Greenville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Greenville clear sky chart from 2005-11-05 to

2017-09-12
.

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
36%
15968
15%
46758
9%
15927
41%
15927
20%
32843

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
17%
900
9%
2506
3%
895
21%
895
11%
2037
January16th to endNight
22%
960
8%
2688
4%
960
25%
960
11%
2198
February1st to 15thNight
18%
707
10%
2216
3%
707
25%
707
10%
1733
February16th to endNight
23%
631
12%
1893
5%
631
30%
631
13%
1452
March1st to 15thNight
29%
720
16%
2127
9%
720
34%
720
20%
1476
March16th to endNight
31%
741
18%
2085
10%
741
38%
741
22%
1442
April1st to 15thNight
32%
539
13%
1797
9%
539
39%
539
18%
1256
April16th to endNight
34%
540
20%
1629
9%
540
44%
540
25%
1053
May1st to 15thNight
35%
540
15%
1620
8%
540
42%
540
22%
1126
May16th to endNight
44%
561
15%
1562
10%
561
49%
561
28%
1028
June1st to 15thNight
49%
540
14%
1440
10%
540
53%
540
32%
918
June16th to endNight
52%
540
15%
1440
9%
540
56%
540
34%
918
July1st to 15thNight
65%
510
16%
1360
13%
510
67%
510
44%
769
July16th to endNight
63%
564
20%
1417
16%
531
66%
531
40%
846
August1st to 15thNight
64%
539
21%
1604
16%
536
68%
536
37%
912
August16th to endNight
62%
573
22%
1806
19%
573
66%
573
34%
1047
September1st to 15thNight
59%
605
25%
1842
21%
605
64%
605
36%
1039
September16th to endNight
55%
657
22%
1815
17%
657
58%
657
33%
1130
October1st to 15thNight
46%
660
22%
1856
17%
660
50%
660
29%
1205
October16th to endNight
26%
704
13%
2274
6%
704
34%
704
17%
1610
November1st to 15thNight
34%
700
19%
2276
17%
700
40%
700
21%
1530
November16th to endNight
26%
720
13%
2340
7%
720
32%
720
13%
1770
December1st to 15thNight
17%
857
5%
2477
2%
857
20%
857
9%
2078
December16th to endNight
15%
960
7%
2688
1%
960
21%
960
9%
2270

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%8%46%6%35%45%7%33%
47912
Night
14%9%46%5%3445%6%34%
46927
Cloud CoverDay
14%8%46%6%35%45%7%33%
47921
Night
14%9%46%5%3445%6%35%
46932
TransparencyDay
49%6%11%20%10%1
47599
Night
49%5%11%20%11%1
46758
SeeingDay
16%8%27%25%15%7%
5958
Night
18%8%29%30%12%1
15973

By Month

Percentage Cloud Cover NE (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
16%15%6%9%8%6%6%5%6%414%
1432
16th to endDay
13%17%11%11%9%46%345%11%
1536
February1st to 15thDay
12%14%7%11%10%5%5%34418%
1645
16th to endDay
14%11%7%10%9%35%45%6%20%
1580
March1st to 15thDay
15%10%47%5%35%35%7%30%
1823
16th to endDay
16%10%47%5%24346%34%
2148
April1st to 15thDay
20%11%35%5%3345%5%31%
2151
16th to endDay
16%7%35%5%35%35%6%37%
2331
May1st to 15thDay
20%6%26%43435%8%34%
2331
16th to endDay
11%5%35%5%36%46%7%40%
2550
June1st to 15thDay
11%6%35%5%36%45%8%40%
2520
16th to endDay
10%5%25%6%35%5%6%8%40%
2520
July1st to 15thDay
6%415%435%5%5%10%46%
2520
16th to endDay
8%424435%5%6%9%43%
2655
August1st to 15thDay
9%5%25%5%37%6%5%9%38%
2346
16th to endDay
12%5%244345%6%8%42%
2394
September1st to 15thDay
11%5%25%5%3446%7%44%
2026
16th to endDay
11%435%5%35%46%9%39%
1815
October1st to 15thDay
16%7%37%6%25%335%38%
1774
16th to endDay
21%9%38%7%44446%27%
1595
November1st to 15thDay
13%10%46%5%23446%37%
1582
16th to endDay
20%15%47%5%34446%23%
1620
December1st to 15thDay
15%14%9%12%7%445%45%17%
1482
16th to endDay
19%17%9%10%7%2445%313%
1536
January1st to 15thNight
19%14%6%10%7%33445%19%
2506
16th to endNight
12%12%9%10%8%45%5%5%7%18%
2688
February1st to 15thNight
13%15%6%8%6%45%5%5%5%23%
2214
16th to endNight
14%12%5%9%8%35%5%5%6%23%
1893
March1st to 15thNight
15%9%46%5%23347%36%
2114
16th to endNight
16%7%36%5%24347%37%
2085
April1st to 15thNight
19%9%35%5%35%446%33%
1797
16th to endNight
17%7%2342335%6%41%
1629
May1st to 15thNight
17%436%5%445%5%5%36%
1620
16th to endNight
11%6%35%5%25%35%9%41%
1560
June1st to 15thNight
10%425%5%2446%7%46%
1440
16th to endNight
8%325%6%246%5%9%44%
1440
July1st to 15thNight
6%31332446%9%54%
1440
16th to endNight
6%214425%46%8%52%
1513
August1st to 15thNight
5%3244245%6%8%51%
1614
16th to endNight
10%414433447%52%
1806
September1st to 15thNight
11%31332336%6%53%
1842
16th to endNight
9%6%344245%46%49%
1815
October1st to 15thNight
15%7%25%423447%44%
1856
16th to endNight
20%8%36%5%34446%32%
2274
November1st to 15thNight
14%9%26%5%35%46%6%36%
2276
16th to endNight
19%13%36%6%35%45%6%24%
2340
December1st to 15thNight
20%14%5%9%7%46%446%16%
2477
16th to endNight
21%16%7%8%7%34445%15%
2688

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
16%16%6%10%9%6%6%46%414%
1432
16th to endDay
13%17%11%11%9%45%44412%
1536
February1st to 15thDay
12%15%6%12%11%45%34418%
1645
16th to endDay
14%11%6%10%9%35%5%5%6%21%
1580
March1st to 15thDay
15%10%47%5%35%45%7%30%
1833
16th to endDay
16%10%5%7%5%24246%34%
2147
April1st to 15thDay
20%11%36%42445%5%30%
2151
16th to endDay
16%7%35%5%35%35%7%37%
2331
May1st to 15thDay
20%7%26%434448%34%
2331
16th to endDay
11%5%35%5%35%45%8%40%
2550
June1st to 15thDay
11%6%25%436%45%8%40%
2520
16th to endDay
10%5%25%5%35%5%6%7%40%
2520
July1st to 15thDay
6%424435%5%5%10%45%
2520
16th to endDay
8%4245%26%5%6%9%43%
2655
August1st to 15thDay
9%5%25%5%46%6%6%9%39%
2346
16th to endDay
12%5%25%5%2446%8%42%
2394
September1st to 15thDay
11%5%245%3446%7%44%
2026
16th to endDay
11%425%5%35%46%9%40%
1815
October1st to 15thDay
16%7%36%6%25%345%38%
1774
16th to endDay
21%10%36%7%35%446%27%
1595
November1st to 15thDay
13%9%45%5%2445%6%38%
1582
16th to endDay
19%15%5%7%5%35%446%23%
1620
December1st to 15thDay
15%14%8%12%7%44445%17%
1482
16th to endDay
20%16%10%9%7%245%5%413%
1536
January1st to 15thNight
19%14%7%9%7%23345%20%
2506
16th to endNight
12%12%9%10%8%45%5%5%7%18%
2688
February1st to 15thNight
13%14%7%8%6%45%45%5%23%
2207
16th to endNight
14%12%5%10%7%35%5%5%6%23%
1893
March1st to 15thNight
15%10%36%5%23347%36%
2127
16th to endNight
16%7%36%5%24347%37%
2085
April1st to 15thNight
19%9%35%4345%46%33%
1797
16th to endNight
17%7%23424347%41%
1629
May1st to 15thNight
17%5%36%5%45%446%36%
1619
16th to endNight
11%6%25%6%2445%8%41%
1560
June1st to 15thNight
10%5%25%5%245%5%7%45%
1440
16th to endNight
8%4246%25%5%6%9%44%
1440
July1st to 15thNight
6%32331445%8%55%
1440
16th to endNight
6%31342446%8%52%
1513
August1st to 15thNight
6%3244245%6%8%51%
1614
16th to endNight
10%414323447%52%
1806
September1st to 15thNight
11%31332345%6%53%
1842
16th to endNight
9%6%25%42345%6%49%
1815
October1st to 15thNight
15%6%24423437%44%
1856
16th to endNight
20%8%36%5%24436%33%
2274
November1st to 15thNight
14%8%25%5%35%46%6%36%
2276
16th to endNight
19%12%46%6%35%45%5%25%
2340
December1st to 15thNight
20%15%5%8%7%45%436%16%
2477
16th to endNight
21%16%8%8%6%34445%15%
2688

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
71%6%10%9%2
1433
16th to endDay
76%47%9%2
1536
February1st to 15thDay
68%6%7%13%3
1647
16th to endDay
62%6%9%14%6%
1580
March1st to 15thDay
53%5%11%20%8%
1833
16th to endDay
51%412%22%7%1
2148
April1st to 15thDay
54%48%19%11%
2151
16th to endDay
46%5%12%19%12%3
2331
May1st to 15thDay
48%5%12%21%10%1
2331
16th to endDay
40%7%11%27%12%
2554
June1st to 15thDay
40%6%13%23%15%
2520
16th to endDay
39%8%13%21%17%1
2520
July1st to 15thDay
32%6%13%26%18%2
2371
16th to endDay
35%7%12%26%16%2
2488
August1st to 15thDay
39%8%10%26%12%2
2332
16th to endDay
37%6%11%26%15%2
2394
September1st to 15thDay
37%6%11%28%14%1
2026
16th to endDay
39%6%13%25%14%
1815
October1st to 15thDay
49%5%9%22%12%1
1774
16th to endDay
58%5%14%16%4
1595
November1st to 15thDay
46%5%13%23%10%
1582
16th to endDay
61%5%12%14%4
1620
December1st to 15thDay
69%6%10%11%2
1482
16th to endDay
72%6%9%9%1
1536
January1st to 15thNight
66%410%13%5%
2506
16th to endNight
64%7%13%10%3
2688
February1st to 15thNight
61%6%9%16%5%
2216
16th to endNight
59%5%11%16%6%
1893
March1st to 15thNight
48%412%21%10%1
2127
16th to endNight
47%412%22%10%2
2085
April1st to 15thNight
50%5%9%18%15%
1797
16th to endNight
43%312%21%15%3
1629
May1st to 15thNight
47%5%10%20%12%2
1620
16th to endNight
41%5%11%23%16%1
1562
June1st to 15thNight
36%5%11%27%15%1
1440
16th to endNight
34%6%15%25%16%
1440
July1st to 15thNight
25%5%13%30%21%3
1360
16th to endNight
28%6%15%26%19%2
1417
August1st to 15thNight
29%6%12%32%18%1
1604
16th to endNight
31%6%10%28%20%2
1806
September1st to 15thNight
29%5%13%31%18%1
1842
16th to endNight
34%6%12%31%14%
1815
October1st to 15thNight
40%410%26%15%1
1856
16th to endNight
52%413%20%7%
2274
November1st to 15thNight
46%5%11%22%12%1
2276
16th to endNight
58%6%12%18%4
2340
December1st to 15thNight
68%6%11%9%4
2477
16th to endNight
70%5%11%10%2
2688

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
20%16%42%17%3
90
16th to endDay
31%10%34%14%8%1
96
February1st to 15thDay
22%24%44%6%2
90
16th to endDay
19%18%32%25%21
81
March1st to 15thDay
34%11%26%17%9%
123
16th to endDay
26%5%28%27%9%3
288
April1st to 15thDay
27%8%32%21%8%2
270
16th to endDay
20%11%28%21%11%5%
270
May1st to 15thDay
25%10%25%24%8%6%
288
16th to endDay
13%10%30%25%15%5%
450
June1st to 15thDay
12%6%33%29%12%5%
495
16th to endDay
12%8%34%26%13%5%
495
July1st to 15thDay
7%6%22%31%20%11%
475
16th to endDay
9%426%29%20%9%
515
August1st to 15thDay
8%317%27%25%18%
319
16th to endDay
15%417%24%23%15%
332
September1st to 15thDay
11%316%32%23%13%
299
16th to endDay
15%314%29%26%10%
254
October1st to 15thDay
20%6%23%27%18%3
255
16th to endDay
27%7%42%20%2
107
November1st to 15thDay
12%16%32%23%13%2
90
16th to endDay
34%12%35%12%5%
90
December1st to 15thDay
20%26%37%12%3
90
16th to endDay
27%31%33%8%
96
January1st to 15thNight
25%14%32%20%7%
900
16th to endNight
18%10%34%30%5%
960
February1st to 15thNight
19%14%36%24%4
710
16th to endNight
21%12%31%28%5%
631
March1st to 15thNight
19%10%33%28%7%
720
16th to endNight
19%8%33%28%7%1
741
April1st to 15thNight
20%10%32%28%5%
539
16th to endNight
21%8%33%27%7%1
540
May1st to 15thNight
20%5%33%30%9%1
540
16th to endNight
13%6%28%32%17%1
563
June1st to 15thNight
10%5%28%36%17%
540
16th to endNight
10%326%38%19%1
540
July1st to 15thNight
9%117%45%23%3
510
16th to endNight
6%121%40%26%2
564
August1st to 15thNight
7%118%44%25%2
539
16th to endNight
10%216%36%28%4
573
September1st to 15thNight
12%320%35%23%4
605
16th to endNight
12%6%19%33%23%5%
657
October1st to 15thNight
18%5%23%35%15%1
660
16th to endNight
25%11%31%22%8%
704
November1st to 15thNight
19%9%30%28%11%
700
16th to endNight
25%12%29%26%6%
720
December1st to 15thNight
26%11%35%22%3
857
16th to endNight
26%11%35%21%4
960
Page generated at 2017-09-13 07:39:17. Version ac04

Copyright 2017 A. Danko


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