Oconee Observing Field
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oconee Observing Field clear sky chart from 2005-11-05 to 2017-09-23.

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%
15643
23%
46993
15%
15600
56%
15600
28%
29057

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
25%
719
23%
2327
9%
716
43%
716
21%
1421
January16th to endNight
26%
768
24%
2490
12%
768
42%
768
21%
1548
February1st to 15thNight
31%
704
26%
2111
10%
700
47%
700
25%
1285
February16th to endNight
26%
631
25%
1893
9%
631
42%
631
24%
1161
March1st to 15thNight
32%
720
26%
2019
11%
720
44%
720
28%
1233
March16th to endNight
37%
768
21%
2112
10%
768
45%
768
29%
1304
April1st to 15thNight
40%
715
25%
1973
15%
715
49%
715
33%
1172
April16th to endNight
48%
540
28%
1662
17%
540
58%
540
33%
954
May1st to 15thNight
54%
540
22%
1620
14%
540
61%
540
33%
964
May16th to endNight
61%
561
21%
1682
16%
561
64%
561
30%
1046
June1st to 15thNight
64%
540
16%
1620
13%
540
66%
540
28%
1057
June16th to endNight
73%
540
17%
1620
14%
540
74%
540
32%
1004
July1st to 15thNight
69%
510
12%
1530
9%
510
70%
510
24%
1038
July16th to endNight
74%
564
14%
1595
13%
531
75%
531
27%
1045
August1st to 15thNight
70%
539
17%
1609
16%
536
71%
536
23%
1106
August16th to endNight
64%
603
16%
1909
16%
603
65%
603
21%
1297
September1st to 15thNight
63%
720
18%
1980
16%
720
64%
720
27%
1319
September16th to endNight
57%
689
22%
1903
16%
689
61%
689
28%
1241
October1st to 15thNight
53%
660
31%
1856
24%
660
61%
660
35%
1111
October16th to endNight
52%
704
34%
2112
26%
704
65%
704
38%
1158
November1st to 15thNight
52%
700
31%
2194
25%
700
63%
700
36%
1185
November16th to endNight
41%
720
27%
2340
18%
720
54%
720
29%
1336
December1st to 15thNight
38%
720
25%
2340
16%
720
51%
720
24%
1433
December16th to endNight
34%
768
22%
2496
15%
768
45%
768
20%
1639

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
12%5%25%5%35%5%5%7%42%
47905
Night
11%42442445%7%45%
47193
TransparencyDay
39%6%11%19%17%5%
47606
Night
36%6%10%19%19%7%
46996
SeeingDay
14%6%19%24%23%11%
5511
Night
14%8%22%29%21%3
15646

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
16%7%25%323445%45%
1611
16th to endDay
17%6%2331445%6%45%
1732
February1st to 15thDay
15%5%24415%346%46%
1750
16th to endDay
17%6%14323445%46%
1580
March1st to 15thDay
15%424324346%48%
1941
16th to endDay
14%5%23424446%45%
2111
April1st to 15thDay
11%425%423446%49%
1984
16th to endDay
8%3235%34448%50%
2295
May1st to 15thDay
10%425%425%5%5%7%46%
2331
16th to endDay
8%5%246%36%5%6%8%40%
2431
June1st to 15thDay
9%426%7%46%6%7%10%35%
2340
16th to endDay
43246%46%7%8%12%39%
2340
July1st to 15thDay
7%5%36%7%47%7%8%10%31%
2340
16th to endDay
6%436%8%48%8%9%11%28%
2465
August1st to 15thDay
10%5%27%7%48%6%8%9%28%
2340
16th to endDay
12%6%36%8%46%6%6%8%29%
2277
September1st to 15thDay
12%5%25%5%36%5%6%8%38%
1980
16th to endDay
15%6%25%4245%46%41%
1894
October1st to 15thDay
15%5%13313346%52%
1774
16th to endDay
11%31332243459%
1760
November1st to 15thDay
12%423323336%54%
1661
16th to endDay
14%424323346%50%
1620
December1st to 15thDay
16%6%2442445%5%44%
1620
16th to endDay
22%8%34314335%38%
1728
January1st to 15thNight
14%7%3431435%6%45%
2327
16th to endNight
17%5%35%423345%46%
2490
February1st to 15thNight
16%424324345%48%
2103
16th to endNight
15%424314446%47%
1893
March1st to 15thNight
11%424324446%49%
2019
16th to endNight
12%5%2432435%7%49%
2112
April1st to 15thNight
13%31332335%7%51%
1973
16th to endNight
8%414424448%51%
1662
May1st to 15thNight
8%424435%45%8%48%
1619
16th to endNight
6%3245%35%5%7%8%45%
1682
June1st to 15thNight
9%5%245%45%7%6%12%37%
1620
16th to endNight
4325%5%36%6%8%12%41%
1620
July1st to 15thNight
8%325%6%46%7%10%12%33%
1620
16th to endNight
43245%47%7%10%14%35%
1703
August1st to 15thNight
7%336%5%5%7%6%9%11%32%
1620
16th to endNight
10%6%26%6%45%5%9%8%34%
1909
September1st to 15thNight
10%425%6%45%5%6%11%38%
1980
16th to endNight
12%5%26%4235%5%6%43%
1903
October1st to 15thNight
13%42341333453%
1856
16th to endNight
9%31232434458%
2112
November1st to 15thNight
9%414322246%57%
2194
16th to endNight
12%423323345%52%
2340
December1st to 15thNight
14%5%34423446%46%
2340
16th to endNight
19%8%24424345%40%
2496

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%48%15%26%4
1612
16th to endDay
39%46%18%23%7%
1732
February1st to 15thDay
40%27%21%21%6%
1752
16th to endDay
39%35%20%23%6%
1580
March1st to 15thDay
37%48%20%19%9%
1941
16th to endDay
38%5%10%21%18%5%
2112
April1st to 15thDay
35%310%20%22%7%
1984
16th to endDay
32%5%11%19%23%6%
2295
May1st to 15thDay
36%6%12%20%19%4
2331
16th to endDay
38%8%12%23%14%2
2435
June1st to 15thDay
41%8%15%22%9%1
2340
16th to endDay
32%11%17%21%14%2
2340
July1st to 15thDay
40%12%19%18%7%2
2201
16th to endDay
42%12%17%18%6%1
2310
August1st to 15thDay
47%11%14%17%7%1
2327
16th to endDay
50%9%13%15%10%
2277
September1st to 15thDay
42%8%11%17%17%2
1980
16th to endDay
41%6%10%20%16%4
1894
October1st to 15thDay
33%49%20%25%7%
1774
16th to endDay
29%3417%31%13%
1760
November1st to 15thDay
31%36%17%27%13%
1661
16th to endDay
35%46%19%26%8%
1620
December1st to 15thDay
41%49%17%17%8%
1620
16th to endDay
48%37%18%14%7%
1728
January1st to 15thNight
39%46%17%25%7%
2327
16th to endNight
41%3417%22%10%
2490
February1st to 15thNight
38%36%18%21%11%
2112
16th to endNight
37%46%18%24%9%
1893
March1st to 15thNight
35%49%19%21%9%
2019
16th to endNight
35%411%19%21%8%
2112
April1st to 15thNight
32%47%24%22%8%
1973
16th to endNight
30%6%10%21%20%11%
1662
May1st to 15thNight
33%6%13%22%19%5%
1620
16th to endNight
33%9%13%24%14%3
1684
June1st to 15thNight
37%9%18%23%10%
1620
16th to endNight
32%9%18%22%14%2
1620
July1st to 15thNight
37%13%19%19%6%3
1530
16th to endNight
33%14%23%19%7%2
1595
August1st to 15thNight
39%12%16%21%9%1
1609
16th to endNight
41%11%18%16%10%
1909
September1st to 15thNight
39%8%15%16%15%4
1980
16th to endNight
39%6%12%17%18%5%
1903
October1st to 15thNight
34%39%17%26%8%
1856
16th to endNight
28%35%17%29%15%
2112
November1st to 15thNight
29%35%17%27%16%
2194
16th to endNight
34%37%15%26%12%
2340
December1st to 15thNight
38%48%19%19%8%
2340
16th to endNight
46%47%18%17%6%
2496

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
26%13%38%10%10%1
90
16th to endDay
25%26%35%7%6%
96
February1st to 15thDay
20%22%41%16%
90
16th to endDay
22%9%54%11%2
81
March1st to 15thDay
16%16%29%28%8%1
231
16th to endDay
16%10%32%25%14%1
288
April1st to 15thDay
16%14%25%20%19%4
270
16th to endDay
10%7%22%29%25%4
270
May1st to 15thDay
12%10%29%21%15%10%
288
16th to endDay
14%415%24%27%13%
331
June1st to 15thDay
11%113%26%24%22%
315
16th to endDay
7%13%27%26%24%
315
July1st to 15thDay
7%19%25%35%20%
305
16th to endDay
8%17%21%40%21%
326
August1st to 15thDay
14%11%25%30%17%
313
16th to endDay
14%112%23%30%18%
332
September1st to 15thDay
15%213%23%31%13%
315
16th to endDay
20%214%30%20%12%
283
October1st to 15thDay
22%418%26%21%5%
255
16th to endDay
11%7%20%25%25%9%
272
November1st to 15thDay
22%7%26%22%18%2
169
16th to endDay
10%13%24%35%13%3
90
December1st to 15thDay
20%13%36%20%10%
90
16th to endDay
35%13%25%16%8%1
96
January1st to 15thNight
20%16%31%23%7%
720
16th to endNight
19%18%31%26%4
768
February1st to 15thNight
20%14%29%30%4
704
16th to endNight
18%17%34%26%3
631
March1st to 15thNight
15%15%32%29%6%
720
16th to endNight
16%11%29%27%13%
768
April1st to 15thNight
16%12%28%27%15%
715
16th to endNight
10%7%28%35%16%1
540
May1st to 15thNight
10%426%33%21%2
540
16th to endNight
9%118%33%31%5%
563
June1st to 15thNight
10%211%36%32%7%
540
16th to endNight
6%110%35%38%9%
540
July1st to 15thNight
9%18%28%39%12%
510
16th to endNight
5%8%27%49%7%
564
August1st to 15thNight
9%6%31%44%8%
539
16th to endNight
14%18%27%39%8%
603
September1st to 15thNight
12%110%28%40%7%
720
16th to endNight
14%216%32%28%4
689
October1st to 15thNight
15%421%27%25%4
660
16th to endNight
11%7%24%31%22%3
704
November1st to 15thNight
11%8%22%34%20%2
700
16th to endNight
13%12%28%27%15%1
720
December1st to 15thNight
18%12%25%28%13%1
720
16th to endNight
23%12%26%28%8%
768
Page generated at 2017-09-24 09:15:51. Version ac04

Copyright 2017 A. Danko


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