Wytheville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wytheville clear sky chart from 2005-11-06 to 2024-01-16.

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
39%
24190
20%
74523
12%
24137
48%
24137
22%
47913

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
16%
760
20%
2459
6%
757
33%
757
14%
1578
January11th to 20thNight
19%
744
20%
2417
7%
744
35%
744
13%
1642
January21st to endNight
16%
792
22%
2574
7%
792
34%
792
15%
1644
February1st to 10thNight
19%
720
19%
2340
8%
720
33%
720
17%
1492
February11th to 20thNight
11%
702
17%
2155
3%
699
27%
699
11%
1468
February21st to endNight
14%
592
22%
1758
7%
592
30%
592
16%
1197
March1st to 10thNight
21%
720
24%
1980
10%
720
33%
720
22%
1283
March11th to 20thNight
23%
720
17%
1980
7%
720
32%
720
18%
1387
March21st to endNight
24%
792
16%
2178
8%
792
31%
792
21%
1482
April1st to 10thNight
28%
720
19%
1972
7%
720
38%
720
22%
1279
April11th to 20thNight
33%
709
22%
1773
8%
709
42%
709
27%
1145
April21st to endNight
39%
540
23%
1620
12%
540
48%
540
25%
1029
May1st to 10thNight
38%
540
16%
1620
8%
540
44%
540
24%
1046
May11th to 20thNight
46%
531
15%
1592
8%
531
50%
531
23%
1066
May21st to endNight
56%
582
14%
1745
11%
582
58%
582
27%
1124
June1st to 10thNight
62%
540
15%
1620
13%
540
64%
540
29%
1037
June11th to 20thNight
61%
540
14%
1620
11%
540
65%
540
32%
1010
June21st to endNight
62%
540
18%
1620
15%
540
66%
540
32%
993
July1st to 10thNight
68%
525
14%
1575
13%
525
69%
525
29%
1014
July11th to 20thNight
74%
522
14%
1566
12%
522
75%
522
34%
941
July21st to endNight
70%
591
16%
1672
12%
558
72%
558
31%
1041
August1st to 10thNight
63%
537
14%
1600
11%
534
65%
534
26%
1069
August11th to 20thNight
65%
534
19%
1598
16%
534
67%
534
26%
1064
August21st to endNight
65%
698
20%
1886
16%
698
66%
698
32%
1224
September1st to 10thNight
66%
720
22%
1926
16%
720
68%
720
32%
1237
September11th to 20thNight
57%
720
23%
1980
19%
720
60%
720
30%
1277
September21st to endNight
48%
720
21%
1980
15%
720
53%
720
25%
1341
October1st to 10thNight
49%
720
23%
2094
19%
720
56%
720
29%
1325
October11th to 20thNight
40%
720
26%
2160
19%
720
52%
720
28%
1311
October21st to endNight
41%
792
30%
2376
21%
792
53%
792
28%
1415
November1st to 10thNight
42%
740
28%
2243
19%
740
54%
740
29%
1343
November11th to 20thNight
35%
760
26%
2470
16%
760
49%
760
25%
1433
November21st to endNight
33%
760
26%
2470
14%
760
47%
760
24%
1480
December1st to 10thNight
21%
760
20%
2470
8%
760
37%
760
15%
1666
December11th to 20thNight
24%
759
23%
2982
10%
759
42%
759
14%
1931
December21st to endNight
21%
828
13%
4452
7%
817
35%
817
9%
2899

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
13%7%36%6%45%5%6%8%37%
74958
Night
13%6%36%5%35%5%6%8%41%
74871
TransparencyDay
45%5%11%21%14%3
74680
Night
42%5%12%23%15%3
74667
SeeingDay
21%16%24%20%13%6%
14057
Night
18%14%22%27%16%2
24202

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
13%9%38%6%3445%7%38%
1706
11th to 20thDay
16%10%38%7%4446%5%33%
1671
21st to endDay
13%9%5%6%6%3445%5%41%
1782
February1st to 10thDay
13%9%48%6%46%5%5%6%36%
1620
11th to 20thDay
17%8%49%6%34347%36%
1690
21st to endDay
18%7%47%6%44446%37%
1498
March1st to 10thDay
13%5%35%5%3445%8%44%
1980
11th to 20thDay
16%10%47%5%3446%7%34%
1980
21st to endDay
16%8%37%5%35%446%37%
2178
April1st to 10thDay
11%6%36%5%4445%8%44%
1988
11th to 20thDay
14%6%36%5%3446%7%43%
2151
21st to endDay
15%6%27%6%45%5%6%7%37%
2340
May1st to 10thDay
14%7%37%7%46%5%6%8%34%
2340
11th to 20thDay
16%7%37%6%46%5%7%10%30%
2301
21st to endDay
13%5%26%7%47%7%7%10%33%
2531
June1st to 10thDay
11%6%35%6%46%5%8%9%37%
2340
11th to 20thDay
9%5%36%6%5%7%8%7%9%35%
2340
21st to endDay
9%5%35%7%5%6%6%8%10%36%
2340
July1st to 10thDay
9%7%37%7%5%6%7%8%9%32%
2340
11th to 20thDay
9%5%36%8%5%8%7%9%10%31%
2340
21st to endDay
10%7%38%8%5%7%8%7%10%27%
2547
August1st to 10thDay
12%6%37%8%47%7%7%11%28%
2327
11th to 20thDay
13%6%36%6%6%8%7%8%9%29%
2303
21st to endDay
10%6%36%6%46%6%7%10%36%
2450
September1st to 10thDay
14%5%35%5%45%6%7%6%41%
2030
11th to 20thDay
14%7%37%6%46%5%6%8%36%
1980
21st to endDay
22%7%25%4345%5%6%37%
1980
October1st to 10thDay
16%6%24433446%46%
1864
11th to 20thDay
13%7%35%43445%6%46%
1800
21st to endDay
14%7%35%424347%46%
1980
November1st to 10thDay
12%6%2443335%6%51%
1834
11th to 20thDay
11%7%245%35%46%7%46%
1710
21st to endDay
13%7%36%5%2445%7%44%
1710
December1st to 10thDay
15%11%38%6%345%5%7%34%
1710
11th to 20thDay
14%8%35%5%3345%8%42%
2153
21st to endDay
16%11%26%5%25%6%7%8%31%
3124
January1st to 10thNight
12%7%46%6%45%6%6%8%37%
2459
11th to 20thNight
14%8%47%6%45%5%6%6%35%
2417
21st to endNight
12%8%5%6%5%35%6%5%6%39%
2574
February1st to 10thNight
13%7%27%6%35%5%6%8%39%
2340
11th to 20thNight
18%8%26%6%45%5%6%6%33%
2155
21st to endNight
14%7%48%6%35%5%5%6%37%
1758
March1st to 10thNight
12%7%35%6%345%6%6%44%
1980
11th to 20thNight
15%8%46%6%35%5%6%7%34%
1980
21st to endNight
13%7%36%6%36%5%6%7%38%
2178
April1st to 10thNight
10%6%36%5%45%5%6%9%41%
1972
11th to 20thNight
11%6%35%4345%6%8%45%
1773
21st to endNight
14%5%246%345%6%7%43%
1620
May1st to 10thNight
12%6%25%6%345%7%7%42%
1620
11th to 20thNight
13%6%26%7%36%6%6%9%38%
1592
21st to endNight
14%5%25%435%47%10%40%
1744
June1st to 10thNight
9%4245%46%8%7%11%41%
1620
11th to 20thNight
9%425%5%45%5%6%10%46%
1620
21st to endNight
7%335%6%35%5%7%12%43%
1620
July1st to 10thNight
8%435%6%36%6%7%10%42%
1620
11th to 20thNight
6%324436%6%9%14%43%
1620
21st to endNight
6%425%6%47%6%8%13%39%
1771
August1st to 10thNight
9%6%36%6%5%5%5%8%12%36%
1611
11th to 20thNight
12%6%25%5%46%5%6%9%39%
1598
21st to endNight
9%5%35%6%346%7%10%42%
1886
September1st to 10thNight
11%435%5%3447%8%47%
1926
11th to 20thNight
15%6%25%5%3445%7%44%
1980
21st to endNight
17%7%25%434446%43%
1980
October1st to 10thNight
16%5%25%433447%47%
2094
11th to 20thNight
13%7%25%5%24346%49%
2160
21st to endNight
13%6%3442445%7%48%
2376
November1st to 10thNight
13%6%34434346%51%
2243
11th to 20thNight
11%6%25%42445%7%48%
2470
21st to endNight
12%7%35%4245%6%7%46%
2470
December1st to 10thNight
15%8%37%6%35%5%5%9%34%
2470
11th to 20thNight
13%7%48%6%45%5%5%7%37%
3042
21st to endNight
17%9%47%6%35%6%6%7%29%
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
47%39%22%15%4
1707
11th to 20thDay
53%36%22%14%3
1671
21st to endDay
46%29%24%17%3
1782
February1st to 10thDay
50%310%20%15%2
1620
11th to 20thDay
51%38%21%14%3
1699
21st to endDay
50%311%15%16%6%
1498
March1st to 10thDay
39%38%26%19%5%
1980
11th to 20thDay
50%410%18%15%4
1980
21st to endDay
50%410%23%11%3
2178
April1st to 10thDay
40%411%24%17%4
1988
11th to 20thDay
41%310%22%18%5%
2151
21st to endDay
46%412%24%12%2
2340
May1st to 10thDay
49%5%14%18%12%2
2340
11th to 20thDay
50%6%15%20%7%1
2305
21st to endDay
46%7%15%24%8%
2531
June1st to 10thDay
43%7%15%22%12%
2340
11th to 20thDay
43%8%15%18%14%1
2340
21st to endDay
42%7%15%21%13%2
2340
July1st to 10thDay
45%8%16%19%10%2
2275
11th to 20thDay
46%8%17%16%11%2
2271
21st to endDay
49%7%15%19%9%1
2405
August1st to 10thDay
49%7%16%20%7%
2314
11th to 20thDay
50%7%15%18%9%
2303
21st to endDay
43%7%18%19%11%3
2450
September1st to 10thDay
43%6%11%21%15%5%
2030
11th to 20thDay
46%5%7%24%16%1
1980
21st to endDay
49%49%21%15%2
1980
October1st to 10thDay
41%39%24%18%4
1864
11th to 20thDay
41%38%24%20%4
1800
21st to endDay
40%36%27%18%5%
1980
November1st to 10thDay
35%38%22%27%6%
1834
11th to 20thDay
38%28%23%23%5%
1710
21st to endDay
40%39%22%22%4
1710
December1st to 10thDay
50%411%17%15%3
1710
11th to 20thDay
41%39%19%24%4
2150
21st to endDay
49%46%24%15%2
3124
January1st to 10thNight
46%311%20%17%5%
2459
11th to 20thNight
50%48%18%17%3
2417
21st to endNight
44%49%24%17%2
2574
February1st to 10thNight
44%412%24%15%1
2340
11th to 20thNight
50%39%20%14%4
2156
21st to endNight
48%410%22%11%5%
1758
March1st to 10thNight
40%5%9%22%20%4
1980
11th to 20thNight
49%49%24%13%1
1980
21st to endNight
44%5%11%23%13%3
2178
April1st to 10thNight
40%5%12%24%16%4
1972
11th to 20thNight
37%411%23%19%5%
1773
21st to endNight
40%5%14%27%13%1
1620
May1st to 10thNight
41%6%15%25%12%1
1620
11th to 20thNight
43%7%18%24%7%1
1593
21st to endNight
39%7%21%26%6%
1745
June1st to 10thNight
36%9%20%23%12%1
1620
11th to 20thNight
35%6%21%24%12%1
1620
21st to endNight
33%8%18%26%13%2
1620
July1st to 10thNight
36%9%16%25%11%3
1575
11th to 20thNight
30%9%24%23%11%3
1566
21st to endNight
33%9%22%26%9%1
1672
August1st to 10thNight
41%7%20%21%10%
1600
11th to 20thNight
41%7%18%22%11%1
1598
21st to endNight
38%6%17%27%10%2
1886
September1st to 10thNight
36%7%15%23%15%4
1926
11th to 20thNight
40%412%24%18%1
1980
21st to endNight
45%5%8%26%15%2
1980
October1st to 10thNight
39%5%9%25%20%3
2094
11th to 20thNight
38%39%27%19%5%
2160
21st to endNight
36%37%26%21%7%
2376
November1st to 10thNight
37%39%21%25%6%
2243
11th to 20thNight
36%38%23%23%7%
2470
21st to endNight
39%38%26%20%4
2470
December1st to 10thNight
49%49%22%13%3
2470
11th to 20thNight
47%47%20%19%3
3044
21st to endNight
53%38%20%15%1
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
40%26%24%7%21
270
11th to 20thDay
38%26%28%7%1
257
21st to endDay
39%33%19%8%2
264
February1st to 10thDay
36%33%20%8%3
240
11th to 20thDay
47%30%20%4
240
21st to endDay
43%28%22%7%
216
March1st to 10thDay
27%27%26%16%4
420
11th to 20thDay
31%27%23%14%41
420
21st to endDay
29%23%24%18%6%
462
April1st to 10thDay
24%28%23%15%10%
420
11th to 20thDay
24%21%23%20%9%3
412
21st to endDay
25%20%27%15%11%2
420
May1st to 10thDay
22%20%31%14%8%4
423
11th to 20thDay
19%13%31%19%11%6%
447
21st to endDay
18%9%24%22%16%11%
485
June1st to 10thDay
14%8%28%26%18%7%
450
11th to 20thDay
9%10%26%29%17%9%
450
21st to endDay
11%12%29%27%13%8%
450
July1st to 10thDay
10%7%22%27%22%12%
445
11th to 20thDay
5%5%21%36%23%11%
444
21st to endDay
8%6%23%29%23%11%
488
August1st to 10thDay
17%7%20%22%21%13%
446
11th to 20thDay
11%420%27%23%14%
439
21st to endDay
11%5%19%28%19%18%
495
September1st to 10thDay
13%5%19%26%24%13%
450
11th to 20thDay
14%6%17%26%24%12%
450
21st to endDay
26%10%19%24%17%4
450
October1st to 10thDay
21%10%22%21%21%5%
450
11th to 20thDay
18%20%20%26%14%2
450
21st to endDay
22%16%25%22%11%3
495
November1st to 10thDay
19%16%27%25%11%3
432
11th to 20thDay
26%19%29%19%5%1
270
21st to endDay
23%25%28%19%41
270
December1st to 10thDay
33%27%28%10%2
270
11th to 20thDay
30%24%28%11%6%1
270
21st to endDay
30%26%28%11%5%1
297
January1st to 10thNight
25%28%27%17%3
760
11th to 20thNight
27%24%27%21%1
744
21st to endNight
23%30%29%17%1
792
February1st to 10thNight
27%21%31%20%2
720
11th to 20thNight
32%28%26%14%
703
21st to endNight
24%28%31%15%2
592
March1st to 10thNight
20%23%32%22%3
720
11th to 20thNight
25%21%29%19%6%
720
21st to endNight
19%18%33%23%6%
792
April1st to 10thNight
20%22%25%26%6%
720
11th to 20thNight
17%20%25%28%9%1
709
21st to endNight
17%15%25%34%9%
540
May1st to 10thNight
14%15%28%28%13%1
540
11th to 20thNight
16%9%22%32%21%1
531
21st to endNight
15%416%30%31%5%
584
June1st to 10thNight
10%318%40%25%4
540
11th to 20thNight
9%319%34%32%4
540
21st to endNight
6%417%39%29%4
540
July1st to 10thNight
8%213%34%38%5%
525
11th to 20thNight
6%28%35%43%6%
522
21st to endNight
6%311%37%36%6%
591
August1st to 10thNight
11%311%34%37%4
537
11th to 20thNight
14%211%33%34%6%
534
21st to endNight
11%210%32%37%8%
698
September1st to 10thNight
12%312%31%37%5%
720
11th to 20thNight
16%5%14%30%31%5%
720
21st to endNight
21%5%18%31%24%1
720
October1st to 10thNight
18%10%18%25%25%4
720
11th to 20thNight
18%13%24%29%14%2
720
21st to endNight
18%16%22%32%11%2
792
November1st to 10thNight
17%13%24%29%15%2
740
11th to 20thNight
21%15%24%30%9%1
760
21st to endNight
20%17%27%26%9%1
760
December1st to 10thNight
25%21%28%22%4
760
11th to 20thNight
19%22%29%25%5%
760
21st to endNight
26%20%27%23%4
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