Asheville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Asheville clear sky chart from 2005-11-06 to 2024-11-01.

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	11% 7% 3 7% 5% 5% 5% 5% 6% 8% 38%	101092
	Night	10% 7% 3 7% 5% 5% 5% 4 6% 8% 39%	97814
Transparency	Day	40% 10% 13% 19% 14% 4	100905
	Night	38% 10% 14% 19% 15% 4	97671
Seeing	Day	17% 15% 24% 22% 15% 7%	15037
	Night	16% 13% 22% 28% 19% 3	25079

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	12% 5% 2 6% 4 4 4 4 6% 9% 44%	2836
	11th to 20th	Day	11% 6% 2 6% 4 5% 5% 4 7% 6% 44%	2840
	21st to end	Day	15% 11% 5% 9% 4 3 3 3 4 6% 38%	3124
February	1st to 10th	Day	12% 9% 2 6% 5% 5% 4 4 6% 7% 40%	1790
	11th to 20th	Day	12% 10% 3 7% 5% 4 4 3 5% 6% 38%	1848
	21st to end	Day	12% 9% 3 7% 5% 5% 5% 4 5% 6% 39%	1570
March	1st to 10th	Day	18% 9% 3 7% 4 3 4 3 5% 6% 38%	3363
	11th to 20th	Day	10% 7% 3 6% 4 4 4 3 5% 5% 49%	3480
	21st to end	Day	15% 8% 2 7% 5% 4 4 4 6% 7% 39%	3815
April	1st to 10th	Day	9% 6% 2 6% 4 5% 5% 4 7% 8% 43%	2090
	11th to 20th	Day	12% 8% 2 6% 5% 3 4 4 5% 8% 42%	2275
	21st to end	Day	11% 6% 2 6% 4 5% 5% 5% 5% 7% 45%	2470
May	1st to 10th	Day	9% 8% 3 9% 6% 5% 6% 5% 7% 8% 33%	4082
	11th to 20th	Day	14% 8% 3 8% 5% 6% 6% 5% 6% 7% 30%	4081
	21st to end	Day	7% 5% 2 7% 5% 6% 6% 5% 8% 10% 39%	4476
June	1st to 10th	Day	9% 7% 2 8% 6% 7% 7% 5% 8% 10% 31%	2470
	11th to 20th	Day	6% 6% 3 7% 6% 6% 6% 6% 9% 9% 35%	2470
	21st to end	Day	7% 6% 2 7% 7% 6% 7% 6% 8% 9% 34%	2470
July	1st to 10th	Day	5% 6% 3 8% 7% 7% 7% 6% 8% 10% 32%	4120
	11th to 20th	Day	8% 6% 3 8% 6% 7% 7% 6% 8% 8% 31%	4120
	21st to end	Day	11% 8% 4 12% 9% 8% 9% 6% 7% 7% 17%	4466
August	1st to 10th	Day	10% 8% 3 9% 7% 7% 7% 6% 9% 11% 24%	4104
	11th to 20th	Day	7% 5% 3 7% 6% 7% 7% 5% 9% 12% 32%	4044
	21st to end	Day	6% 4 2 6% 5% 5% 5% 5% 6% 8% 47%	4195
September	1st to 10th	Day	9% 7% 3 8% 6% 6% 6% 5% 7% 7% 36%	2090
	11th to 20th	Day	15% 6% 3 8% 6% 6% 5% 4 7% 8% 32%	2090
	21st to end	Day	12% 6% 3 7% 5% 5% 6% 5% 6% 6% 38%	2090
October	1st to 10th	Day	11% 6% 2 7% 4 4 4 4 5% 5% 48%	2057
	11th to 20th	Day	8% 5% 3 6% 4 3 5% 3 4 5% 54%	1900
	21st to end	Day	10% 7% 2 6% 4 3 3 3 4 5% 53%	2090
November	1st to 10th	Day	8% 7% 2 5% 4 3 4 3 3 6% 56%	1769
	11th to 20th	Day	9% 6% 2 5% 5% 3 4 3 5% 6% 50%	1710
	21st to end	Day	11% 7% 3 6% 3 3 4 3 6% 7% 47%	1710
December	1st to 10th	Day	14% 8% 3 8% 5% 5% 7% 4 6% 6% 35%	1710
	11th to 20th	Day	11% 6% 2 7% 5% 5% 4 4 6% 8% 42%	2153
	21st to end	Day	15% 7% 2 6% 6% 5% 6% 5% 5% 7% 37%	3124
January	1st to 10th	Night	13% 7% 3 8% 5% 5% 6% 5% 6% 8% 35%	4109
	11th to 20th	Night	11% 8% 3 8% 5% 4 4 3 5% 7% 42%	4120
	21st to end	Night	15% 12% 4 8% 5% 4 4 3 5% 5% 36%	4532
February	1st to 10th	Night	10% 8% 3 6% 5% 4 5% 4 6% 7% 41%	2385
	11th to 20th	Night	14% 9% 3 7% 4 5% 5% 3 5% 7% 38%	2218
	21st to end	Night	12% 7% 4 8% 5% 6% 6% 5% 5% 6% 36%	1884
March	1st to 10th	Night	17% 13% 5% 10% 5% 5% 4 4 5% 4 28%	3488
	11th to 20th	Night	8% 6% 2 7% 5% 4 5% 4 6% 8% 45%	3480
	21st to end	Night	15% 7% 2 5% 5% 4 4 4 5% 7% 41%	3817
April	1st to 10th	Night	10% 7% 3 6% 5% 4 4 4 6% 8% 45%	2090
	11th to 20th	Night	9% 7% 3 6% 4 5% 4 4 6% 8% 45%	1869
	21st to end	Night	9% 6% 2 6% 5% 4 4 3 5% 8% 48%	1710
May	1st to 10th	Night	9% 8% 4 9% 5% 5% 4 4 6% 9% 36%	2813
	11th to 20th	Night	12% 8% 4 9% 6% 5% 5% 5% 6% 8% 33%	2812
	21st to end	Night	7% 4 2 7% 5% 5% 5% 5% 8% 12% 39%	3079
June	1st to 10th	Night	6% 7% 3 7% 5% 6% 7% 5% 8% 13% 34%	1710
	11th to 20th	Night	5% 7% 2 5% 5% 4 4 5% 9% 12% 41%	1710
	21st to end	Night	6% 6% 2 5% 6% 5% 6% 5% 8% 11% 42%	1710
July	1st to 10th	Night	5% 7% 3 9% 7% 6% 8% 5% 7% 11% 32%	2840
	11th to 20th	Night	7% 5% 2 7% 6% 6% 6% 6% 9% 11% 35%	2840
	21st to end	Night	10% 10% 5% 13% 8% 7% 7% 5% 7% 8% 21%	3087
August	1st to 10th	Night	7% 7% 3 8% 7% 6% 7% 6% 8% 10% 31%	2825
	11th to 20th	Night	7% 7% 3 9% 7% 7% 7% 5% 8% 9% 31%	2785
	21st to end	Night	6% 5% 2 5% 3 4 6% 4 7% 9% 48%	3423
September	1st to 10th	Night	9% 5% 2 7% 6% 6% 5% 5% 6% 8% 40%	2090
	11th to 20th	Night	13% 7% 3 10% 5% 6% 5% 3 5% 7% 35%	2090
	21st to end	Night	10% 6% 3 7% 4 5% 5% 4 5% 6% 45%	2090
October	1st to 10th	Night	12% 6% 2 7% 4 4 4 3 5% 6% 48%	2123
	11th to 20th	Night	10% 6% 2 6% 4 5% 4 4 6% 6% 48%	2280
	21st to end	Night	10% 7% 2 5% 3 3 4 3 5% 5% 53%	2508
November	1st to 10th	Night	10% 5% 3 5% 3 4 4 4 5% 6% 50%	2313
	11th to 20th	Night	11% 6% 2 6% 5% 4 4 3 5% 7% 48%	2470
	21st to end	Night	11% 6% 2 6% 4 5% 4 4 6% 7% 45%	2470
December	1st to 10th	Night	14% 8% 4 8% 5% 4 6% 5% 6% 6% 35%	2470
	11th to 20th	Night	13% 9% 3 8% 4 4 4 4 5% 7% 40%	3042
	21st to end	Night	14% 9% 3 7% 5% 5% 5% 4 6% 7% 33%	4532

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	31% 5% 11% 24% 23% 5%	2837
	11th to 20th	Day	34% 8% 11% 16% 25% 7%	2840
	21st to end	Day	42% 6% 9% 19% 20% 4	3124
February	1st to 10th	Day	41% 6% 11% 20% 18% 4	1790
	11th to 20th	Day	43% 6% 10% 18% 17% 5%	1858
	21st to end	Day	44% 7% 10% 15% 17% 6%	1570
March	1st to 10th	Day	41% 8% 10% 17% 16% 7%	3363
	11th to 20th	Day	33% 7% 10% 17% 23% 10%	3480
	21st to end	Day	41% 9% 11% 21% 14% 4	3815
April	1st to 10th	Day	34% 9% 14% 21% 18% 4	2090
	11th to 20th	Day	39% 7% 10% 18% 20% 6%	2275
	21st to end	Day	36% 9% 13% 24% 15% 3	2470
May	1st to 10th	Day	44% 11% 15% 19% 11% 1	4120
	11th to 20th	Day	45% 14% 13% 17% 10% 1	4085
	21st to end	Day	34% 13% 18% 19% 16% 1	4489
June	1st to 10th	Day	43% 15% 18% 16% 7% 1	2470
	11th to 20th	Day	40% 13% 18% 17% 10% 1	2470
	21st to end	Day	42% 13% 16% 15% 11% 2	2470
July	1st to 10th	Day	41% 16% 18% 18% 7%	4055
	11th to 20th	Day	44% 15% 20% 16% 5% 1	4051
	21st to end	Day	60% 15% 13% 9% 4	4324
August	1st to 10th	Day	48% 14% 17% 17% 3	4091
	11th to 20th	Day	37% 14% 22% 15% 9% 3	4083
	21st to end	Day	32% 11% 13% 31% 12% 2	4195
September	1st to 10th	Day	42% 10% 14% 16% 14% 3	2090
	11th to 20th	Day	46% 11% 11% 17% 13% 2	2090
	21st to end	Day	43% 9% 13% 17% 14% 5%	2090
October	1st to 10th	Day	34% 7% 13% 17% 23% 5%	2057
	11th to 20th	Day	30% 6% 11% 23% 20% 10%	1900
	21st to end	Day	32% 4 8% 23% 23% 9%	2090
November	1st to 10th	Day	30% 5% 8% 20% 27% 9%	1769
	11th to 20th	Day	32% 6% 8% 22% 25% 7%	1710
	21st to end	Day	34% 6% 9% 23% 23% 5%	1710
December	1st to 10th	Day	46% 7% 9% 19% 14% 5%	1710
	11th to 20th	Day	34% 6% 11% 21% 22% 6%	2150
	21st to end	Day	39% 8% 10% 24% 17% 2	3124
January	1st to 10th	Night	34% 8% 13% 23% 18% 5%	4109
	11th to 20th	Night	33% 8% 12% 17% 24% 7%	4120
	21st to end	Night	45% 7% 8% 16% 20% 4	4532
February	1st to 10th	Night	38% 6% 14% 20% 18% 4	2385
	11th to 20th	Night	42% 6% 11% 19% 16% 5%	2219
	21st to end	Night	43% 8% 11% 17% 16% 5%	1884
March	1st to 10th	Night	47% 13% 12% 11% 13% 4	3488
	11th to 20th	Night	30% 9% 10% 22% 20% 10%	3480
	21st to end	Night	40% 10% 11% 22% 13% 5%	3817
April	1st to 10th	Night	34% 8% 15% 22% 18% 3	2090
	11th to 20th	Night	34% 7% 12% 22% 20% 5%	1869
	21st to end	Night	32% 9% 15% 25% 16% 2	1710
May	1st to 10th	Night	40% 12% 16% 23% 9% 1	2840
	11th to 20th	Night	41% 13% 17% 20% 8%	2813
	21st to end	Night	28% 14% 23% 25% 10% 1	3087
June	1st to 10th	Night	37% 16% 20% 19% 7% 1	1710
	11th to 20th	Night	32% 13% 25% 21% 8% 1	1710
	21st to end	Night	32% 15% 19% 19% 12% 2	1710
July	1st to 10th	Night	42% 16% 19% 16% 6%	2795
	11th to 20th	Night	36% 19% 25% 16% 4 1	2786
	21st to end	Night	54% 16% 14% 11% 4	2988
August	1st to 10th	Night	40% 18% 24% 14% 4	2814
	11th to 20th	Night	39% 18% 21% 14% 8%	2812
	21st to end	Night	30% 12% 16% 33% 9% 1	3423
September	1st to 10th	Night	39% 13% 14% 19% 12% 3	2090
	11th to 20th	Night	45% 11% 13% 15% 15% 1	2090
	21st to end	Night	38% 8% 13% 21% 17% 3	2090
October	1st to 10th	Night	36% 8% 12% 18% 23% 4	2123
	11th to 20th	Night	33% 8% 11% 21% 19% 8%	2280
	21st to end	Night	30% 6% 9% 22% 25% 8%	2508
November	1st to 10th	Night	33% 8% 9% 19% 22% 8%	2313
	11th to 20th	Night	34% 5% 9% 19% 24% 9%	2470
	21st to end	Night	35% 7% 8% 23% 21% 6%	2470
December	1st to 10th	Night	44% 8% 13% 17% 14% 4	2470
	11th to 20th	Night	36% 8% 12% 17% 23% 4	3044
	21st to end	Night	42% 7% 12% 20% 15% 2	4532

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	30% 27% 33% 8% 1	270
	11th to 20th	Day	36% 22% 26% 14% 3	270
	21st to end	Day	26% 34% 28% 10% 2	297
February	1st to 10th	Day	28% 28% 30% 13% 1	270
	11th to 20th	Day	38% 31% 25% 6% 1	270
	21st to end	Day	37% 33% 22% 7% 1	225
March	1st to 10th	Day	25% 24% 29% 16% 6%	410
	11th to 20th	Day	27% 24% 29% 15% 4 1	460
	21st to end	Day	25% 25% 29% 16% 5%	506
April	1st to 10th	Day	24% 23% 26% 19% 8% 1	460
	11th to 20th	Day	19% 22% 26% 21% 10% 2	452
	21st to end	Day	19% 17% 28% 20% 12% 4	460
May	1st to 10th	Day	16% 21% 27% 21% 10% 5%	463
	11th to 20th	Day	16% 13% 24% 26% 13% 8%	487
	21st to end	Day	12% 10% 24% 24% 18% 12%	529
June	1st to 10th	Day	13% 6% 27% 27% 16% 11%	490
	11th to 20th	Day	8% 7% 24% 24% 23% 13%	490
	21st to end	Day	9% 7% 28% 25% 18% 12%	490
July	1st to 10th	Day	8% 4 14% 28% 29% 15%	485
	11th to 20th	Day	7% 4 14% 28% 26% 20%	484
	21st to end	Day	9% 2 14% 27% 31% 16%	532
August	1st to 10th	Day	17% 5% 19% 23% 19% 17%	486
	11th to 20th	Day	8% 4 20% 30% 22% 15%	479
	21st to end	Day	10% 3 16% 27% 29% 15%	539
September	1st to 10th	Day	9% 5% 17% 30% 27% 13%	490
	11th to 20th	Day	16% 7% 18% 23% 27% 10%	490
	21st to end	Day	16% 10% 18% 30% 22% 5%	490
October	1st to 10th	Day	17% 10% 19% 29% 18% 7%	490
	11th to 20th	Day	13% 17% 23% 28% 15% 3	490
	21st to end	Day	18% 14% 24% 28% 12% 3	539
November	1st to 10th	Day	17% 15% 29% 26% 11% 2	367
	11th to 20th	Day	21% 21% 34% 17% 5%	270
	21st to end	Day	17% 24% 34% 17% 7% 1	270
December	1st to 10th	Day	26% 28% 30% 14% 1	270
	11th to 20th	Day	23% 22% 32% 17% 6% 1	270
	21st to end	Day	25% 23% 36% 11% 5% 1	297
January	1st to 10th	Night	25% 22% 26% 22% 5%	760
	11th to 20th	Night	20% 22% 30% 23% 4	760
	21st to end	Night	20% 22% 33% 23% 3	836
February	1st to 10th	Night	18% 18% 31% 28% 4	760
	11th to 20th	Night	25% 26% 28% 20% 1	743
	21st to end	Night	22% 26% 30% 20% 2	628
March	1st to 10th	Night	19% 22% 29% 26% 4	760
	11th to 20th	Night	21% 18% 32% 21% 8% 1	760
	21st to end	Night	20% 18% 33% 22% 7%	836
April	1st to 10th	Night	17% 23% 28% 25% 8%	760
	11th to 20th	Night	17% 18% 27% 26% 11% 1	655
	21st to end	Night	13% 13% 23% 35% 15% 1	570
May	1st to 10th	Night	14% 12% 25% 32% 17% 1	570
	11th to 20th	Night	14% 9% 20% 32% 22% 2	561
	21st to end	Night	11% 5% 16% 29% 33% 7%	617
June	1st to 10th	Night	8% 4 16% 37% 30% 6%	570
	11th to 20th	Night	7% 2 16% 29% 35% 10%	570
	21st to end	Night	6% 3 12% 35% 37% 6%	570
July	1st to 10th	Night	10% 3 8% 25% 46% 7%	555
	11th to 20th	Night	8% 4 7% 24% 45% 12%	552
	21st to end	Night	8% 2 7% 29% 43% 12%	624
August	1st to 10th	Night	10% 2 11% 26% 41% 10%	567
	11th to 20th	Night	12% 3 11% 28% 38% 9%	564
	21st to end	Night	9% 2 9% 28% 43% 9%	676
September	1st to 10th	Night	10% 3 15% 29% 37% 6%	760
	11th to 20th	Night	15% 6% 16% 27% 32% 5%	760
	21st to end	Night	15% 7% 17% 31% 27% 3	760
October	1st to 10th	Night	15% 10% 18% 26% 25% 6%	760
	11th to 20th	Night	15% 11% 25% 29% 18% 2	760
	21st to end	Night	16% 13% 19% 34% 15% 3	836
November	1st to 10th	Night	16% 10% 21% 34% 17% 3	743
	11th to 20th	Night	18% 14% 24% 33% 11% 1	760
	21st to end	Night	18% 16% 23% 30% 13% 1	760
December	1st to 10th	Night	23% 18% 25% 28% 6%	760
	11th to 20th	Night	17% 15% 29% 30% 7% 1	760
	21st to end	Night	23% 18% 26% 28% 6%	836

Page generated at 2024-10-29 11:20:48. Version ac07

Copyright © 2024 Attilla Danko.