Marion
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Marion clear sky chart from 2005-11-05 to 2017-12-04.

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
38%
16147
17%
47755
11%
16105
44%
16105
22%
32594

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
15%
900
11%
2506
4%
895
22%
895
13%
1982
January16th to endNight
18%
907
11%
2635
4%
907
24%
907
13%
2052
February1st to 15thNight
20%
701
9%
2145
3%
701
25%
701
14%
1583
February16th to endNight
21%
631
14%
1893
5%
631
29%
631
15%
1405
March1st to 15thNight
28%
720
13%
2133
9%
720
32%
720
16%
1549
March16th to endNight
29%
735
15%
2079
8%
735
35%
735
20%
1479
April1st to 15thNight
31%
539
15%
1797
9%
539
41%
539
19%
1214
April16th to endNight
35%
540
20%
1671
10%
540
45%
540
25%
1094
May1st to 15thNight
36%
540
13%
1620
9%
540
40%
540
20%
1158
May16th to endNight
52%
562
16%
1643
12%
561
56%
561
28%
1067
June1st to 15thNight
60%
540
18%
1440
12%
540
64%
540
37%
890
June16th to endNight
57%
540
18%
1440
12%
540
61%
540
33%
926
July1st to 15thNight
64%
510
16%
1360
13%
510
65%
510
34%
866
July16th to endNight
72%
564
22%
1464
18%
531
75%
531
42%
851
August1st to 15thNight
70%
539
21%
1609
18%
536
72%
536
37%
928
August16th to endNight
68%
573
21%
1872
20%
573
71%
573
34%
1053
September1st to 15thNight
64%
618
26%
1878
22%
618
68%
618
35%
1092
September16th to endNight
61%
717
28%
1980
21%
717
65%
717
36%
1188
October1st to 15thNight
50%
720
25%
1992
20%
720
56%
720
33%
1232
October16th to endNight
31%
768
19%
2466
15%
768
39%
768
22%
1611
November1st to 15thNight
36%
760
23%
2471
16%
760
46%
760
25%
1507
November16th to endNight
27%
780
18%
2535
11%
780
36%
780
17%
1763
December1st to 15thNight
22%
783
9%
2438
4%
783
27%
783
13%
1870
December16th to endNight
15%
960
9%
2688
2%
960
22%
960
10%
2234

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%8%36%5%3445%7%35%
48736
Night
14%8%36%5%24446%37%
47929
Cloud CoverDay
14%8%36%5%35%45%7%35%
48745
Night
14%8%36%5%24446%37%
47934
TransparencyDay
47%6%12%19%11%1
48428
Night
46%5%11%20%13%2
47755
SeeingDay
16%6%25%24%19%8%
6112
Night
19%7%27%29%14%1
16151

By Month

Percentage Cloud Cover NE (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
21%15%5%8%6%43346%20%
1432
16th to endDay
13%17%8%9%6%35%44421%
1587
February1st to 15thDay
15%14%6%11%7%34345%23%
1714
16th to endDay
14%13%6%9%7%35%345%25%
1580
March1st to 15thDay
20%12%5%7%5%24447%24%
1817
16th to endDay
17%10%5%7%5%2335%7%30%
2154
April1st to 15thDay
20%9%35%5%24446%34%
2151
16th to endDay
18%7%26%5%3345%7%34%
2289
May1st to 15thDay
21%7%36%7%35%45%6%28%
2331
16th to endDay
12%5%25%6%35%5%7%7%37%
2469
June1st to 15thDay
11%425%5%45%5%5%7%41%
2520
16th to endDay
10%425%5%36%5%6%10%38%
2520
July1st to 15thDay
10%425%5%345%6%10%40%
2520
16th to endDay
8%4245%36%6%7%10%40%
2601
August1st to 15thDay
6%4245%35%6%7%9%44%
2340
16th to endDay
8%415%5%35%6%6%8%43%
2327
September1st to 15thDay
12%6%24434447%44%
2070
16th to endDay
11%5%24425%447%46%
1980
October1st to 15thDay
14%5%26%434446%41%
1968
16th to endDay
19%7%25%5%25%35%6%35%
1756
November1st to 15thDay
14%6%25%434345%44%
1717
16th to endDay
19%9%5%7%6%23346%30%
1755
December1st to 15thDay
19%15%5%11%5%3433423%
1602
16th to endDay
22%16%5%9%5%25%44418%
1536
January1st to 15thNight
20%14%5%8%7%3323425%
2506
16th to endNight
16%14%7%9%6%3444425%
2635
February1st to 15thNight
16%13%5%7%6%24345%29%
2143
16th to endNight
14%12%5%8%6%34345%30%
1893
March1st to 15thNight
17%10%47%6%25%345%32%
2120
16th to endNight
15%9%37%5%3445%6%33%
2079
April1st to 15thNight
17%7%25%5%35%45%5%36%
1797
16th to endNight
17%6%245%2345%7%40%
1671
May1st to 15thNight
20%7%26%5%3435%7%32%
1620
16th to endNight
12%5%25%42446%9%41%
1641
June1st to 15thNight
8%335%4245%49%49%
1440
16th to endNight
8%5%24435%5%49%45%
1440
July1st to 15thNight
8%4235%345%5%9%47%
1440
16th to endNight
5%325%4235%6%8%52%
1564
August1st to 15thNight
5%4244345%5%9%50%
1620
16th to endNight
7%3244345%5%8%50%
1872
September1st to 15thNight
10%414423447%51%
1878
16th to endNight
10%324423346%52%
1980
October1st to 15thNight
13%5%2442335%7%47%
1992
16th to endNight
18%6%35%424345%40%
2466
November1st to 15thNight
14%8%35%41335%6%44%
2471
16th to endNight
18%10%36%5%34347%32%
2535
December1st to 15thNight
20%12%6%8%6%2334426%
2438
16th to endNight
23%15%5%8%6%2433419%
2688

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
21%15%5%9%6%43346%21%
1432
16th to endDay
14%17%7%9%6%35%345%21%
1587
February1st to 15thDay
15%14%7%11%7%25%345%23%
1714
16th to endDay
14%13%6%9%7%34445%25%
1580
March1st to 15thDay
21%12%5%8%424447%24%
1827
16th to endDay
17%10%5%7%5%1436%7%30%
2153
April1st to 15thDay
19%9%35%424447%33%
2151
16th to endDay
18%8%26%5%3345%7%34%
2289
May1st to 15thDay
21%7%46%7%35%446%28%
2331
16th to endDay
12%5%25%6%35%5%7%7%37%
2469
June1st to 15thDay
11%425%5%35%5%5%7%41%
2520
16th to endDay
10%325%5%36%5%7%9%38%
2520
July1st to 15thDay
10%5%25%5%25%5%6%10%40%
2520
16th to endDay
8%4245%26%6%8%10%40%
2601
August1st to 15thDay
6%4245%45%6%6%9%44%
2340
16th to endDay
8%425%5%36%5%6%8%43%
2327
September1st to 15thDay
12%6%2443445%7%44%
2070
16th to endDay
11%5%24325%35%6%47%
1980
October1st to 15thDay
14%5%36%5%245%46%41%
1968
16th to endDay
19%7%25%5%2435%6%35%
1756
November1st to 15thDay
13%6%25%5%34345%44%
1717
16th to endDay
19%10%5%8%6%24345%30%
1755
December1st to 15thDay
18%15%5%11%5%2443423%
1602
16th to endDay
22%16%5%9%5%25%45%418%
1536
January1st to 15thNight
20%14%5%8%7%3323425%
2506
16th to endNight
16%14%7%9%6%3334425%
2635
February1st to 15thNight
16%13%5%7%6%33345%29%
2136
16th to endNight
14%12%5%8%6%35%345%29%
1893
March1st to 15thNight
17%10%46%6%35%345%32%
2133
16th to endNight
15%10%37%5%3445%7%33%
2079
April1st to 15thNight
17%6%245%35%45%5%36%
1797
16th to endNight
17%7%245%2345%7%40%
1671
May1st to 15thNight
20%7%26%5%3435%6%32%
1619
16th to endNight
12%5%25%42446%9%41%
1641
June1st to 15thNight
8%425%4245%48%49%
1440
16th to endNight
8%5%25%435%5%5%9%45%
1440
July1st to 15thNight
8%4135%245%5%9%47%
1440
16th to endNight
5%325%4245%6%8%53%
1564
August1st to 15thNight
5%4244336%49%50%
1620
16th to endNight
7%325%4245%5%8%50%
1872
September1st to 15thNight
10%413414447%51%
1878
16th to endNight
10%314433346%52%
1980
October1st to 15thNight
13%5%24433347%48%
1992
16th to endNight
18%6%26%424345%40%
2466
November1st to 15thNight
14%7%35%41335%6%44%
2471
16th to endNight
18%10%46%5%3435%6%32%
2535
December1st to 15thNight
20%12%6%8%6%3334426%
2438
16th to endNight
23%16%5%8%6%3333419%
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
65%311%12%6%
1433
16th to endDay
65%412%12%4
1587
February1st to 15thDay
63%39%14%7%
1716
16th to endDay
59%5%13%17%4
1580
March1st to 15thDay
58%5%12%16%6%
1827
16th to endDay
52%5%15%19%41
2154
April1st to 15thDay
50%412%20%11%
2151
16th to endDay
48%5%11%19%10%5%
2289
May1st to 15thDay
55%8%10%16%8%
2331
16th to endDay
41%9%12%21%13%2
2473
June1st to 15thDay
39%6%10%23%16%1
2520
16th to endDay
38%9%14%20%15%2
2520
July1st to 15thDay
38%7%12%21%17%2
2371
16th to endDay
34%9%17%23%12%2
2438
August1st to 15thDay
33%8%14%25%16%1
2327
16th to endDay
35%9%12%21%15%5%
2327
September1st to 15thDay
38%6%11%22%17%3
2070
16th to endDay
36%5%10%24%22%1
1980
October1st to 15thDay
41%6%10%23%15%1
1968
16th to endDay
47%412%22%11%
1756
November1st to 15thDay
40%411%21%18%2
1717
16th to endDay
55%412%19%7%
1755
December1st to 15thDay
64%5%9%16%3
1602
16th to endDay
68%5%9%12%3
1536
January1st to 15thNight
62%38%14%9%
2506
16th to endNight
61%412%14%6%
2635
February1st to 15thNight
57%413%15%7%
2145
16th to endNight
56%411%18%7%
1893
March1st to 15thNight
53%5%11%18%8%1
2133
16th to endNight
50%5%12%22%7%1
2079
April1st to 15thNight
47%6%10%22%12%1
1797
16th to endNight
42%5%11%21%13%5%
1671
May1st to 15thNight
50%5%12%19%9%1
1620
16th to endNight
38%7%12%22%14%3
1643
June1st to 15thNight
31%6%11%27%20%1
1440
16th to endNight
34%8%14%22%16%4
1440
July1st to 15thNight
33%7%12%21%20%4
1360
16th to endNight
26%7%16%28%17%4
1464
August1st to 15thNight
29%6%15%22%23%2
1609
16th to endNight
30%5%12%24%20%5%
1872
September1st to 15thNight
31%6%11%23%22%5%
1878
16th to endNight
32%5%9%24%25%2
1980
October1st to 15thNight
35%410%25%21%1
1992
16th to endNight
45%49%27%11%1
2466
November1st to 15thNight
40%49%23%18%3
2471
16th to endNight
52%411%23%8%
2535
December1st to 15thNight
61%410%16%7%
2438
16th to endNight
68%5%8%12%4
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
31%14%36%8%7%1
90
16th to endDay
25%15%40%15%3
96
February1st to 15thDay
21%18%45%11%3
90
16th to endDay
16%16%41%16%8%1
81
March1st to 15thDay
33%14%31%16%3
117
16th to endDay
27%9%30%21%9%1
288
April1st to 15thDay
24%11%29%22%11%1
270
16th to endDay
18%8%32%19%15%6%
270
May1st to 15thDay
28%8%25%23%9%4
288
16th to endDay
16%5%28%23%16%9%
369
June1st to 15thDay
12%326%31%20%6%
495
16th to endDay
12%6%29%27%17%6%
495
July1st to 15thDay
12%323%28%20%12%
475
16th to endDay
7%112%32%29%16%
461
August1st to 15thDay
8%112%25%30%22%
313
16th to endDay
9%113%21%37%15%
332
September1st to 15thDay
13%313%24%32%13%
315
16th to endDay
14%315%19%34%12%
314
October1st to 15thDay
15%7%20%30%18%7%
315
16th to endDay
23%8%34%26%6%
172
November1st to 15thDay
16%11%24%21%20%5%
135
16th to endDay
23%10%42%18%4
135
December1st to 15thDay
23%14%33%19%11%
100
16th to endDay
22%21%46%6%2
96
January1st to 15thNight
26%15%35%18%3
900
16th to endNight
22%14%35%23%3
907
February1st to 15thNight
22%12%35%25%3
704
16th to endNight
21%11%37%25%4
631
March1st to 15thNight
21%13%31%26%6%
720
16th to endNight
20%8%35%25%7%1
735
April1st to 15thNight
19%9%34%30%6%
539
16th to endNight
22%5%32%26%11%1
540
May1st to 15thNight
25%5%25%32%10%
540
16th to endNight
14%224%36%19%2
563
June1st to 15thNight
9%222%45%20%
540
16th to endNight
11%121%40%23%
540
July1st to 15thNight
10%117%41%27%1
510
16th to endNight
6%11%38%37%4
564
August1st to 15thNight
6%14%41%30%5%
539
16th to endNight
7%113%32%38%6%
573
September1st to 15thNight
14%213%35%28%5%
618
16th to endNight
12%315%31%32%4
717
October1st to 15thNight
16%5%22%32%19%3
720
16th to endNight
21%11%32%24%9%
768
November1st to 15thNight
18%9%31%26%12%1
760
16th to endNight
24%12%30%23%8%
780
December1st to 15thNight
27%11%31%21%7%1
783
16th to endNight
31%11%31%19%4
960
Page generated at 2017-12-05 10:18:58. Version ac04

Copyright 2017 A. Danko


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