Stone Mountain State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stone Mountain State Park clear sky chart from 2005-11-06 to 2024-01-12.

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
44%
24197
21%
74372
13%
24149
53%
24149
26%
46787

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
26%
758
24%
2459
9%
757
46%
757
25%
1443
January11th to 20thNight
29%
725
23%
2354
11%
725
44%
725
22%
1478
January21st to endNight
26%
792
27%
2574
11%
792
47%
792
27%
1503
February1st to 10thNight
30%
720
21%
2340
10%
720
44%
720
24%
1427
February11th to 20thNight
20%
700
22%
2145
7%
699
36%
699
21%
1376
February21st to endNight
24%
592
24%
1748
10%
592
39%
592
23%
1144
March1st to 10thNight
30%
720
26%
1980
11%
720
43%
720
30%
1223
March11th to 20thNight
30%
720
20%
1980
7%
720
41%
720
23%
1318
March21st to endNight
30%
792
17%
2178
7%
792
38%
792
23%
1459
April1st to 10thNight
32%
720
21%
1974
8%
720
44%
720
28%
1227
April11th to 20thNight
37%
711
23%
1775
9%
711
46%
711
31%
1155
April21st to endNight
42%
558
26%
1638
13%
558
51%
558
29%
1004
May1st to 10thNight
40%
540
16%
1620
7%
540
46%
540
25%
1045
May11th to 20thNight
46%
531
14%
1593
8%
531
50%
531
23%
1080
May21st to endNight
58%
582
15%
1745
10%
582
61%
582
26%
1167
June1st to 10thNight
66%
540
16%
1620
15%
540
68%
540
28%
1054
June11th to 20thNight
62%
540
15%
1620
12%
540
65%
540
30%
1016
June21st to endNight
68%
540
17%
1620
14%
540
71%
540
29%
1043
July1st to 10thNight
70%
525
13%
1575
11%
525
71%
525
26%
1050
July11th to 20thNight
74%
522
12%
1566
10%
522
75%
522
27%
1046
July21st to endNight
72%
591
15%
1672
13%
558
74%
558
28%
1109
August1st to 10thNight
61%
537
13%
1600
11%
534
61%
534
22%
1127
August11th to 20thNight
65%
534
19%
1598
16%
534
66%
534
24%
1105
August21st to endNight
67%
710
18%
1898
14%
710
68%
710
28%
1305
September1st to 10thNight
66%
720
20%
1932
16%
720
67%
720
31%
1269
September11th to 20thNight
55%
720
20%
1980
16%
720
57%
720
25%
1347
September21st to endNight
49%
720
19%
1980
15%
720
53%
720
23%
1367
October1st to 10thNight
50%
720
23%
2093
20%
720
55%
720
29%
1324
October11th to 20thNight
47%
720
29%
2160
22%
720
59%
720
32%
1272
October21st to endNight
49%
792
32%
2376
24%
792
62%
792
34%
1360
November1st to 10thNight
47%
740
28%
2221
21%
740
57%
740
32%
1303
November11th to 20thNight
43%
760
28%
2467
19%
760
57%
760
32%
1359
November21st to endNight
41%
760
27%
2470
17%
760
54%
760
31%
1399
December1st to 10thNight
31%
760
24%
2470
12%
760
48%
760
22%
1601
December11th to 20thNight
32%
760
27%
2926
15%
758
47%
758
23%
1656
December21st to endNight
32%
825
15%
4425
11%
817
44%
817
12%
2626

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
15%5%25%5%35%5%6%8%41%
74915
Night
15%5%2443445%7%45%
74802
TransparencyDay
39%8%12%21%16%4
74638
Night
38%7%12%22%18%4
74598
SeeingDay
19%11%22%24%17%7%
14074
Night
17%8%23%30%19%3
24215

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
17%6%2442445%5%48%
1706
11th to 20thDay
17%7%26%5%345%45%44%
1629
21st to endDay
16%5%2443335%5%50%
1782
February1st to 10thDay
14%7%25%5%35%5%6%8%41%
1620
11th to 20thDay
18%8%24434446%43%
1699
21st to endDay
20%7%345%25%5%5%6%41%
1506
March1st to 10thDay
14%4144245%6%6%50%
1980
11th to 20thDay
20%5%344245%6%9%38%
1980
21st to endDay
20%6%25%5%34447%40%
2178
April1st to 10thDay
11%42342446%8%51%
1984
11th to 20thDay
16%5%245%3446%7%45%
2134
21st to endDay
15%6%245%45%5%5%7%42%
2335
May1st to 10thDay
13%5%25%5%35%5%7%9%39%
2340
11th to 20thDay
17%5%36%5%5%5%6%7%9%33%
2301
21st to endDay
15%5%25%6%46%6%7%10%36%
2531
June1st to 10thDay
12%5%35%6%47%6%8%10%34%
2340
11th to 20thDay
10%5%26%7%5%6%7%7%10%37%
2340
21st to endDay
9%435%6%5%7%7%9%11%35%
2340
July1st to 10thDay
10%6%27%7%47%7%8%10%32%
2340
11th to 20thDay
9%6%35%6%5%8%10%8%10%30%
2340
21st to endDay
10%6%27%8%5%8%7%8%10%28%
2547
August1st to 10thDay
14%6%37%7%46%6%8%11%29%
2327
11th to 20thDay
11%6%37%7%5%8%7%8%9%28%
2303
21st to endDay
11%6%26%6%5%7%6%7%10%35%
2440
September1st to 10thDay
13%5%25%5%45%5%6%9%41%
2024
11th to 20thDay
17%5%25%5%4446%8%39%
1980
21st to endDay
22%7%25%5%345%46%38%
1980
October1st to 10thDay
18%424433445%51%
1865
11th to 20thDay
15%424424346%52%
1800
21st to endDay
16%424322346%54%
1980
November1st to 10thDay
13%414323345%57%
1857
11th to 20thDay
14%41332435%7%54%
1710
21st to endDay
15%424433447%51%
1710
December1st to 10thDay
18%8%25%5%34346%39%
1710
11th to 20thDay
14%5%2332345%6%54%
2153
21st to endDay
22%6%243345%5%7%40%
3124
January1st to 10thNight
16%5%2432445%6%49%
2459
11th to 20thNight
17%6%35%43445%6%45%
2354
21st to endNight
16%6%2342445%6%49%
2574
February1st to 10thNight
14%7%234345%6%6%44%
2340
11th to 20thNight
20%5%25%5%24346%44%
2145
21st to endNight
16%6%35%4345%5%7%41%
1748
March1st to 10thNight
14%6%243245%46%50%
1980
11th to 20thNight
17%425%437%46%6%42%
1980
21st to endNight
16%7%35%5%35%45%7%41%
2178
April1st to 10thNight
13%6%2443446%7%47%
1974
11th to 20thNight
16%5%2342435%8%47%
1775
21st to endNight
16%5%2433445%7%48%
1638
May1st to 10thNight
14%6%35%4345%6%7%43%
1620
11th to 20thNight
16%6%26%6%4445%9%39%
1592
21st to endNight
17%5%25%5%246%6%10%38%
1744
June1st to 10thNight
11%4245%45%6%8%10%41%
1620
11th to 20thNight
12%5%243345%7%10%44%
1620
21st to endNight
8%5%25%6%36%5%7%12%42%
1620
July1st to 10thNight
10%5%25%5%446%8%11%40%
1620
11th to 20thNight
7%425%5%5%5%7%9%12%38%
1620
21st to endNight
6%5%26%6%46%7%8%12%38%
1771
August1st to 10thNight
15%6%36%5%35%6%7%10%34%
1611
11th to 20thNight
13%6%26%5%445%7%9%38%
1598
21st to endNight
11%6%25%6%446%6%9%40%
1898
September1st to 10thNight
12%425%6%35%5%6%8%45%
1932
11th to 20thNight
17%7%35%5%3345%7%41%
1980
21st to endNight
21%5%25%5%35%35%5%41%
1980
October1st to 10thNight
17%6%25%423446%47%
2093
11th to 20thNight
16%423323446%53%
2160
21st to endNight
15%423323445%56%
2376
November1st to 10thNight
16%5%2342333455%
2221
11th to 20thNight
15%422323447%55%
2467
21st to endNight
14%5%244235%46%51%
2470
December1st to 10thNight
19%6%25%434445%44%
2470
11th to 20thNight
17%5%24423346%50%
3042
21st to endNight
24%6%2443446%7%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
38%5%9%24%19%5%
1707
11th to 20thDay
42%5%8%21%20%5%
1629
21st to endDay
37%38%25%20%7%
1782
February1st to 10thDay
40%6%12%21%17%4
1620
11th to 20thDay
42%49%20%19%5%
1709
21st to endDay
43%7%11%16%17%7%
1506
March1st to 10thDay
34%5%8%24%22%7%
1980
11th to 20thDay
42%7%10%17%17%6%
1980
21st to endDay
45%5%9%23%14%4
2178
April1st to 10thDay
30%6%13%25%21%6%
1984
11th to 20thDay
36%6%11%19%20%8%
2134
21st to endDay
39%8%12%22%15%4
2335
May1st to 10thDay
39%10%15%19%14%3
2340
11th to 20thDay
44%11%13%20%9%2
2305
21st to endDay
40%10%17%24%9%1
2531
June1st to 10thDay
40%10%16%22%10%1
2340
11th to 20thDay
38%11%16%18%14%2
2340
21st to endDay
37%13%16%19%14%1
2340
July1st to 10thDay
42%13%16%16%11%2
2275
11th to 20thDay
40%15%19%15%9%1
2271
21st to endDay
43%12%18%17%8%2
2405
August1st to 10thDay
45%13%16%18%7%1
2314
11th to 20thDay
45%14%15%17%8%1
2303
21st to endDay
41%10%17%19%9%3
2440
September1st to 10thDay
37%11%13%20%16%3
2024
11th to 20thDay
41%8%12%20%17%2
1980
21st to endDay
47%5%10%19%16%3
1980
October1st to 10thDay
36%6%9%22%23%5%
1865
11th to 20thDay
34%5%8%26%20%7%
1800
21st to endDay
33%46%27%22%9%
1980
November1st to 10thDay
30%48%22%28%8%
1857
11th to 20thDay
31%49%23%26%7%
1710
21st to endDay
34%48%22%27%5%
1710
December1st to 10thDay
46%5%9%19%17%5%
1710
11th to 20thDay
31%49%23%23%9%
2150
21st to endDay
42%410%25%16%3
3124
January1st to 10thNight
35%5%11%21%21%7%
2459
11th to 20thNight
41%6%10%20%20%5%
2354
21st to endNight
36%48%24%24%4
2574
February1st to 10thNight
39%411%23%18%4
2340
11th to 20thNight
42%5%8%21%18%7%
2146
21st to endNight
42%5%12%18%18%6%
1748
March1st to 10thNight
35%5%8%21%22%8%
1980
11th to 20thNight
41%6%10%23%16%3
1980
21st to endNight
42%6%11%21%16%4
2178
April1st to 10thNight
36%5%11%22%21%5%
1974
11th to 20thNight
35%6%10%22%19%8%
1775
21st to endNight
36%6%12%26%17%3
1638
May1st to 10thNight
38%8%15%23%14%2
1620
11th to 20thNight
43%8%15%21%11%1
1593
21st to endNight
39%10%16%25%8%1
1745
June1st to 10thNight
35%11%16%24%12%2
1620
11th to 20thNight
35%9%19%23%13%1
1620
21st to endNight
33%12%18%21%12%4
1620
July1st to 10thNight
35%13%16%20%13%3
1575
11th to 20thNight
35%14%22%18%8%3
1566
21st to endNight
33%14%21%23%8%1
1672
August1st to 10thNight
43%12%17%19%9%1
1600
11th to 20thNight
42%10%15%21%10%2
1598
21st to endNight
38%11%16%24%9%2
1898
September1st to 10thNight
37%8%16%20%15%4
1932
11th to 20thNight
43%7%12%19%18%1
1980
21st to endNight
45%7%10%18%17%3
1980
October1st to 10thNight
39%5%8%22%22%3
2093
11th to 20thNight
34%48%27%20%6%
2160
21st to endNight
31%47%22%25%10%
2376
November1st to 10thNight
34%48%21%24%9%
2221
11th to 20thNight
31%49%21%26%9%
2467
21st to endNight
33%48%25%25%5%
2470
December1st to 10thNight
42%6%7%21%18%5%
2470
11th to 20thNight
36%49%18%24%9%
3044
21st to endNight
44%6%12%21%17%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
26%27%30%13%4
270
11th to 20thDay
28%20%34%17%1
243
21st to endDay
24%30%32%10%4
264
February1st to 10thDay
25%26%30%16%3
240
11th to 20thDay
35%25%31%8%
240
21st to endDay
27%25%34%12%2
224
March1st to 10thDay
20%22%31%20%7%
420
11th to 20thDay
23%24%29%19%5%1
420
21st to endDay
26%17%31%20%6%1
462
April1st to 10thDay
17%20%30%20%11%1
420
11th to 20thDay
19%16%25%24%13%4
412
21st to endDay
21%14%26%24%11%4
420
May1st to 10thDay
18%15%32%19%11%5%
423
11th to 20thDay
18%6%24%27%17%8%
447
21st to endDay
20%5%17%26%20%13%
485
June1st to 10thDay
14%6%16%34%20%10%
450
11th to 20thDay
12%6%19%23%29%12%
450
21st to endDay
11%320%33%22%10%
450
July1st to 10thDay
12%311%26%30%17%
445
11th to 20thDay
8%213%27%31%18%
444
21st to endDay
13%210%29%29%17%
488
August1st to 10thDay
17%318%23%20%20%
446
11th to 20thDay
14%211%30%25%18%
439
21st to endDay
11%210%27%31%19%
495
September1st to 10thDay
15%112%24%32%16%
450
11th to 20thDay
17%5%12%22%32%12%
450
21st to endDay
24%7%17%28%18%6%
450
October1st to 10thDay
22%6%15%25%25%6%
450
11th to 20thDay
15%13%23%26%20%3
450
21st to endDay
20%9%23%32%13%3
495
November1st to 10thDay
21%10%24%28%14%3
455
11th to 20thDay
16%22%29%24%7%1
270
21st to endDay
15%20%30%26%8%1
270
December1st to 10thDay
27%20%29%19%4
270
11th to 20thDay
21%17%33%22%7%
270
21st to endDay
26%17%31%20%5%1
297
January1st to 10thNight
19%15%35%26%6%
760
11th to 20thNight
21%11%34%31%3
725
21st to endNight
18%10%41%28%3
792
February1st to 10thNight
19%13%33%31%4
720
11th to 20thNight
23%15%37%23%1
703
21st to endNight
18%15%38%27%2
592
March1st to 10thNight
17%13%35%31%4
720
11th to 20thNight
19%13%35%26%7%1
720
21st to endNight
19%13%32%29%7%
792
April1st to 10thNight
17%15%31%28%8%
720
11th to 20thNight
18%13%27%29%12%1
711
21st to endNight
17%7%28%35%13%
558
May1st to 10thNight
15%10%28%30%16%1
540
11th to 20thNight
18%7%19%33%21%3
531
21st to endNight
20%111%29%34%6%
584
June1st to 10thNight
11%211%39%32%5%
540
11th to 20thNight
13%213%29%36%6%
540
21st to endNight
9%111%35%40%4
540
July1st to 10thNight
10%18%26%46%7%
525
11th to 20thNight
9%15%29%48%8%
522
21st to endNight
8%17%29%46%9%
591
August1st to 10thNight
15%27%28%39%8%
537
11th to 20thNight
14%27%30%38%8%
534
21st to endNight
13%28%26%41%10%
710
September1st to 10thNight
12%38%28%39%9%
720
11th to 20thNight
19%213%25%35%6%
720
21st to endNight
23%316%30%25%3
720
October1st to 10thNight
19%5%19%26%25%6%
720
11th to 20thNight
19%6%24%31%18%3
720
21st to endNight
17%10%20%38%14%2
792
November1st to 10thNight
18%7%21%36%15%2
740
11th to 20thNight
16%10%26%35%11%1
760
21st to endNight
15%10%30%33%11%1
760
December1st to 10thNight
23%10%31%29%8%
760
11th to 20thNight
19%8%33%32%7%
760
21st to endNight
27%12%24%32%5%
836
Page generated at 2024-01-08 22:31:23. Version ac07

Copyright 2024 Attilla Danko


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