Colleton State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Colleton State Park clear sky chart from 2005-11-05 to 2018-08-29.

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%
17148
22%
50625
14%
17105
55%
17105
27%
31887

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
32%
780
22%
2522
11%
776
46%
776
22%
1521
January16th to endNight
30%
832
24%
2704
14%
832
44%
832
24%
1645
February1st to 15thNight
32%
764
21%
2415
10%
761
46%
761
23%
1483
February16th to endNight
29%
683
26%
1978
12%
683
44%
683
28%
1216
March1st to 15thNight
30%
780
27%
2145
14%
780
43%
780
32%
1308
March16th to endNight
36%
832
20%
2288
10%
832
44%
832
30%
1419
April1st to 15thNight
37%
778
25%
2083
14%
778
45%
778
34%
1268
April16th to endNight
41%
758
26%
1914
12%
758
49%
758
36%
1183
May1st to 15thNight
52%
584
23%
1755
13%
584
58%
584
33%
1042
May16th to endNight
56%
609
17%
1828
11%
609
60%
609
28%
1169
June1st to 15thNight
63%
585
13%
1755
11%
585
65%
585
27%
1147
June16th to endNight
70%
585
14%
1755
11%
585
71%
585
27%
1143
July1st to 15thNight
67%
555
13%
1665
11%
555
68%
555
27%
1085
July16th to endNight
69%
612
10%
1739
8%
579
71%
579
22%
1217
August1st to 15thNight
70%
575
14%
1715
12%
572
70%
572
21%
1210
August16th to endNight
60%
759
14%
1989
11%
759
60%
759
21%
1483
September1st to 15thNight
66%
720
19%
1967
16%
720
67%
720
27%
1337
September16th to endNight
53%
717
15%
1980
12%
717
56%
717
23%
1395
October1st to 15thNight
50%
720
28%
2118
26%
720
56%
720
33%
1266
October16th to endNight
52%
768
35%
2304
27%
768
66%
768
37%
1260
November1st to 15thNight
51%
760
30%
2281
22%
760
63%
760
36%
1298
November16th to endNight
43%
780
28%
2486
20%
780
55%
780
30%
1446
December1st to 15thNight
39%
780
22%
2535
15%
780
49%
780
23%
1583
December16th to endNight
35%
832
22%
2704
15%
832
45%
832
20%
1763

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%7%39%
51621
Night
11%5%25%43445%8%44%
50822
TransparencyDay
41%7%11%17%15%5%
51322
Night
36%7%12%18%17%7%
50625
SeeingDay
13%7%21%25%20%10%
6988
Night
13%8%23%31%19%2
17151

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
14%5%25%42344446%
1746
16th to endDay
16%6%24323446%45%
1872
February1st to 15thDay
15%6%2442445%6%43%
1775
16th to endDay
14%5%35%323335%49%
1779
March1st to 15thDay
13%5%14324346%49%
2145
16th to endDay
13%5%25%5%24346%44%
2287
April1st to 15thDay
10%415%424446%49%
2193
16th to endDay
9%3246%3445%7%48%
2331
May1st to 15thDay
8%5%25%6%35%5%5%7%43%
2526
16th to endDay
10%6%37%7%47%5%6%7%33%
2639
June1st to 15thDay
10%436%6%5%6%6%8%10%29%
2535
16th to endDay
6%426%7%5%7%7%8%10%32%
2535
July1st to 15thDay
9%5%26%7%5%8%7%8%9%28%
2535
16th to endDay
8%6%37%9%48%7%8%11%22%
2673
August1st to 15thDay
9%6%37%8%5%8%7%7%11%24%
2487
16th to endDay
12%7%37%8%6%7%7%6%9%23%
2497
September1st to 15thDay
9%5%26%7%5%6%6%7%8%34%
1990
16th to endDay
17%7%37%6%35%6%5%6%31%
1980
October1st to 15thDay
14%434424346%48%
1842
16th to endDay
10%41332333458%
1920
November1st to 15thDay
11%423322246%55%
1907
16th to endDay
12%42442335%6%50%
1800
December1st to 15thDay
15%7%25%413446%43%
1755
16th to endDay
17%6%25%424435%42%
1872
January1st to 15thNight
12%6%25%433445%47%
2522
16th to endNight
14%6%24423346%46%
2704
February1st to 15thNight
17%424333346%45%
2406
16th to endNight
11%6%25%32445%6%48%
1978
March1st to 15thNight
9%5%2442446%7%49%
2145
16th to endNight
11%5%24324448%48%
2288
April1st to 15thNight
10%323423347%52%
2083
16th to endNight
9%32342446%9%49%
1914
May1st to 15thNight
6%5%2433445%8%49%
1754
16th to endNight
8%5%35%5%345%5%9%43%
1826
June1st to 15thNight
8%425%6%35%6%7%12%36%
1755
16th to endNight
4316%436%7%8%12%39%
1755
July1st to 15thNight
8%5%25%6%346%7%11%37%
1755
16th to endNight
6%436%7%47%7%10%12%29%
1847
August1st to 15thNight
6%5%26%6%47%7%9%13%30%
1726
16th to endNight
9%6%37%7%47%5%7%8%32%
1989
September1st to 15thNight
9%316%6%25%5%7%12%38%
1967
16th to endNight
14%5%26%6%345%6%8%35%
1980
October1st to 15thNight
14%6%23422336%52%
2118
16th to endNight
8%423223445%58%
2304
November1st to 15thNight
10%424313346%56%
2281
16th to endNight
12%414323345%52%
2486
December1st to 15thNight
16%5%2442345%6%44%
2535
16th to endNight
16%7%35%42445%6%39%
2704

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
40%5%7%15%23%7%
1747
16th to endDay
39%38%18%21%9%
1872
February1st to 15thDay
41%47%17%21%8%
1777
16th to endDay
38%36%21%21%7%
1779
March1st to 15thDay
34%5%9%20%18%12%
2145
16th to endDay
40%5%9%18%18%7%
2288
April1st to 15thDay
35%5%10%20%20%7%
2193
16th to endDay
33%5%9%20%20%9%
2331
May1st to 15thDay
36%8%12%18%20%4
2526
16th to endDay
47%8%12%18%11%1
2643
June1st to 15thDay
44%11%18%17%7%
2535
16th to endDay
42%11%17%19%7%
2535
July1st to 15thDay
44%12%18%17%5%2
2396
16th to endDay
50%13%18%12%4
2518
August1st to 15thDay
50%11%15%16%5%
2474
16th to endDay
53%13%13%13%5%
2497
September1st to 15thDay
44%9%14%13%13%4
1990
16th to endDay
51%8%10%13%12%4
1980
October1st to 15thDay
37%310%19%20%8%
1842
16th to endDay
30%45%15%28%15%
1920
November1st to 15thDay
32%37%19%24%13%
1907
16th to endDay
34%49%18%21%12%
1800
December1st to 15thDay
41%410%18%17%7%
1755
16th to endDay
43%49%20%15%6%
1872
January1st to 15thNight
38%49%16%22%8%
2522
16th to endNight
39%37%15%22%10%
2704
February1st to 15thNight
39%38%18%18%11%
2415
16th to endNight
36%5%9%18%21%9%
1978
March1st to 15thNight
31%6%10%20%20%10%
2145
16th to endNight
35%5%13%18%18%8%
2288
April1st to 15thNight
31%5%10%21%21%9%
2083
16th to endNight
30%5%11%20%21%9%
1914
May1st to 15thNight
31%7%15%19%22%3
1755
16th to endNight
36%9%15%23%13%1
1828
June1st to 15thNight
37%10%22%21%8%
1755
16th to endNight
32%14%20%23%7%1
1755
July1st to 15thNight
36%10%23%20%7%2
1665
16th to endNight
38%15%22%16%5%
1739
August1st to 15thNight
38%16%19%18%6%
1715
16th to endNight
46%11%16%18%5%
1989
September1st to 15thNight
34%14%15%17%12%4
1967
16th to endNight
44%9%13%16%12%3
1980
October1st to 15thNight
35%39%20%21%9%
2118
16th to endNight
27%47%18%26%15%
2304
November1st to 15thNight
30%47%17%25%14%
2281
16th to endNight
33%48%16%22%13%
2486
December1st to 15thNight
40%5%12%16%17%7%
2535
16th to endNight
44%5%8%19%15%6%
2704

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%18%37%15%5%1
135
16th to endDay
21%25%32%16%4
144
February1st to 15thDay
17%25%40%14%2
135
16th to endDay
12%19%41%20%5%
189
March1st to 15thDay
16%16%34%22%10%
330
16th to endDay
13%13%39%19%11%2
352
April1st to 15thDay
16%13%26%21%17%3
330
16th to endDay
10%429%26%16%11%
319
May1st to 15thDay
8%8%29%24%20%8%
348
16th to endDay
13%5%17%25%20%17%
395
June1st to 15thDay
12%211%28%26%18%
375
16th to endDay
9%111%28%30%19%
375
July1st to 15thDay
6%9%26%39%16%
365
16th to endDay
8%12%30%34%13%
390
August1st to 15thDay
15%11%25%25%21%
358
16th to endDay
13%11%24%28%21%
384
September1st to 15thDay
13%115%26%26%16%
315
16th to endDay
22%214%26%24%8%
314
October1st to 15thDay
19%220%25%21%10%
315
16th to endDay
11%8%17%31%21%9%
336
November1st to 15thDay
16%7%24%28%19%3
325
16th to endDay
11%10%27%34%14%2
180
December1st to 15thDay
25%12%33%19%6%2
135
16th to endDay
24%14%33%20%5%1
144
January1st to 15thNight
15%17%29%28%8%
780
16th to endNight
18%16%31%28%5%
832
February1st to 15thNight
20%16%28%30%4
764
16th to endNight
13%14%37%28%5%
683
March1st to 15thNight
14%13%38%26%6%
780
16th to endNight
14%12%33%30%9%
832
April1st to 15thNight
13%13%33%29%10%
778
16th to endNight
12%11%31%30%13%
758
May1st to 15thNight
8%5%28%39%17%1
585
16th to endNight
11%218%34%28%3
611
June1st to 15thNight
10%111%41%28%6%
585
16th to endNight
6%110%37%35%9%
585
July1st to 15thNight
9%10%40%34%5%
555
16th to endNight
6%7%39%40%5%
612
August1st to 15thNight
9%5%35%40%9%
575
16th to endNight
13%18%29%38%9%
759
September1st to 15thNight
9%110%37%36%5%
720
16th to endNight
18%214%32%27%4
717
October1st to 15thNight
17%322%28%23%5%
720
16th to endNight
10%9%24%28%24%2
768
November1st to 15thNight
12%6%24%35%17%2
760
16th to endNight
14%11%27%26%18%1
780
December1st to 15thNight
18%10%25%30%12%1
780
16th to endNight
19%12%28%29%9%
832
Page generated at 2018-08-30 05:34:19. Version ac04

Copyright 2018 A. Danko


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