Fayetteville(AR)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fayetteville(AR) clear sky chart from 2005-11-06 to 2025-11-18.

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	11% 7% 2 6% 4 4 4 4 5% 7% 46%	126463
	Night	10% 7% 2 5% 4 3 4 3 5% 7% 50%	124155
Transparency	Day	36% 6% 11% 24% 18% 4	130075
	Night	33% 5% 11% 25% 20% 6%	128619
Seeing	Day	14% 11% 26% 27% 17% 4	16859
	Night	14% 11% 30% 30% 14% 1	26642

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	13% 12% 4 6% 5% 3 3 3 4 5% 42%	4077
	11th to 20th	Day	7% 7% 3 7% 4 3 3 3 4 5% 53%	4080
	21st to end	Day	19% 8% 2 5% 2 3 3 3 4 3 46%	4488
February	1st to 10th	Day	17% 10% 3 7% 6% 4 4 2 4 4 40%	1800
	11th to 20th	Day	13% 10% 3 8% 3 4 3 3 4 6% 42%	1759
	21st to end	Day	14% 10% 3 6% 4 4 4 3 4 5% 42%	1805
March	1st to 10th	Day	12% 8% 2 5% 4 4 4 4 5% 6% 47%	4936
	11th to 20th	Day	9% 6% 2 5% 3 3 4 4 5% 7% 53%	4980
	21st to end	Day	13% 8% 3 8% 5% 5% 5% 4 5% 7% 37%	5462
April	1st to 10th	Day	12% 6% 2 6% 5% 4 4 4 6% 7% 44%	2310
	11th to 20th	Day	15% 7% 2 6% 4 4 5% 4 5% 6% 42%	2374
	21st to end	Day	15% 9% 3 7% 5% 4 4 4 5% 5% 39%	2400
May	1st to 10th	Day	15% 8% 3 7% 5% 5% 5% 5% 6% 6% 36%	5852
	11th to 20th	Day	10% 6% 3 8% 5% 5% 6% 4 6% 7% 41%	5862
	21st to end	Day	17% 6% 3 7% 5% 4 5% 4 6% 7% 36%	6434
June	1st to 10th	Day	8% 5% 2 6% 4 5% 6% 4 6% 9% 45%	2600
	11th to 20th	Day	6% 4 2 6% 5% 4 5% 5% 7% 9% 46%	2600
	21st to end	Day	3 3 1 5% 5% 4 5% 4 7% 9% 54%	2600
July	1st to 10th	Day	8% 5% 2 6% 5% 5% 6% 5% 8% 11% 42%	5900
	11th to 20th	Day	5% 5% 2 6% 4 4 5% 4 6% 9% 49%	5900
	21st to end	Day	5% 3 1 5% 4 5% 5% 5% 8% 11% 47%	6422
August	1st to 10th	Day	5% 3 2 4 3 4 4 3 5% 9% 57%	4234
	11th to 20th	Day	10% 5% 2 6% 4 4 4 4 6% 8% 47%	4110
	21st to end	Day	5% 4 2 5% 3 5% 5% 4 6% 8% 53%	4312
September	1st to 10th	Day	11% 5% 2 5% 3 3 3 3 5% 7% 53%	2400
	11th to 20th	Day	11% 6% 1 6% 4 5% 4 4 6% 7% 46%	2235
	21st to end	Day	8% 5% 2 5% 3 4 4 4 5% 7% 54%	2170
October	1st to 10th	Day	9% 3 2 5% 3 3 4 3 5% 7% 56%	2000
	11th to 20th	Day	12% 5% 2 4 3 2 2 3 4 6% 59%	2000
	21st to end	Day	17% 6% 2 5% 3 3 3 2 4 5% 50%	2200
November	1st to 10th	Day	10% 6% 2 4 3 3 3 3 3 6% 58%	2058
	11th to 20th	Day	10% 6% 2 5% 3 3 3 3 5% 6% 53%	2029
	21st to end	Day	13% 8% 3 5% 4 3 3 3 5% 7% 47%	1717
December	1st to 10th	Day	10% 8% 3 6% 4 3 4 3 3 4 53%	2610
	11th to 20th	Day	9% 10% 3 7% 5% 4 4 3 4 5% 48%	3259
	21st to end	Day	15% 16% 6% 7% 4 4 4 3 4 5% 32%	4488
January	1st to 10th	Night	12% 8% 4 9% 5% 4 4 3 4 6% 41%	5888
	11th to 20th	Night	8% 6% 2 7% 4 3 4 3 4 6% 52%	5900
	21st to end	Night	17% 10% 4 6% 3 3 2 2 3 4 45%	6490
February	1st to 10th	Night	14% 11% 3 6% 4 4 4 3 5% 6% 42%	2600
	11th to 20th	Night	14% 9% 3 7% 4 3 3 3 4 6% 45%	2533
	21st to end	Night	12% 8% 2 6% 5% 3 5% 3 5% 6% 46%	1836
March	1st to 10th	Night	15% 8% 2 6% 3 4 4 3 4 4 46%	4919
	11th to 20th	Night	9% 8% 2 5% 3 3 3 3 5% 7% 53%	4980
	21st to end	Night	9% 7% 2 7% 5% 4 5% 4 6% 8% 44%	5467
April	1st to 10th	Night	12% 7% 2 4 4 3 3 3 5% 6% 50%	2089
	11th to 20th	Night	12% 7% 2 4 3 3 3 4 5% 7% 49%	1975
	21st to end	Night	15% 6% 2 6% 4 4 4 3 6% 6% 45%	2000
May	1st to 10th	Night	12% 8% 2 6% 4 3 4 3 5% 8% 45%	4058
	11th to 20th	Night	10% 6% 2 6% 5% 5% 5% 4 7% 8% 43%	4053
	21st to end	Night	15% 8% 2 6% 4 4 4 3 6% 7% 40%	4443
June	1st to 10th	Night	6% 4 2 5% 3 3 3 4 5% 10% 55%	1800
	11th to 20th	Night	5% 4 1 4 3 3 3 4 7% 10% 57%	1800
	21st to end	Night	2 2 1 2 3 3 4 4 7% 8% 65%	1800
July	1st to 10th	Night	8% 4 2 5% 4 5% 5% 4 7% 10% 47%	4078
	11th to 20th	Night	4 3 1 4 3 3 3 3 5% 8% 63%	4077
	21st to end	Night	4 3 2 4 3 3 3 4 6% 11% 58%	4449
August	1st to 10th	Night	3 2 1 4 4 3 4 4 6% 10% 58%	2926
	11th to 20th	Night	6% 4 1 5% 4 4 5% 4 6% 8% 53%	2946
	21st to end	Night	4 3 1 4 3 3 4 3 5% 9% 62%	3586
September	1st to 10th	Night	8% 4 1 4 4 4 4 3 5% 8% 56%	2000
	11th to 20th	Night	9% 4 2 5% 4 4 4 3 5% 7% 52%	2160
	21st to end	Night	8% 5% 2 4 3 3 3 4 5% 6% 56%	2210
October	1st to 10th	Night	6% 3 1 3 3 3 3 3 5% 8% 63%	2400
	11th to 20th	Night	12% 3 1 3 3 3 3 3 5% 5% 59%	2400
	21st to end	Night	16% 7% 2 4 3 3 3 3 4 5% 52%	2640
November	1st to 10th	Night	10% 5% 2 4 3 3 4 2 4 5% 59%	2460
	11th to 20th	Night	9% 6% 2 3 3 2 3 3 5% 6% 58%	2524
	21st to end	Night	13% 7% 2 4 3 3 3 3 5% 6% 51%	2673
December	1st to 10th	Night	10% 9% 2 5% 3 3 3 2 4 5% 53%	4580
	11th to 20th	Night	12% 8% 3 8% 4 4 4 3 3 4 49%	4925
	21st to end	Night	16% 12% 6% 8% 4 4 4 3 4 4 35%	6490

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	44% 4 9% 23% 19% 2	4078
	11th to 20th	Day	34% 4 10% 23% 25% 5%	4080
	21st to end	Day	42% 3 6% 20% 21% 7%	4488
February	1st to 10th	Day	48% 5% 9% 20% 14% 4	1800
	11th to 20th	Day	44% 5% 10% 21% 17% 3	1768
	21st to end	Day	44% 5% 7% 18% 18% 8%	1805
March	1st to 10th	Day	38% 5% 7% 20% 15% 16%	4936
	11th to 20th	Day	31% 5% 8% 19% 23% 14%	4980
	21st to end	Day	45% 6% 9% 28% 11% 1	5464
April	1st to 10th	Day	39% 6% 12% 21% 18% 4	2310
	11th to 20th	Day	43% 7% 11% 19% 17% 4	2374
	21st to end	Day	47% 7% 9% 22% 14% 2	2400
May	1st to 10th	Day	46% 8% 10% 21% 14% 1	5890
	11th to 20th	Day	40% 10% 11% 22% 16% 1	5866
	21st to end	Day	46% 8% 12% 17% 16% 1	6447
June	1st to 10th	Day	35% 9% 15% 26% 15% 1	2600
	11th to 20th	Day	32% 8% 15% 27% 15% 2	2600
	21st to end	Day	25% 8% 16% 30% 18% 4	2600
July	1st to 10th	Day	32% 8% 18% 29% 12% 1	5836
	11th to 20th	Day	29% 7% 14% 34% 15% 1	5831
	21st to end	Day	28% 8% 19% 34% 11%	6240
August	1st to 10th	Day	24% 7% 15% 29% 20% 4	4220
	11th to 20th	Day	34% 7% 16% 28% 14% 1	4149
	21st to end	Day	28% 7% 14% 33% 14% 3	4311
September	1st to 10th	Day	32% 5% 11% 27% 17% 9%	2400
	11th to 20th	Day	34% 8% 11% 22% 21% 4	2235
	21st to end	Day	30% 5% 10% 24% 27% 4	2170
October	1st to 10th	Day	17% 3 7% 16% 38% 19%	3260
	11th to 20th	Day	19% 3 4 20% 38% 16%	3240
	21st to end	Day	27% 4 9% 31% 24% 5%	3538
November	1st to 10th	Day	29% 5% 10% 25% 23% 8%	2058
	11th to 20th	Day	32% 5% 8% 24% 22% 10%	2029
	21st to end	Day	38% 5% 8% 21% 24% 4	1717
December	1st to 10th	Day	36% 3 7% 28% 23% 2	2610
	11th to 20th	Day	39% 4 6% 24% 24% 3	3257
	21st to end	Day	54% 6% 6% 19% 13% 2	4488
January	1st to 10th	Night	45% 5% 9% 21% 16% 3	5888
	11th to 20th	Night	33% 5% 10% 19% 30% 3	5900
	21st to end	Night	44% 3 7% 17% 24% 5%	6490
February	1st to 10th	Night	43% 4 10% 24% 15% 4	2600
	11th to 20th	Night	41% 5% 8% 23% 18% 5%	2534
	21st to end	Night	40% 5% 8% 18% 22% 8%	1836
March	1st to 10th	Night	41% 5% 6% 17% 19% 11%	4919
	11th to 20th	Night	32% 5% 8% 23% 20% 12%	4980
	21st to end	Night	37% 7% 12% 28% 14% 2	5467
April	1st to 10th	Night	34% 7% 10% 24% 19% 6%	2089
	11th to 20th	Night	34% 6% 9% 24% 21% 6%	1975
	21st to end	Night	40% 7% 11% 24% 17% 2	2000
May	1st to 10th	Night	39% 7% 13% 25% 14% 2	4085
	11th to 20th	Night	36% 9% 15% 24% 13% 4	4054
	21st to end	Night	41% 8% 15% 20% 13% 2	4452
June	1st to 10th	Night	24% 9% 16% 31% 18% 3	1800
	11th to 20th	Night	21% 8% 16% 32% 21% 2	1800
	21st to end	Night	17% 7% 17% 31% 23% 5%	1800
July	1st to 10th	Night	30% 8% 18% 28% 13% 3	4035
	11th to 20th	Night	19% 6% 16% 38% 19% 1	4026
	21st to end	Night	20% 6% 20% 36% 17% 1	4320
August	1st to 10th	Night	19% 7% 16% 34% 22% 2	2916
	11th to 20th	Night	27% 7% 20% 28% 16% 2	2973
	21st to end	Night	19% 6% 13% 38% 21% 3	3586
September	1st to 10th	Night	26% 6% 11% 28% 19% 9%	2000
	11th to 20th	Night	31% 6% 11% 24% 24% 5%	2160
	21st to end	Night	28% 5% 8% 23% 30% 6%	2210
October	1st to 10th	Night	13% 4 7% 15% 37% 25%	3920
	11th to 20th	Night	19% 4 5% 18% 33% 21%	3899
	21st to end	Night	29% 4 6% 29% 24% 8%	4252
November	1st to 10th	Night	29% 4 8% 24% 26% 9%	2460
	11th to 20th	Night	28% 4 8% 26% 26% 9%	2524
	21st to end	Night	36% 4 8% 22% 25% 6%	2673
December	1st to 10th	Night	34% 4 8% 33% 19% 2	4580
	11th to 20th	Night	40% 4 5% 22% 21% 7%	4926
	21st to end	Night	52% 5% 8% 20% 11% 4	6490

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	21% 19% 38% 17% 5%	300
	11th to 20th	Day	21% 25% 38% 13% 2	300
	21st to end	Day	18% 25% 39% 14% 5%	330
February	1st to 10th	Day	27% 21% 34% 15% 3	300
	11th to 20th	Day	24% 30% 33% 12% 1	300
	21st to end	Day	28% 28% 31% 12% 2	249
March	1st to 10th	Day	21% 22% 34% 19% 3	300
	11th to 20th	Day	25% 24% 34% 15% 2	300
	21st to end	Day	25% 25% 37% 10% 3	330
April	1st to 10th	Day	23% 24% 30% 16% 6% 1	410
	11th to 20th	Day	23% 20% 33% 19% 5%	492
	21st to end	Day	23% 18% 33% 18% 7%	500
May	1st to 10th	Day	17% 15% 36% 26% 5%	693
	11th to 20th	Day	15% 11% 32% 28% 12% 1	725
	21st to end	Day	13% 8% 36% 23% 16% 4	789
June	1st to 10th	Day	9% 5% 21% 36% 22% 7%	730
	11th to 20th	Day	6% 4 22% 38% 25% 5%	730
	21st to end	Day	3 4 25% 36% 27% 5%	730
July	1st to 10th	Day	8% 2 17% 32% 29% 12%	721
	11th to 20th	Day	5% 2 14% 36% 32% 10%	718
	21st to end	Day	7% 1 9% 35% 34% 13%	794
August	1st to 10th	Day	9% 2 14% 40% 29% 6%	726
	11th to 20th	Day	10% 3 10% 35% 34% 8%	680
	21st to end	Day	8% 2 11% 33% 34% 13%	583
September	1st to 10th	Day	11% 2 11% 35% 32% 9%	530
	11th to 20th	Day	7% 2 16% 39% 26% 10%	365
	21st to end	Day	10% 5% 23% 29% 25% 8%	330
October	1st to 10th	Day	10% 5% 29% 32% 20% 4	330
	11th to 20th	Day	13% 12% 37% 27% 9% 2	330
	21st to end	Day	27% 13% 31% 22% 6% 1	363
November	1st to 10th	Day	14% 16% 40% 22% 7% 2	330
	11th to 20th	Day	13% 20% 35% 23% 8% 1	321
	21st to end	Day	19% 20% 33% 21% 7%	300
December	1st to 10th	Day	17% 21% 37% 19% 5% 1	300
	11th to 20th	Day	21% 23% 36% 15% 5% 1	300
	21st to end	Day	21% 21% 40% 16% 2	330
January	1st to 10th	Night	17% 17% 35% 25% 5%	1000
	11th to 20th	Night	17% 20% 40% 20% 3	1000
	21st to end	Night	18% 16% 39% 24% 3	1100
February	1st to 10th	Night	20% 18% 38% 22% 4	1000
	11th to 20th	Night	17% 21% 43% 17% 3	979
	21st to end	Night	19% 19% 38% 22% 2	516
March	1st to 10th	Night	20% 15% 35% 27% 4	600
	11th to 20th	Night	20% 14% 37% 25% 3	600
	21st to end	Night	17% 15% 42% 20% 5%	660
April	1st to 10th	Night	16% 17% 38% 25% 4	600
	11th to 20th	Night	17% 15% 37% 24% 7%	593
	21st to end	Night	17% 12% 42% 20% 9% 1	600
May	1st to 10th	Night	13% 9% 35% 35% 8%	600
	11th to 20th	Night	14% 7% 29% 34% 16% 1	591
	21st to end	Night	13% 6% 31% 31% 16% 3	650
June	1st to 10th	Night	7% 5% 17% 42% 29% 1	600
	11th to 20th	Night	5% 1 25% 43% 24% 2	600
	21st to end	Night	3 1 21% 45% 28% 3	600
July	1st to 10th	Night	6% 1 10% 42% 38% 3	585
	11th to 20th	Night	4 2 10% 42% 37% 4	582
	21st to end	Night	4 1 9% 41% 40% 5%	657
August	1st to 10th	Night	3 2 11% 46% 34% 4	597
	11th to 20th	Night	7% 3 10% 45% 31% 4	594
	21st to end	Night	6% 1 11% 39% 39% 4	660
September	1st to 10th	Night	10% 2 11% 41% 34% 3	600
	11th to 20th	Night	12% 1 11% 42% 30% 5%	600
	21st to end	Night	10% 3 20% 37% 27% 3	610
October	1st to 10th	Night	8% 4 22% 39% 25% 3	800
	11th to 20th	Night	14% 7% 34% 33% 12%	800
	21st to end	Night	20% 11% 31% 28% 9% 1	880
November	1st to 10th	Night	12% 11% 37% 30% 10%	820
	11th to 20th	Night	13% 12% 37% 31% 7%	868
	21st to end	Night	19% 14% 35% 24% 8%	1000
December	1st to 10th	Night	18% 14% 37% 26% 4	1000
	11th to 20th	Night	19% 15% 36% 26% 5%	1000
	21st to end	Night	18% 17% 38% 23% 4	1100

Page generated at 2025-11-14 23:55:56. Version ac07

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