Fayetteville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fayetteville clear sky chart from 2005-11-06 to 2025-07-06.

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	12% 6% 2 6% 4 4 4 4 6% 8% 42%	120129
	Night	13% 6% 2 6% 4 4 4 3 5% 7% 44%	118685
Transparency	Day	38% 7% 11% 19% 19% 6%	123775
	Night	38% 6% 10% 18% 20% 7%	123176
Seeing	Day	15% 9% 23% 25% 20% 9%	16472
	Night	15% 7% 24% 33% 18% 2	26590

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	14% 5% 2 4 4 3 3 2 2 5% 57%	4056
	11th to 20th	Day	12% 6% 2 4 3 3 2 2 3 4 59%	4060
	21st to end	Day	13% 8% 3 6% 5% 4 4 3 4 4 45%	4466
February	1st to 10th	Day	15% 7% 2 6% 4 3 4 4 6% 7% 43%	1800
	11th to 20th	Day	22% 6% 2 5% 3 3 3 3 4 5% 44%	1785
	21st to end	Day	17% 7% 2 5% 5% 4 4 3 5% 6% 42%	1815
March	1st to 10th	Day	20% 7% 2 6% 4 4 5% 3 5% 6% 39%	4935
	11th to 20th	Day	9% 5% 2 5% 3 4 4 3 5% 7% 52%	4980
	21st to end	Day	13% 6% 2 6% 4 4 4 3 4 5% 49%	5465
April	1st to 10th	Day	10% 4 2 4 3 4 3 4 5% 8% 53%	2315
	11th to 20th	Day	10% 5% 1 4 4 4 4 4 6% 7% 50%	2374
	21st to end	Day	11% 5% 1 5% 4 4 4 4 6% 7% 49%	2400
May	1st to 10th	Day	8% 7% 2 8% 6% 6% 5% 4 7% 11% 35%	5726
	11th to 20th	Day	17% 7% 3 7% 5% 5% 5% 5% 7% 9% 30%	5861
	21st to end	Day	11% 5% 2 6% 4 5% 5% 4 6% 9% 44%	6433
June	1st to 10th	Day	10% 5% 3 6% 6% 5% 5% 5% 7% 9% 38%	2600
	11th to 20th	Day	8% 5% 2 6% 5% 5% 5% 5% 7% 11% 42%	2600
	21st to end	Day	7% 5% 2 7% 6% 5% 6% 5% 9% 11% 39%	2600
July	1st to 10th	Day	7% 5% 2 8% 6% 6% 7% 7% 9% 11% 32%	4185
	11th to 20th	Day	9% 7% 3 9% 6% 6% 7% 6% 9% 11% 28%	4120
	21st to end	Day	9% 9% 3 9% 7% 6% 6% 6% 8% 11% 27%	4466
August	1st to 10th	Day	20% 9% 4 9% 6% 5% 6% 5% 7% 8% 20%	4104
	11th to 20th	Day	10% 7% 3 7% 6% 6% 6% 5% 8% 10% 32%	3887
	21st to end	Day	6% 4 1 5% 5% 5% 5% 5% 7% 11% 47%	4180
September	1st to 10th	Day	9% 4 2 5% 5% 5% 6% 5% 8% 9% 43%	2280
	11th to 20th	Day	13% 6% 2 8% 4 4 5% 3 6% 8% 41%	2142
	21st to end	Day	17% 7% 2 7% 4 4 4 4 6% 6% 37%	2051
October	1st to 10th	Day	15% 6% 2 5% 4 3 3 3 5% 6% 47%	1900
	11th to 20th	Day	11% 5% 1 4 3 3 3 3 5% 6% 57%	1900
	21st to end	Day	11% 4 2 6% 3 3 3 2 4 6% 57%	2090
November	1st to 10th	Day	14% 5% 2 4 3 3 3 3 5% 6% 53%	1957
	11th to 20th	Day	15% 6% 1 5% 3 3 4 3 5% 6% 52%	2000
	21st to end	Day	13% 6% 2 5% 4 3 4 3 5% 7% 50%	1827
December	1st to 10th	Day	11% 5% 2 6% 4 4 3 4 4 5% 52%	2930
	11th to 20th	Day	15% 6% 3 6% 4 4 3 3 5% 6% 46%	3373
	21st to end	Day	16% 7% 3 6% 4 3 3 3 4 6% 45%	4466
January	1st to 10th	Night	11% 5% 2 5% 3 3 3 3 5% 5% 56%	5889
	11th to 20th	Night	13% 6% 2 5% 3 4 4 3 4 5% 52%	5900
	21st to end	Night	14% 8% 3 6% 4 4 4 3 4 6% 46%	6490
February	1st to 10th	Night	17% 6% 2 5% 4 4 4 3 5% 6% 45%	2600
	11th to 20th	Night	19% 6% 2 6% 4 4 3 3 5% 5% 42%	2495
	21st to end	Night	14% 7% 2 5% 3 4 4 3 5% 6% 47%	1815
March	1st to 10th	Night	18% 8% 3 7% 4 3 4 3 4 5% 40%	4918
	11th to 20th	Night	12% 4 2 4 3 4 5% 3 5% 7% 52%	4980
	21st to end	Night	13% 5% 2 5% 4 4 4 4 5% 5% 49%	5467
April	1st to 10th	Night	12% 6% 2 5% 4 4 4 3 5% 6% 49%	2083
	11th to 20th	Night	10% 4 2 5% 4 4 4 3 5% 7% 52%	1975
	21st to end	Night	10% 4 1 5% 4 5% 5% 5% 6% 7% 48%	2000
May	1st to 10th	Night	9% 7% 3 8% 5% 5% 5% 4 6% 10% 38%	4197
	11th to 20th	Night	17% 8% 3 7% 5% 4 5% 3 5% 9% 34%	4032
	21st to end	Night	13% 6% 2 6% 5% 4 5% 4 6% 9% 41%	4421
June	1st to 10th	Night	10% 6% 2 5% 5% 6% 6% 5% 9% 10% 36%	1800
	11th to 20th	Night	10% 7% 2 6% 5% 5% 5% 4 6% 10% 39%	1800
	21st to end	Night	7% 5% 2 6% 5% 5% 6% 5% 9% 11% 38%	1800
July	1st to 10th	Night	9% 7% 3 8% 6% 6% 7% 6% 8% 11% 30%	2885
	11th to 20th	Night	12% 8% 3 7% 5% 5% 6% 5% 9% 12% 29%	2840
	21st to end	Night	15% 11% 4 9% 6% 5% 6% 4 6% 8% 25%	3087
August	1st to 10th	Night	20% 9% 3 9% 6% 5% 6% 4 6% 9% 24%	2825
	11th to 20th	Night	8% 6% 2 9% 6% 5% 7% 5% 8% 11% 32%	2908
	21st to end	Night	6% 4 2 5% 5% 5% 5% 5% 7% 10% 46%	3476
September	1st to 10th	Night	9% 5% 2 6% 4 4 4 4 7% 9% 44%	1900
	11th to 20th	Night	13% 6% 3 7% 5% 5% 4 4 6% 8% 39%	2033
	21st to end	Night	18% 7% 2 8% 5% 4 4 3 4 6% 38%	2128
October	1st to 10th	Night	14% 6% 2 5% 3 3 3 3 5% 6% 49%	2280
	11th to 20th	Night	11% 5% 2 5% 4 3 4 2 4 5% 55%	2280
	21st to end	Night	10% 5% 2 5% 3 3 3 2 4 7% 56%	2508
November	1st to 10th	Night	13% 6% 2 5% 3 3 3 3 4 4 54%	2341
	11th to 20th	Night	14% 7% 2 5% 4 3 3 3 4 6% 49%	2400
	21st to end	Night	13% 4 2 5% 4 3 4 2 5% 6% 52%	2570
December	1st to 10th	Night	12% 6% 2 5% 3 3 3 2 4 5% 54%	4250
	11th to 20th	Night	15% 8% 3 8% 5% 4 4 3 4 5% 41%	4822
	21st to end	Night	14% 6% 2 6% 4 4 4 3 4 6% 47%	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	33% 3 5% 19% 32% 9%	4057
	11th to 20th	Day	32% 3 4 17% 34% 11%	4060
	21st to end	Day	42% 4 5% 16% 22% 11%	4466
February	1st to 10th	Day	40% 4 12% 19% 19% 6%	1800
	11th to 20th	Day	43% 4 7% 17% 23% 6%	1794
	21st to end	Day	43% 5% 9% 17% 21% 6%	1815
March	1st to 10th	Day	47% 4 6% 15% 19% 10%	4935
	11th to 20th	Day	32% 5% 8% 14% 28% 14%	4980
	21st to end	Day	38% 4 9% 21% 21% 7%	5465
April	1st to 10th	Day	30% 4 13% 22% 24% 7%	2315
	11th to 20th	Day	32% 5% 11% 24% 21% 8%	2374
	21st to end	Day	33% 7% 13% 24% 19% 5%	2400
May	1st to 10th	Day	40% 9% 17% 23% 10% 1	5759
	11th to 20th	Day	48% 8% 13% 20% 11% 1	5865
	21st to end	Day	35% 7% 14% 21% 19% 3	6447
June	1st to 10th	Day	39% 9% 15% 21% 15% 1	2600
	11th to 20th	Day	34% 10% 18% 22% 14% 2	2600
	21st to end	Day	35% 11% 19% 21% 13% 2	2600
July	1st to 10th	Day	38% 12% 18% 20% 10% 2	4120
	11th to 20th	Day	45% 13% 23% 13% 4 1	4051
	21st to end	Day	47% 12% 16% 16% 9% 1	4324
August	1st to 10th	Day	58% 10% 17% 10% 5%	4091
	11th to 20th	Day	43% 10% 15% 21% 10% 1	3926
	21st to end	Day	30% 7% 15% 30% 15% 2	4180
September	1st to 10th	Day	35% 11% 15% 17% 18% 4	2280
	11th to 20th	Day	40% 7% 12% 16% 21% 4	2142
	21st to end	Day	45% 6% 9% 18% 16% 4	2051
October	1st to 10th	Day	36% 4 7% 21% 25% 7%	3160
	11th to 20th	Day	20% 3 6% 19% 26% 27%	3140
	21st to end	Day	24% 3 5% 25% 26% 17%	3428
November	1st to 10th	Day	33% 4 7% 21% 26% 8%	1957
	11th to 20th	Day	35% 4 8% 21% 25% 8%	2000
	21st to end	Day	35% 4 7% 23% 23% 8%	1827
December	1st to 10th	Day	34% 5% 7% 18% 24% 12%	2930
	11th to 20th	Day	40% 4 12% 18% 20% 6%	3370
	21st to end	Day	40% 4 9% 23% 21% 2	4466
January	1st to 10th	Night	30% 4 6% 17% 37% 8%	5889
	11th to 20th	Night	36% 4 6% 14% 33% 8%	5900
	21st to end	Night	40% 4 5% 16% 27% 8%	6490
February	1st to 10th	Night	40% 4 9% 19% 20% 7%	2600
	11th to 20th	Night	44% 4 9% 15% 21% 7%	2497
	21st to end	Night	38% 4 9% 17% 23% 9%	1815
March	1st to 10th	Night	47% 5% 5% 12% 24% 7%	4918
	11th to 20th	Night	32% 5% 7% 12% 26% 17%	4980
	21st to end	Night	37% 5% 9% 21% 22% 7%	5467
April	1st to 10th	Night	35% 5% 11% 18% 22% 9%	2083
	11th to 20th	Night	32% 6% 10% 23% 21% 9%	1975
	21st to end	Night	33% 7% 13% 24% 19% 5%	2000
May	1st to 10th	Night	39% 8% 19% 20% 13% 2	4226
	11th to 20th	Night	46% 7% 15% 19% 12%	4033
	21st to end	Night	37% 8% 14% 23% 16% 2	4429
June	1st to 10th	Night	38% 11% 18% 21% 12% 1	1800
	11th to 20th	Night	38% 10% 19% 20% 12% 1	1800
	21st to end	Night	36% 11% 18% 23% 11% 2	1800
July	1st to 10th	Night	44% 13% 17% 18% 7% 1	2840
	11th to 20th	Night	45% 12% 24% 13% 4 1	2786
	21st to end	Night	55% 9% 13% 15% 9%	2988
August	1st to 10th	Night	56% 9% 18% 14% 4	2814
	11th to 20th	Night	43% 11% 20% 20% 6% 1	2935
	21st to end	Night	31% 8% 13% 31% 16% 2	3476
September	1st to 10th	Night	35% 9% 16% 20% 15% 5%	1900
	11th to 20th	Night	42% 7% 13% 17% 18% 3	2033
	21st to end	Night	48% 6% 12% 16% 15% 4	2128
October	1st to 10th	Night	38% 5% 7% 21% 23% 7%	3800
	11th to 20th	Night	22% 3 5% 16% 27% 27%	3779
	21st to end	Night	24% 4 7% 24% 24% 17%	4120
November	1st to 10th	Night	35% 4 6% 18% 26% 11%	2341
	11th to 20th	Night	37% 4 7% 16% 25% 11%	2400
	21st to end	Night	33% 4 7% 21% 26% 8%	2570
December	1st to 10th	Night	33% 4 7% 16% 30% 10%	4250
	11th to 20th	Night	46% 5% 9% 16% 16% 8%	4824
	21st to end	Night	39% 4 10% 23% 22% 2	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	15% 22% 37% 22% 4	300
	11th to 20th	Day	17% 23% 36% 18% 6% 1	300
	21st to end	Day	18% 19% 38% 19% 5%	330
February	1st to 10th	Day	18% 16% 40% 21% 5%	300
	11th to 20th	Day	33% 14% 37% 14% 2	327
	21st to end	Day	21% 15% 33% 22% 8%	414
March	1st to 10th	Day	20% 16% 30% 24% 9%	500
	11th to 20th	Day	20% 14% 37% 21% 6% 1	500
	21st to end	Day	19% 13% 34% 24% 9% 1	550
April	1st to 10th	Day	18% 17% 30% 24% 10% 2	500
	11th to 20th	Day	11% 15% 29% 26% 15% 4	492
	21st to end	Day	14% 10% 27% 24% 21% 4	500
May	1st to 10th	Day	10% 13% 34% 24% 14% 5%	503
	11th to 20th	Day	15% 6% 20% 28% 23% 9%	527
	21st to end	Day	14% 7% 17% 24% 23% 15%	573
June	1st to 10th	Day	12% 3 20% 30% 25% 10%	530
	11th to 20th	Day	11% 2 14% 28% 29% 15%	530
	21st to end	Day	6% 3 15% 26% 34% 17%	530
July	1st to 10th	Day	10% 2 6% 26% 34% 22%	505
	11th to 20th	Day	9% 1 8% 24% 37% 21%	484
	21st to end	Day	6% 2 10% 29% 39% 13%	532
August	1st to 10th	Day	14% 4 11% 24% 28% 19%	486
	11th to 20th	Day	11% 3 10% 22% 33% 22%	479
	21st to end	Day	12% 2 8% 26% 29% 24%	539
September	1st to 10th	Day	10% 3 13% 25% 25% 24%	490
	11th to 20th	Day	16% 4 12% 25% 30% 13%	490
	21st to end	Day	20% 4 20% 26% 23% 7%	490
October	1st to 10th	Day	19% 6% 20% 22% 24% 10%	490
	11th to 20th	Day	12% 7% 26% 27% 22% 6%	490
	21st to end	Day	12% 7% 23% 31% 22% 6%	539
November	1st to 10th	Day	18% 7% 22% 32% 16% 5%	495
	11th to 20th	Day	17% 8% 33% 29% 11% 2	500
	21st to end	Day	14% 13% 27% 29% 15% 2	327
December	1st to 10th	Day	19% 12% 43% 19% 7%	300
	11th to 20th	Day	19% 10% 35% 23% 11% 2	300
	21st to end	Day	22% 13% 35% 19% 9% 3	330
January	1st to 10th	Night	18% 12% 34% 29% 7% 1	800
	11th to 20th	Night	17% 12% 33% 31% 7%	800
	21st to end	Night	19% 9% 38% 31% 3	880
February	1st to 10th	Night	19% 10% 36% 31% 4	800
	11th to 20th	Night	23% 14% 37% 24% 1	783
	21st to end	Night	18% 12% 37% 29% 4	660
March	1st to 10th	Night	17% 12% 35% 30% 6% 1	800
	11th to 20th	Night	17% 11% 37% 27% 7% 1	800
	21st to end	Night	18% 11% 35% 30% 6%	880
April	1st to 10th	Night	16% 13% 34% 30% 7%	800
	11th to 20th	Night	12% 11% 33% 32% 11%	791
	21st to end	Night	12% 6% 31% 40% 10%	800
May	1st to 10th	Night	10% 10% 31% 37% 12%	675
	11th to 20th	Night	14% 6% 22% 40% 17% 1	591
	21st to end	Night	11% 2 17% 37% 31% 2	650
June	1st to 10th	Night	12% 2 17% 44% 22% 3	600
	11th to 20th	Night	11% 3 13% 39% 29% 6%	600
	21st to end	Night	7% 3 14% 38% 34% 4	600
July	1st to 10th	Night	10% 2 9% 36% 39% 5%	570
	11th to 20th	Night	9% 1 7% 37% 41% 5%	552
	21st to end	Night	8% 3 10% 40% 36% 3	624
August	1st to 10th	Night	12% 2 9% 34% 38% 4	567
	11th to 20th	Night	11% 2 9% 36% 37% 5%	635
	21st to end	Night	12% 2 9% 33% 38% 7%	836
September	1st to 10th	Night	11% 2 10% 33% 38% 6%	760
	11th to 20th	Night	16% 2 12% 31% 35% 5%	760
	21st to end	Night	22% 5% 16% 31% 24% 3	760
October	1st to 10th	Night	17% 4 16% 29% 29% 5%	760
	11th to 20th	Night	13% 4 26% 32% 22% 2	760
	21st to end	Night	13% 6% 24% 33% 22% 3	836
November	1st to 10th	Night	16% 6% 22% 37% 17% 3	780
	11th to 20th	Night	17% 8% 27% 33% 14% 1	800
	21st to end	Night	14% 7% 29% 33% 16% 1	800
December	1st to 10th	Night	19% 10% 28% 36% 8%	800
	11th to 20th	Night	19% 8% 27% 35% 10%	800
	21st to end	Night	20% 10% 26% 35% 9%	880

Page generated at 2025-07-03 01:30:18. Version ac07

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