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 2019-06-02.

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%
18219
22%
53800
14%
18176
55%
18176
27%
33940

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%
840
23%
2717
12%
836
46%
836
22%
1650
January16th to endNight
30%
896
23%
2912
13%
896
44%
896
23%
1779
February1st to 15thNight
32%
824
22%
2605
11%
821
47%
821
23%
1600
February16th to endNight
29%
735
25%
2129
11%
735
43%
735
26%
1342
March1st to 15thNight
30%
840
27%
2310
14%
840
42%
840
30%
1437
March16th to endNight
35%
896
20%
2464
10%
896
44%
896
30%
1526
April1st to 15thNight
37%
838
24%
2244
14%
838
44%
838
33%
1383
April16th to endNight
42%
817
26%
2063
12%
817
50%
817
37%
1261
May1st to 15thNight
53%
629
23%
1890
13%
629
59%
629
33%
1122
May16th to endNight
58%
657
18%
1972
12%
657
62%
657
30%
1222
June1st to 15thNight
63%
588
14%
1765
11%
588
65%
588
27%
1152
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
61%
767
14%
2009
11%
767
61%
767
21%
1491
September1st to 15thNight
67%
780
19%
2131
16%
780
68%
780
27%
1446
September16th to endNight
55%
777
14%
2145
12%
777
57%
777
23%
1504
October1st to 15thNight
52%
780
29%
2294
26%
780
58%
780
34%
1360
October16th to endNight
51%
832
33%
2496
25%
832
64%
832
36%
1382
November1st to 15thNight
49%
820
29%
2461
21%
820
60%
820
33%
1449
November16th to endNight
43%
840
27%
2677
19%
840
55%
840
29%
1551
December1st to 15thNight
38%
840
23%
2730
16%
840
48%
840
23%
1724
December16th to endNight
35%
896
21%
2912
14%
896
45%
896
20%
1904

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%
54530
Night
11%5%25%43445%8%44%
53997
TransparencyDay
41%7%11%17%15%5%
54231
Night
36%7%12%19%17%6%
53800
SeeingDay
13%8%22%25%20%9%
8000
Night
13%8%23%31%19%3
18222

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%
1881
16th to endDay
15%6%24423446%45%
2016
February1st to 15thDay
14%6%25%425%45%6%42%
1915
16th to endDay
15%5%35%424335%46%
1914
March1st to 15thDay
13%5%1432445%6%47%
2310
16th to endDay
12%5%25%5%3435%6%44%
2463
April1st to 15thDay
10%5%15%434446%47%
2362
16th to endDay
9%3246%3445%7%48%
2512
May1st to 15thDay
8%5%25%6%35%5%6%7%42%
2721
16th to endDay
9%5%37%7%47%5%6%8%35%
2847
June1st to 15thDay
10%436%6%5%6%6%8%10%30%
2548
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
11%7%36%8%6%7%7%7%9%23%
2532
September1st to 15thDay
9%5%36%7%5%6%6%7%8%33%
2156
16th to endDay
16%7%37%6%35%6%5%6%32%
2145
October1st to 15thDay
13%424424446%47%
1996
16th to endDay
10%42442333457%
2080
November1st to 15thDay
13%5%23322345%52%
2057
16th to endDay
12%5%2432335%6%50%
1939
December1st to 15thDay
16%7%25%413446%41%
1890
16th to endDay
17%7%25%5%23335%42%
2016
January1st to 15thNight
11%6%25%433445%47%
2717
16th to endNight
14%5%24423446%45%
2912
February1st to 15thNight
16%424333347%45%
2596
16th to endNight
12%6%25%32445%6%45%
2129
March1st to 15thNight
9%424425%46%7%47%
2310
16th to endNight
10%5%25%424448%48%
2464
April1st to 15thNight
10%423424348%51%
2244
16th to endNight
8%32342445%9%51%
2063
May1st to 15thNight
6%5%2433446%9%49%
1889
16th to endNight
7%5%25%4345%5%9%45%
1970
June1st to 15thNight
8%425%6%35%6%7%12%36%
1765
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%
2009
September1st to 15thNight
9%216%6%35%5%7%12%38%
2131
16th to endNight
13%5%26%6%345%6%8%35%
2145
October1st to 15thNight
13%5%23422336%52%
2294
16th to endNight
8%423223445%58%
2496
November1st to 15thNight
12%5%24313346%53%
2461
16th to endNight
11%5%1432335%5%52%
2677
December1st to 15thNight
17%5%2442335%6%43%
2730
16th to endNight
16%7%35%424446%39%
2912

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%5%7%15%23%6%
1882
16th to endDay
39%37%18%21%8%
2016
February1st to 15thDay
41%5%8%17%20%7%
1917
16th to endDay
40%46%19%20%7%
1914
March1st to 15thDay
36%5%9%19%17%11%
2310
16th to endDay
39%5%9%17%19%7%
2464
April1st to 15thDay
36%5%10%20%19%7%
2362
16th to endDay
33%5%9%22%20%8%
2512
May1st to 15thDay
37%8%12%18%19%3
2721
16th to endDay
44%8%12%19%12%1
2851
June1st to 15thDay
44%11%18%17%7%
2548
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
52%13%14%13%5%
2532
September1st to 15thDay
44%10%14%12%12%4
2156
16th to endDay
49%8%11%15%11%3
2145
October1st to 15thDay
36%411%19%19%7%
1996
16th to endDay
31%46%16%27%14%
2080
November1st to 15thDay
34%37%19%23%12%
2057
16th to endDay
34%39%19%21%11%
1939
December1st to 15thDay
43%410%17%17%6%
1890
16th to endDay
43%48%20%15%6%
2016
January1st to 15thNight
39%49%16%22%7%
2717
16th to endNight
39%47%16%22%10%
2912
February1st to 15thNight
39%48%18%17%10%
2605
16th to endNight
37%5%9%17%20%9%
2129
March1st to 15thNight
33%6%10%19%19%10%
2310
16th to endNight
35%5%13%18%18%8%
2464
April1st to 15thNight
32%5%10%21%20%8%
2244
16th to endNight
29%5%11%21%21%9%
2063
May1st to 15thNight
31%8%15%20%21%3
1890
16th to endNight
33%8%15%26%13%1
1972
June1st to 15thNight
37%10%22%21%9%
1765
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%19%5%
2009
September1st to 15thNight
34%14%16%18%11%4
2131
16th to endNight
43%9%13%17%12%3
2145
October1st to 15thNight
34%410%22%19%8%
2294
16th to endNight
28%47%18%26%14%
2496
November1st to 15thNight
33%47%16%24%13%
2461
16th to endNight
33%48%17%22%12%
2677
December1st to 15thNight
41%411%16%17%7%
2730
16th to endNight
44%5%8%19%15%6%
2912

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
19%18%38%16%6%1
180
16th to endDay
19%22%37%16%3
192
February1st to 15thDay
15%25%39%15%4
180
16th to endDay
16%19%40%19%4
233
March1st to 15thDay
15%17%35%21%8%
390
16th to endDay
11%18%37%19%11%1
416
April1st to 15thDay
16%14%28%21%16%3
390
16th to endDay
10%6%28%26%18%10%
379
May1st to 15thDay
7%8%29%25%20%9%
408
16th to endDay
11%5%16%26%23%16%
459
June1st to 15thDay
12%211%28%26%18%
379
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
12%10%24%29%21%
396
September1st to 15thDay
13%113%26%26%17%
375
16th to endDay
20%213%28%27%8%
374
October1st to 15thDay
17%220%26%21%12%
375
16th to endDay
12%8%20%31%20%7%
400
November1st to 15thDay
19%9%25%26%16%2
385
16th to endDay
11%11%30%32%12%2
229
December1st to 15thDay
30%12%30%20%5%1
180
16th to endDay
25%13%35%19%5%1
192
January1st to 15thNight
15%16%29%28%8%
840
16th to endNight
18%16%30%28%5%
896
February1st to 15thNight
19%16%28%31%4
824
16th to endNight
14%15%36%28%5%
735
March1st to 15thNight
14%13%38%27%5%
840
16th to endNight
13%12%33%30%9%
896
April1st to 15thNight
13%13%33%29%10%
838
16th to endNight
11%11%30%31%14%
817
May1st to 15thNight
8%427%38%19%1
630
16th to endNight
10%218%35%29%3
659
June1st to 15thNight
10%111%41%28%6%
588
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
12%18%28%38%9%
767
September1st to 15thNight
9%110%35%37%6%
780
16th to endNight
17%113%33%28%5%
777
October1st to 15thNight
16%322%28%23%6%
780
16th to endNight
10%9%24%28%23%2
832
November1st to 15thNight
14%7%24%33%16%2
820
16th to endNight
14%11%27%27%18%1
840
December1st to 15thNight
20%10%25%30%12%1
840
16th to endNight
19%12%28%29%9%
896
Page generated at 2019-06-02 19:43:06. Version ac04

Copyright 2019 A. Danko


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