Arkansas Oklahoma Regional Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Arkansas Oklahoma Regional Star Party clear sky chart from 2005-11-06 to 2026-06-01.

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	14% 6% 2 5% 4 4 4 3 5% 6% 45%	131803
	Night	14% 6% 2 5% 3 3 3 3 5% 6% 49%	131626
Transparency	Day	38% 4 10% 24% 18% 5%	135414
	Night	35% 4 10% 24% 21% 6%	136092
Seeing	Day	19% 13% 26% 25% 14% 3	17502
	Night	17% 12% 24% 29% 15% 2	27377

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% 3 3 3 3 3 4 47%	5289
	11th to 20th	Day	7% 6% 3 6% 3 3 4 3 3 4 58%	5310
	21st to end	Day	19% 7% 2 5% 3 2 3 2 3 4 50%	5812
February	1st to 10th	Day	21% 10% 2 5% 4 3 3 2 4 4 43%	1890
	11th to 20th	Day	19% 8% 2 6% 4 3 3 3 5% 5% 43%	1865
	21st to end	Day	19% 8% 3 6% 3 3 3 3 4 5% 42%	1886
March	1st to 10th	Day	20% 9% 3 5% 3 3 3 3 4 4 41%	5046
	11th to 20th	Day	12% 5% 2 4 3 3 4 4 5% 6% 52%	5090
	21st to end	Day	17% 8% 3 6% 4 3 4 3 5% 7% 39%	5583
April	1st to 10th	Day	19% 6% 2 5% 4 3 4 4 5% 5% 43%	2444
	11th to 20th	Day	21% 7% 2 6% 4 3 4 4 5% 5% 39%	2494
	21st to end	Day	25% 8% 2 6% 4 3 4 3 5% 5% 36%	2520
May	1st to 10th	Day	23% 7% 3 6% 5% 4 4 3 5% 5% 35%	5866
	11th to 20th	Day	15% 6% 3 7% 5% 5% 5% 4 6% 6% 38%	5992
	21st to end	Day	23% 7% 2 7% 5% 4 5% 4 5% 6% 33%	6577
June	1st to 10th	Day	11% 5% 2 6% 5% 5% 5% 4 6% 8% 42%	2601
	11th to 20th	Day	8% 5% 3 7% 5% 4 6% 5% 7% 9% 41%	2600
	21st to end	Day	7% 4 1 4 4 4 6% 5% 7% 9% 50%	2600
July	1st to 10th	Day	8% 5% 2 5% 5% 4 6% 4 8% 11% 41%	5900
	11th to 20th	Day	6% 4 2 4 4 4 5% 4 6% 9% 52%	5900
	21st to end	Day	6% 4 2 6% 5% 5% 6% 6% 8% 9% 42%	6422
August	1st to 10th	Day	5% 3 1 4 3 5% 5% 4 6% 10% 55%	4234
	11th to 20th	Day	12% 5% 2 5% 4 4 4 4 6% 9% 45%	4052
	21st to end	Day	6% 3 1 5% 4 5% 5% 4 6% 9% 53%	4312
September	1st to 10th	Day	11% 6% 2 5% 3 4 4 3 5% 7% 51%	2400
	11th to 20th	Day	11% 4 1 5% 4 4 5% 5% 6% 9% 44%	2270
	21st to end	Day	9% 4 2 5% 4 4 5% 3 5% 5% 53%	2150
October	1st to 10th	Day	10% 5% 1 5% 4 3 4 2 4 5% 57%	2000
	11th to 20th	Day	14% 5% 2 4 3 2 2 2 4 4 57%	2000
	21st to end	Day	22% 6% 2 4 2 3 2 2 3 4 50%	2200
November	1st to 10th	Day	15% 6% 2 3 3 2 2 2 3 6% 56%	2058
	11th to 20th	Day	14% 7% 2 4 3 2 3 3 4 5% 55%	2100
	21st to end	Day	21% 7% 2 5% 2 2 2 3 4 6% 46%	1768
December	1st to 10th	Day	15% 10% 2 4 3 3 3 2 3 4 52%	2690
	11th to 20th	Day	18% 8% 2 5% 4 3 3 2 4 5% 46%	3295
	21st to end	Day	22% 13% 4 6% 3 3 3 3 4 5% 35%	4587
January	1st to 10th	Night	13% 7% 3 7% 4 4 4 3 4 5% 47%	7634
	11th to 20th	Night	8% 6% 2 4 2 2 2 2 3 5% 63%	7680
	21st to end	Night	20% 8% 3 5% 3 2 3 3 4 5% 44%	8402
February	1st to 10th	Night	18% 8% 2 6% 4 3 3 3 4 6% 42%	2730
	11th to 20th	Night	17% 8% 3 5% 3 3 3 3 5% 7% 44%	2640
	21st to end	Night	18% 6% 2 5% 3 3 3 3 4 5% 48%	1938
March	1st to 10th	Night	22% 8% 2 4 4 3 3 2 3 4 43%	5029
	11th to 20th	Night	13% 8% 2 5% 4 3 3 3 5% 6% 50%	5090
	21st to end	Night	16% 5% 2 6% 4 4 3 3 5% 8% 44%	5588
April	1st to 10th	Night	17% 6% 2 5% 3 3 4 3 5% 6% 46%	2174
	11th to 20th	Night	18% 6% 2 5% 3 4 3 2 5% 6% 47%	2075
	21st to end	Night	20% 6% 2 6% 3 3 3 3 5% 6% 41%	2100
May	1st to 10th	Night	20% 7% 2 4 3 3 3 3 5% 7% 43%	4260
	11th to 20th	Night	16% 6% 2 7% 4 4 5% 4 6% 7% 39%	4143
	21st to end	Night	21% 7% 2 5% 4 4 3 3 6% 7% 38%	4542
June	1st to 10th	Night	8% 4 1 4 3 3 4 4 6% 9% 53%	1800
	11th to 20th	Night	7% 4 1 3 3 4 5% 4 6% 10% 54%	1800
	21st to end	Night	6% 3 1 3 4 2 3 4 6% 9% 61%	1800
July	1st to 10th	Night	8% 4 2 5% 4 4 5% 5% 8% 10% 44%	4078
	11th to 20th	Night	4 4 1 4 3 3 3 4 5% 9% 61%	4077
	21st to end	Night	7% 5% 2 5% 4 3 4 4 6% 9% 51%	4449
August	1st to 10th	Night	3 3 1 4 4 3 4 3 5% 9% 60%	2926
	11th to 20th	Night	5% 4 2 6% 4 4 5% 3 6% 9% 53%	3001
	21st to end	Night	5% 3 1 4 3 3 3 3 6% 8% 62%	3586
September	1st to 10th	Night	8% 5% 1 4 3 3 3 4 5% 8% 56%	2000
	11th to 20th	Night	10% 5% 2 5% 4 3 5% 4 5% 7% 51%	2125
	21st to end	Night	9% 5% 2 4 3 3 4 4 5% 6% 55%	2228
October	1st to 10th	Night	7% 3 1 3 3 3 4 4 5% 7% 61%	2400
	11th to 20th	Night	13% 4 1 4 3 2 3 3 4 5% 58%	2400
	21st to end	Night	20% 6% 2 4 2 2 3 2 3 4 51%	2640
November	1st to 10th	Night	15% 5% 2 4 3 2 3 3 3 4 57%	2460
	11th to 20th	Night	14% 6% 2 3 2 2 2 3 4 6% 56%	2520
	21st to end	Night	19% 6% 2 4 3 3 2 2 4 6% 49%	2841
December	1st to 10th	Night	12% 9% 2 4 3 3 3 2 4 5% 52%	4720
	11th to 20th	Night	20% 7% 2 5% 3 3 3 2 3 4 49%	5117
	21st to end	Night	24% 10% 4 7% 4 3 3 2 3 3 37%	6633

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	42% 2 6% 26% 22% 2	5290
	11th to 20th	Day	32% 2 6% 25% 29% 6%	5310
	21st to end	Day	41% 2 4 21% 23% 9%	5812
February	1st to 10th	Day	46% 4 10% 21% 16% 4	1890
	11th to 20th	Day	44% 3 9% 21% 19% 3	1874
	21st to end	Day	44% 4 8% 16% 20% 8%	1886
March	1st to 10th	Day	45% 4 5% 18% 14% 15%	5046
	11th to 20th	Day	33% 3 8% 20% 23% 13%	5090
	21st to end	Day	45% 4 9% 27% 14% 1	5585
April	1st to 10th	Day	43% 5% 9% 19% 20% 3	2444
	11th to 20th	Day	46% 5% 10% 19% 16% 5%	2494
	21st to end	Day	50% 5% 8% 21% 14% 2	2520
May	1st to 10th	Day	50% 5% 9% 21% 15% 1	5903
	11th to 20th	Day	44% 7% 12% 22% 14% 1	5996
	21st to end	Day	51% 6% 10% 16% 16% 1	6590
June	1st to 10th	Day	38% 8% 14% 25% 13% 1	2601
	11th to 20th	Day	37% 9% 13% 25% 15% 2	2600
	21st to end	Day	27% 8% 16% 29% 17% 4	2600
July	1st to 10th	Day	35% 4 19% 29% 11% 1	5836
	11th to 20th	Day	29% 4 16% 37% 13% 1	5831
	21st to end	Day	36% 5% 18% 30% 10% 1	6240
August	1st to 10th	Day	25% 6% 16% 28% 20% 5%	4220
	11th to 20th	Day	36% 5% 17% 29% 12% 1	4091
	21st to end	Day	28% 5% 16% 35% 13% 2	4311
September	1st to 10th	Day	33% 6% 11% 26% 16% 9%	2400
	11th to 20th	Day	34% 6% 12% 24% 20% 4	2270
	21st to end	Day	32% 5% 9% 21% 28% 5%	2150
October	1st to 10th	Day	18% 3 7% 13% 38% 22%	3260
	11th to 20th	Day	20% 2 4 21% 37% 16%	3240
	21st to end	Day	33% 3 8% 29% 23% 5%	3538
November	1st to 10th	Day	32% 4 7% 27% 21% 9%	2058
	11th to 20th	Day	33% 3 7% 25% 22% 10%	2100
	21st to end	Day	40% 3 7% 20% 24% 4	1768
December	1st to 10th	Day	38% 2 6% 29% 22% 3	2690
	11th to 20th	Day	42% 2 6% 22% 25% 3	3293
	21st to end	Day	53% 4 7% 21% 13% 2	4587
January	1st to 10th	Night	40% 3 9% 28% 18% 3	7635
	11th to 20th	Night	26% 2 7% 19% 37% 9%	7680
	21st to end	Night	44% 2 5% 18% 23% 7%	8402
February	1st to 10th	Night	44% 4 8% 24% 16% 4	2730
	11th to 20th	Night	41% 4 7% 24% 19% 5%	2641
	21st to end	Night	38% 4 8% 18% 22% 10%	1938
March	1st to 10th	Night	45% 4 5% 17% 17% 12%	5029
	11th to 20th	Night	36% 4 7% 22% 20% 11%	5090
	21st to end	Night	39% 4 12% 27% 15% 2	5588
April	1st to 10th	Night	39% 4 9% 22% 19% 6%	2174
	11th to 20th	Night	39% 4 8% 22% 20% 7%	2075
	21st to end	Night	42% 6% 10% 23% 17% 2	2100
May	1st to 10th	Night	42% 5% 14% 23% 13% 3	4288
	11th to 20th	Night	43% 6% 14% 22% 12% 2	4144
	21st to end	Night	44% 7% 14% 18% 13% 4	4551
June	1st to 10th	Night	26% 8% 15% 30% 18% 3	1800
	11th to 20th	Night	24% 7% 15% 32% 20% 2	1800
	21st to end	Night	21% 6% 17% 28% 23% 6%	1800
July	1st to 10th	Night	34% 5% 20% 26% 13% 2	4035
	11th to 20th	Night	22% 4 16% 40% 17% 1	4026
	21st to end	Night	31% 4 16% 34% 14% 1	4320
August	1st to 10th	Night	21% 5% 17% 33% 23% 1	2916
	11th to 20th	Night	29% 4 21% 29% 15% 2	3028
	21st to end	Night	22% 5% 14% 37% 20% 2	3586
September	1st to 10th	Night	27% 6% 10% 30% 18% 9%	2000
	11th to 20th	Night	32% 6% 11% 23% 22% 5%	2125
	21st to end	Night	29% 5% 8% 24% 28% 7%	2228
October	1st to 10th	Night	14% 4 8% 13% 35% 26%	3920
	11th to 20th	Night	19% 2 4 17% 38% 19%	3899
	21st to end	Night	31% 2 5% 29% 25% 8%	4252
November	1st to 10th	Night	32% 3 8% 22% 26% 9%	2460
	11th to 20th	Night	30% 3 7% 26% 25% 9%	2520
	21st to end	Night	38% 3 7% 22% 25% 5%	2841
December	1st to 10th	Night	36% 2 8% 30% 21% 3	4720
	11th to 20th	Night	42% 2 5% 21% 20% 9%	5118
	21st to end	Night	51% 5% 7% 21% 12% 4	6633

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	32% 22% 29% 12% 4	330
	11th to 20th	Day	29% 27% 31% 11% 2	330
	21st to end	Day	25% 29% 31% 12% 3	363
February	1st to 10th	Day	33% 22% 32% 9% 3	330
	11th to 20th	Day	35% 29% 28% 6% 2	330
	21st to end	Day	37% 25% 29% 5% 4	273
March	1st to 10th	Day	32% 24% 31% 10% 2 1	330
	11th to 20th	Day	33% 25% 33% 8% 2	330
	21st to end	Day	32% 30% 28% 9% 2	363
April	1st to 10th	Day	29% 24% 27% 13% 6%	464
	11th to 20th	Day	33% 20% 28% 14% 4	532
	21st to end	Day	29% 19% 31% 15% 6%	540
May	1st to 10th	Day	23% 21% 34% 18% 4	691
	11th to 20th	Day	20% 14% 30% 25% 9% 2	775
	21st to end	Day	17% 11% 32% 26% 11% 2	844
June	1st to 10th	Day	11% 7% 25% 34% 19% 4	731
	11th to 20th	Day	9% 5% 24% 38% 21% 3	730
	21st to end	Day	6% 4 30% 36% 20% 5%	730
July	1st to 10th	Day	10% 3 17% 36% 26% 8%	721
	11th to 20th	Day	7% 3 19% 34% 29% 8%	718
	21st to end	Day	7% 2 13% 36% 32% 9%	794
August	1st to 10th	Day	9% 4 17% 39% 27% 5%	726
	11th to 20th	Day	14% 2 13% 35% 27% 8%	648
	21st to end	Day	9% 3 13% 31% 32% 11%	583
September	1st to 10th	Day	11% 3 14% 33% 32% 7%	530
	11th to 20th	Day	8% 3 22% 38% 24% 6%	400
	21st to end	Day	13% 9% 24% 33% 18% 2	330
October	1st to 10th	Day	8% 11% 31% 30% 18% 2	330
	11th to 20th	Day	15% 15% 37% 24% 7% 2	330
	21st to end	Day	29% 17% 33% 17% 4	363
November	1st to 10th	Day	21% 17% 33% 21% 8% 1	330
	11th to 20th	Day	22% 20% 35% 16% 6% 1	330
	21st to end	Day	30% 21% 24% 18% 6% 1	330
December	1st to 10th	Day	25% 25% 29% 15% 6% 1	330
	11th to 20th	Day	27% 24% 29% 16% 4	330
	21st to end	Day	29% 22% 34% 13% 2	363
January	1st to 10th	Night	21% 20% 28% 26% 4	1050
	11th to 20th	Night	22% 20% 29% 25% 4	1050
	21st to end	Night	21% 19% 29% 27% 4	1155
February	1st to 10th	Night	22% 21% 29% 24% 4	1050
	11th to 20th	Night	25% 22% 31% 19% 3	1006
	21st to end	Night	26% 19% 32% 21% 2	554
March	1st to 10th	Night	24% 16% 29% 27% 4	630
	11th to 20th	Night	24% 15% 29% 28% 4	630
	21st to end	Night	23% 18% 33% 21% 5%	693
April	1st to 10th	Night	22% 17% 30% 24% 6%	630
	11th to 20th	Night	20% 17% 30% 25% 7% 1	623
	21st to end	Night	22% 15% 32% 22% 9%	630
May	1st to 10th	Night	19% 9% 32% 30% 9%	630
	11th to 20th	Night	17% 10% 25% 30% 17% 1	621
	21st to end	Night	15% 5% 28% 30% 18% 4	683
June	1st to 10th	Night	9% 4 14% 40% 30% 3	600
	11th to 20th	Night	7% 3 20% 39% 28% 3	600
	21st to end	Night	6% 3 17% 37% 33% 5%	600
July	1st to 10th	Night	7% 2 9% 33% 44% 6%	585
	11th to 20th	Night	4 2 10% 35% 40% 8%	582
	21st to end	Night	5% 2 7% 35% 44% 8%	657
August	1st to 10th	Night	4 2 11% 40% 37% 6%	597
	11th to 20th	Night	8% 1 11% 36% 38% 6%	594
	21st to end	Night	8% 2 10% 37% 39% 5%	660
September	1st to 10th	Night	10% 3 13% 33% 38% 3	600
	11th to 20th	Night	12% 2 11% 39% 31% 4	600
	21st to end	Night	11% 5% 18% 34% 28% 4	628
October	1st to 10th	Night	9% 5% 22% 36% 25% 3	800
	11th to 20th	Night	15% 12% 27% 31% 14%	800
	21st to end	Night	23% 14% 23% 25% 12% 1	880
November	1st to 10th	Night	17% 13% 27% 30% 13% 1	820
	11th to 20th	Night	18% 14% 30% 31% 8%	840
	21st to end	Night	24% 16% 24% 26% 10%	1044
December	1st to 10th	Night	21% 16% 29% 28% 6%	1050
	11th to 20th	Night	24% 16% 25% 30% 5%	1050
	21st to end	Night	25% 18% 24% 28% 4	1155

Page generated at 2026-05-29 00:53:27. Version ac07

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