Lynchburg College Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lynchburg College Observatory 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
45%
24373
22%
74948
13%
24324
54%
24324
27%
46203

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
27%
759
25%
2459
10%
757
45%
757
23%
1455
January11th to 20thNight
28%
744
24%
2417
11%
744
45%
744
21%
1521
January21st to endNight
26%
792
26%
2574
10%
792
46%
792
25%
1527
February1st to 10thNight
27%
720
20%
2340
10%
720
41%
720
24%
1420
February11th to 20thNight
20%
700
19%
2267
6%
699
36%
699
18%
1441
February21st to endNight
27%
592
27%
1679
12%
592
43%
592
24%
1097
March1st to 10thNight
34%
720
27%
1980
13%
720
48%
720
31%
1202
March11th to 20thNight
29%
720
20%
1980
9%
720
40%
720
23%
1312
March21st to endNight
34%
792
20%
2178
10%
792
42%
792
27%
1421
April1st to 10thNight
31%
720
21%
1888
8%
720
41%
720
28%
1205
April11th to 20thNight
39%
711
24%
1775
9%
711
48%
711
34%
1115
April21st to endNight
42%
650
23%
1730
9%
650
50%
650
31%
1109
May1st to 10thNight
42%
540
17%
1620
8%
540
49%
540
27%
1036
May11th to 20thNight
48%
531
15%
1592
10%
531
52%
531
23%
1072
May21st to endNight
60%
582
15%
1745
12%
582
63%
582
29%
1109
June1st to 10thNight
65%
540
17%
1620
15%
540
67%
540
33%
971
June11th to 20thNight
66%
540
15%
1620
12%
540
69%
540
32%
998
June21st to endNight
71%
540
18%
1620
15%
540
74%
540
34%
969
July1st to 10thNight
69%
525
14%
1575
13%
525
70%
525
29%
1004
July11th to 20thNight
78%
522
16%
1566
15%
522
79%
522
36%
927
July21st to endNight
68%
591
19%
1672
16%
558
70%
558
33%
1031
August1st to 10thNight
64%
537
17%
1600
12%
534
66%
534
28%
1052
August11th to 20thNight
63%
534
20%
1598
16%
534
65%
534
27%
1036
August21st to endNight
66%
774
18%
1962
13%
774
67%
774
32%
1314
September1st to 10thNight
66%
720
24%
1800
16%
720
67%
720
34%
1183
September11th to 20thNight
61%
720
25%
1963
21%
720
62%
720
30%
1277
September21st to endNight
46%
720
20%
1991
15%
720
51%
720
23%
1388
October1st to 10thNight
52%
720
23%
2160
21%
720
58%
720
32%
1301
October11th to 20thNight
47%
720
28%
2160
20%
720
59%
720
31%
1279
October21st to endNight
47%
792
32%
2376
23%
792
61%
792
35%
1340
November1st to 10thNight
45%
740
29%
2221
20%
740
57%
740
33%
1294
November11th to 20thNight
40%
760
29%
2396
17%
760
55%
760
30%
1356
November21st to endNight
43%
760
26%
2623
18%
760
56%
760
28%
1459
December1st to 10thNight
29%
760
22%
2660
12%
760
44%
760
20%
1647
December11th to 20thNight
33%
759
25%
3153
13%
758
49%
758
21%
1808
December21st to endNight
29%
826
15%
4388
11%
817
44%
817
13%
2527

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
14%5%25%5%35%5%6%8%42%
74390
Night
15%5%25%5%3445%7%45%
75419
TransparencyDay
40%412%23%16%3
74111
Night
39%411%24%18%4
75217
SeeingDay
20%9%23%25%16%7%
13974
Night
18%7%22%33%18%2
24390

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
16%6%25%5%245%5%7%45%
1706
11th to 20thDay
18%8%25%4345%5%6%40%
1671
21st to endDay
16%5%36%5%24445%45%
1782
February1st to 10thDay
12%7%36%6%36%6%5%7%39%
1620
11th to 20thDay
19%6%245%35%447%41%
1577
21st to endDay
20%6%36%5%44446%38%
1574
March1st to 10thDay
14%5%24324447%52%
1980
11th to 20thDay
16%7%35%5%35%5%5%7%39%
1980
21st to endDay
17%6%36%6%246%5%7%38%
2178
April1st to 10thDay
12%42442446%7%50%
2070
11th to 20thDay
15%5%24435%45%7%46%
2134
21st to endDay
17%5%26%6%3445%6%42%
2244
May1st to 10thDay
14%6%35%447%6%6%8%37%
2340
11th to 20thDay
16%7%25%6%35%6%7%8%35%
2301
21st to endDay
13%5%26%5%46%5%6%9%38%
2531
June1st to 10thDay
11%4235%46%6%6%10%44%
2340
11th to 20thDay
11%426%5%45%6%8%10%40%
2340
21st to endDay
8%426%5%36%7%8%11%40%
2340
July1st to 10thDay
9%436%7%46%7%8%10%38%
2340
11th to 20thDay
6%435%6%47%7%8%11%38%
2340
21st to endDay
9%6%37%6%5%8%6%8%10%33%
2547
August1st to 10thDay
12%6%36%6%46%6%7%11%33%
2327
11th to 20thDay
15%5%26%6%45%7%7%10%33%
2303
21st to endDay
11%6%26%6%35%6%7%9%39%
2376
September1st to 10thDay
12%6%25%43445%8%47%
2160
11th to 20thDay
15%5%25%5%3446%7%43%
1993
21st to endDay
23%6%25%5%35%45%6%38%
1967
October1st to 10thDay
17%6%1342335%6%50%
1800
11th to 20thDay
16%42332245%6%52%
1800
21st to endDay
14%6%24433446%50%
1980
November1st to 10thDay
13%423424336%56%
1857
11th to 20thDay
14%5%14424347%52%
1782
21st to endDay
15%4244235%5%8%48%
1552
December1st to 10thDay
18%6%36%5%25%5%6%8%37%
1520
11th to 20thDay
17%424413346%53%
1914
21st to endDay
20%6%34435%5%7%8%34%
3124
January1st to 10thNight
16%42443445%6%48%
2459
11th to 20thNight
16%6%25%5%345%5%7%41%
2417
21st to endNight
14%5%35%4245%5%6%46%
2574
February1st to 10thNight
15%6%35%435%5%6%7%42%
2340
11th to 20thNight
20%6%25%5%34446%42%
2267
21st to endNight
16%6%345%3445%7%41%
1679
March1st to 10thNight
13%43442445%6%51%
1980
11th to 20thNight
19%5%24435%5%5%6%41%
1980
21st to endNight
15%6%35%5%3445%6%45%
2178
April1st to 10thNight
15%5%35%43445%8%45%
1888
11th to 20thNight
14%4244245%47%49%
1775
21st to endNight
16%5%245%25%45%7%45%
1730
May1st to 10thNight
14%6%25%6%3447%8%42%
1620
11th to 20thNight
17%7%35%6%35%45%8%37%
1592
21st to endNight
15%5%25%5%345%5%10%41%
1744
June1st to 10thNight
9%425%435%5%7%10%44%
1620
11th to 20thNight
11%336%5%3446%10%45%
1620
21st to endNight
9%324445%6%7%12%45%
1620
July1st to 10thNight
9%5%25%6%5%5%5%7%9%43%
1620
11th to 20thNight
6%4245%46%6%7%12%45%
1620
21st to endNight
7%5%36%7%36%5%7%10%42%
1771
August1st to 10thNight
13%5%26%5%35%5%8%10%38%
1611
11th to 20thNight
11%6%35%5%5%5%6%6%8%40%
1598
21st to endNight
10%5%35%6%45%5%7%10%39%
1962
September1st to 10thNight
11%6%25%5%45%5%6%6%47%
1800
11th to 20thNight
16%5%25%6%335%5%6%43%
1963
21st to endNight
22%7%36%5%3445%5%38%
1991
October1st to 10thNight
17%5%245%23347%49%
2160
11th to 20thNight
15%5%245%23346%51%
2160
21st to endNight
15%324323447%53%
2376
November1st to 10thNight
14%6%24323345%54%
2221
11th to 20thNight
14%424434445%52%
2396
21st to endNight
14%42443445%7%50%
2623
December1st to 10thNight
19%7%35%433445%43%
2660
11th to 20thNight
15%6%25%43345%5%47%
3272
21st to endNight
18%6%245%35%5%6%8%38%
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
39%311%23%19%5%
1707
11th to 20thDay
45%39%22%18%2
1671
21st to endDay
42%28%24%20%4
1782
February1st to 10thDay
43%411%23%15%3
1620
11th to 20thDay
44%29%22%18%4
1586
21st to endDay
48%310%17%17%5%
1574
March1st to 10thDay
33%310%25%23%5%
1980
11th to 20thDay
46%410%18%17%6%
1980
21st to endDay
45%410%22%15%4
2178
April1st to 10thDay
33%312%24%19%8%
2070
11th to 20thDay
38%311%23%20%6%
2134
21st to endDay
43%411%24%14%5%
2244
May1st to 10thDay
43%5%16%21%13%3
2340
11th to 20thDay
45%5%15%22%10%2
2305
21st to endDay
42%5%17%25%10%
2531
June1st to 10thDay
35%6%17%27%14%1
2340
11th to 20thDay
38%6%17%21%16%2
2340
21st to endDay
34%8%16%26%14%2
2340
July1st to 10thDay
40%7%16%21%14%3
2275
11th to 20thDay
35%7%19%21%16%1
2271
21st to endDay
43%6%14%24%12%1
2405
August1st to 10thDay
43%6%16%26%8%1
2314
11th to 20thDay
44%6%16%22%11%1
2303
21st to endDay
39%5%19%22%13%2
2376
September1st to 10thDay
36%6%15%21%20%4
2160
11th to 20thDay
40%48%27%19%3
1993
21st to endDay
48%38%20%19%2
1967
October1st to 10thDay
36%39%28%19%5%
1800
11th to 20thDay
34%211%27%21%5%
1800
21st to endDay
36%28%27%21%6%
1980
November1st to 10thDay
32%39%23%28%5%
1857
11th to 20thDay
34%38%25%22%8%
1782
21st to endDay
35%39%25%24%4
1552
December1st to 10thDay
45%311%20%16%4
1520
11th to 20thDay
35%38%25%22%7%
1910
21st to endDay
46%39%27%13%2
3124
January1st to 10thNight
38%310%22%20%6%
2459
11th to 20thNight
43%49%22%18%4
2417
21st to endNight
39%29%26%20%4
2574
February1st to 10thNight
40%312%24%19%2
2340
11th to 20thNight
45%29%19%18%6%
2269
21st to endNight
43%49%24%15%6%
1679
March1st to 10thNight
34%49%26%22%5%
1980
11th to 20thNight
44%49%22%19%3
1980
21st to endNight
41%410%23%18%5%
2178
April1st to 10thNight
38%311%21%21%5%
1888
11th to 20thNight
34%312%23%22%6%
1775
21st to endNight
39%411%25%17%4
1730
May1st to 10thNight
39%6%15%22%15%3
1620
11th to 20thNight
46%6%13%24%10%2
1593
21st to endNight
40%417%27%11%1
1745
June1st to 10thNight
34%6%16%28%15%1
1620
11th to 20thNight
35%6%18%22%16%2
1620
21st to endNight
31%8%17%23%17%4
1620
July1st to 10thNight
37%8%17%19%14%5%
1575
11th to 20thNight
30%7%22%25%13%3
1566
21st to endNight
35%6%17%28%13%
1672
August1st to 10thNight
41%7%18%21%12%1
1600
11th to 20thNight
40%7%15%24%13%1
1598
21st to endNight
39%7%16%24%12%3
1962
September1st to 10thNight
37%6%14%21%17%5%
1800
11th to 20thNight
40%5%8%25%19%3
1963
21st to endNight
49%47%21%16%3
1991
October1st to 10thNight
37%39%25%22%4
2160
11th to 20thNight
36%38%28%21%4
2160
21st to endNight
32%28%25%26%6%
2376
November1st to 10thNight
35%27%23%25%7%
2221
11th to 20thNight
34%28%23%25%7%
2396
21st to endNight
35%39%27%21%6%
2623
December1st to 10thNight
45%28%25%16%4
2660
11th to 20thNight
39%28%23%22%6%
3275
21st to endNight
45%210%22%20%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%21%27%18%31
270
11th to 20thDay
35%12%36%16%1
257
21st to endDay
31%19%35%11%4
264
February1st to 10thDay
27%17%39%14%3
240
11th to 20thDay
42%15%34%8%1
240
21st to endDay
30%18%30%19%3
292
March1st to 10thDay
25%14%33%23%4
420
11th to 20thDay
23%21%28%21%6%1
420
21st to endDay
24%12%34%23%7%1
462
April1st to 10thDay
22%18%27%22%9%2
420
11th to 20thDay
20%13%27%23%14%4
412
21st to endDay
25%10%30%21%12%4
420
May1st to 10thDay
21%11%33%22%9%4
423
11th to 20thDay
22%6%23%27%16%5%
447
21st to endDay
20%217%29%22%10%
485
June1st to 10thDay
13%323%32%19%10%
450
11th to 20thDay
13%6%17%30%22%12%
450
21st to endDay
12%420%32%23%9%
450
July1st to 10thDay
13%14%27%29%17%
445
11th to 20thDay
5%111%35%32%16%
444
21st to endDay
11%116%30%27%14%
488
August1st to 10thDay
15%415%24%25%17%
446
11th to 20thDay
15%113%28%26%18%
439
21st to endDay
12%110%28%25%24%
495
September1st to 10thDay
14%311%24%30%19%
450
11th to 20thDay
18%39%27%30%14%
450
21st to endDay
27%7%16%23%20%7%
450
October1st to 10thDay
24%416%27%23%6%
450
11th to 20thDay
16%11%20%29%19%4
450
21st to endDay
18%9%28%30%12%3
495
November1st to 10thDay
19%8%26%31%13%3
455
11th to 20thDay
21%15%24%26%13%1
342
21st to endDay
21%17%27%22%11%2
194
December1st to 10thDay
26%14%33%19%8%
180
11th to 20thDay
23%12%29%28%6%2
182
21st to endDay
28%13%30%20%8%1
297
January1st to 10thNight
21%14%32%29%3
760
11th to 20thNight
21%13%31%33%3
744
21st to endNight
19%11%38%29%3
792
February1st to 10thNight
19%13%35%29%4
720
11th to 20thNight
27%14%33%25%1
703
21st to endNight
21%13%35%29%3
592
March1st to 10thNight
17%13%31%34%5%
720
11th to 20thNight
23%12%30%26%7%1
720
21st to endNight
19%10%31%33%7%1
792
April1st to 10thNight
18%15%30%29%8%
720
11th to 20thNight
17%12%27%30%13%1
711
21st to endNight
19%427%38%11%
650
May1st to 10thNight
17%7%26%33%15%1
540
11th to 20thNight
19%5%17%38%20%2
531
21st to endNight
19%19%33%34%5%
584
June1st to 10thNight
11%111%43%31%3
540
11th to 20thNight
12%29%35%37%5%
540
21st to endNight
9%210%41%32%6%
540
July1st to 10thNight
10%16%34%42%7%
525
11th to 20thNight
6%1430%50%8%
522
21st to endNight
9%17%40%39%5%
591
August1st to 10thNight
15%26%35%38%4
537
11th to 20thNight
14%27%31%40%6%
534
21st to endNight
12%27%33%39%7%
774
September1st to 10thNight
14%27%30%38%7%
720
11th to 20thNight
16%38%33%35%6%
720
21st to endNight
26%414%31%24%2
720
October1st to 10thNight
19%417%29%26%4
720
11th to 20thNight
17%6%22%36%17%2
720
21st to endNight
17%6%22%39%14%2
792
November1st to 10thNight
18%7%23%36%14%2
740
11th to 20thNight
17%9%27%34%12%1
760
21st to endNight
17%8%26%37%11%1
760
December1st to 10thNight
24%9%31%29%6%
760
11th to 20thNight
18%8%34%35%6%
760
21st to endNight
22%11%28%34%4
836
Page generated at 2024-01-13 19:28:29. Version ac07

Copyright 2024 Attilla Danko


Lynchburg College Observatory Clear Sky Chart |Charts Home