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 2018-02-14.

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
48%
16317
22%
48884
15%
16281
56%
16281
29%
30370

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
33%
776
22%
2522
13%
776
45%
776
23%
1569
January16th to endNight
31%
832
24%
2704
14%
832
45%
832
26%
1660
February1st to 15thNight
32%
757
20%
2455
11%
757
45%
757
25%
1494
February16th to endNight
30%
631
28%
1875
14%
631
47%
631
30%
1090
March1st to 15thNight
36%
720
26%
1980
15%
720
47%
720
35%
1198
March16th to endNight
41%
768
22%
2106
14%
768
48%
768
30%
1344
April1st to 15thNight
39%
718
23%
1796
10%
718
47%
718
34%
1168
April16th to endNight
45%
720
22%
1800
10%
720
50%
720
36%
1142
May1st to 15thNight
47%
660
16%
1740
7%
660
52%
660
31%
1135
May16th to endNight
61%
510
17%
1632
13%
510
63%
510
30%
976
June1st to 15thNight
63%
360
15%
1440
18%
360
65%
360
23%
855
June16th to endNight
66%
372
16%
1452
18%
372
69%
372
24%
895
July1st to 15thNight
69%
510
12%
1530
11%
510
70%
510
27%
993
July16th to endNight
70%
564
13%
1595
11%
531
71%
531
30%
994
August1st to 15thNight
68%
578
15%
1648
12%
575
68%
575
29%
1092
August16th to endNight
64%
764
16%
1910
11%
764
65%
764
26%
1343
September1st to 15thNight
63%
720
24%
1800
18%
720
64%
720
31%
1207
September16th to endNight
53%
717
18%
1980
16%
717
55%
717
24%
1394
October1st to 15thNight
55%
720
27%
2160
25%
720
62%
720
31%
1317
October16th to endNight
51%
768
35%
2304
27%
768
65%
768
39%
1270
November1st to 15thNight
51%
760
27%
2297
20%
760
60%
760
33%
1354
November16th to endNight
48%
780
27%
2581
22%
780
57%
780
31%
1458
December1st to 15thNight
43%
780
20%
2730
15%
780
53%
780
24%
1653
December16th to endNight
39%
832
23%
2847
17%
832
50%
832
23%
1769

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
13%5%25%5%3445%7%42%
49161
Night
13%5%2442445%7%44%
49078
Cloud CoverDay
12%5%25%5%35%45%7%42%
49171
Night
12%5%2442445%7%44%
49082
TransparencyDay
39%5%11%21%17%3
48872
Night
38%411%21%18%4
48885
SeeingDay
16%418%24%23%12%
6319
Night
15%5%22%35%19%2
16326

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
17%5%2442334347%
1746
16th to endDay
17%6%23224435%47%
1872
February1st to 15thDay
17%5%26%413326%45%
1706
16th to endDay
14%424424346%48%
1597
March1st to 15thDay
13%414424336%50%
1969
16th to endDay
16%6%24414445%44%
2117
April1st to 15thDay
11%324323347%52%
2152
16th to endDay
10%42442445%7%46%
2160
May1st to 15thDay
12%6%25%6%35%45%7%39%
2221
16th to endDay
9%425%6%35%5%6%9%40%
2479
June1st to 15thDay
9%425%5%36%6%6%9%39%
2520
16th to endDay
7%3245%36%7%7%11%39%
2503
July1st to 15thDay
8%435%6%36%7%7%11%35%
2340
16th to endDay
6%6%36%6%36%6%7%10%36%
2465
August1st to 15thDay
13%5%26%6%46%6%7%9%31%
2286
16th to endDay
10%5%47%6%5%6%7%7%9%30%
2292
September1st to 15thDay
11%5%25%5%345%7%7%40%
2160
16th to endDay
17%8%36%5%35%5%46%33%
1977
October1st to 15thDay
17%5%245%23335%46%
1800
16th to endDay
12%415%32323456%
1920
November1st to 15thDay
16%413313346%50%
1887
16th to endDay
13%423414336%52%
1706
December1st to 15thDay
17%5%345%23336%44%
1560
16th to endDay
19%5%24423345%42%
1726
January1st to 15thNight
14%6%25%433446%43%
2522
16th to endNight
16%5%34423345%45%
2704
February1st to 15thNight
18%5%24323345%45%
2453
16th to endNight
13%424233345%52%
1875
March1st to 15thNight
14%314213347%51%
1968
16th to endNight
15%41442345%7%44%
2106
April1st to 15thNight
11%6%2443435%6%48%
1796
16th to endNight
12%41434445%8%46%
1800
May1st to 15thNight
9%6%25%5%43448%43%
1740
16th to endNight
9%425%5%25%36%8%46%
1631
June1st to 15thNight
8%425%6%35%6%7%9%39%
1440
16th to endNight
7%425%6%347%7%11%39%
1452
July1st to 15thNight
8%5%25%5%26%5%8%13%35%
1620
16th to endNight
6%325%6%37%6%8%10%39%
1703
August1st to 15thNight
9%5%26%5%35%6%6%11%36%
1659
16th to endNight
10%5%35%6%46%6%7%9%34%
1910
September1st to 15thNight
12%425%6%3346%8%42%
1800
16th to endNight
17%5%46%6%345%46%34%
1980
October1st to 15thNight
16%5%13324345%48%
2160
16th to endNight
11%41332233459%
2304
November1st to 15thNight
14%5%23313246%51%
2297
16th to endNight
13%5%14323346%50%
2581
December1st to 15thNight
14%5%25%43445%6%42%
2730
16th to endNight
17%6%24423446%42%
2847

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%5%25%41343447%
1746
16th to endDay
17%6%13324335%47%
1872
February1st to 15thDay
17%6%26%423245%44%
1706
16th to endDay
13%5%24424346%49%
1597
March1st to 15thDay
13%424424345%50%
1980
16th to endDay
17%6%24424445%44%
2116
April1st to 15thDay
11%324323447%51%
2152
16th to endDay
10%434425%45%7%47%
2160
May1st to 15thDay
12%5%26%5%45%46%7%38%
2221
16th to endDay
8%5%246%35%5%6%9%40%
2479
June1st to 15thDay
9%425%6%35%6%6%9%38%
2520
16th to endDay
7%3146%27%6%7%10%39%
2503
July1st to 15thDay
8%435%6%36%7%7%12%34%
2340
16th to endDay
7%5%36%6%36%6%7%10%35%
2465
August1st to 15thDay
12%6%26%6%45%7%7%10%30%
2286
16th to endDay
10%6%27%7%46%6%8%8%29%
2292
September1st to 15thDay
11%426%5%35%5%5%7%41%
2160
16th to endDay
17%8%36%5%45%45%6%32%
1977
October1st to 15thDay
17%5%25%424345%45%
1800
16th to endDay
11%42431333356%
1920
November1st to 15thDay
16%414423245%50%
1887
16th to endDay
13%423413336%52%
1706
December1st to 15thDay
16%6%24433345%44%
1560
16th to endDay
19%6%25%414235%43%
1726
January1st to 15thNight
13%6%35%5%2345%6%43%
2522
16th to endNight
16%5%25%424345%45%
2704
February1st to 15thNight
17%5%24322446%45%
2446
16th to endNight
13%424324345%52%
1875
March1st to 15thNight
14%324313347%51%
1980
16th to endNight
15%42442445%7%44%
2106
April1st to 15thNight
11%6%2442435%6%47%
1796
16th to endNight
12%41432445%8%47%
1800
May1st to 15thNight
10%6%35%5%44449%42%
1739
16th to endNight
9%5%24435%46%8%46%
1631
June1st to 15thNight
9%425%6%35%5%8%9%39%
1440
16th to endNight
6%425%6%347%7%11%38%
1452
July1st to 15thNight
8%335%5%35%6%8%12%36%
1620
16th to endNight
6%425%447%6%8%11%39%
1703
August1st to 15thNight
10%5%26%5%35%5%7%11%36%
1659
16th to endNight
9%5%35%6%37%6%7%9%34%
1910
September1st to 15thNight
10%5%25%6%3445%8%43%
1800
16th to endNight
17%5%37%5%35%5%46%34%
1980
October1st to 15thNight
15%5%14323346%48%
2160
16th to endNight
11%413323235%58%
2304
November1st to 15thNight
14%5%24312345%51%
2297
16th to endNight
13%5%13422347%50%
2581
December1st to 15thNight
14%5%25%43445%6%43%
2730
16th to endNight
17%6%25%433446%42%
2847

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
41%39%16%23%6%
1747
16th to endDay
39%27%20%20%8%
1872
February1st to 15thDay
42%16%21%22%4
1708
16th to endDay
37%38%25%21%3
1597
March1st to 15thDay
36%310%22%21%6%
1980
16th to endDay
42%49%20%18%4
2117
April1st to 15thDay
31%39%25%22%6%
2152
16th to endDay
35%412%20%19%6%
2160
May1st to 15thDay
43%5%14%20%14%1
2221
16th to endDay
37%6%16%24%13%1
2483
June1st to 15thDay
39%6%14%22%14%1
2520
16th to endDay
35%9%17%21%13%2
2503
July1st to 15thDay
40%8%16%21%11%2
2201
16th to endDay
39%8%19%21%10%1
2310
August1st to 15thDay
45%6%16%19%11%1
2273
16th to endDay
47%7%15%19%9%1
2292
September1st to 15thDay
39%8%12%17%17%3
2160
16th to endDay
50%49%17%16%1
1977
October1st to 15thDay
41%47%22%20%3
1800
16th to endDay
33%26%20%32%5%
1920
November1st to 15thDay
36%29%21%23%6%
1887
16th to endDay
34%28%21%24%7%
1706
December1st to 15thDay
42%29%24%13%5%
1560
16th to endDay
44%29%21%17%3
1726
January1st to 15thNight
41%48%17%22%5%
2522
16th to endNight
41%27%20%19%7%
2704
February1st to 15thNight
41%27%18%22%6%
2455
16th to endNight
34%39%24%21%7%
1875
March1st to 15thNight
33%411%24%20%6%
1980
16th to endNight
38%49%22%19%4
2106
April1st to 15thNight
36%49%21%22%6%
1796
16th to endNight
34%413%22%16%7%
1800
May1st to 15thNight
39%316%22%15%2
1740
16th to endNight
34%6%17%25%13%1
1633
June1st to 15thNight
37%8%17%21%13%2
1440
16th to endNight
36%10%17%20%13%1
1452
July1st to 15thNight
36%10%19%21%10%1
1530
16th to endNight
34%8%22%23%9%1
1595
August1st to 15thNight
39%7%20%20%10%1
1648
16th to endNight
42%8%16%22%8%1
1910
September1st to 15thNight
38%7%14%17%17%3
1800
16th to endNight
48%410%18%15%2
1980
October1st to 15thNight
37%38%20%24%4
2160
16th to endNight
29%26%23%29%8%
2304
November1st to 15thNight
36%28%19%26%6%
2297
16th to endNight
34%28%20%24%9%
2581
December1st to 15thNight
41%311%20%18%4
2730
16th to endNight
43%39%20%17%5%
2847

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
17%9%39%22%10%
135
16th to endDay
25%15%29%15%12%1
144
February1st to 15thDay
21%11%43%16%7%
142
16th to endDay
15%8%40%27%8%
239
March1st to 15thDay
11%11%32%31%11%1
270
16th to endDay
17%7%27%31%12%3
288
April1st to 15thDay
15%11%24%25%14%8%
270
16th to endDay
14%321%30%24%5%
270
May1st to 15thDay
20%425%26%15%6%
288
16th to endDay
12%112%22%28%22%
331
June1st to 15thDay
12%19%25%28%22%
315
16th to endDay
13%113%20%34%17%
315
July1st to 15thDay
9%15%24%40%18%
305
16th to endDay
11%319%41%23%
326
August1st to 15thDay
16%26%19%30%25%
313
16th to endDay
12%25%17%30%32%
332
September1st to 15thDay
15%19%23%25%23%
315
16th to endDay
24%212%23%24%13%
314
October1st to 15thDay
23%211%27%23%11%
315
16th to endDay
13%222%25%24%11%
336
November1st to 15thDay
20%421%29%18%5%
320
16th to endDay
15%422%33%22%2
236
December1st to 15thDay
24%337%20%11%3
90
16th to endDay
24%6%35%28%4
110
January1st to 15thNight
16%11%30%31%8%
780
16th to endNight
18%7%36%31%5%
832
February1st to 15thNight
21%9%31%33%3
760
16th to endNight
15%11%38%30%3
631
March1st to 15thNight
15%8%34%32%7%
720
16th to endNight
17%5%31%34%10%
768
April1st to 15thNight
14%8%32%34%9%
718
16th to endNight
15%5%29%37%11%1
720
May1st to 15thNight
13%5%26%41%12%1
660
16th to endNight
11%114%40%30%
512
June1st to 15thNight
9%213%45%26%2
360
16th to endNight
7%211%48%26%3
372
July1st to 15thNight
10%6%39%39%4
510
16th to endNight
7%16%36%41%6%
564
August1st to 15thNight
12%1339%36%6%
578
16th to endNight
13%25%30%40%7%
764
September1st to 15thNight
13%17%34%37%4
720
16th to endNight
20%19%35%31%1
717
October1st to 15thNight
19%214%34%25%3
720
16th to endNight
12%5%26%30%20%3
768
November1st to 15thNight
16%420%38%16%3
760
16th to endNight
15%7%23%33%18%1
780
December1st to 15thNight
16%6%25%40%11%
780
16th to endNight
19%7%26%38%7%
832
Page generated at 2018-02-15 10:58:50. Version ac04

Copyright 2018 A. Danko


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