Effingham
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Effingham 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
43%
15860
21%
46915
14%
15815
50%
15815
28%
29731

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
24%
899
18%
2506
7%
895
34%
895
22%
1749
January16th to endNight
24%
960
18%
2574
7%
960
33%
960
21%
1827
February1st to 15thNight
23%
761
15%
2169
5%
758
30%
758
20%
1514
February16th to endNight
26%
631
19%
1893
8%
631
35%
631
21%
1247
March1st to 15thNight
26%
720
16%
2160
8%
720
33%
720
20%
1490
March16th to endNight
33%
603
15%
2004
11%
603
40%
603
21%
1315
April1st to 15thNight
35%
539
21%
1797
12%
539
49%
539
25%
1095
April16th to endNight
42%
540
22%
1794
18%
540
51%
540
26%
1114
May1st to 15thNight
41%
539
17%
1619
10%
539
47%
539
24%
1094
May16th to endNight
54%
563
19%
1537
13%
561
58%
561
32%
987
June1st to 15thNight
64%
540
21%
1440
16%
540
67%
540
42%
836
June16th to endNight
62%
540
23%
1440
17%
540
65%
540
39%
868
July1st to 15thNight
67%
510
20%
1360
16%
510
69%
510
40%
814
July16th to endNight
75%
564
27%
1417
22%
531
77%
531
48%
781
August1st to 15thNight
77%
539
23%
1710
25%
536
78%
536
40%
923
August16th to endNight
74%
573
26%
1910
28%
573
77%
573
39%
1013
September1st to 15thNight
65%
540
29%
1800
31%
540
69%
540
35%
980
September16th to endNight
62%
689
32%
1903
24%
689
66%
689
37%
1126
October1st to 15thNight
55%
660
31%
1895
23%
660
62%
660
38%
1090
October16th to endNight
37%
704
25%
2197
18%
704
47%
704
28%
1328
November1st to 15thNight
41%
700
29%
2276
20%
700
53%
700
31%
1292
November16th to endNight
33%
720
22%
2340
16%
720
42%
720
23%
1493
December1st to 15thNight
28%
866
15%
2486
7%
866
35%
866
20%
1769
December16th to endNight
21%
960
15%
2688
5%
960
30%
960
17%
1986

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%6%25%43445%7%40%
48010
Night
14%6%25%42445%7%43%
47090
TransparencyDay
41%412%24%14%2
47687
Night
41%310%24%16%3
46917
SeeingDay
14%5%20%27%22%10%
5884
Night
17%7%25%31%16%2
15862

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
18%8%48%6%34445%31%
1432
16th to endDay
13%11%46%5%34446%36%
1650
February1st to 15thDay
14%9%5%7%425%45%7%32%
1693
16th to endDay
12%11%38%5%346%5%7%30%
1580
March1st to 15thDay
18%8%36%43445%5%35%
1800
16th to endDay
18%10%45%5%24446%31%
2229
April1st to 15thDay
16%6%35%323437%41%
2151
16th to endDay
18%6%35%6%24346%38%
2163
May1st to 15thDay
20%6%25%435%446%34%
2331
16th to endDay
11%5%25%5%26%5%6%8%39%
2575
June1st to 15thDay
7%5%24435%5%6%7%47%
2520
16th to endDay
8%425%4445%6%9%44%
2520
July1st to 15thDay
9%425%5%35%6%6%9%42%
2520
16th to endDay
5%314436%6%8%11%44%
2655
August1st to 15thDay
7%4145%345%6%9%46%
2238
16th to endDay
7%425%5%345%7%9%44%
2292
September1st to 15thDay
12%425%435%35%6%44%
2148
16th to endDay
9%5%15%42345%8%48%
1894
October1st to 15thDay
15%42332445%5%49%
1733
16th to endDay
14%5%24323446%48%
1675
November1st to 15thDay
13%5%23323446%50%
1582
16th to endDay
18%8%34323245%41%
1620
December1st to 15thDay
21%9%46%423346%33%
1473
16th to endDay
20%12%46%314435%32%
1536
January1st to 15thNight
16%8%37%5%25%345%37%
2506
16th to endNight
14%10%37%6%33446%35%
2574
February1st to 15thNight
16%7%5%7%5%2445%6%34%
2160
16th to endNight
16%9%36%423336%39%
1893
March1st to 15thNight
18%9%35%5%33445%36%
2160
16th to endNight
17%6%35%5%25%45%6%36%
2004
April1st to 15thNight
14%5%345%25%335%46%
1797
16th to endNight
16%7%2442435%6%42%
1794
May1st to 15thNight
17%5%25%6%2445%6%38%
1619
16th to endNight
8%425%445%5%5%9%43%
1536
June1st to 15thNight
7%31443345%9%51%
1440
16th to endNight
7%414425%46%11%47%
1440
July1st to 15thNight
8%42432447%7%49%
1440
16th to endNight
5%31332436%8%55%
1513
August1st to 15thNight
5%3233245%6%10%52%
1719
16th to endNight
5%22342445%8%53%
1910
September1st to 15thNight
9%5%2432345%8%51%
1800
16th to endNight
8%425%42445%6%51%
1903
October1st to 15thNight
11%314423347%53%
1895
16th to endNight
17%6%14412345%48%
2197
November1st to 15thNight
11%5%24423345%51%
2276
16th to endNight
18%8%35%423235%42%
2340
December1st to 15thNight
23%8%35%42445%6%31%
2486
16th to endNight
23%10%45%5%24345%31%
2688

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
55%38%20%11%
1433
16th to endDay
49%211%26%8%
1650
February1st to 15thDay
49%412%24%8%
1695
16th to endDay
51%5%11%22%8%
1580
March1st to 15thDay
50%412%22%9%1
1800
16th to endDay
52%313%22%6%
2230
April1st to 15thDay
42%411%26%14%
2151
16th to endDay
47%210%24%11%2
2163
May1st to 15thDay
50%412%22%9%
2331
16th to endDay
40%6%15%19%15%2
2579
June1st to 15thDay
33%5%14%26%18%2
2520
16th to endDay
36%5%14%23%16%3
2520
July1st to 15thDay
37%411%25%16%3
2371
16th to endDay
29%7%15%28%16%2
2488
August1st to 15thDay
32%415%28%17%2
2223
16th to endDay
33%5%13%25%16%6%
2292
September1st to 15thDay
38%49%21%20%4
2148
16th to endDay
34%48%28%21%3
1894
October1st to 15thDay
36%39%27%19%3
1733
16th to endDay
36%210%28%19%1
1675
November1st to 15thDay
35%310%23%19%6%
1582
16th to endDay
46%210%25%13%2
1620
December1st to 15thDay
53%313%18%10%
1473
16th to endDay
54%310%22%7%1
1536
January1st to 15thNight
49%28%24%13%
2506
16th to endNight
50%311%24%9%
2574
February1st to 15thNight
51%212%20%11%1
2169
16th to endNight
47%213%24%11%
1893
March1st to 15thNight
50%39%22%12%2
2160
16th to endNight
46%315%22%10%1
2004
April1st to 15thNight
41%29%25%18%2
1797
16th to endNight
42%38%26%15%4
1794
May1st to 15thNight
45%5%13%22%13%
1620
16th to endNight
37%6%14%19%18%4
1538
June1st to 15thNight
29%312%28%22%2
1440
16th to endNight
32%412%23%20%7%
1440
July1st to 15thNight
30%5%12%27%18%6%
1360
16th to endNight
24%315%32%21%2
1417
August1st to 15thNight
25%6%14%27%22%3
1710
16th to endNight
27%412%26%22%6%
1910
September1st to 15thNight
31%37%28%22%7%
1800
16th to endNight
32%35%26%25%5%
1903
October1st to 15thNight
31%29%28%21%6%
1895
16th to endNight
39%27%28%17%3
2197
November1st to 15thNight
34%38%23%23%6%
2276
16th to endNight
45%28%24%18%
2340
December1st to 15thNight
52%311%21%10%
2486
16th to endNight
55%310%19%9%1
2688

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
32%12%35%13%6%
90
16th to endDay
10%22%48%14%3
96
February1st to 15thDay
18%22%36%20%2
90
16th to endDay
13%19%27%33%6%
81
March1st to 15thDay
31%8%36%14%8%
90
16th to endDay
23%13%28%23%10%
231
April1st to 15thDay
18%11%29%25%13%1
270
16th to endDay
22%426%27%15%4
270
May1st to 15thDay
23%7%24%26%11%5%
288
16th to endDay
13%326%30%16%8%
475
June1st to 15thDay
9%216%32%29%9%
495
16th to endDay
7%5%27%32%19%7%
495
July1st to 15thDay
12%116%34%21%14%
475
16th to endDay
5%26%34%34%17%
515
August1st to 15thDay
11%15%24%33%24%
358
16th to endDay
7%28%24%39%18%
332
September1st to 15thDay
14%111%22%34%15%
315
16th to endDay
11%311%24%31%16%
283
October1st to 15thDay
12%320%26%31%6%
173
16th to endDay
16%431%36%7%4
96
November1st to 15thDay
7%8%20%23%28%11%
90
16th to endDay
34%14%24%16%7%2
90
December1st to 15thDay
20%10%35%25%5%3
90
16th to endDay
33%12%39%12%2
96
January1st to 15thNight
20%14%36%24%4
900
16th to endNight
20%13%35%28%2
960
February1st to 15thNight
22%13%32%29%2
761
16th to endNight
21%9%36%29%2
631
March1st to 15thNight
23%10%35%25%5%
720
16th to endNight
20%6%32%31%7%
603
April1st to 15thNight
17%11%30%29%10%
539
16th to endNight
21%5%25%33%12%1
540
May1st to 15thNight
18%424%37%12%1
540
16th to endNight
9%225%36%22%2
563
June1st to 15thNight
10%118%43%25%1
540
16th to endNight
9%217%41%27%1
540
July1st to 15thNight
10%210%38%34%3
510
16th to endNight
5%18%35%40%8%
564
August1st to 15thNight
6%7%37%41%6%
539
16th to endNight
6%19%32%42%7%
573
September1st to 15thNight
12%210%34%34%6%
540
16th to endNight
10%215%28%35%7%
689
October1st to 15thNight
11%421%33%24%4
660
16th to endNight
22%8%28%29%10%
704
November1st to 15thNight
14%8%30%31%14%1
700
16th to endNight
22%9%29%28%10%
720
December1st to 15thNight
28%7%30%25%6%1
866
16th to endNight
29%8%33%24%3
960
Page generated at 2017-09-24 08:15:47. Version ac04

Copyright 2017 A. Danko


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