Okie-Tex Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Okie-Tex Star Party clear sky chart from 2005-11-06 to 2025-09-04.

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	5% 4 1 4 3 3 4 3 5% 7% 61%	134444
	Night	5% 4 2 4 3 3 4 3 5% 7% 59%	131637
Transparency	Day	23% 3 9% 22% 28% 15%	129514
	Night	25% 3 8% 23% 26% 14%	127577
Seeing	Day	8% 8% 27% 32% 19% 5%	16589
	Night	7% 7% 34% 39% 12% 1	26488

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	4 9% 2 5% 3 3 3 3 4 5% 59%	3638
	11th to 20th	Day	2 5% 2 6% 3 3 3 3 5% 6% 62%	3704
	21st to end	Day	4 6% 2 4 2 3 2 3 4 5% 65%	4642
February	1st to 10th	Day	3 7% 3 5% 3 3 4 3 4 7% 58%	2000
	11th to 20th	Day	3 6% 3 7% 4 4 3 3 4 6% 58%	1949
	21st to end	Day	3 4 2 4 3 2 3 3 5% 6% 66%	1650
March	1st to 10th	Day	4 5% 2 4 3 3 2 2 4 5% 67%	4500
	11th to 20th	Day	7% 5% 2 5% 3 3 4 3 4 6% 58%	4641
	21st to end	Day	3 5% 2 4 3 3 3 3 5% 7% 61%	5969
April	1st to 10th	Day	4 4 1 4 2 2 3 4 5% 7% 64%	2400
	11th to 20th	Day	7% 5% 2 4 3 3 3 3 5% 6% 59%	2371
	21st to end	Day	7% 5% 2 3 4 3 4 3 5% 8% 57%	2400
May	1st to 10th	Day	12% 4 2 4 3 3 4 4 5% 6% 54%	5854
	11th to 20th	Day	5% 3 1 4 3 3 3 3 4 6% 66%	5862
	21st to end	Day	7% 4 2 3 2 3 4 3 5% 8% 59%	6531
June	1st to 10th	Day	4 3 1 4 3 3 4 4 9% 10% 55%	2800
	11th to 20th	Day	4 3 1 2 2 3 3 3 6% 8% 65%	2800
	21st to end	Day	4 4 2 5% 4 4 4 4 7% 9% 53%	2800
July	1st to 10th	Day	4 3 1 4 3 4 5% 5% 7% 10% 55%	6339
	11th to 20th	Day	2 2 1 4 3 3 4 4 6% 10% 59%	6340
	21st to end	Day	4 3 2 4 4 4 5% 5% 7% 10% 51%	6702
August	1st to 10th	Day	4 4 2 4 4 4 5% 5% 7% 10% 51%	5348
	11th to 20th	Day	3 2 1 3 3 4 4 4 7% 10% 59%	5366
	21st to end	Day	5% 4 1 5% 4 4 5% 5% 8% 10% 50%	5981
September	1st to 10th	Day	7% 3 1 4 4 3 4 3 5% 7% 60%	2317
	11th to 20th	Day	6% 3 1 4 2 3 3 3 5% 6% 62%	2146
	21st to end	Day	6% 3 1 2 2 2 4 2 3 6% 68%	2090
October	1st to 10th	Day	5% 2 1 2 2 2 2 2 4 5% 73%	3480
	11th to 20th	Day	6% 4 1 4 3 2 3 2 4 5% 66%	3195
	21st to end	Day	4 3 1 1 1 2 2 2 2 4 78%	3200
November	1st to 10th	Day	4 3 1 3 2 2 2 2 4 5% 73%	1763
	11th to 20th	Day	3 4 1 3 2 2 2 2 3 6% 72%	1800
	21st to end	Day	5% 6% 2 4 2 2 3 2 4 6% 65%	1800
December	1st to 10th	Day	1 3 1 3 2 1 2 2 3 5% 76%	2940
	11th to 20th	Day	3 4 1 3 2 2 3 3 5% 6% 67%	3122
	21st to end	Day	3 5% 2 4 3 2 3 2 5% 6% 64%	4004
January	1st to 10th	Night	3 7% 2 6% 5% 4 4 3 5% 6% 55%	6327
	11th to 20th	Night	2 6% 2 5% 3 3 4 3 5% 6% 62%	6320
	21st to end	Night	3 4 2 5% 3 3 3 3 5% 7% 64%	6320
February	1st to 10th	Night	3 6% 3 5% 3 3 3 3 5% 6% 60%	2400
	11th to 20th	Night	4 6% 2 6% 5% 3 5% 4 6% 7% 52%	2338
	21st to end	Night	5% 4 2 3 2 3 2 3 4 7% 65%	1980
March	1st to 10th	Night	5% 5% 1 3 2 2 2 2 3 6% 69%	5374
	11th to 20th	Night	6% 6% 2 5% 4 4 4 3 5% 6% 56%	5317
	21st to end	Night	4 4 1 4 3 4 4 4 6% 7% 60%	4984
April	1st to 10th	Night	5% 4 1 3 3 3 4 3 6% 8% 61%	2000
	11th to 20th	Night	7% 5% 2 4 3 4 4 3 6% 7% 56%	1977
	21st to end	Night	10% 5% 2 4 3 4 4 3 5% 6% 56%	2000
May	1st to 10th	Night	12% 6% 2 4 2 2 3 2 4 6% 56%	4126
	11th to 20th	Night	8% 3 1 3 3 2 3 3 4 6% 63%	4053
	21st to end	Night	11% 5% 2 3 3 4 3 3 5% 6% 56%	4348
June	1st to 10th	Night	4 3 2 5% 4 4 5% 4 7% 10% 53%	1600
	11th to 20th	Night	2 2 1 3 3 3 4 4 8% 10% 61%	1600
	21st to end	Night	5% 4 2 6% 4 5% 4 4 7% 9% 48%	1600
July	1st to 10th	Night	6% 4 1 4 3 4 4 4 7% 10% 51%	3640
	11th to 20th	Night	3 3 1 6% 4 5% 5% 5% 10% 13% 44%	3640
	21st to end	Night	6% 5% 2 7% 5% 4 5% 5% 9% 13% 41%	4143
August	1st to 10th	Night	8% 5% 2 5% 3 4 5% 5% 8% 12% 44%	4463
	11th to 20th	Night	4 3 1 4 3 4 6% 6% 10% 14% 44%	4483
	21st to end	Night	11% 5% 2 6% 4 5% 5% 5% 8% 8% 40%	4993
September	1st to 10th	Night	6% 3 1 4 2 3 3 3 6% 8% 60%	1930
	11th to 20th	Night	7% 4 2 3 3 3 4 3 5% 7% 61%	2033
	21st to end	Night	5% 3 1 4 3 2 3 3 5% 5% 67%	2090
October	1st to 10th	Night	6% 2 1 2 2 2 3 3 4 6% 69%	3480
	11th to 20th	Night	8% 3 1 3 2 3 3 2 5% 6% 63%	3714
	21st to end	Night	5% 3 1 3 2 1 2 2 4 5% 72%	4325
November	1st to 10th	Night	4 3 1 3 2 2 2 3 4 5% 70%	2535
	11th to 20th	Night	2 4 1 3 2 2 3 2 4 4 74%	2600
	21st to end	Night	4 5% 1 3 3 3 3 3 5% 6% 64%	2600
December	1st to 10th	Night	2 4 2 4 2 2 2 2 3 5% 73%	4250
	11th to 20th	Night	2 3 1 3 3 2 3 2 4 7% 70%	5080
	21st to end	Night	3 5% 2 6% 4 4 4 4 5% 6% 59%	6974

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	30% 1 4 27% 29% 9%	3639
	11th to 20th	Day	25% 1 7% 20% 28% 20%	3704
	21st to end	Day	23% 1 6% 22% 36% 12%	4642
February	1st to 10th	Day	28% 2 8% 23% 25% 15%	2000
	11th to 20th	Day	28% 3 6% 24% 26% 14%	1959
	21st to end	Day	20% 2 3 20% 31% 23%	1650
March	1st to 10th	Day	23% 2 3 14% 30% 29%	4500
	11th to 20th	Day	29% 1 4 16% 32% 17%	4641
	21st to end	Day	24% 2 5% 30% 32% 7%	5969
April	1st to 10th	Day	21% 3 7% 22% 30% 18%	2400
	11th to 20th	Day	27% 2 6% 24% 23% 18%	2374
	21st to end	Day	26% 2 8% 27% 26% 10%	2400
May	1st to 10th	Day	31% 3 10% 22% 22% 13%	5854
	11th to 20th	Day	23% 2 7% 16% 26% 27%	5866
	21st to end	Day	24% 3 12% 22% 21% 18%	6532
June	1st to 10th	Day	23% 4 16% 27% 20% 11%	2800
	11th to 20th	Day	18% 3 8% 22% 26% 23%	2800
	21st to end	Day	27% 3 9% 24% 21% 16%	2800
July	1st to 10th	Day	23% 6% 14% 21% 27% 9%	6271
	11th to 20th	Day	20% 5% 15% 29% 24% 8%	6265
	21st to end	Day	26% 6% 16% 23% 22% 7%	6508
August	1st to 10th	Day	29% 6% 17% 25% 18% 5%	3892
	11th to 20th	Day	21% 4 13% 22% 29% 12%	3882
	21st to end	Day	22% 5% 15% 26% 25% 7%	4311
September	1st to 10th	Day	24% 3 10% 23% 23% 17%	2317
	11th to 20th	Day	23% 3 7% 22% 27% 19%	2146
	21st to end	Day	20% 2 6% 20% 35% 18%	2090
October	1st to 10th	Day	15% 2 5% 17% 38% 23%	3480
	11th to 20th	Day	22% 2 6% 20% 34% 16%	3195
	21st to end	Day	14% 1 3 16% 42% 25%	3200
November	1st to 10th	Day	16% 2 5% 21% 32% 24%	1763
	11th to 20th	Day	16% 2 3 26% 35% 18%	1800
	21st to end	Day	23% 1 5% 17% 30% 23%	1800
December	1st to 10th	Day	13% 2 6% 27% 38% 14%	2940
	11th to 20th	Day	19% 2 3 20% 44% 12%	3120
	21st to end	Day	22% 1 6% 26% 30% 15%	4004
January	1st to 10th	Night	32% 2 4 32% 24% 7%	6327
	11th to 20th	Night	25% 1 8% 20% 28% 18%	6320
	21st to end	Night	23% 1 9% 22% 33% 12%	6320
February	1st to 10th	Night	26% 2 7% 21% 29% 13%	2400
	11th to 20th	Night	31% 3 7% 23% 25% 12%	2338
	21st to end	Night	21% 3 2 21% 33% 20%	1980
March	1st to 10th	Night	20% 1 3 16% 29% 31%	5374
	11th to 20th	Night	30% 2 5% 16% 25% 21%	5317
	21st to end	Night	24% 3 6% 32% 26% 9%	4984
April	1st to 10th	Night	22% 3 6% 23% 28% 18%	2000
	11th to 20th	Night	27% 4 9% 23% 22% 15%	1977
	21st to end	Night	29% 3 12% 25% 20% 12%	2000
May	1st to 10th	Night	32% 3 11% 22% 16% 16%	4125
	11th to 20th	Night	24% 2 9% 20% 19% 26%	4054
	21st to end	Night	30% 3 13% 17% 15% 22%	4349
June	1st to 10th	Night	26% 5% 20% 25% 13% 10%	1600
	11th to 20th	Night	17% 5% 14% 24% 20% 20%	1600
	21st to end	Night	31% 4 11% 24% 18% 12%	1600
July	1st to 10th	Night	27% 7% 16% 25% 20% 5%	3600
	11th to 20th	Night	28% 5% 17% 28% 18% 3	3592
	21st to end	Night	33% 5% 15% 26% 16% 5%	4024
August	1st to 10th	Night	34% 5% 17% 23% 17% 3	3244
	11th to 20th	Night	27% 6% 17% 24% 22% 4	3243
	21st to end	Night	32% 5% 14% 26% 18% 5%	3597
September	1st to 10th	Night	23% 4 13% 24% 22% 13%	1930
	11th to 20th	Night	23% 4 10% 21% 24% 17%	2033
	21st to end	Night	20% 3 6% 22% 33% 16%	2090
October	1st to 10th	Night	17% 3 5% 19% 36% 19%	3480
	11th to 20th	Night	23% 3 7% 22% 28% 17%	3714
	21st to end	Night	16% 2 3 19% 43% 17%	4325
November	1st to 10th	Night	17% 2 6% 20% 31% 23%	2535
	11th to 20th	Night	16% 1 3 24% 37% 18%	2600
	21st to end	Night	22% 2 5% 19% 29% 22%	2600
December	1st to 10th	Night	17% 2 5% 29% 37% 10%	4250
	11th to 20th	Night	17% 2 3 23% 41% 14%	5081
	21st to end	Night	27% 2 6% 22% 30% 13%	6974

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	7% 7% 28% 39% 15% 3	300
	11th to 20th	Day	9% 10% 35% 29% 12% 5%	300
	21st to end	Day	5% 11% 28% 35% 18% 3	330
February	1st to 10th	Day	7% 13% 43% 25% 11% 3	300
	11th to 20th	Day	6% 10% 43% 28% 9% 3	300
	21st to end	Day	6% 14% 43% 28% 8% 1	249
March	1st to 10th	Day	8% 11% 36% 33% 11% 2	300
	11th to 20th	Day	15% 10% 32% 28% 13% 2	305
	21st to end	Day	13% 19% 37% 21% 7% 2	550
April	1st to 10th	Day	9% 18% 38% 24% 9% 2	500
	11th to 20th	Day	11% 21% 39% 22% 6% 1	492
	21st to end	Day	14% 17% 35% 25% 7% 3	500
May	1st to 10th	Day	9% 12% 32% 30% 14% 2	683
	11th to 20th	Day	11% 9% 29% 31% 17% 3	725
	21st to end	Day	8% 9% 37% 34% 11% 2	789
June	1st to 10th	Day	7% 7% 24% 33% 22% 7%	730
	11th to 20th	Day	5% 6% 30% 36% 19% 4	730
	21st to end	Day	7% 4 27% 35% 21% 5%	730
July	1st to 10th	Day	4 2 19% 37% 29% 9%	721
	11th to 20th	Day	3 2 11% 38% 36% 10%	718
	21st to end	Day	6% 2 10% 34% 39% 10%	791
August	1st to 10th	Day	5% 3 16% 33% 30% 13%	527
	11th to 20th	Day	3 2 19% 38% 29% 8%	517
	21st to end	Day	5% 2 15% 42% 25% 10%	583
September	1st to 10th	Day	6% 1 21% 36% 27% 9%	503
	11th to 20th	Day	6% 21% 38% 23% 11%	356
	21st to end	Day	10% 5% 17% 31% 29% 9%	300
October	1st to 10th	Day	12% 6% 23% 29% 22% 8%	300
	11th to 20th	Day	5% 5% 30% 34% 16% 10%	300
	21st to end	Day	11% 6% 29% 26% 21% 7%	330
November	1st to 10th	Day	8% 10% 28% 32% 20% 3	300
	11th to 20th	Day	7% 10% 24% 35% 19% 6%	300
	21st to end	Day	11% 11% 31% 24% 17% 7%	300
December	1st to 10th	Day	3 8% 29% 38% 16% 5%	300
	11th to 20th	Day	10% 7% 33% 34% 15% 2	300
	21st to end	Day	9% 10% 38% 31% 11% 1	330
January	1st to 10th	Night	5% 7% 37% 39% 10% 1	1000
	11th to 20th	Night	6% 9% 35% 37% 11% 2	993
	21st to end	Night	5% 5% 36% 40% 12% 1	880
February	1st to 10th	Night	7% 8% 42% 34% 10%	800
	11th to 20th	Night	7% 9% 50% 27% 6% 1	784
	21st to end	Night	8% 8% 49% 31% 4	660
March	1st to 10th	Night	7% 11% 42% 34% 6% 1	800
	11th to 20th	Night	10% 11% 36% 34% 8%	763
	21st to end	Night	7% 13% 51% 25% 4	660
April	1st to 10th	Night	9% 12% 47% 29% 4	600
	11th to 20th	Night	10% 13% 48% 26% 4	593
	21st to end	Night	12% 10% 39% 33% 6%	600
May	1st to 10th	Night	9% 10% 38% 36% 7%	600
	11th to 20th	Night	11% 7% 38% 32% 11% 1	591
	21st to end	Night	9% 8% 45% 30% 7% 1	650
June	1st to 10th	Night	5% 6% 34% 43% 12% 1	600
	11th to 20th	Night	3 5% 46% 38% 9%	600
	21st to end	Night	6% 6% 32% 44% 13%	600
July	1st to 10th	Night	4 3 22% 50% 20% 1	585
	11th to 20th	Night	4 2 15% 55% 23% 1	582
	21st to end	Night	8% 3 15% 45% 27% 2	657
August	1st to 10th	Night	7% 2 16% 45% 30% 2	597
	11th to 20th	Night	9% 2 14% 52% 23% 1	594
	21st to end	Night	7% 2 19% 47% 24% 2	660
September	1st to 10th	Night	7% 1 19% 55% 18% 1	579
	11th to 20th	Night	9% 2 31% 42% 15% 2	570
	21st to end	Night	6% 4 30% 44% 15% 1	570
October	1st to 10th	Night	11% 4 31% 40% 12% 1	570
	11th to 20th	Night	6% 5% 32% 42% 13% 2	722
	21st to end	Night	9% 6% 30% 37% 16% 3	953
November	1st to 10th	Night	6% 5% 30% 45% 13% 2	975
	11th to 20th	Night	4 7% 35% 41% 12% 1	1000
	21st to end	Night	7% 7% 32% 39% 14% 2	1000
December	1st to 10th	Night	5% 7% 35% 42% 11% 1	1000
	11th to 20th	Night	6% 7% 38% 39% 10% 1	1000
	21st to end	Night	8% 10% 38% 35% 8% 1	1100

Page generated at 2025-09-01 00:51:06. Version ac07

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