Central-Clemson
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Central-Clemson clear sky chart from 2005-11-06 to 2024-02-25.

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
47%
24187
21%
79605
15%
24081
55%
24081
25%
49512

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
29%
754
27%
3977
11%
737
45%
737
17%
2075
January11th to 20thNight
30%
759
28%
3924
12%
740
45%
740
16%
2072
January21st to endNight
25%
831
18%
4440
12%
814
44%
814
16%
2603
February1st to 10thNight
37%
760
26%
2336
14%
760
49%
760
27%
1448
February11th to 20thNight
27%
741
22%
2218
9%
739
41%
739
24%
1455
February21st to endNight
29%
611
22%
1831
11%
611
39%
611
24%
1184
March1st to 10thNight
37%
720
26%
2034
15%
720
46%
720
32%
1262
March11th to 20thNight
35%
720
20%
1980
10%
720
44%
720
27%
1307
March21st to endNight
37%
792
20%
2178
10%
792
45%
792
26%
1443
April1st to 10thNight
41%
720
25%
1980
13%
720
50%
720
32%
1212
April11th to 20thNight
44%
617
25%
1799
14%
617
53%
617
33%
1077
April21st to endNight
52%
540
30%
1620
21%
540
58%
540
33%
956
May1st to 10thNight
52%
540
20%
1620
10%
540
58%
540
29%
1002
May11th to 20thNight
49%
531
13%
1593
8%
531
53%
531
23%
1086
May21st to endNight
59%
582
18%
1744
14%
582
61%
582
26%
1149
June1st to 10thNight
62%
540
14%
1620
12%
540
64%
540
23%
1107
June11th to 20thNight
65%
540
14%
1620
11%
540
68%
540
29%
1042
June21st to endNight
70%
540
13%
1620
10%
540
71%
540
25%
1071
July1st to 10thNight
62%
525
8%
1575
8%
525
62%
525
18%
1166
July11th to 20thNight
70%
522
11%
1566
9%
522
71%
522
22%
1096
July21st to endNight
69%
591
13%
1672
11%
558
70%
558
23%
1176
August1st to 10thNight
63%
537
11%
1600
10%
534
63%
534
20%
1148
August11th to 20thNight
65%
534
16%
1598
14%
534
67%
534
21%
1135
August21st to endNight
61%
638
15%
1993
15%
638
61%
638
20%
1376
September1st to 10thNight
64%
720
17%
1980
15%
720
64%
720
27%
1324
September11th to 20thNight
56%
720
18%
1980
14%
720
59%
720
24%
1373
September21st to endNight
56%
720
23%
1980
18%
720
60%
720
30%
1281
October1st to 10thNight
55%
720
26%
1986
22%
720
60%
720
34%
1221
October11th to 20thNight
52%
720
28%
2160
23%
720
61%
720
33%
1275
October21st to endNight
54%
792
32%
2376
26%
792
64%
792
38%
1326
November1st to 10thNight
53%
740
29%
2297
25%
740
61%
740
35%
1296
November11th to 20thNight
41%
760
28%
2470
19%
760
54%
760
31%
1412
November21st to endNight
47%
760
26%
2470
21%
760
56%
760
28%
1468
December1st to 10thNight
35%
760
24%
2470
14%
760
48%
760
21%
1611
December11th to 20thNight
39%
759
28%
2900
17%
758
51%
758
24%
1645
December21st to endNight
33%
831
14%
4398
14%
817
43%
817
12%
2632

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%345%6%8%44%
78805
Night
15%5%25%5%3445%7%44%
80509
TransparencyDay
37%7%12%20%18%5%
78528
Night
38%7%10%18%20%6%
80305
SeeingDay
16%8%21%26%19%10%
14046
Night
17%6%23%31%20%4
24209

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
18%42342345%8%48%
2836
11th to 20thDay
15%5%2443334453%
2840
21st to endDay
26%423312246%46%
3124
February1st to 10thDay
17%6%245%345%5%7%42%
1843
11th to 20thDay
21%5%25%423346%44%
1848
21st to endDay
21%5%35%4335%46%41%
1520
March1st to 10thDay
17%414423436%51%
1926
11th to 20thDay
19%5%3443445%7%41%
1980
21st to endDay
18%5%25%336%5%6%7%41%
2178
April1st to 10thDay
13%414435%5%6%8%49%
1980
11th to 20thDay
13%425%5%3445%7%48%
2124
21st to endDay
11%4244335%5%8%52%
2340
May1st to 10thDay
10%5%245%25%5%6%8%48%
2340
11th to 20thDay
13%5%25%5%45%5%6%9%41%
2301
21st to endDay
11%6%246%25%6%7%11%40%
2531
June1st to 10thDay
10%5%35%7%46%6%9%12%33%
2340
11th to 20thDay
5%425%6%46%7%9%12%39%
2340
21st to endDay
7%425%7%5%7%6%8%11%39%
2340
July1st to 10thDay
8%5%37%8%47%8%8%10%32%
2340
11th to 20thDay
9%5%25%6%5%7%8%9%11%32%
2340
21st to endDay
6%426%7%6%8%7%8%11%34%
2547
August1st to 10thDay
10%5%37%7%46%8%8%11%31%
2327
11th to 20thDay
11%5%36%7%47%7%8%10%34%
2303
21st to endDay
12%6%36%6%46%6%8%10%34%
2341
September1st to 10thDay
8%425%6%46%6%6%9%42%
1980
11th to 20thDay
14%6%25%6%345%6%9%40%
1980
21st to endDay
14%6%25%42346%7%47%
1980
October1st to 10thDay
14%5%13323236%56%
1972
11th to 20thDay
12%424422446%56%
1800
21st to endDay
14%42332334458%
1980
November1st to 10thDay
13%5%23323346%58%
1777
11th to 20thDay
15%42433435%6%52%
1710
21st to endDay
17%42432346%6%49%
1710
December1st to 10thDay
23%7%25%43345%6%39%
1710
11th to 20thDay
18%5%24324445%49%
2153
21st to endDay
23%5%23433447%43%
3124
January1st to 10thNight
18%424424446%48%
4109
11th to 20thNight
13%6%25%43345%6%49%
4120
21st to endNight
26%6%24322345%44%
4532
February1st to 10thNight
16%5%34424446%47%
2336
11th to 20thNight
22%5%25%42434444%
2218
21st to endNight
20%6%35%43445%5%43%
1831
March1st to 10thNight
15%6%24424447%49%
2034
11th to 20thNight
16%425%435%5%5%7%43%
1980
21st to endNight
16%6%245%35%45%6%43%
2178
April1st to 10thNight
13%425%424347%50%
1980
11th to 20thNight
13%425%32345%6%51%
1799
21st to endNight
12%4245%25%447%52%
1620
May1st to 10thNight
11%5%25%4345%5%9%47%
1620
11th to 20thNight
13%6%26%7%46%5%6%7%38%
1592
21st to endNight
13%5%26%6%445%6%9%40%
1744
June1st to 10thNight
10%5%26%7%45%6%9%11%34%
1620
11th to 20thNight
9%425%5%37%7%7%11%40%
1620
21st to endNight
8%436%5%36%8%8%12%38%
1620
July1st to 10thNight
11%6%37%7%5%7%7%8%10%27%
1620
11th to 20thNight
9%5%247%5%6%7%11%13%30%
1620
21st to endNight
6%5%36%8%47%8%10%11%31%
1771
August1st to 10thNight
11%6%37%7%5%6%7%9%11%29%
1611
11th to 20thNight
11%6%36%6%5%6%7%7%11%33%
1598
21st to endNight
12%7%36%6%46%5%7%10%33%
1993
September1st to 10thNight
10%5%36%6%45%6%7%9%39%
1980
11th to 20thNight
16%6%35%5%46%5%5%8%37%
1980
21st to endNight
14%426%5%3445%6%47%
1980
October1st to 10thNight
14%424424446%52%
1986
11th to 20thNight
13%42443345%5%52%
2160
21st to endNight
14%323323445%58%
2376
November1st to 10thNight
14%424423235%58%
2297
11th to 20thNight
17%6%24313346%53%
2470
21st to endNight
18%3234345%5%6%48%
2470
December1st to 10thNight
21%6%245%34345%42%
2470
11th to 20thNight
17%5%24323335%53%
3042
21st to endNight
21%6%345%35%45%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
35%5%7%22%23%8%
2837
11th to 20thDay
36%46%16%31%6%
2840
21st to endDay
41%35%19%25%7%
3124
February1st to 10thDay
41%410%20%19%6%
1843
11th to 20thDay
42%47%18%22%6%
1858
21st to endDay
44%5%8%15%19%9%
1520
March1st to 10thDay
36%5%7%19%23%10%
1926
11th to 20thDay
43%5%11%17%16%7%
1980
21st to endDay
42%7%10%20%19%3
2178
April1st to 10thDay
33%6%11%20%24%6%
1980
11th to 20thDay
36%5%8%20%21%9%
2124
21st to endDay
30%6%12%28%20%4
2340
May1st to 10thDay
34%7%14%21%19%5%
2340
11th to 20thDay
38%10%15%20%14%2
2305
21st to endDay
36%11%15%22%15%2
2531
June1st to 10thDay
39%12%18%22%8%2
2340
11th to 20thDay
33%13%19%23%11%2
2340
21st to endDay
35%12%18%19%12%4
2340
July1st to 10thDay
41%15%17%16%9%2
2275
11th to 20thDay
38%15%21%16%7%3
2271
21st to endDay
38%13%21%19%9%1
2405
August1st to 10thDay
43%13%17%20%7%
2314
11th to 20thDay
42%12%19%17%9%1
2303
21st to endDay
42%12%17%18%9%3
2341
September1st to 10thDay
36%11%14%18%18%3
1980
11th to 20thDay
40%8%12%18%19%3
1980
21st to endDay
37%6%11%21%20%6%
1980
October1st to 10thDay
32%410%19%29%6%
1972
11th to 20thDay
29%5%9%24%24%10%
1800
21st to endDay
31%35%22%29%11%
1980
November1st to 10thDay
31%39%18%29%10%
1777
11th to 20thDay
34%37%21%26%9%
1710
21st to endDay
36%48%21%24%7%
1710
December1st to 10thDay
46%5%6%19%17%6%
1710
11th to 20thDay
38%5%7%18%21%11%
2150
21st to endDay
41%48%21%23%3
3124
January1st to 10thNight
36%5%7%18%26%8%
4109
11th to 20thNight
36%5%7%17%27%8%
4120
21st to endNight
44%35%16%25%6%
4532
February1st to 10thNight
39%48%20%22%7%
2336
11th to 20thNight
44%5%5%17%24%7%
2219
21st to endNight
43%49%17%18%9%
1831
March1st to 10thNight
37%48%17%22%12%
2034
11th to 20thNight
40%7%11%14%21%7%
1980
21st to endNight
41%6%10%20%20%4
2178
April1st to 10thNight
34%5%9%19%26%7%
1980
11th to 20thNight
34%5%7%21%23%10%
1799
21st to endNight
33%6%10%25%22%4
1620
May1st to 10thNight
33%10%12%21%21%3
1620
11th to 20thNight
43%9%14%19%14%1
1593
21st to endNight
39%9%12%24%13%3
1745
June1st to 10thNight
39%13%16%19%11%2
1620
11th to 20thNight
35%10%18%24%10%2
1620
21st to endNight
35%14%18%16%12%4
1620
July1st to 10thNight
46%14%18%12%8%2
1575
11th to 20thNight
37%17%23%15%7%2
1566
21st to endNight
38%16%20%19%7%1
1672
August1st to 10thNight
43%14%19%17%6%
1600
11th to 20thNight
42%14%18%15%10%1
1598
21st to endNight
43%12%17%17%8%3
1993
September1st to 10thNight
38%10%16%18%14%4
1980
11th to 20thNight
43%9%13%17%16%2
1980
21st to endNight
38%6%12%19%18%7%
1980
October1st to 10thNight
33%6%10%17%27%6%
1986
11th to 20thNight
33%6%9%21%22%10%
2160
21st to endNight
29%46%20%28%13%
2376
November1st to 10thNight
32%47%19%27%11%
2297
11th to 20thNight
35%36%17%28%12%
2470
21st to endNight
36%5%7%18%26%7%
2470
December1st to 10thNight
45%47%18%19%7%
2470
11th to 20thNight
36%47%17%26%10%
3044
21st to endNight
44%5%9%19%18%4
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
22%16%36%22%4
270
11th to 20thDay
25%19%28%23%5%
270
21st to endDay
22%17%41%15%41
297
February1st to 10thDay
21%16%34%24%4
270
11th to 20thDay
34%16%32%15%2
270
21st to endDay
28%24%33%13%1
210
March1st to 10thDay
19%13%31%28%8%
366
11th to 20thDay
20%12%39%22%6%1
420
21st to endDay
23%14%30%23%9%1
462
April1st to 10thDay
17%15%27%26%14%2
420
11th to 20thDay
13%12%32%26%14%3
412
21st to endDay
18%9%23%26%16%7%
420
May1st to 10thDay
13%9%31%26%14%6%
423
11th to 20thDay
17%417%31%20%11%
447
21st to endDay
16%6%17%24%23%15%
485
June1st to 10thDay
13%5%15%28%25%14%
450
11th to 20thDay
8%6%14%26%24%22%
450
21st to endDay
10%315%31%23%19%
450
July1st to 10thDay
9%310%23%29%26%
445
11th to 20thDay
6%38%25%34%23%
444
21st to endDay
7%17%27%35%22%
488
August1st to 10thDay
15%411%24%25%20%
446
11th to 20thDay
13%17%26%35%18%
439
21st to endDay
13%311%24%27%22%
495
September1st to 10thDay
9%212%27%31%18%
450
11th to 20thDay
17%212%22%31%15%
450
21st to endDay
18%414%29%24%10%
450
October1st to 10thDay
19%416%29%20%12%
450
11th to 20thDay
13%7%20%32%23%5%
450
21st to endDay
18%7%21%32%19%4
495
November1st to 10thDay
19%7%25%28%17%5%
375
11th to 20thDay
16%13%33%29%8%1
270
21st to endDay
11%11%35%28%13%2
270
December1st to 10thDay
28%13%26%26%6%
270
11th to 20thDay
22%12%32%25%7%1
270
21st to endDay
31%16%27%16%8%2
297
January1st to 10thNight
22%9%34%29%6%
760
11th to 20thNight
21%12%32%30%5%
760
21st to endNight
20%10%40%28%3
836
February1st to 10thNight
19%8%31%38%4
760
11th to 20thNight
25%8%35%28%3
743
21st to endNight
20%13%34%29%4
611
March1st to 10thNight
18%8%34%35%5%
720
11th to 20thNight
16%8%36%30%9%1
720
21st to endNight
18%9%30%32%10%1
792
April1st to 10thNight
15%11%28%34%12%
720
11th to 20thNight
15%9%27%33%16%1
617
21st to endNight
13%5%24%36%20%2
540
May1st to 10thNight
13%5%24%37%20%1
540
11th to 20thNight
15%5%19%32%26%3
531
21st to endNight
15%213%28%36%6%
584
June1st to 10thNight
13%211%33%35%6%
540
11th to 20thNight
10%314%24%34%14%
540
21st to endNight
9%29%36%36%8%
540
July1st to 10thNight
13%28%26%39%13%
525
11th to 20thNight
12%25%24%43%15%
522
21st to endNight
8%28%27%46%10%
591
August1st to 10thNight
15%28%25%38%12%
537
11th to 20thNight
14%28%26%39%10%
534
21st to endNight
14%38%25%40%9%
638
September1st to 10thNight
10%211%28%38%10%
720
11th to 20thNight
18%313%27%34%6%
720
21st to endNight
16%414%33%31%3
720
October1st to 10thNight
15%5%19%26%29%6%
720
11th to 20thNight
15%5%22%33%21%3
720
21st to endNight
16%6%20%35%21%3
792
November1st to 10thNight
15%5%21%35%19%4
740
11th to 20thNight
17%8%30%31%13%1
760
21st to endNight
18%6%23%37%14%1
760
December1st to 10thNight
23%8%27%32%10%1
760
11th to 20thNight
19%6%30%33%11%1
760
21st to endNight
26%8%27%31%8%
836
Page generated at 2024-02-22 06:05:44. Version ac07

Copyright 2024 Attilla Danko


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