Greenville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Greenville clear sky chart from 2005-11-06 to 2024-03-08.

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
59%
23437
25%
80534
23%
23350
65%
23350
33%
45066

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
43%
751
16%
4343
15%
736
48%
736
14%
2494
January11th to 20thNight
45%
753
15%
4288
15%
740
53%
740
13%
2843
January21st to endNight
42%
831
15%
4468
19%
814
52%
814
13%
3110
February1st to 10thNight
46%
760
24%
2470
20%
760
55%
760
28%
1486
February11th to 20thNight
47%
740
24%
2301
19%
740
56%
740
28%
1397
February21st to endNight
45%
628
21%
1884
19%
628
50%
628
25%
1194
March1st to 10thNight
37%
750
14%
2216
10%
750
43%
750
19%
1547
March11th to 20thNight
47%
720
21%
1980
16%
720
53%
720
29%
1276
March21st to endNight
39%
792
16%
2080
8%
792
44%
792
24%
1443
April1st to 10thNight
47%
720
20%
1800
10%
720
51%
720
30%
1196
April11th to 20thNight
47%
711
23%
1779
11%
711
52%
711
35%
1122
April21st to endNight
57%
720
22%
1800
11%
720
61%
720
41%
1073
May1st to 10thNight
51%
572
25%
1652
15%
572
58%
572
38%
915
May11th to 20thNight
62%
354
24%
1416
26%
354
66%
354
29%
725
May21st to endNight
62%
388
20%
1552
21%
388
68%
388
28%
831
June1st to 10thNight
67%
360
22%
1440
27%
360
72%
360
36%
704
June11th to 20thNight
72%
360
31%
1440
37%
360
79%
360
50%
561
June21st to endNight
80%
360
32%
1440
43%
360
85%
360
58%
521
July1st to 10thNight
90%
350
33%
1400
47%
350
92%
350
70%
447
July11th to 20thNight
89%
348
39%
1392
52%
348
91%
348
76%
422
July21st to endNight
90%
488
40%
1577
44%
461
90%
461
67%
596
August1st to 10thNight
90%
537
38%
1602
33%
534
91%
534
66%
689
August11th to 20thNight
83%
652
39%
1720
26%
652
84%
652
74%
765
August21st to endNight
85%
792
43%
1980
27%
792
86%
792
80%
898
September1st to 10thNight
83%
720
44%
1800
28%
720
85%
720
75%
839
September11th to 20thNight
80%
720
43%
1800
32%
720
83%
720
67%
890
September21st to endNight
76%
720
40%
2011
35%
720
81%
720
65%
908
October1st to 10thNight
66%
720
30%
2160
27%
720
74%
720
48%
1054
October11th to 20thNight
70%
720
36%
2160
36%
720
78%
720
52%
1035
October21st to endNight
66%
792
36%
2384
33%
792
74%
792
50%
1161
November1st to 10thNight
56%
740
26%
2405
25%
740
62%
740
31%
1390
November11th to 20thNight
56%
760
24%
2470
19%
760
64%
760
33%
1363
November21st to endNight
53%
760
25%
2642
22%
760
61%
760
34%
1405
December1st to 10thNight
50%
760
23%
2660
20%
760
58%
760
26%
1569
December11th to 20thNight
44%
760
19%
3221
17%
759
52%
759
16%
2231
December21st to endNight
36%
828
14%
4801
15%
817
46%
817
12%
2966

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
8%7%23323346%58%
78618
Night
10%8%23323346%55%
80979
TransparencyDay
29%49%20%22%17%
78327
Night
32%5%10%20%20%12%
80791
SeeingDay
15%15%27%24%14%5%
14070
Night
13%6%17%37%24%3
23471

By Month

Percentage Cloud Cover SW (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
10%20%35%5%2445%6%37%
2539
11th to 20thDay
18%15%26%6%34345%34%
2649
21st to endDay
18%14%47%5%34346%33%
3146
February1st to 10thDay
14%10%2442445%7%45%
1710
11th to 20thDay
8%13%35%42335%8%46%
1768
21st to endDay
9%17%3442435%7%43%
1570
March1st to 10thDay
13%16%5%7%4345%46%34%
1901
11th to 20thDay
14%14%3442335%7%41%
1980
21st to endDay
13%16%25%423447%41%
2275
April1st to 10thDay
12%13%3443346%7%42%
2160
11th to 20thDay
10%9%24423446%52%
2129
21st to endDay
9%6%2333345%6%55%
2160
May1st to 10thDay
7%5%24324346%59%
2304
11th to 20thDay
8%6%24433346%58%
2477
21st to endDay
10%7%35%5%3345%6%49%
2723
June1st to 10thDay
7%4233245%6%7%58%
2520
11th to 20thDay
3213323345%73%
2520
21st to endDay
311221223480%
2520
July1st to 10thDay
11111223483%
2520
11th to 20thDay
11111212386%
2520
21st to endDay
211121233480%
2645
August1st to 10thDay
321221223478%
2328
11th to 20thDay
11111123485%
2179
21st to endDay
11111112389%
2376
September1st to 10thDay
21121222484%
2160
11th to 20thDay
3212223345%74%
2160
21st to endDay
4211212236%74%
1946
October1st to 10thDay
6%32332333469%
1800
11th to 20thDay
7%423222246%67%
1800
21st to endDay
9%312223446%64%
1972
November1st to 10thDay
11%7%1342445%7%52%
1674
11th to 20thDay
11%5%24335%5%6%7%49%
1710
21st to endDay
8%7%333335%47%53%
1535
December1st to 10thDay
14%9%2432335%8%46%
1520
11th to 20thDay
20%12%36%5%35%5%6%7%30%
1928
21st to endDay
11%10%345%35%5%6%10%37%
2794
January1st to 10thNight
10%15%25%425%45%7%41%
4406
11th to 20thNight
18%14%36%5%34446%35%
4313
21st to endNight
18%17%35%434446%32%
4521
February1st to 10thNight
13%10%24323347%48%
2470
11th to 20thNight
10%12%2332345%8%48%
2299
21st to endNight
9%15%44433345%47%
1884
March1st to 10thNight
12%19%44424446%37%
2216
11th to 20thNight
12%13%2332346%8%44%
1980
21st to endNight
11%15%3433445%7%42%
2080
April1st to 10thNight
9%10%335%35%46%7%46%
1800
11th to 20thNight
11%9%23322447%52%
1779
21st to endNight
8%7%1332345%8%57%
1800
May1st to 10thNight
10%5%14323346%60%
1652
11th to 20thNight
8%5%2443446%7%54%
1416
21st to endNight
10%7%24424445%54%
1552
June1st to 10thNight
6%6%1332345%7%60%
1440
11th to 20thNight
4312222335%73%
1440
21st to endNight
321221223379%
1440
July1st to 10thNight
121211213484%
1440
11th to 20thNight
11211112388%
1440
21st to endNight
121211123480%
1670
August1st to 10thNight
211222234477%
1611
11th to 20thNight
1212212235%79%
1720
21st to endNight
111111122385%
1980
September1st to 10thNight
211111122384%
1800
11th to 20thNight
3212212335%77%
1800
21st to endNight
4212222236%76%
2011
October1st to 10thNight
6%31322332471%
2160
11th to 20thNight
6%31321233471%
2160
21st to endNight
8%411212346%68%
2384
November1st to 10thNight
11%9%2332346%6%51%
2405
11th to 20thNight
10%6%1333346%10%52%
2470
21st to endNight
8%7%2432445%7%55%
2642
December1st to 10thNight
14%10%23222348%49%
2660
11th to 20thNight
22%13%2443335%7%34%
3276
21st to endNight
15%12%45%5%345%5%7%36%
4862

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%5%12%26%8%1
2539
11th to 20thDay
53%6%12%17%8%4
2649
21st to endDay
52%412%18%11%2
3146
February1st to 10thDay
40%412%24%16%5%
1710
11th to 20thDay
39%49%25%18%3
1777
21st to endDay
42%410%25%14%4
1570
March1st to 10thDay
52%5%9%19%12%3
1901
11th to 20thDay
44%311%21%17%3
1980
21st to endDay
46%6%14%21%11%3
2275
April1st to 10thDay
42%5%13%21%16%3
2160
11th to 20thDay
34%412%24%19%6%
2132
21st to endDay
30%5%15%25%22%4
2160
May1st to 10thDay
27%411%25%28%6%
2304
11th to 20thDay
29%411%25%25%6%
2480
21st to endDay
36%6%12%24%19%4
2724
June1st to 10thDay
25%5%10%23%28%9%
2520
11th to 20thDay
16%38%21%35%18%
2520
21st to endDay
10%2415%37%33%
2520
July1st to 10thDay
6%2411%26%51%
2451
11th to 20thDay
6%1211%26%52%
2445
21st to endDay
10%238%24%53%
2498
August1st to 10thDay
12%2412%30%41%
2312
11th to 20thDay
6%1311%32%46%
2179
21st to endDay
5%1212%34%45%
2376
September1st to 10thDay
8%139%29%50%
2160
11th to 20thDay
14%27%20%32%25%
2160
21st to endDay
14%26%22%32%24%
1946
October1st to 10thDay
22%36%21%29%20%
1800
11th to 20thDay
21%38%19%33%17%
1800
21st to endDay
22%39%24%25%16%
1972
November1st to 10thDay
32%6%11%21%22%9%
1674
11th to 20thDay
34%5%12%25%20%3
1710
21st to endDay
32%411%23%23%7%
1535
December1st to 10thDay
38%5%9%24%21%3
1520
11th to 20thDay
53%6%9%18%13%1
1928
21st to endDay
39%8%18%24%10%2
2794
January1st to 10thNight
41%7%17%24%9%1
4406
11th to 20thNight
48%9%13%15%11%4
4313
21st to endNight
55%5%10%16%12%2
4521
February1st to 10thNight
37%5%9%26%17%6%
2470
11th to 20thNight
38%5%11%26%19%2
2301
21st to endNight
40%5%12%23%16%5%
1884
March1st to 10thNight
50%5%12%19%12%4
2216
11th to 20thNight
39%5%12%21%19%4
1980
21st to endNight
43%8%13%23%11%2
2080
April1st to 10thNight
39%6%15%21%15%4
1800
11th to 20thNight
34%5%15%24%17%6%
1779
21st to endNight
27%6%15%31%17%3
1800
May1st to 10thNight
28%412%26%26%4
1652
11th to 20thNight
30%5%14%27%18%6%
1416
21st to endNight
31%7%15%26%19%2
1552
June1st to 10thNight
24%8%14%25%24%6%
1440
11th to 20thNight
16%312%23%33%14%
1440
21st to endNight
12%35%17%34%29%
1440
July1st to 10thNight
8%1411%31%45%
1400
11th to 20thNight
5%2314%25%51%
1392
21st to endNight
10%228%25%52%
1577
August1st to 10thNight
12%3414%29%38%
1602
11th to 20thNight
9%1313%33%40%
1720
21st to endNight
7%2414%29%44%
1980
September1st to 10thNight
9%229%31%47%
1800
11th to 20thNight
13%37%19%34%24%
1800
21st to endNight
13%26%23%33%24%
2011
October1st to 10thNight
20%37%20%29%21%
2160
11th to 20thNight
18%37%22%30%20%
2160
21st to endNight
20%310%25%28%14%
2384
November1st to 10thNight
34%5%10%21%20%10%
2405
11th to 20thNight
30%6%12%26%21%4
2470
21st to endNight
30%411%25%22%8%
2642
December1st to 10thNight
36%6%10%21%22%5%
2660
11th to 20thNight
52%47%18%17%1
3276
21st to endNight
47%6%14%19%12%2
4862

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
37%9%20%22%11%1
180
11th to 20thDay
29%11%21%24%13%2
250
21st to endDay
23%15%23%25%12%2
407
February1st to 10thDay
28%12%24%24%11%1
370
11th to 20thDay
26%19%28%20%8%1
414
21st to endDay
20%19%29%24%7%
382
March1st to 10thDay
35%23%22%13%5%2
449
11th to 20thDay
29%15%26%19%10%1
420
21st to endDay
26%22%29%15%8%
462
April1st to 10thDay
25%20%28%19%6%1
420
11th to 20thDay
26%22%23%19%8%2
412
21st to endDay
18%19%28%20%12%3
420
May1st to 10thDay
17%24%26%22%9%2
423
11th to 20thDay
20%16%29%21%10%5%
448
21st to endDay
15%15%26%25%13%6%
485
June1st to 10thDay
12%16%29%21%14%8%
450
11th to 20thDay
10%19%32%22%13%4
450
21st to endDay
415%29%29%16%8%
450
July1st to 10thDay
37%40%27%14%9%
446
11th to 20thDay
19%35%28%16%10%
444
21st to endDay
29%33%27%18%11%
487
August1st to 10thDay
411%31%26%17%11%
447
11th to 20thDay
39%28%31%19%11%
437
21st to endDay
311%30%32%18%6%
495
September1st to 10thDay
311%28%32%20%4
450
11th to 20thDay
6%15%26%28%21%4
450
21st to endDay
6%15%29%32%14%4
450
October1st to 10thDay
6%16%28%24%21%5%
450
11th to 20thDay
12%12%21%28%22%5%
450
21st to endDay
16%12%23%27%18%5%
487
November1st to 10thDay
19%10%17%29%21%5%
270
11th to 20thDay
11%7%26%27%22%7%
270
21st to endDay
14%13%20%28%20%4
187
December1st to 10thDay
24%9%21%23%16%7%
180
11th to 20thDay
21%12%23%21%19%4
180
21st to endDay
24%12%19%25%17%2
198
January1st to 10thNight
19%8%23%36%12%1
760
11th to 20thNight
17%7%25%40%10%1
760
21st to endNight
21%6%25%32%14%2
836
February1st to 10thNight
21%6%22%39%12%1
760
11th to 20thNight
19%8%22%36%14%1
744
21st to endNight
21%9%20%40%9%1
628
March1st to 10thNight
25%13%19%30%10%3
750
11th to 20thNight
22%7%20%30%21%1
720
21st to endNight
22%13%20%29%15%1
792
April1st to 10thNight
16%9%22%38%14%1
720
11th to 20thNight
17%10%22%32%16%3
711
21st to endNight
13%9%19%35%21%3
720
May1st to 10thNight
12%11%21%34%20%2
572
11th to 20thNight
12%5%14%40%27%3
354
21st to endNight
14%414%28%36%4
389
June1st to 10thNight
9%5%14%34%36%3
360
11th to 20thNight
5%5%16%41%31%2
360
21st to endNight
5%210%42%39%2
360
July1st to 10thNight
215%42%47%3
350
11th to 20thNight
116%48%43%1
348
21st to endNight
11236%55%5%
488
August1st to 10thNight
21340%50%5%
537
11th to 20thNight
229%40%42%5%
652
21st to endNight
1110%46%39%3
792
September1st to 10thNight
2310%44%37%4
720
11th to 20thNight
3310%36%40%7%
720
21st to endNight
45%12%43%28%8%
720
October1st to 10thNight
8%7%16%38%28%4
720
11th to 20thNight
8%5%12%39%31%3
720
21st to endNight
11%5%16%36%27%5%
792
November1st to 10thNight
15%6%17%35%24%3
740
11th to 20thNight
14%5%20%44%16%1
760
21st to endNight
14%6%22%38%19%1
760
December1st to 10thNight
22%7%18%38%14%1
760
11th to 20thNight
25%6%19%35%14%1
760
21st to endNight
24%9%25%34%9%
836
Page generated at 2024-03-05 04:24:00. Version ac07

Copyright © 2024 Attilla Danko.


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