292
	21st to end	Day	3 1 1 1 1 1 1 1 2 3 85%	3548
November	1st to 10th	Day	4 3 1 2 2 2 2 2 3 5% 75%	2059
	11th to 20th	Day	3 3 1 3 3 3 3 2 5% 5% 70%	1916
	21st to end	Day	6% 4 2 4 3 3 3 3 4 5% 64%	1890
December	1st to 10th	Day	4 7% 2 5% 3 3 3 3 7% 8% 57%	3030
	11th to 20th	Day	2 4 1 4 3 3 3 2 4 4 70%	3481
	21st to end	Day	2 2 1 2 2 2 2 3 4 5% 75%	5009
January	1st to 10th	Night	3 2 1 2 2 2 2 2 4 7% 72%	5440
	11th to 20th	Night	3 2 1 2 2 2 3 2 4 5% 74%	5440
	21st to end	Night	5% 3 1 5% 3 3 3 3 5% 6% 62%	5984
February	1st to 10th	Night	4 4 2 3 3 3 2 3 5% 6% 65%	2400
	11th to 20th	Night	6% 5% 2 4 4 3 3 3 4 6% 59%	2338
	21st to end	Night	4 4 1 4 3 4 5% 3 5% 6% 62%	1980
March	1st to 10th	Night	3 3 1 4 2 3 3 4 5% 7% 64%	5374
	11th to 20th	Night	4 4 1 3 2 2 3 2 4 6% 68%	5012
	21st to end	Night	4 5% 1 4 3 3 3 3 4 5% 66%	5086
April	1st to 10th	Night	4 4 1 5% 3 3 3 3 4 5% 64%	2000
	11th to 20th	Night	4 3 2 4 2 4 3 3 4 6% 65%	1977
	21st to end	Night	3 4 1 3 3 3 3 2 4 4 71%	2000
May	1st to 10th	Night	1 1 1 2 2 2 2 2 3 5% 79%	4540
	11th to 20th	Night	6% 4 2 4 3 3 4 4 5% 6% 59%	4510
	21st to end	Night	4 3 1 4 4 4 4 4 5% 7% 62%	4935
June	1st to 10th	Night	3 2 1 4 4 5% 5% 5% 9% 10% 51%	1800
	11th to 20th	Night	4 3 1 5% 4 4 6% 5% 7% 8% 52%	1800
	21st to end	Night	4 4 2 5% 4 5% 5% 5% 8% 9% 50%	1992
July	1st to 10th	Night	3 4 1 5% 4 5% 5% 5% 8% 11% 47%	4540
	11th to 20th	Night	2 1 1 3 4 4 5% 5% 8% 11% 56%	4540
	21st to end	Night	2 3 1 5% 5% 6% 7% 5% 8% 12% 45%	4951
August	1st to 10th	Night	2 2 1 3 3 4 5% 4 7% 10% 60%	4464
	11th to 20th	Night	2 2 1 4 3 5% 5% 6% 10% 16% 46%	4483
	21st to end	Night	2 2 1 4 3 4 5% 5% 8% 12% 53%	4993
September	1st to 10th	Night	6% 6% 2 8% 4 5% 5% 4 7% 9% 46%	2000
	11th to 20th	Night	6% 3 2 6% 5% 5% 6% 6% 8% 10% 43%	2095
	21st to end	Night	4 3 2 5% 5% 4 5% 5% 7% 7% 52%	2200
October	1st to 10th	Night	2 1 1 2 2 2 3 3 3 5% 75%	3590
	11th to 20th	Night	4 2 1 4 3 2 3 3 4 6% 67%	3850
	21st to end	Night	2 2 1 2 1 2 2 1 3 4 81%	4252
November	1st to 10th	Night	4 2 1 2 2 2 2 2 3 4 75%	2460
	11th to 20th	Night	3 3 1 3 2 2 3 3 5% 6% 69%	2678
	21st to end	Night	4 3 1 4 3 3 3 3 5% 6% 65%	2730
December	1st to 10th	Night	4 2 2 10% 5% 4 4 3 5% 7% 55%	4380
	11th to 20th	Night	2 4 1 4 3 2 3 2 4 6% 70%	4946
	21st to end	Night	2 2 1 2 2 2 3 2 4 5% 73%	6239

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	14% 2 3 21% 29% 31%	4548
	11th to 20th	Day	13% 2 4 17% 38% 26%	4540
	21st to end	Day	21% 2 4 20% 33% 20%	4994
February	1st to 10th	Day	22% 2 3 13% 26% 34%	2000
	11th to 20th	Day	22% 4 5% 16% 27% 28%	1959
	21st to end	Day	19% 2 3 11% 31% 34%	1650
March	1st to 10th	Day	17% 5% 2 8% 26% 42%	4500
	11th to 20th	Day	16% 4 4 9% 24% 43%	4971
	21st to end	Day	19% 4 3 6% 29% 38%	5871
April	1st to 10th	Day	18% 3 3 11% 27% 38%	2400
	11th to 20th	Day	16% 5% 3 11% 25% 39%	2374
	21st to end	Day	15% 2 3 11% 28% 42%	2400
May	1st to 10th	Day	10% 2 3 10% 23% 51%	5440
	11th to 20th	Day	16% 2 4 12% 26% 39%	5408
	21st to end	Day	11% 4 6% 16% 20% 43%	5945
June	1st to 10th	Day	12% 4 7% 23% 32% 22%	2590
	11th to 20th	Day	15% 4 6% 17% 34% 25%	2592
	21st to end	Day	23% 6% 11% 22% 23% 15%	2400
July	1st to 10th	Day	24% 8% 16% 29% 19% 3	5381
	11th to 20th	Day	16% 8% 21% 38% 14% 4	5377
	21st to end	Day	22% 8% 21% 25% 20% 4	5752
August	1st to 10th	Day	17% 6% 14% 31% 26% 6%	3892
	11th to 20th	Day	21% 9% 16% 31% 19% 4	3882
	21st to end	Day	24% 10% 15% 28% 19% 5%	4311
September	1st to 10th	Day	32% 7% 13% 22% 16% 10%	2400
	11th to 20th	Day	30% 7% 12% 20% 22% 9%	2304
	21st to end	Day	24% 4 8% 23% 27% 14%	2200
October	1st to 10th	Day	9% 3 6% 16% 27% 39%	3590
	11th to 20th	Day	15% 3 7% 22% 19% 34%	3292
	21st to end	Day	8% 1 2 11% 48% 29%	3548
November	1st to 10th	Day	15% 3 5% 19% 31% 27%	2059
	11th to 20th	Day	16% 4 7% 20% 30% 23%	1916
	21st to end	Day	23% 3 6% 19% 28% 20%	1890
December	1st to 10th	Day	24% 3 6% 23% 26% 17%	3030
	11th to 20th	Day	19% 3 4 20% 33% 22%	3479
	21st to end	Day	12% 2 3 14% 37% 32%	5009
January	1st to 10th	Night	14% 2 2 14% 37% 31%	5440
	11th to 20th	Night	14% 3 3 14% 29% 38%	5440
	21st to end	Night	22% 4 3 18% 32% 22%	5984
February	1st to 10th	Night	19% 3 3 14% 24% 36%	2400
	11th to 20th	Night	25% 4 6% 12% 23% 30%	2338
	21st to end	Night	22% 4 3 7% 28% 36%	1980
March	1st to 10th	Night	18% 3 2 9% 24% 44%	5374
	11th to 20th	Night	17% 4 5% 11% 21% 42%	5012
	21st to end	Night	20% 3 4 8% 24% 41%	5086
April	1st to 10th	Night	22% 3 3 10% 24% 37%	2000
	11th to 20th	Night	20% 5% 4 13% 20% 38%	1977
	21st to end	Night	18% 3 4 15% 22% 39%	2000
May	1st to 10th	Night	10% 2 5% 12% 22% 48%	4537
	11th to 20th	Night	23% 5% 6% 12% 18% 36%	4511
	21st to end	Night	20% 5% 8% 15% 17% 35%	4936
June	1st to 10th	Night	23% 7% 9% 24% 22% 15%	1800
	11th to 20th	Night	25% 6% 8% 17% 26% 19%	1800
	21st to end	Night	26% 6% 14% 21% 19% 13%	1992
July	1st to 10th	Night	28% 8% 21% 29% 13% 2	4490
	11th to 20th	Night	18% 7% 20% 36% 15% 3	4480
	21st to end	Night	26% 9% 19% 25% 18% 2	4808
August	1st to 10th	Night	21% 6% 13% 31% 25% 4	3244
	11th to 20th	Night	20% 7% 20% 35% 15% 2	3243
	21st to end	Night	24% 9% 19% 28% 16% 4	3597
September	1st to 10th	Night	33% 8% 14% 21% 16% 8%	2000
	11th to 20th	Night	31% 10% 16% 19% 16% 9%	2095
	21st to end	Night	27% 7% 11% 21% 20% 14%	2200
October	1st to 10th	Night	13% 4 7% 12% 25% 39%	3590
	11th to 20th	Night	19% 3 8% 19% 16% 35%	3850
	21st to end	Night	9% 2 3 15% 41% 30%	4252
November	1st to 10th	Night	15% 3 5% 15% 33% 30%	2460
	11th to 20th	Night	17% 4 4 20% 28% 27%	2678
	21st to end	Night	20% 4 6% 16% 29% 25%	2730
December	1st to 10th	Night	29% 3 5% 19% 23% 20%	4380
	11th to 20th	Night	16% 3 3 17% 35% 26%	4947
	21st to end	Night	14% 3 3 13% 37% 31%	6239

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	11% 9% 29% 36% 14% 2	303
	11th to 20th	Day	5% 10% 39% 28% 17%	300
	21st to end	Day	5% 15% 38% 29% 10% 2	330
February	1st to 10th	Day	8% 12% 26% 33% 17% 4	300
	11th to 20th	Day	12% 9% 36% 30% 12% 1	300
	21st to end	Day	12% 15% 38% 25% 10% 1	249
March	1st to 10th	Day	12% 13% 36% 28% 9% 2	300
	11th to 20th	Day	13% 16% 34% 24% 11% 2	484
	21st to end	Day	8% 20% 36% 25% 10% 1	550
April	1st to 10th	Day	9% 15% 38% 29% 8% 1	500
	11th to 20th	Day	6% 17% 46% 22% 8% 1	492
	21st to end	Day	5% 14% 42% 33% 6%	500
May	1st to 10th	Day	4 9% 44% 30% 12% 2	503
	11th to 20th	Day	4 11% 36% 35% 14% 1	528
	21st to end	Day	3 6% 33% 43% 14% 1	573
June	1st to 10th	Day	3 3 18% 41% 31% 5%	720
	11th to 20th	Day	4 1 12% 40% 38% 4	722
	21st to end	Day	3 2 10% 37% 39% 9%	530
July	1st to 10th	Day	6% 1 7% 27% 40% 19%	526
	11th to 20th	Day	3 1 4 34% 42% 17%	524
	21st to end	Day	3 1 5% 37% 38% 15%	575
August	1st to 10th	Day	3 1 3 29% 48% 16%	527
	11th to 20th	Day	9% 1 5% 30% 37% 18%	517
	21st to end	Day	7% 6% 28% 40% 19%	583
September	1st to 10th	Day	9% 2 11% 33% 33% 12%	530
	11th to 20th	Day	8% 2 6% 30% 41% 13%	434
	21st to end	Day	8% 2 9% 31% 37% 13%	330
October	1st to 10th	Day	6% 2 13% 34% 33% 12%	330
	11th to 20th	Day	7% 2 22% 31% 30% 8%	330
	21st to end	Day	7% 5% 20% 35% 24% 9%	363
November	1st to 10th	Day	7% 3 25% 35% 21% 10%	330
	11th to 20th	Day	7% 9% 21% 35% 23% 6%	330
	21st to end	Day	10% 11% 28% 33% 12% 5%	330
December	1st to 10th	Day	8% 7% 28% 36% 19% 2	330
	11th to 20th	Day	4 10% 28% 40% 16% 2	330
	21st to end	Day	5% 9% 33% 33% 17% 4	363
January	1st to 10th	Night	7% 5% 22% 47% 18% 1	804
	11th to 20th	Night	8% 8% 23% 42% 19% 1	800
	21st to end	Night	7% 9% 28% 41% 14% 1	880
February	1st to 10th	Night	7% 7% 25% 40% 19% 2	800
	11th to 20th	Night	9% 6% 32% 40% 11% 1	784
	21st to end	Night	5% 12% 35% 40% 7%	660
March	1st to 10th	Night	9% 10% 33% 37% 10% 1	800
	11th to 20th	Night	10% 10% 31% 33% 14% 2	800
	21st to end	Night	6% 11% 35% 36% 11% 1	710
April	1st to 10th	Night	6% 14% 34% 37% 9% 1	600
	11th to 20th	Night	7% 13% 39% 35% 6%	593
	21st to end	Night	4 11% 39% 37% 9% 1	600
May	1st to 10th	Night	4 8% 39% 39% 10% 1	600
	11th to 20th	Night	7% 7% 31% 45% 10% 1	591
	21st to end	Night	6% 5% 30% 46% 14%	650
June	1st to 10th	Night	4 3 24% 50% 19% 1	600
	11th to 20th	Night	6% 1 21% 47% 25% 1	600
	21st to end	Night	7% 2 16% 46% 28% 1	600
July	1st to 10th	Night	6% 1 12% 43% 35% 3	585
	11th to 20th	Night	5% 1 9% 46% 37% 2	582
	21st to end	Night	4 1 6% 45% 39% 5%	657
August	1st to 10th	Night	4 1 7% 37% 46% 5%	597
	11th to 20th	Night	6% 1 6% 32% 48% 8%	594
	21st to end	Night	7% 7% 36% 45% 5%	660
September	1st to 10th	Night	8% 2 8% 42% 38% 3	600
	11th to 20th	Night	7% 1 12% 43% 36% 3	600
	21st to end	Night	6% 2 14% 44% 32% 3	600
October	1st to 10th	Night	4 1 16% 48% 29% 3	600
	11th to 20th	Night	8% 3 19% 42% 24% 3	765
	21st to end	Night	5% 4 17% 41% 28% 6%	880
November	1st to 10th	Night	7% 2 16% 39% 32% 4	820
	11th to 20th	Night	6% 3 18% 46% 25% 2	998
	21st to end	Night	6% 6% 25% 41% 19% 3	1050
December	1st to 10th	Night	7% 5% 20% 46% 20% 2	1050
	11th to 20th	Night	5% 7% 22% 47% 18% 1	1050
	21st to end	Night	5% 8% 20% 48% 18% 1	982

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