Aiken
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Aiken clear sky chart from 2005-11-05 to 2017-09-10.

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
51%
15733
22%
46833
15%
15691
58%
15691
29%
29314

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 15thNight
34%
719
23%
2327
12%
716
47%
716
25%
1415
January16th to endNight
30%
768
24%
2496
14%
768
44%
768
25%
1556
February1st to 15thNight
37%
704
24%
2178
12%
701
50%
701
28%
1330
February16th to endNight
30%
631
26%
1878
10%
631
45%
631
30%
1136
March1st to 15thNight
37%
720
26%
1980
13%
720
48%
720
32%
1244
March16th to endNight
41%
768
21%
2112
11%
768
48%
768
31%
1332
April1st to 15thNight
45%
718
24%
1961
14%
718
53%
718
36%
1180
April16th to endNight
50%
626
26%
1706
16%
626
57%
626
34%
1045
May1st to 15thNight
50%
539
19%
1620
10%
539
56%
539
30%
1006
May16th to endNight
64%
561
18%
1682
14%
561
67%
561
29%
1053
June1st to 15thNight
63%
540
15%
1620
13%
540
64%
540
26%
1067
June16th to endNight
71%
540
14%
1620
13%
540
72%
540
27%
1034
July1st to 15thNight
68%
510
12%
1530
10%
510
69%
510
23%
1031
July16th to endNight
70%
564
11%
1595
10%
531
72%
531
24%
1089
August1st to 15thNight
71%
539
14%
1609
13%
536
71%
536
22%
1130
August16th to endNight
63%
657
15%
1860
13%
657
63%
657
23%
1303
September1st to 15thNight
68%
700
18%
1925
16%
700
69%
700
28%
1283
September16th to endNight
57%
657
17%
1815
14%
657
59%
657
24%
1263
October1st to 15thNight
57%
660
30%
1906
28%
660
62%
660
34%
1151
October16th to endNight
58%
704
34%
2112
28%
704
68%
704
40%
1152
November1st to 15thNight
56%
700
32%
2125
27%
700
65%
700
39%
1163
November16th to endNight
45%
720
27%
2340
19%
720
57%
720
31%
1351
December1st to 15thNight
46%
720
24%
2340
17%
720
56%
720
27%
1411
December16th to endNight
38%
768
23%
2496
18%
768
47%
768
24%
1589

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%5%25%5%35%5%5%8%42%
47789
Night
11%5%2442445%7%44%
47032
TransparencyDay
38%6%12%19%17%5%
47490
Night
37%6%11%18%18%7%
46835
SeeingDay
13%417%24%24%15%
5584
Night
14%422%32%23%3
15737

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 15thDay
15%5%2442345%5%45%
1611
16th to endDay
15%6%24423346%46%
1728
February1st to 15thDay
14%5%26%323447%45%
1681
16th to endDay
16%5%23423425%48%
1595
March1st to 15thDay
13%424423445%49%
1980
16th to endDay
14%5%25%42335%5%46%
2111
April1st to 15thDay
9%414435%447%48%
1986
16th to endDay
7%4245%2445%8%48%
2263
May1st to 15thDay
9%4245%35%45%8%45%
2331
16th to endDay
10%5%25%6%36%5%7%9%37%
2431
June1st to 15thDay
9%436%5%36%5%6%10%37%
2340
16th to endDay
5%2246%46%7%8%11%40%
2340
July1st to 15thDay
6%6%36%7%37%7%8%8%33%
2340
16th to endDay
6%427%7%37%8%9%12%29%
2465
August1st to 15thDay
8%5%26%7%46%7%8%11%30%
2340
16th to endDay
11%5%36%6%5%8%6%7%10%27%
2327
September1st to 15thDay
7%5%26%6%46%6%6%9%39%
1923
16th to endDay
16%7%35%5%3345%7%38%
1815
October1st to 15thDay
14%5%1442333453%
1724
16th to endDay
10%413423335%58%
1760
November1st to 15thDay
11%5%13313245%55%
1730
16th to endDay
13%42442335%5%50%
1620
December1st to 15thDay
15%7%2433345%8%41%
1620
16th to endDay
19%7%24424446%38%
1728
January1st to 15thNight
13%6%24423446%46%
2327
16th to endNight
16%6%25%323335%46%
2496
February1st to 15thNight
16%425%323446%46%
2169
16th to endNight
14%41442435%6%48%
1878
March1st to 15thNight
11%4245%2445%5%48%
1980
16th to endNight
12%424325%45%7%46%
2112
April1st to 15thNight
11%423424346%52%
1961
16th to endNight
8%3245%2445%7%49%
1706
May1st to 15thNight
8%5%25%5%345%6%8%44%
1619
16th to endNight
6%3245%35%5%8%9%42%
1682
June1st to 15thNight
11%5%25%5%35%6%7%11%35%
1620
16th to endNight
4435%5%36%7%8%12%37%
1620
July1st to 15thNight
8%5%36%6%37%7%8%10%33%
1620
16th to endNight
45%36%7%37%6%9%11%33%
1703
August1st to 15thNight
8%425%6%47%7%9%11%31%
1620
16th to endNight
10%7%35%6%45%6%6%11%32%
1860
September1st to 15thNight
7%5%25%6%26%7%6%9%39%
1925
16th to endNight
14%6%25%6%25%45%7%38%
1815
October1st to 15thNight
14%5%24322225%52%
1906
16th to endNight
8%414323435%58%
2112
November1st to 15thNight
10%413213346%56%
2125
16th to endNight
13%5%23324335%52%
2340
December1st to 15thNight
14%5%2442335%7%45%
2340
16th to endNight
18%7%24424346%41%
2496

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 15thDay
39%5%9%16%23%6%
1612
16th to endDay
39%37%17%23%7%
1728
February1st to 15thDay
38%37%20%22%7%
1683
16th to endDay
39%35%20%23%7%
1595
March1st to 15thDay
36%48%20%20%9%
1980
16th to endDay
39%411%19%19%5%
2112
April1st to 15thDay
33%5%9%20%24%6%
1986
16th to endDay
32%5%12%21%22%6%
2263
May1st to 15thDay
36%5%14%21%19%2
2331
16th to endDay
40%8%14%23%11%1
2435
June1st to 15thDay
39%8%16%23%10%
2340
16th to endDay
31%11%18%24%11%2
2340
July1st to 15thDay
40%12%18%18%7%3
2201
16th to endDay
39%13%19%19%6%1
2310
August1st to 15thDay
43%11%15%19%8%1
2327
16th to endDay
46%13%15%15%8%
2327
September1st to 15thDay
39%8%15%16%16%3
1923
16th to endDay
45%5%10%16%15%6%
1815
October1st to 15thDay
34%48%20%23%9%
1724
16th to endDay
30%3419%29%13%
1760
November1st to 15thDay
32%26%18%26%12%
1730
16th to endDay
35%49%18%22%9%
1620
December1st to 15thDay
41%5%9%17%18%7%
1620
16th to endDay
45%49%16%17%6%
1728
January1st to 15thNight
38%48%15%25%7%
2327
16th to endNight
41%3417%22%10%
2496
February1st to 15thNight
37%47%19%20%10%
2178
16th to endNight
36%48%18%23%9%
1878
March1st to 15thNight
35%5%9%18%22%8%
1980
16th to endNight
36%5%11%19%19%8%
2112
April1st to 15thNight
32%49%21%23%8%
1961
16th to endNight
32%6%8%20%22%9%
1706
May1st to 15thNight
35%7%14%20%17%4
1620
16th to endNight
34%9%15%24%14%1
1684
June1st to 15thNight
40%8%16%22%11%
1620
16th to endNight
33%12%18%20%11%2
1620
July1st to 15thNight
39%11%20%16%7%3
1530
16th to endNight
37%13%21%17%7%1
1595
August1st to 15thNight
40%14%16%18%9%
1609
16th to endNight
43%10%18%18%8%
1860
September1st to 15thNight
36%10%16%17%12%5%
1925
16th to endNight
45%6%11%17%13%5%
1815
October1st to 15thNight
36%39%18%23%9%
1906
16th to endNight
28%36%20%26%14%
2112
November1st to 15thNight
29%37%16%27%15%
2125
16th to endNight
35%37%15%24%13%
2340
December1st to 15thNight
37%5%11%18%19%8%
2340
16th to endNight
43%39%19%16%7%
2496

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 15thDay
16%13%32%28%8%
90
16th to endDay
15%25%36%16%6%
96
February1st to 15thDay
14%15%46%23%
90
16th to endDay
14%12%41%23%7%
96
March1st to 15thDay
10%11%32%32%12%
270
16th to endDay
14%5%35%25%17%1
288
April1st to 15thDay
13%11%24%21%23%5%
270
16th to endDay
7%322%28%28%9%
270
May1st to 15thDay
11%5%21%29%20%11%
288
16th to endDay
16%115%19%24%23%
331
June1st to 15thDay
13%18%20%28%27%
315
16th to endDay
9%6%27%25%30%
315
July1st to 15thDay
6%15%20%38%28%
305
16th to endDay
7%6%21%35%29%
326
August1st to 15thDay
13%6%19%34%24%
313
16th to endDay
13%15%19%28%31%
332
September1st to 15thDay
10%29%21%32%23%
294
16th to endDay
22%213%25%23%12%
254
October1st to 15thDay
20%214%27%25%8%
255
16th to endDay
10%220%25%28%11%
272
November1st to 15thDay
18%419%33%17%6%
238
16th to endDay
8%6%26%30%23%4
90
December1st to 15thDay
20%8%33%24%12%1
90
16th to endDay
32%12%23%19%9%2
96
January1st to 15thNight
16%9%34%31%8%
720
16th to endNight
18%10%36%29%5%
768
February1st to 15thNight
18%9%31%34%5%
704
16th to endNight
15%9%39%30%4
631
March1st to 15thNight
14%8%34%34%7%
720
16th to endNight
14%6%32%31%14%
768
April1st to 15thNight
13%6%30%32%16%
718
16th to endNight
11%426%37%19%
626
May1st to 15thNight
12%225%36%20%2
540
16th to endNight
7%214%36%33%4
563
June1st to 15thNight
13%18%34%34%6%
540
16th to endNight
6%17%32%40%11%
540
July1st to 15thNight
10%6%30%43%9%
510
16th to endNight
7%15%28%50%7%
564
August1st to 15thNight
11%428%47%8%
539
16th to endNight
14%9%25%41%8%
657
September1st to 15thNight
9%18%28%46%5%
700
16th to endNight
17%113%33%29%4
657
October1st to 15thNight
16%317%31%27%4
660
16th to endNight
10%323%34%25%2
704
November1st to 15thNight
12%423%35%20%4
700
16th to endNight
15%6%29%28%18%1
720
December1st to 15thNight
16%6%25%33%15%1
720
16th to endNight
21%7%28%32%9%
768
Page generated at 2017-09-11 19:35:24. Version ac04

Copyright 2017 A. Danko


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