Effingham
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Effingham clear sky chart from 2005-11-06 to 2024-01-27.

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
41%
24464
21%
74832
14%
24407
48%
24407
26%
48136

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 10thNight
23%
949
18%
2648
7%
946
33%
946
21%
1857
January11th to 20thNight
19%
950
16%
2660
6%
950
27%
950
17%
1976
January21st to endNight
22%
1025
17%
2692
6%
1025
31%
1025
20%
1952
February1st to 10thNight
21%
805
14%
2245
5%
805
28%
805
18%
1646
February11th to 20thNight
22%
703
18%
2099
7%
700
32%
700
20%
1409
February21st to endNight
20%
592
19%
1776
6%
592
31%
592
18%
1208
March1st to 10thNight
25%
720
18%
2160
9%
720
33%
720
21%
1449
March11th to 20thNight
29%
671
16%
2107
8%
671
36%
671
20%
1401
March21st to endNight
29%
594
15%
1980
9%
594
38%
594
18%
1360
April1st to 10thNight
33%
540
22%
1800
13%
540
46%
540
24%
1101
April11th to 20thNight
38%
533
24%
1775
18%
533
49%
533
26%
1084
April21st to endNight
34%
540
19%
1793
12%
540
44%
540
21%
1174
May1st to 10thNight
37%
540
17%
1620
9%
540
45%
540
26%
1075
May11th to 20thNight
47%
531
17%
1570
13%
531
51%
531
26%
1030
May21st to endNight
55%
584
20%
1551
12%
582
60%
582
32%
1007
June1st to 10thNight
60%
540
21%
1440
16%
540
63%
540
40%
860
June11th to 20thNight
65%
540
26%
1440
19%
540
70%
540
42%
833
June21st to endNight
59%
540
22%
1440
16%
540
64%
540
39%
873
July1st to 10thNight
69%
525
19%
1400
17%
525
70%
525
38%
863
July11th to 20thNight
71%
522
24%
1392
19%
522
74%
522
44%
808
July21st to endNight
70%
591
29%
1487
24%
558
72%
558
45%
837
August1st to 10thNight
72%
537
24%
1659
25%
534
74%
534
37%
934
August11th to 20thNight
72%
534
24%
1776
25%
534
75%
534
35%
994
August21st to endNight
74%
594
27%
1980
31%
594
77%
594
42%
1016
September1st to 10thNight
67%
540
27%
1800
29%
540
71%
540
36%
978
September11th to 20thNight
66%
629
35%
1889
32%
629
70%
629
40%
1040
September21st to endNight
57%
720
32%
1980
22%
720
63%
720
39%
1155
October1st to 10thNight
58%
720
30%
2020
22%
720
63%
720
42%
1139
October11th to 20thNight
40%
720
30%
2160
17%
720
52%
720
32%
1269
October21st to endNight
33%
792
22%
2513
15%
792
43%
792
24%
1618
November1st to 10thNight
38%
740
27%
2406
19%
740
51%
740
32%
1347
November11th to 20thNight
35%
760
28%
2470
17%
760
50%
760
28%
1465
November21st to endNight
31%
760
22%
2470
14%
760
41%
760
22%
1599
December1st to 10thNight
27%
896
17%
2606
7%
896
36%
896
22%
1803
December11th to 20thNight
31%
949
19%
3177
9%
948
39%
948
19%
2123
December21st to endNight
19%
1038
9%
4851
5%
1026
28%
1026
8%
3853

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%7%36%5%35%5%5%7%41%
74919
Night
15%7%36%5%3445%7%42%
75150
TransparencyDay
42%412%25%15%2
74620
Night
43%410%24%16%3
74970
SeeingDay
16%8%24%26%18%7%
14499
Night
17%8%27%31%15%2
24473

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 10thDay
15%10%6%9%6%34446%33%
1517
11th to 20thDay
19%12%5%8%5%34445%32%
1520
21st to endDay
15%13%5%7%6%34446%33%
1807
February1st to 10thDay
18%10%5%8%5%35%46%7%32%
1714
11th to 20thDay
17%9%47%6%25%5%6%7%32%
1748
21st to endDay
16%12%39%5%335%5%7%32%
1480
March1st to 10thDay
17%9%36%43445%7%39%
1800
11th to 20thDay
18%11%46%5%25%45%6%34%
1868
21st to endDay
22%11%5%7%5%3445%6%29%
2376
April1st to 10thDay
13%7%36%4345%49%41%
2160
11th to 20thDay
17%8%36%5%34446%41%
2134
21st to endDay
19%6%36%6%3435%6%38%
2164
May1st to 10thDay
19%7%25%5%46%5%5%7%35%
2340
11th to 20thDay
19%6%35%5%35%46%6%37%
2322
21st to endDay
9%5%35%6%37%6%7%10%38%
2725
June1st to 10thDay
9%5%24435%6%6%7%48%
2520
11th to 20thDay
8%425%5%35%6%6%8%49%
2520
21st to endDay
7%425%5%45%6%7%10%44%
2520
July1st to 10thDay
9%425%5%45%6%7%10%42%
2520
11th to 20thDay
7%3245%35%6%7%10%49%
2520
21st to endDay
8%4245%35%5%7%9%47%
2743
August1st to 10thDay
9%425%5%35%5%5%10%47%
2266
11th to 20thDay
9%425%6%35%5%8%11%43%
2125
21st to endDay
7%4245%35%5%6%8%51%
2376
September1st to 10thDay
13%5%25%43445%7%47%
2160
11th to 20thDay
8%4245%36%5%6%7%49%
2052
21st to endDay
9%5%2443345%7%53%
1980
October1st to 10thDay
12%42442335%6%54%
1936
11th to 20thDay
16%5%25%43445%5%47%
1800
21st to endDay
19%7%25%324446%43%
1841
November1st to 10thDay
10%5%2442445%6%54%
1672
11th to 20thDay
17%8%345%33446%44%
1710
21st to endDay
16%9%36%5%3435%5%40%
1710
December1st to 10thDay
17%11%5%6%5%2335%5%37%
1572
11th to 20thDay
16%12%5%9%5%2445%6%32%
1918
21st to endDay
23%16%5%10%6%34445%22%
2783
January1st to 10thNight
15%9%47%5%36%45%6%36%
2648
11th to 20thNight
18%10%6%9%6%3444432%
2660
21st to endNight
16%11%48%7%34446%33%
2692
February1st to 10thNight
19%10%5%8%6%3445%6%31%
2245
11th to 20thNight
17%7%47%6%25%347%38%
2098
21st to endNight
21%9%37%423346%37%
1776
March1st to 10thNight
17%10%35%4345%45%40%
2160
11th to 20thNight
18%8%46%6%2435%7%37%
2107
21st to endNight
21%8%45%5%35%45%6%33%
1980
April1st to 10thNight
13%6%36%5%35%445%46%
1800
11th to 20thNight
16%6%345%24447%44%
1775
21st to endNight
19%8%35%5%25%45%6%39%
1793
May1st to 10thNight
15%6%36%6%35%5%6%7%40%
1620
11th to 20thNight
13%6%35%6%35%46%8%41%
1569
21st to endNight
9%5%36%5%46%6%6%11%40%
1551
June1st to 10thNight
8%5%25%5%2436%8%51%
1440
11th to 20thNight
6%4145%445%6%10%52%
1440
21st to endNight
7%425%5%36%6%7%11%46%
1440
July1st to 10thNight
9%424435%5%6%9%49%
1440
11th to 20thNight
6%3245%3447%7%54%
1440
21st to endNight
7%324425%47%8%54%
1575
August1st to 10thNight
7%4245%345%6%10%50%
1668
11th to 20thNight
6%325%5%35%6%6%9%49%
1776
21st to endNight
7%3134245%5%8%57%
1980
September1st to 10thNight
12%5%2432345%8%53%
1800
11th to 20thNight
6%425%42445%8%54%
1889
21st to endNight
10%42443445%6%54%
1980
October1st to 10thNight
9%42442435%6%57%
2020
11th to 20thNight
15%5%24433346%52%
2160
21st to endNight
19%8%25%5%33445%43%
2513
November1st to 10thNight
11%6%25%433346%53%
2406
11th to 20thNight
14%6%25%5%3335%6%49%
2470
21st to endNight
20%8%46%433336%41%
2470
December1st to 10thNight
18%10%46%43445%7%35%
2606
11th to 20thNight
19%7%47%5%24446%39%
3279
21st to endNight
26%16%5%7%6%3443422%
4884

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 10thDay
54%38%20%14%1
1518
11th to 20thDay
57%39%23%9%
1520
21st to endDay
54%310%24%9%1
1807
February1st to 10thDay
52%411%22%10%1
1714
11th to 20thDay
51%410%23%10%2
1758
21st to endDay
53%48%22%10%2
1480
March1st to 10thDay
46%410%25%13%1
1800
11th to 20thDay
52%412%21%10%1
1868
21st to endDay
57%310%21%7%1
2376
April1st to 10thDay
41%5%13%26%15%1
2160
11th to 20thDay
46%39%25%13%3
2134
21st to endDay
47%311%24%12%3
2164
May1st to 10thDay
49%5%14%23%8%1
2340
11th to 20thDay
46%5%14%20%14%1
2326
21st to endDay
39%7%16%22%14%2
2725
June1st to 10thDay
33%5%14%28%16%3
2520
11th to 20thDay
33%5%12%26%21%4
2520
21st to endDay
35%6%17%24%15%4
2520
July1st to 10thDay
36%6%13%27%15%3
2451
11th to 20thDay
30%6%14%30%17%3
2445
21st to endDay
32%6%14%28%17%3
2591
August1st to 10thDay
32%6%14%31%15%1
2251
11th to 20thDay
33%5%17%29%14%2
2125
21st to endDay
30%413%28%18%7%
2376
September1st to 10thDay
37%5%11%26%18%4
2160
11th to 20thDay
32%5%10%27%24%2
2052
21st to endDay
31%47%29%25%4
1980
October1st to 10thDay
32%311%29%22%4
1936
11th to 20thDay
39%48%23%23%3
1800
21st to endDay
44%39%26%17%2
1841
November1st to 10thDay
32%412%29%19%5%
1672
11th to 20thDay
43%28%24%17%5%
1710
21st to endDay
48%29%24%15%1
1710
December1st to 10thDay
50%312%22%12%1
1572
11th to 20thDay
55%37%26%8%1
1915
21st to endDay
66%39%14%6%1
2783
January1st to 10thNight
50%38%23%14%1
2648
11th to 20thNight
56%38%22%9%
2660
21st to endNight
52%311%22%10%1
2692
February1st to 10thNight
55%312%19%9%2
2245
11th to 20thNight
49%210%22%15%2
2099
21st to endNight
50%310%22%12%2
1776
March1st to 10thNight
47%38%23%17%2
2160
11th to 20thNight
48%312%21%13%2
2107
21st to endNight
52%313%22%8%2
1980
April1st to 10thNight
41%310%27%17%3
1800
11th to 20thNight
40%38%25%20%3
1775
21st to endNight
47%49%23%14%3
1793
May1st to 10thNight
43%5%13%25%12%2
1620
11th to 20thNight
41%7%13%23%15%1
1570
21st to endNight
38%6%14%21%17%5%
1552
June1st to 10thNight
32%411%27%23%3
1440
11th to 20thNight
28%5%12%27%23%6%
1440
21st to endNight
31%6%14%24%18%7%
1440
July1st to 10thNight
32%6%15%26%16%5%
1400
11th to 20thNight
28%5%13%31%20%4
1392
21st to endNight
26%413%31%22%3
1487
August1st to 10thNight
30%5%14%29%19%2
1659
11th to 20thNight
31%6%12%29%20%3
1776
21st to endNight
24%6%13%28%22%7%
1980
September1st to 10thNight
31%49%31%20%6%
1800
11th to 20thNight
29%46%31%26%5%
1889
21st to endNight
31%48%25%27%6%
1980
October1st to 10thNight
29%310%27%25%5%
2020
11th to 20thNight
36%37%27%24%5%
2160
21st to endNight
44%37%24%18%3
2513
November1st to 10thNight
33%310%25%23%6%
2406
11th to 20thNight
38%38%26%23%3
2470
21st to endNight
47%29%24%17%1
2470
December1st to 10thNight
50%311%23%13%1
2606
11th to 20thNight
48%410%24%14%1
3281
21st to endNight
68%38%14%7%1
4884

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 10thDay
23%13%37%19%7%
270
11th to 20thDay
28%16%33%19%3
270
21st to endDay
23%17%37%19%4
282
February1st to 10thDay
29%15%40%15%2
240
11th to 20thDay
28%22%26%21%3
240
21st to endDay
27%15%35%20%31
198
March1st to 10thDay
23%19%38%16%4
240
11th to 20thDay
30%14%36%15%5%1
244
21st to endDay
32%11%33%15%7%1
462
April1st to 10thDay
20%12%33%25%8%2
420
11th to 20thDay
22%13%27%22%14%2
412
21st to endDay
24%8%35%21%9%2
420
May1st to 10thDay
22%12%28%25%10%3
423
11th to 20thDay
19%6%24%28%17%6%
468
21st to endDay
10%5%25%32%20%9%
679
June1st to 10thDay
11%418%32%27%9%
630
11th to 20thDay
9%322%32%26%7%
630
21st to endDay
7%5%26%31%22%9%
630
July1st to 10thDay
11%212%28%27%20%
621
11th to 20thDay
8%213%34%29%13%
618
21st to endDay
10%212%33%32%11%
684
August1st to 10thDay
10%210%30%34%14%
514
11th to 20thDay
10%312%31%27%16%
439
21st to endDay
7%212%28%34%17%
495
September1st to 10thDay
15%315%25%32%10%
450
11th to 20thDay
9%111%32%31%17%
450
21st to endDay
11%6%21%25%24%12%
450
October1st to 10thDay
11%424%34%22%4
406
11th to 20thDay
17%12%36%24%9%2
270
21st to endDay
30%11%32%23%3
297
November1st to 10thDay
13%10%34%23%16%4
270
11th to 20thDay
20%16%31%23%8%2
270
21st to endDay
25%10%31%24%10%
270
December1st to 10thDay
21%13%38%17%6%4
270
11th to 20thDay
23%10%38%23%6%
270
21st to endDay
32%14%33%15%6%
297
January1st to 10thNight
19%15%37%25%4
950
11th to 20thNight
23%14%35%23%4
950
21st to endNight
22%13%36%27%2
1025
February1st to 10thNight
25%13%34%26%2
805
11th to 20thNight
21%16%35%26%2
703
21st to endNight
28%11%36%22%2
592
March1st to 10thNight
23%12%37%24%4
720
11th to 20thNight
20%12%34%28%6%1
671
21st to endNight
26%5%33%29%7%
594
April1st to 10thNight
16%11%33%32%7%
540
11th to 20thNight
19%11%28%30%12%1
533
21st to endNight
24%6%30%30%9%1
540
May1st to 10thNight
16%5%34%35%10%1
540
11th to 20thNight
15%325%37%17%3
531
21st to endNight
9%223%38%24%3
584
June1st to 10thNight
10%220%42%25%1
540
11th to 20thNight
8%218%44%27%1
540
21st to endNight
9%221%39%28%1
540
July1st to 10thNight
11%18%33%38%8%
525
11th to 20thNight
4412%39%35%6%
522
21st to endNight
7%211%41%35%4
591
August1st to 10thNight
8%38%39%37%5%
537
11th to 20thNight
7%29%43%35%4
534
21st to endNight
8%211%32%42%6%
594
September1st to 10thNight
14%210%37%32%5%
540
11th to 20thNight
7%214%37%35%5%
629
21st to endNight
11%321%30%29%5%
720
October1st to 10thNight
11%422%38%21%4
720
11th to 20thNight
17%10%29%27%16%1
720
21st to endNight
22%11%32%29%7%
792
November1st to 10thNight
14%7%35%33%10%1
740
11th to 20thNight
17%11%32%31%9%1
760
21st to endNight
23%11%30%27%8%
760
December1st to 10thNight
23%10%35%27%5%
896
11th to 20thNight
24%8%31%31%6%1
950
21st to endNight
31%11%32%22%3
1045
Page generated at 2024-01-24 08:37:32. Version ac07

Copyright 2024 Attilla Danko


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