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 TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(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

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
43%
24932
17%
95966
12%
24718
50%
24718
18%
59982

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
24%
756
20%
4001
8%
737
39%
737
12%
2099
January11th to 20thNight
23%
758
27%
3945
8%
740
38%
740
12%
2061
January21st to endNight
22%
833
15%
4453
9%
814
40%
814
11%
2785
February1st to 10thNight
29%
760
21%
2385
12%
760
40%
760
22%
1487
February11th to 20thNight
19%
742
18%
2218
6%
739
30%
739
16%
1455
February21st to endNight
21%
628
20%
1884
8%
628
32%
628
17%
1279
March1st to 10thNight
27%
759
14%
3479
11%
745
36%
745
11%
2494
March11th to 20thNight
24%
756
24%
3409
6%
740
33%
740
16%
1704
March21st to endNight
26%
834
13%
3712
6%
814
34%
814
13%
2277
April1st to 10thNight
30%
760
20%
2090
9%
760
40%
760
24%
1309
April11th to 20thNight
34%
655
22%
1869
10%
655
45%
655
26%
1157
April21st to endNight
46%
570
22%
1710
13%
570
54%
570
28%
1052
May1st to 10thNight
43%
564
16%
2785
7%
559
49%
559
14%
1757
May11th to 20thNight
47%
552
12%
2787
7%
541
51%
541
12%
1777
May21st to endNight
58%
605
12%
3047
11%
593
61%
593
18%
1605
June1st to 10thNight
61%
570
12%
1710
9%
570
63%
570
22%
1167
June11th to 20thNight
62%
570
11%
1710
8%
570
66%
570
28%
1094
June21st to endNight
67%
570
13%
1710
11%
570
69%
570
28%
1121
July1st to 10thNight
66%
539
10%
2728
8%
535
68%
535
13%
1893
July11th to 20thNight
68%
538
8%
2663
8%
533
69%
533
13%
1771
July21st to endNight
69%
608
7%
2979
9%
569
70%
569
11%
2370
August1st to 10thNight
65%
552
8%
2769
9%
544
67%
544
13%
1890
August11th to 20thNight
61%
549
9%
2691
13%
543
63%
543
13%
1849
August21st to endNight
67%
656
14%
2967
13%
654
67%
654
17%
1704
September1st to 10thNight
59%
760
18%
2090
15%
760
61%
760
24%
1451
September11th to 20thNight
51%
760
16%
2090
14%
760
53%
760
21%
1502
September21st to endNight
53%
760
21%
2090
16%
760
57%
760
27%
1367
October1st to 10thNight
50%
760
24%
2123
19%
760
56%
760
29%
1351
October11th to 20thNight
44%
760
24%
2280
18%
760
53%
760
28%
1383
October21st to endNight
47%
836
30%
2508
22%
836
59%
836
32%
1433
November1st to 10thNight
49%
743
25%
2313
19%
743
59%
743
27%
1398
November11th to 20thNight
41%
760
26%
2470
19%
760
52%
760
27%
1429
November21st to endNight
40%
760
24%
2470
16%
760
51%
760
24%
1485
December1st to 10thNight
30%
760
18%
2470
10%
760
41%
760
16%
1650
December11th to 20thNight
33%
759
22%
2959
15%
759
45%
759
20%
1759
December21st to endNight
29%
830
13%
4402
11%
817
39%
817
11%
2617

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 ForecastData
Points
Cloud CoverDay
11%7%37%5%5%5%5%6%8%38%
101092
Night
10%7%37%5%5%5%46%8%39%
97814
TransparencyDay
40%10%13%19%14%4
100905
Night
38%10%14%19%15%4
97671
SeeingDay
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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
12%5%26%44446%9%44%
2836
11th to 20thDay
11%6%26%45%5%47%6%44%
2840
21st to endDay
15%11%5%9%433346%38%
3124
February1st to 10thDay
12%9%26%5%5%446%7%40%
1790
11th to 20thDay
12%10%37%5%4435%6%38%
1848
21st to endDay
12%9%37%5%5%5%45%6%39%
1570
March1st to 10thDay
18%9%37%43435%6%38%
3363
11th to 20thDay
10%7%36%44435%5%49%
3480
21st to endDay
15%8%27%5%4446%7%39%
3815
April1st to 10thDay
9%6%26%45%5%47%8%43%
2090
11th to 20thDay
12%8%26%5%3445%8%42%
2275
21st to endDay
11%6%26%45%5%5%5%7%45%
2470
May1st to 10thDay
9%8%39%6%5%6%5%7%8%33%
4082
11th to 20thDay
14%8%38%5%6%6%5%6%7%30%
4081
21st to endDay
7%5%27%5%6%6%5%8%10%39%
4476
June1st to 10thDay
9%7%28%6%7%7%5%8%10%31%
2470
11th to 20thDay
6%6%37%6%6%6%6%9%9%35%
2470
21st to endDay
7%6%27%7%6%7%6%8%9%34%
2470
July1st to 10thDay
5%6%38%7%7%7%6%8%10%32%
4120
11th to 20thDay
8%6%38%6%7%7%6%8%8%31%
4120
21st to endDay
11%8%412%9%8%9%6%7%7%17%
4466
August1st to 10thDay
10%8%39%7%7%7%6%9%11%24%
4104
11th to 20thDay
7%5%37%6%7%7%5%9%12%32%
4044
21st to endDay
6%426%5%5%5%5%6%8%47%
4195
September1st to 10thDay
9%7%38%6%6%6%5%7%7%36%
2090
11th to 20thDay
15%6%38%6%6%5%47%8%32%
2090
21st to endDay
12%6%37%5%5%6%5%6%6%38%
2090
October1st to 10thDay
11%6%27%44445%5%48%
2057
11th to 20thDay
8%5%36%435%345%54%
1900
21st to endDay
10%7%26%433345%53%
2090
November1st to 10thDay
8%7%25%434336%56%
1769
11th to 20thDay
9%6%25%5%3435%6%50%
1710
21st to endDay
11%7%36%33436%7%47%
1710
December1st to 10thDay
14%8%38%5%5%7%46%6%35%
1710
11th to 20thDay
11%6%27%5%5%446%8%42%
2153
21st to endDay
15%7%26%6%5%6%5%5%7%37%
3124
January1st to 10thNight
13%7%38%5%5%6%5%6%8%35%
4109
11th to 20thNight
11%8%38%5%4435%7%42%
4120
21st to endNight
15%12%48%5%4435%5%36%
4532
February1st to 10thNight
10%8%36%5%45%46%7%41%
2385
11th to 20thNight
14%9%37%45%5%35%7%38%
2218
21st to endNight
12%7%48%5%6%6%5%5%6%36%
1884
March1st to 10thNight
17%13%5%10%5%5%445%428%
3488
11th to 20thNight
8%6%27%5%45%46%8%45%
3480
21st to endNight
15%7%25%5%4445%7%41%
3817
April1st to 10thNight
10%7%36%5%4446%8%45%
2090
11th to 20thNight
9%7%36%45%446%8%45%
1869
21st to endNight
9%6%26%5%4435%8%48%
1710
May1st to 10thNight
9%8%49%5%5%446%9%36%
2813
11th to 20thNight
12%8%49%6%5%5%5%6%8%33%
2812
21st to endNight
7%427%5%5%5%5%8%12%39%
3079
June1st to 10thNight
6%7%37%5%6%7%5%8%13%34%
1710
11th to 20thNight
5%7%25%5%445%9%12%41%
1710
21st to endNight
6%6%25%6%5%6%5%8%11%42%
1710
July1st to 10thNight
5%7%39%7%6%8%5%7%11%32%
2840
11th to 20thNight
7%5%27%6%6%6%6%9%11%35%
2840
21st to endNight
10%10%5%13%8%7%7%5%7%8%21%
3087
August1st to 10thNight
7%7%38%7%6%7%6%8%10%31%
2825
11th to 20thNight
7%7%39%7%7%7%5%8%9%31%
2785
21st to endNight
6%5%25%346%47%9%48%
3423
September1st to 10thNight
9%5%27%6%6%5%5%6%8%40%
2090
11th to 20thNight
13%7%310%5%6%5%35%7%35%
2090
21st to endNight
10%6%37%45%5%45%6%45%
2090
October1st to 10thNight
12%6%27%44435%6%48%
2123
11th to 20thNight
10%6%26%45%446%6%48%
2280
21st to endNight
10%7%25%33435%5%53%
2508
November1st to 10thNight
10%5%35%34445%6%50%
2313
11th to 20thNight
11%6%26%5%4435%7%48%
2470
21st to endNight
11%6%26%45%446%7%45%
2470
December1st to 10thNight
14%8%48%5%46%5%6%6%35%
2470
11th to 20thNight
13%9%38%44445%7%40%
3042
21st to endNight
14%9%37%5%5%5%46%7%33%
4532

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
31%5%11%24%23%5%
2837
11th to 20thDay
34%8%11%16%25%7%
2840
21st to endDay
42%6%9%19%20%4
3124
February1st to 10thDay
41%6%11%20%18%4
1790
11th to 20thDay
43%6%10%18%17%5%
1858
21st to endDay
44%7%10%15%17%6%
1570
March1st to 10thDay
41%8%10%17%16%7%
3363
11th to 20thDay
33%7%10%17%23%10%
3480
21st to endDay
41%9%11%21%14%4
3815
April1st to 10thDay
34%9%14%21%18%4
2090
11th to 20thDay
39%7%10%18%20%6%
2275
21st to endDay
36%9%13%24%15%3
2470
May1st to 10thDay
44%11%15%19%11%1
4120
11th to 20thDay
45%14%13%17%10%1
4085
21st to endDay
34%13%18%19%16%1
4489
June1st to 10thDay
43%15%18%16%7%1
2470
11th to 20thDay
40%13%18%17%10%1
2470
21st to endDay
42%13%16%15%11%2
2470
July1st to 10thDay
41%16%18%18%7%
4055
11th to 20thDay
44%15%20%16%5%1
4051
21st to endDay
60%15%13%9%4
4324
August1st to 10thDay
48%14%17%17%3
4091
11th to 20thDay
37%14%22%15%9%3
4083
21st to endDay
32%11%13%31%12%2
4195
September1st to 10thDay
42%10%14%16%14%3
2090
11th to 20thDay
46%11%11%17%13%2
2090
21st to endDay
43%9%13%17%14%5%
2090
October1st to 10thDay
34%7%13%17%23%5%
2057
11th to 20thDay
30%6%11%23%20%10%
1900
21st to endDay
32%48%23%23%9%
2090
November1st to 10thDay
30%5%8%20%27%9%
1769
11th to 20thDay
32%6%8%22%25%7%
1710
21st to endDay
34%6%9%23%23%5%
1710
December1st to 10thDay
46%7%9%19%14%5%
1710
11th to 20thDay
34%6%11%21%22%6%
2150
21st to endDay
39%8%10%24%17%2
3124
January1st to 10thNight
34%8%13%23%18%5%
4109
11th to 20thNight
33%8%12%17%24%7%
4120
21st to endNight
45%7%8%16%20%4
4532
February1st to 10thNight
38%6%14%20%18%4
2385
11th to 20thNight
42%6%11%19%16%5%
2219
21st to endNight
43%8%11%17%16%5%
1884
March1st to 10thNight
47%13%12%11%13%4
3488
11th to 20thNight
30%9%10%22%20%10%
3480
21st to endNight
40%10%11%22%13%5%
3817
April1st to 10thNight
34%8%15%22%18%3
2090
11th to 20thNight
34%7%12%22%20%5%
1869
21st to endNight
32%9%15%25%16%2
1710
May1st to 10thNight
40%12%16%23%9%1
2840
11th to 20thNight
41%13%17%20%8%
2813
21st to endNight
28%14%23%25%10%1
3087
June1st to 10thNight
37%16%20%19%7%1
1710
11th to 20thNight
32%13%25%21%8%1
1710
21st to endNight
32%15%19%19%12%2
1710
July1st to 10thNight
42%16%19%16%6%
2795
11th to 20thNight
36%19%25%16%41
2786
21st to endNight
54%16%14%11%4
2988
August1st to 10thNight
40%18%24%14%4
2814
11th to 20thNight
39%18%21%14%8%
2812
21st to endNight
30%12%16%33%9%1
3423
September1st to 10thNight
39%13%14%19%12%3
2090
11th to 20thNight
45%11%13%15%15%1
2090
21st to endNight
38%8%13%21%17%3
2090
October1st to 10thNight
36%8%12%18%23%4
2123
11th to 20thNight
33%8%11%21%19%8%
2280
21st to endNight
30%6%9%22%25%8%
2508
November1st to 10thNight
33%8%9%19%22%8%
2313
11th to 20thNight
34%5%9%19%24%9%
2470
21st to endNight
35%7%8%23%21%6%
2470
December1st to 10thNight
44%8%13%17%14%4
2470
11th to 20thNight
36%8%12%17%23%4
3044
21st to endNight
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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
30%27%33%8%1
270
11th to 20thDay
36%22%26%14%3
270
21st to endDay
26%34%28%10%2
297
February1st to 10thDay
28%28%30%13%1
270
11th to 20thDay
38%31%25%6%1
270
21st to endDay
37%33%22%7%1
225
March1st to 10thDay
25%24%29%16%6%
410
11th to 20thDay
27%24%29%15%41
460
21st to endDay
25%25%29%16%5%
506
April1st to 10thDay
24%23%26%19%8%1
460
11th to 20thDay
19%22%26%21%10%2
452
21st to endDay
19%17%28%20%12%4
460
May1st to 10thDay
16%21%27%21%10%5%
463
11th to 20thDay
16%13%24%26%13%8%
487
21st to endDay
12%10%24%24%18%12%
529
June1st to 10thDay
13%6%27%27%16%11%
490
11th to 20thDay
8%7%24%24%23%13%
490
21st to endDay
9%7%28%25%18%12%
490
July1st to 10thDay
8%414%28%29%15%
485
11th to 20thDay
7%414%28%26%20%
484
21st to endDay
9%214%27%31%16%
532
August1st to 10thDay
17%5%19%23%19%17%
486
11th to 20thDay
8%420%30%22%15%
479
21st to endDay
10%316%27%29%15%
539
September1st to 10thDay
9%5%17%30%27%13%
490
11th to 20thDay
16%7%18%23%27%10%
490
21st to endDay
16%10%18%30%22%5%
490
October1st to 10thDay
17%10%19%29%18%7%
490
11th to 20thDay
13%17%23%28%15%3
490
21st to endDay
18%14%24%28%12%3
539
November1st to 10thDay
17%15%29%26%11%2
367
11th to 20thDay
21%21%34%17%5%
270
21st to endDay
17%24%34%17%7%1
270
December1st to 10thDay
26%28%30%14%1
270
11th to 20thDay
23%22%32%17%6%1
270
21st to endDay
25%23%36%11%5%1
297
January1st to 10thNight
25%22%26%22%5%
760
11th to 20thNight
20%22%30%23%4
760
21st to endNight
20%22%33%23%3
836
February1st to 10thNight
18%18%31%28%4
760
11th to 20thNight
25%26%28%20%1
743
21st to endNight
22%26%30%20%2
628
March1st to 10thNight
19%22%29%26%4
760
11th to 20thNight
21%18%32%21%8%1
760
21st to endNight
20%18%33%22%7%
836
April1st to 10thNight
17%23%28%25%8%
760
11th to 20thNight
17%18%27%26%11%1
655
21st to endNight
13%13%23%35%15%1
570
May1st to 10thNight
14%12%25%32%17%1
570
11th to 20thNight
14%9%20%32%22%2
561
21st to endNight
11%5%16%29%33%7%
617
June1st to 10thNight
8%416%37%30%6%
570
11th to 20thNight
7%216%29%35%10%
570
21st to endNight
6%312%35%37%6%
570
July1st to 10thNight
10%38%25%46%7%
555
11th to 20thNight
8%47%24%45%12%
552
21st to endNight
8%27%29%43%12%
624
August1st to 10thNight
10%211%26%41%10%
567
11th to 20thNight
12%311%28%38%9%
564
21st to endNight
9%29%28%43%9%
676
September1st to 10thNight
10%315%29%37%6%
760
11th to 20thNight
15%6%16%27%32%5%
760
21st to endNight
15%7%17%31%27%3
760
October1st to 10thNight
15%10%18%26%25%6%
760
11th to 20thNight
15%11%25%29%18%2
760
21st to endNight
16%13%19%34%15%3
836
November1st to 10thNight
16%10%21%34%17%3
743
11th to 20thNight
18%14%24%33%11%1
760
21st to endNight
18%16%23%30%13%1
760
December1st to 10thNight
23%18%25%28%6%
760
11th to 20thNight
17%15%29%30%7%1
760
21st to endNight
23%18%26%28%6%
836
Page generated at 2024-10-29 11:20:48. Version ac07

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