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 2024-11-04.

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% 60%	104922
	Night	5% 4 2 4 3 3 4 3 6% 7% 59%	102741
Transparency	Day	24% 3 9% 23% 28% 15%	104669
	Night	25% 3 9% 23% 26% 13%	102585
Seeing	Day	7% 8% 27% 33% 20% 6%	15418
	Night	7% 7% 34% 39% 12% 1	25367

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 8% 2 6% 4 3 3 2 4 6% 60%	2538
	11th to 20th	Day	2 4 1 5% 4 4 4 3 5% 7% 61%	2576
	21st to end	Day	5% 5% 2 4 3 3 3 4 6% 7% 59%	3239
February	1st to 10th	Day	3 7% 3 5% 4 3 4 3 4 6% 58%	1900
	11th to 20th	Day	3 5% 2 7% 4 4 3 3 4 6% 58%	1849
	21st to end	Day	3 5% 2 4 3 2 3 3 5% 6% 65%	1570
March	1st to 10th	Day	3 5% 1 4 2 2 2 2 4 6% 67%	3130
	11th to 20th	Day	9% 5% 2 4 3 3 4 2 5% 6% 57%	3245
	21st to end	Day	5% 6% 2 5% 3 4 3 4 6% 6% 56%	4165
April	1st to 10th	Day	4 3 1 3 2 3 3 4 5% 7% 64%	2280
	11th to 20th	Day	7% 5% 2 4 3 3 3 3 5% 6% 59%	2251
	21st to end	Day	7% 5% 2 3 4 3 4 4 5% 8% 57%	2280
May	1st to 10th	Day	8% 5% 2 4 3 3 4 4 5% 6% 57%	4088
	11th to 20th	Day	7% 4 2 5% 4 4 4 3 5% 7% 56%	4082
	21st to end	Day	4 3 1 3 2 3 4 4 5% 9% 63%	4548
June	1st to 10th	Day	4 3 1 4 3 3 4 4 8% 10% 56%	2660
	11th to 20th	Day	4 3 1 2 2 3 4 3 6% 8% 64%	2660
	21st to end	Day	4 5% 2 5% 4 4 4 4 7% 9% 54%	2660
July	1st to 10th	Day	5% 3 1 4 4 4 5% 5% 7% 9% 54%	4430
	11th to 20th	Day	2 2 1 3 3 3 4 4 7% 10% 61%	4430
	21st to end	Day	4 3 2 4 4 4 5% 5% 7% 9% 54%	4653
August	1st to 10th	Day	5% 4 2 4 5% 4 5% 4 7% 10% 49%	3784
	11th to 20th	Day	4 3 1 3 3 3 4 4 6% 9% 59%	3726
	21st to end	Day	3 3 1 4 3 3 5% 5% 8% 11% 54%	4180
September	1st to 10th	Day	7% 3 1 4 4 3 4 3 5% 7% 59%	2280
	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	3 2 1 3 2 2 2 2 4 5% 74%	1700
	11th to 20th	Day	3 4 1 3 2 2 2 2 3 6% 71%	1710
	21st to end	Day	5% 6% 2 4 2 2 3 2 4 5% 65%	1710
December	1st to 10th	Day	2 5% 2 4 3 2 4 3 5% 7% 63%	1710
	11th to 20th	Day	4 4 2 4 3 3 3 3 6% 6% 64%	1983
	21st to end	Day	4 6% 2 4 3 2 3 3 5% 7% 60%	2794
January	1st to 10th	Night	3 5% 2 5% 5% 5% 4 3 5% 6% 56%	4417
	11th to 20th	Night	3 5% 1 4 3 3 4 3 5% 7% 61%	4424
	21st to end	Night	4 5% 2 5% 3 2 3 3 5% 7% 61%	4425
February	1st to 10th	Night	4 6% 3 5% 3 3 3 3 5% 7% 59%	2280
	11th to 20th	Night	4 6% 2 5% 5% 3 5% 4 6% 7% 53%	2218
	21st to end	Night	5% 4 2 3 2 3 2 3 4 7% 65%	1884
March	1st to 10th	Night	4 5% 2 3 2 2 2 3 3 6% 69%	3734
	11th to 20th	Night	8% 6% 2 5% 4 4 4 3 5% 6% 54%	3718
	21st to end	Night	5% 6% 2 4 3 3 3 3 5% 6% 60%	3477
April	1st to 10th	Night	5% 4 1 3 3 3 4 3 6% 7% 62%	1900
	11th to 20th	Night	7% 5% 2 4 3 4 4 3 6% 7% 56%	1877
	21st to end	Night	10% 4 2 4 3 4 4 3 5% 6% 56%	1900
May	1st to 10th	Night	8% 6% 2 3 3 3 3 3 4 6% 60%	2882
	11th to 20th	Night	11% 5% 2 4 4 3 4 4 5% 7% 51%	2823
	21st to end	Night	6% 4 2 3 3 4 3 3 6% 7% 59%	3021
June	1st to 10th	Night	4 3 2 4 4 4 5% 4 7% 10% 54%	1520
	11th to 20th	Night	2 2 1 3 3 3 4 4 7% 10% 62%	1520
	21st to end	Night	5% 4 2 6% 4 4 4 4 8% 10% 48%	1520
July	1st to 10th	Night	5% 4 1 4 3 4 4 4 8% 10% 52%	2540
	11th to 20th	Night	3 4 1 6% 4 5% 5% 4 9% 12% 47%	2540
	21st to end	Night	6% 5% 2 7% 5% 5% 5% 4 8% 10% 44%	2882
August	1st to 10th	Night	10% 5% 2 6% 4 4 5% 5% 8% 12% 41%	3154
	11th to 20th	Night	5% 3 1 3 3 5% 6% 6% 11% 12% 45%	3113
	21st to end	Night	3 3 2 5% 5% 6% 6% 6% 9% 10% 44%	3487
September	1st to 10th	Night	6% 4 1 4 2 3 3 3 6% 8% 59%	1900
	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	3 3 1 3 2 2 2 2 4 6% 72%	2451
	11th to 20th	Night	2 4 1 3 2 2 3 2 4 4 74%	2470
	21st to end	Night	4 5% 1 4 3 3 3 3 4 6% 63%	2470
December	1st to 10th	Night	3 5% 2 5% 3 3 3 2 4 7% 63%	2470
	11th to 20th	Night	3 5% 2 4 3 3 3 3 5% 7% 63%	3209
	21st to end	Night	3 4 2 6% 4 4 4 4 5% 6% 58%	4873

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	29% 1 4 27% 32% 7%	2539
	11th to 20th	Day	25% 1 11% 26% 28% 11%	2576
	21st to end	Day	26% 1 8% 29% 29% 7%	3239
February	1st to 10th	Day	28% 2 8% 22% 25% 14%	1900
	11th to 20th	Day	28% 3 6% 23% 26% 14%	1859
	21st to end	Day	20% 2 3 21% 31% 22%	1570
March	1st to 10th	Day	21% 1 4 16% 31% 26%	3130
	11th to 20th	Day	30% 1 5% 22% 31% 10%	3245
	21st to end	Day	29% 2 4 24% 31% 10%	4165
April	1st to 10th	Day	21% 3 7% 22% 29% 19%	2280
	11th to 20th	Day	27% 2 6% 24% 24% 17%	2254
	21st to end	Day	26% 2 8% 27% 27% 10%	2280
May	1st to 10th	Day	29% 2 8% 21% 21% 19%	4088
	11th to 20th	Day	30% 2 9% 23% 23% 12%	4086
	21st to end	Day	20% 2 12% 21% 22% 22%	4548
June	1st to 10th	Day	22% 4 16% 27% 21% 11%	2660
	11th to 20th	Day	18% 3 8% 21% 25% 24%	2660
	21st to end	Day	27% 3 9% 24% 21% 16%	2660
July	1st to 10th	Day	25% 6% 10% 23% 26% 9%	4361
	11th to 20th	Day	18% 5% 14% 24% 29% 10%	4355
	21st to end	Day	25% 5% 13% 23% 26% 8%	4505
August	1st to 10th	Day	29% 6% 17% 25% 18% 5%	3772
	11th to 20th	Day	21% 5% 13% 22% 28% 12%	3762
	21st to end	Day	22% 5% 15% 26% 25% 8%	4179
September	1st to 10th	Day	25% 3 10% 23% 22% 17%	2280
	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	15% 2 5% 22% 33% 24%	1700
	11th to 20th	Day	17% 2 3 26% 36% 16%	1710
	21st to end	Day	24% 1 5% 16% 29% 24%	1710
December	1st to 10th	Day	22% 3 10% 28% 26% 13%	1710
	11th to 20th	Day	23% 2 4 22% 35% 14%	1981
	21st to end	Day	25% 1 7% 25% 26% 16%	2794
January	1st to 10th	Night	30% 1 4 30% 27% 7%	4417
	11th to 20th	Night	25% 1 11% 27% 26% 10%	4424
	21st to end	Night	25% 1 11% 25% 30% 6%	4425
February	1st to 10th	Night	27% 2 8% 21% 30% 11%	2280
	11th to 20th	Night	30% 3 6% 23% 25% 12%	2218
	21st to end	Night	22% 2 2 22% 33% 19%	1884
March	1st to 10th	Night	20% 1 3 19% 26% 31%	3734
	11th to 20th	Night	33% 1 7% 22% 25% 12%	3718
	21st to end	Night	27% 1 6% 27% 27% 12%	3477
April	1st to 10th	Night	21% 3 7% 23% 28% 19%	1900
	11th to 20th	Night	28% 3 9% 23% 22% 15%	1877
	21st to end	Night	29% 3 12% 25% 20% 11%	1900
May	1st to 10th	Night	27% 3 11% 20% 15% 23%	2882
	11th to 20th	Night	33% 3 13% 23% 17% 11%	2824
	21st to end	Night	25% 3 13% 17% 20% 23%	3022
June	1st to 10th	Night	26% 5% 19% 25% 14% 11%	1520
	11th to 20th	Night	17% 5% 14% 23% 20% 21%	1520
	21st to end	Night	30% 4 11% 25% 18% 12%	1520
July	1st to 10th	Night	27% 5% 15% 27% 20% 6%	2500
	11th to 20th	Night	26% 5% 17% 24% 23% 5%	2492
	21st to end	Night	33% 5% 14% 22% 19% 8%	2791
August	1st to 10th	Night	34% 5% 17% 23% 17% 4	3144
	11th to 20th	Night	27% 6% 17% 24% 22% 4	3143
	21st to end	Night	31% 5% 14% 27% 18% 5%	3487
September	1st to 10th	Night	23% 5% 14% 24% 22% 13%	1900
	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	16% 2 6% 21% 32% 24%	2451
	11th to 20th	Night	16% 1 3 25% 37% 17%	2470
	21st to end	Night	23% 2 5% 18% 29% 23%	2470
December	1st to 10th	Night	23% 2 8% 29% 27% 11%	2470
	11th to 20th	Night	23% 2 5% 20% 38% 12%	3210
	21st to end	Night	29% 1 6% 23% 29% 11%	4873

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% 6% 28% 40% 16% 3	270
	11th to 20th	Day	9% 9% 34% 30% 13% 5%	270
	21st to end	Day	4 11% 28% 35% 19% 3	297
February	1st to 10th	Day	7% 11% 41% 25% 11% 3	270
	11th to 20th	Day	5% 10% 43% 30% 10% 3	270
	21st to end	Day	7% 14% 44% 27% 7% 1	225
March	1st to 10th	Day	6% 10% 37% 34% 11% 2	270
	11th to 20th	Day	14% 9% 31% 29% 14% 3	275
	21st to end	Day	14% 19% 36% 21% 7% 2	506
April	1st to 10th	Day	8% 19% 39% 25% 8% 2	460
	11th to 20th	Day	10% 21% 38% 23% 7% 1	452
	21st to end	Day	14% 17% 35% 25% 7% 3	460
May	1st to 10th	Day	9% 13% 32% 31% 14% 2	634
	11th to 20th	Day	11% 8% 28% 31% 18% 4	675
	21st to end	Day	7% 8% 38% 33% 12% 2	734
June	1st to 10th	Day	6% 7% 23% 34% 23% 7%	680
	11th to 20th	Day	5% 6% 30% 36% 19% 4	680
	21st to end	Day	7% 4 25% 36% 21% 5%	680
July	1st to 10th	Day	5% 2 18% 37% 30% 9%	671
	11th to 20th	Day	3 2 11% 38% 36% 10%	668
	21st to end	Day	6% 1 9% 33% 40% 11%	736
August	1st to 10th	Day	5% 3 14% 34% 30% 14%	487
	11th to 20th	Day	4 2 20% 38% 29% 8%	477
	21st to end	Day	5% 2 14% 42% 26% 11%	539
September	1st to 10th	Day	6% 1 21% 36% 27% 9%	490
	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	6% 9% 29% 31% 21% 3	279
	11th to 20th	Day	7% 10% 21% 35% 20% 7%	270
	21st to end	Day	12% 12% 28% 25% 16% 7%	270
December	1st to 10th	Day	3 8% 31% 39% 15% 4	270
	11th to 20th	Day	10% 7% 33% 33% 15% 2	270
	21st to end	Day	10% 10% 38% 31% 10%	297
January	1st to 10th	Night	5% 7% 37% 39% 11% 1	950
	11th to 20th	Night	6% 9% 35% 37% 11% 2	944
	21st to end	Night	6% 5% 36% 40% 13% 1	836
February	1st to 10th	Night	7% 8% 41% 34% 10%	760
	11th to 20th	Night	7% 8% 50% 28% 6% 1	744
	21st to end	Night	9% 8% 49% 30% 4	628
March	1st to 10th	Night	6% 11% 42% 34% 6% 1	760
	11th to 20th	Night	10% 11% 35% 34% 9%	725
	21st to end	Night	7% 14% 51% 24% 4	627
April	1st to 10th	Night	9% 11% 48% 28% 4	570
	11th to 20th	Night	10% 12% 48% 27% 4	563
	21st to end	Night	11% 10% 40% 32% 6%	570
May	1st to 10th	Night	8% 11% 40% 36% 6%	570
	11th to 20th	Night	12% 6% 37% 33% 12% 1	561
	21st to end	Night	8% 8% 46% 30% 7% 1	617
June	1st to 10th	Night	4 6% 34% 43% 12% 1	570
	11th to 20th	Night	3 5% 46% 38% 8%	570
	21st to end	Night	5% 5% 31% 44% 14%	570
July	1st to 10th	Night	4 2 21% 50% 21% 1	555
	11th to 20th	Night	4 2 15% 55% 23% 1	552
	21st to end	Night	8% 3 14% 45% 28% 2	624
August	1st to 10th	Night	7% 1 15% 44% 31% 2	567
	11th to 20th	Night	9% 2 13% 52% 23% 1	564
	21st to end	Night	5% 1 19% 48% 24% 2	627
September	1st to 10th	Night	7% 1 19% 54% 18% 1	570
	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	4 5% 30% 46% 13% 2	943
	11th to 20th	Night	4 7% 34% 41% 13% 1	950
	21st to end	Night	7% 7% 31% 39% 14% 2	950
December	1st to 10th	Night	5% 7% 34% 41% 11% 1	950
	11th to 20th	Night	6% 7% 36% 40% 10% 1	950
	21st to end	Night	8% 10% 38% 35% 8% 1	1045

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