Fayette
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fayette clear sky chart from 2005-11-06 to 2025-07-21.

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	13% 8% 3 6% 4 4 4 3 5% 7% 43%	120323
	Night	13% 8% 3 7% 4 4 4 3 5% 6% 45%	119026
Transparency	Day	39% 4 12% 25% 17% 3	123968
	Night	40% 4 11% 24% 18% 3	123524
Seeing	Day	16% 8% 26% 28% 17% 5%	16649
	Night	16% 8% 29% 33% 14% 1	26474

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% 12% 4 10% 4 5% 4 4 4 6% 33%	3801
	11th to 20th	Day	9% 9% 4 10% 5% 7% 5% 3 4 4 41%	4080
	21st to end	Day	15% 14% 5% 9% 4 4 4 3 4 4 36%	4488
February	1st to 10th	Day	17% 9% 4 9% 6% 4 3 4 5% 6% 34%	1800
	11th to 20th	Day	14% 10% 3 8% 5% 4 4 3 4 5% 40%	1778
	21st to end	Day	13% 12% 4 6% 4 3 4 3 4 5% 41%	1650
March	1st to 10th	Day	16% 10% 3 4 3 2 2 2 3 5% 51%	4931
	11th to 20th	Day	10% 6% 2 5% 4 3 3 3 5% 6% 52%	4980
	21st to end	Day	16% 11% 3 8% 5% 4 4 3 5% 7% 33%	5502
April	1st to 10th	Day	16% 8% 3 7% 4 3 3 3 4 6% 43%	2400
	11th to 20th	Day	17% 8% 3 7% 4 3 4 3 5% 6% 41%	2374
	21st to end	Day	22% 6% 3 6% 5% 5% 4 4 6% 5% 34%	2400
May	1st to 10th	Day	14% 8% 2 7% 5% 4 5% 4 7% 9% 36%	5830
	11th to 20th	Day	15% 7% 2 6% 4 4 4 3 5% 7% 42%	6080
	21st to end	Day	18% 7% 2 6% 4 4 4 4 5% 6% 40%	6935
June	1st to 10th	Day	8% 5% 2 6% 5% 4 5% 5% 6% 9% 47%	2800
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 4 6% 9% 47%	2800
	21st to end	Day	7% 4 2 6% 4 5% 5% 4 7% 9% 48%	2800
July	1st to 10th	Day	13% 6% 3 6% 4 4 4 4 6% 9% 41%	4580
	11th to 20th	Day	6% 4 2 5% 4 4 4 4 7% 10% 51%	4364
	21st to end	Day	8% 4 2 6% 5% 5% 5% 5% 7% 10% 44%	4466
August	1st to 10th	Day	4 4 2 4 4 4 5% 5% 7% 11% 51%	4104
	11th to 20th	Day	11% 5% 2 6% 5% 4 4 4 6% 8% 45%	3951
	21st to end	Day	6% 4 2 4 4 4 5% 4 6% 9% 53%	4180
September	1st to 10th	Day	10% 5% 2 4 4 4 4 3 4 6% 53%	2280
	11th to 20th	Day	9% 5% 2 5% 4 3 4 3 4 9% 52%	2277
	21st to end	Day	8% 5% 1 6% 5% 4 5% 3 5% 6% 53%	1981
October	1st to 10th	Day	12% 5% 2 6% 3 2 3 3 5% 4 55%	1900
	11th to 20th	Day	15% 6% 2 5% 3 3 3 2 4 5% 53%	1900
	21st to end	Day	18% 7% 2 6% 3 3 3 3 4 5% 47%	2090
November	1st to 10th	Day	12% 7% 2 5% 2 4 3 2 5% 7% 50%	1886
	11th to 20th	Day	15% 7% 2 6% 3 2 2 3 4 7% 49%	1735
	21st to end	Day	17% 10% 3 6% 4 3 3 3 4 6% 42%	1600
December	1st to 10th	Day	7% 9% 3 7% 3 3 3 3 4 6% 52%	2610
	11th to 20th	Day	12% 9% 4 8% 4 3 4 2 4 6% 44%	3008
	21st to end	Day	21% 20% 7% 10% 4 3 4 3 4 4 21%	3982
January	1st to 10th	Night	14% 11% 7% 14% 5% 4 4 2 4 4 32%	6147
	11th to 20th	Night	12% 9% 4 12% 5% 5% 5% 4 4 4 36%	5900
	21st to end	Night	15% 12% 5% 7% 4 4 4 3 4 5% 37%	6490
February	1st to 10th	Night	15% 11% 4 8% 6% 4 4 3 4 6% 36%	2600
	11th to 20th	Night	15% 9% 4 6% 4 4 4 3 5% 6% 40%	2508
	21st to end	Night	15% 9% 4 7% 3 3 3 3 5% 4 45%	1980
March	1st to 10th	Night	16% 10% 3 7% 3 3 3 2 4 4 45%	4965
	11th to 20th	Night	10% 6% 2 5% 3 3 3 3 4 6% 53%	4980
	21st to end	Night	16% 10% 4 8% 5% 4 5% 3 5% 6% 34%	5427
April	1st to 10th	Night	12% 7% 2 6% 3 4 4 3 5% 6% 47%	2000
	11th to 20th	Night	15% 6% 3 6% 5% 3 4 3 5% 6% 46%	1975
	21st to end	Night	18% 7% 2 7% 4 5% 4 3 5% 6% 40%	2000
May	1st to 10th	Night	16% 7% 2 7% 5% 5% 4 3 6% 8% 37%	4080
	11th to 20th	Night	12% 6% 3 6% 4 3 4 4 5% 9% 44%	3831
	21st to end	Night	15% 6% 2 6% 3 4 3 3 5% 8% 45%	3942
June	1st to 10th	Night	7% 4 2 4 4 4 4 4 6% 8% 54%	1600
	11th to 20th	Night	5% 5% 2 5% 5% 4 5% 4 7% 9% 50%	1600
	21st to end	Night	4 3 1 4 5% 4 4 3 6% 9% 57%	1600
July	1st to 10th	Night	13% 6% 2 6% 3 3 4 3 5% 9% 46%	2610
	11th to 20th	Night	5% 2 1 4 4 4 4 3 5% 9% 59%	2808
	21st to end	Night	7% 3 2 5% 5% 4 5% 5% 6% 10% 48%	3098
August	1st to 10th	Night	4 2 1 3 2 3 4 4 6% 10% 62%	2836
	11th to 20th	Night	12% 5% 2 4 3 4 3 3 5% 7% 52%	2882
	21st to end	Night	4 3 1 4 3 4 4 4 6% 9% 57%	3476
September	1st to 10th	Night	11% 4 1 4 3 3 4 3 4 5% 59%	1900
	11th to 20th	Night	9% 5% 1 5% 3 4 4 4 6% 7% 51%	1900
	21st to end	Night	8% 5% 2 6% 3 3 3 3 4 6% 56%	2178
October	1st to 10th	Night	9% 4 1 4 2 3 3 3 5% 7% 58%	2280
	11th to 20th	Night	14% 6% 2 5% 3 3 3 2 4 5% 54%	2280
	21st to end	Night	17% 8% 2 5% 3 3 3 3 4 5% 48%	2508
November	1st to 10th	Night	11% 5% 2 5% 4 3 3 3 4 6% 56%	2410
	11th to 20th	Night	12% 7% 2 6% 4 3 3 3 5% 6% 50%	2660
	21st to end	Night	17% 8% 2 5% 4 3 3 2 4 4 46%	2800
December	1st to 10th	Night	10% 8% 2 6% 4 3 3 3 4 7% 50%	4580
	11th to 20th	Night	16% 9% 3 6% 3 3 4 3 4 6% 43%	5199
	21st to end	Night	23% 17% 6% 9% 4 4 4 3 3 4 25%	6996

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	53% 4 10% 20% 10% 2	3802
	11th to 20th	Day	48% 3 11% 21% 14% 4	4080
	21st to end	Day	52% 3 10% 14% 18% 3	4488
February	1st to 10th	Day	52% 3 12% 21% 11% 1	1800
	11th to 20th	Day	47% 3 11% 20% 16% 3	1787
	21st to end	Day	47% 2 8% 23% 17% 3	1650
March	1st to 10th	Day	39% 2 8% 25% 23% 2	4931
	11th to 20th	Day	33% 4 9% 25% 23% 6%	4980
	21st to end	Day	51% 4 16% 23% 5%	5504
April	1st to 10th	Day	44% 3 11% 27% 15% 1	2400
	11th to 20th	Day	45% 3 11% 25% 13% 3	2374
	21st to end	Day	50% 5% 12% 21% 12% 1	2400
May	1st to 10th	Day	43% 6% 15% 23% 12% 1	5868
	11th to 20th	Day	42% 5% 12% 26% 12% 2	6084
	21st to end	Day	43% 6% 9% 25% 16% 1	6949
June	1st to 10th	Day	32% 7% 16% 30% 15% 1	2800
	11th to 20th	Day	33% 6% 13% 29% 17% 3	2800
	21st to end	Day	31% 6% 17% 28% 15% 4	2800
July	1st to 10th	Day	39% 6% 12% 25% 16% 2	4511
	11th to 20th	Day	28% 6% 15% 31% 18% 1	4291
	21st to end	Day	33% 9% 18% 29% 12% 1	4326
August	1st to 10th	Day	26% 5% 18% 34% 16% 1	4090
	11th to 20th	Day	36% 5% 13% 28% 16% 1	3990
	21st to end	Day	26% 6% 18% 32% 14% 4	4179
September	1st to 10th	Day	32% 4 11% 25% 22% 6%	2280
	11th to 20th	Day	31% 4 10% 27% 23% 4	2277
	21st to end	Day	31% 5% 10% 28% 23% 4	1981
October	1st to 10th	Day	20% 2 6% 21% 40% 11%	3160
	11th to 20th	Day	23% 2 5% 21% 39% 9%	3140
	21st to end	Day	37% 3 8% 24% 26% 2	3428
November	1st to 10th	Day	35% 3 13% 23% 21% 5%	1886
	11th to 20th	Day	37% 2 10% 26% 21% 4	1735
	21st to end	Day	46% 3 8% 28% 14% 1	1600
December	1st to 10th	Day	35% 3 15% 30% 16% 1	2610
	11th to 20th	Day	43% 3 14% 28% 11% 1	3005
	21st to end	Day	68% 3 12% 12% 5%	3982
January	1st to 10th	Night	57% 3 9% 21% 9% 1	6147
	11th to 20th	Night	51% 3 10% 20% 13% 3	5900
	21st to end	Night	51% 3 10% 18% 16% 2	6490
February	1st to 10th	Night	51% 4 12% 20% 11% 3	2600
	11th to 20th	Night	45% 4 11% 21% 17% 2	2509
	21st to end	Night	43% 3 10% 23% 18% 4	1980
March	1st to 10th	Night	44% 3 8% 21% 22% 3	4965
	11th to 20th	Night	33% 4 7% 25% 26% 5%	4980
	21st to end	Night	50% 5% 12% 23% 8% 2	5427
April	1st to 10th	Night	38% 4 10% 26% 19% 3	2000
	11th to 20th	Night	40% 3 9% 27% 16% 5%	1975
	21st to end	Night	45% 4 10% 23% 17% 1	2000
May	1st to 10th	Night	45% 6% 14% 20% 15% 1	4107
	11th to 20th	Night	38% 6% 12% 27% 14% 4	3832
	21st to end	Night	38% 5% 11% 23% 21% 2	3950
June	1st to 10th	Night	27% 5% 16% 32% 16% 3	1600
	11th to 20th	Night	30% 7% 11% 27% 22% 4	1600
	21st to end	Night	24% 4 16% 30% 20% 5%	1600
July	1st to 10th	Night	37% 4 12% 27% 17% 3	2570
	11th to 20th	Night	22% 5% 14% 36% 21% 2	2758
	21st to end	Night	29% 7% 21% 30% 13% 1	2999
August	1st to 10th	Night	19% 4 20% 34% 21% 1	2826
	11th to 20th	Night	32% 5% 13% 28% 19% 2	2909
	21st to end	Night	23% 5% 17% 34% 16% 4	3476
September	1st to 10th	Night	27% 4 11% 24% 27% 7%	1900
	11th to 20th	Night	30% 5% 9% 26% 24% 6%	1900
	21st to end	Night	30% 4 7% 29% 27% 4	2178
October	1st to 10th	Night	17% 3 6% 21% 46% 8%	3800
	11th to 20th	Night	24% 2 6% 22% 32% 13%	3779
	21st to end	Night	35% 3 8% 26% 26% 2	4120
November	1st to 10th	Night	31% 3 12% 28% 21% 5%	2410
	11th to 20th	Night	36% 3 8% 26% 23% 4	2660
	21st to end	Night	43% 3 9% 25% 17% 2	2800
December	1st to 10th	Night	36% 3 11% 36% 13% 1	4580
	11th to 20th	Night	43% 3 13% 25% 15% 1	5201
	21st to end	Night	65% 3 12% 13% 5% 1	6996

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	22% 13% 34% 25% 6%	300
	11th to 20th	Day	29% 17% 37% 15% 2	300
	21st to end	Day	18% 12% 44% 21% 4	330
February	1st to 10th	Day	23% 13% 45% 16% 3	300
	11th to 20th	Day	25% 17% 35% 17% 5%	300
	21st to end	Day	19% 21% 41% 15% 4	249
March	1st to 10th	Day	19% 17% 41% 20% 2	300
	11th to 20th	Day	28% 12% 33% 22% 6%	300
	21st to end	Day	35% 14% 32% 14% 4	345
April	1st to 10th	Day	23% 14% 32% 23% 7% 1	500
	11th to 20th	Day	23% 15% 31% 21% 9% 1	492
	21st to end	Day	24% 10% 32% 26% 7% 1	500
May	1st to 10th	Day	19% 9% 32% 29% 10% 1	684
	11th to 20th	Day	21% 8% 23% 28% 15% 4	725
	21st to end	Day	15% 7% 27% 26% 19% 6%	789
June	1st to 10th	Day	9% 3 17% 36% 25% 9%	730
	11th to 20th	Day	10% 3 22% 35% 23% 7%	730
	21st to end	Day	6% 5% 27% 37% 20% 4	730
July	1st to 10th	Day	10% 2 14% 29% 32% 14%	721
	11th to 20th	Day	7% 2 16% 36% 27% 11%	718
	21st to end	Day	9% 2 14% 35% 32% 9%	740
August	1st to 10th	Day	7% 1 16% 38% 31% 8%	676
	11th to 20th	Day	10% 2 15% 37% 29% 8%	614
	21st to end	Day	9% 1 12% 31% 35% 12%	539
September	1st to 10th	Day	11% 2 13% 33% 30% 11%	490
	11th to 20th	Day	7% 3 15% 35% 30% 11%	487
	21st to end	Day	9% 6% 26% 26% 24% 8%	300
October	1st to 10th	Day	15% 7% 29% 25% 18% 7%	300
	11th to 20th	Day	14% 16% 34% 24% 11% 1	300
	21st to end	Day	27% 15% 32% 21% 6%	330
November	1st to 10th	Day	17% 10% 36% 24% 10% 4	300
	11th to 20th	Day	19% 15% 32% 24% 8% 2	300
	21st to end	Day	27% 11% 31% 24% 7%	300
December	1st to 10th	Day	13% 16% 37% 25% 7% 3	300
	11th to 20th	Day	20% 15% 36% 23% 4 1	300
	21st to end	Day	28% 17% 35% 19% 1	330
January	1st to 10th	Night	18% 13% 36% 26% 7%	1000
	11th to 20th	Night	19% 15% 36% 24% 6% 1	1000
	21st to end	Night	18% 12% 38% 28% 3	1100
February	1st to 10th	Night	20% 13% 38% 25% 4	1000
	11th to 20th	Night	22% 14% 34% 27% 3	954
	21st to end	Night	22% 13% 40% 22% 3	660
March	1st to 10th	Night	19% 14% 37% 26% 4	622
	11th to 20th	Night	22% 11% 32% 30% 6% 1	600
	21st to end	Night	26% 12% 35% 23% 5%	660
April	1st to 10th	Night	16% 11% 39% 29% 5%	600
	11th to 20th	Night	20% 11% 32% 29% 8%	593
	21st to end	Night	20% 6% 36% 33% 6%	600
May	1st to 10th	Night	17% 5% 31% 36% 10% 1	600
	11th to 20th	Night	16% 5% 23% 38% 17% 1	591
	21st to end	Night	15% 4 24% 34% 21% 2	650
June	1st to 10th	Night	9% 2 16% 45% 26% 3	600
	11th to 20th	Night	8% 2 20% 43% 25% 2	600
	21st to end	Night	5% 2 23% 50% 21% 1	600
July	1st to 10th	Night	12% 1 9% 38% 36% 4	585
	11th to 20th	Night	6% 1 12% 44% 36% 2	582
	21st to end	Night	8% 1 12% 45% 33% 2	624
August	1st to 10th	Night	7% 1 10% 47% 32% 3	567
	11th to 20th	Night	7% 2 11% 44% 34% 2	564
	21st to end	Night	6% 1 10% 40% 39% 4	627
September	1st to 10th	Night	11% 1 14% 40% 32% 3	570
	11th to 20th	Night	11% 2 13% 41% 28% 4	570
	21st to end	Night	10% 4 24% 36% 22% 4	659
October	1st to 10th	Night	12% 3 26% 33% 23% 3	760
	11th to 20th	Night	18% 8% 32% 31% 11%	760
	21st to end	Night	21% 11% 29% 30% 9%	836
November	1st to 10th	Night	13% 7% 32% 36% 11%	780
	11th to 20th	Night	15% 11% 37% 29% 7%	860
	21st to end	Night	21% 12% 33% 28% 7%	1000
December	1st to 10th	Night	19% 11% 37% 27% 6% 1	1000
	11th to 20th	Night	22% 9% 32% 30% 6%	1000
	21st to end	Night	24% 14% 31% 27% 3	1100

Page generated at 2025-07-18 00:10:01. Version ac07

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