Corona
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Corona clear sky chart from 2005-11-06 to 2024-01-12.

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
77%
24553
33%
74104
30%
24501
80%
24501
50%
36943

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
66%
759
29%
2457
30%
756
70%
756
40%
1270
January11th to 20thNight
71%
726
35%
2251
32%
726
77%
726
43%
1168
January21st to endNight
63%
792
36%
2376
30%
792
72%
792
41%
1269
February1st to 10thNight
69%
720
35%
2160
34%
720
74%
720
47%
1100
February11th to 20thNight
68%
700
33%
2098
31%
700
74%
700
46%
1082
February21st to endNight
62%
592
29%
1776
30%
592
66%
592
38%
995
March1st to 10thNight
68%
720
25%
2160
26%
720
73%
720
37%
1216
March11th to 20thNight
71%
720
27%
2104
27%
720
74%
720
44%
1117
March21st to endNight
69%
792
29%
2008
22%
792
73%
792
46%
1162
April1st to 10thNight
71%
720
28%
1800
21%
720
73%
720
47%
1050
April11th to 20thNight
73%
711
32%
1779
21%
711
75%
711
54%
963
April21st to endNight
77%
720
30%
1800
19%
720
78%
720
55%
974
May1st to 10thNight
74%
625
28%
1705
19%
625
75%
625
53%
901
May11th to 20thNight
79%
531
28%
1595
22%
531
79%
531
52%
811
May21st to endNight
78%
582
27%
1746
22%
582
79%
582
51%
878
June1st to 10thNight
82%
540
29%
1620
25%
540
83%
540
55%
783
June11th to 20thNight
88%
480
35%
1560
33%
480
89%
480
64%
650
June21st to endNight
93%
360
39%
1440
48%
360
93%
360
68%
475
July1st to 10thNight
97%
350
38%
1400
45%
350
97%
350
71%
447
July11th to 20thNight
94%
492
35%
1536
32%
492
94%
492
66%
634
July21st to endNight
90%
708
32%
1785
23%
669
90%
669
63%
872
August1st to 10thNight
91%
716
35%
1780
23%
712
91%
712
75%
838
August11th to 20thNight
93%
712
40%
1780
26%
712
93%
712
82%
793
August21st to endNight
93%
792
43%
1980
30%
792
93%
792
78%
908
September1st to 10thNight
87%
720
40%
1800
32%
720
87%
720
68%
894
September11th to 20thNight
89%
720
43%
1962
40%
720
90%
720
75%
848
September21st to endNight
86%
720
43%
1980
41%
720
88%
720
70%
884
October1st to 10thNight
84%
720
36%
1980
36%
720
85%
720
59%
958
October11th to 20thNight
81%
720
41%
2035
41%
720
84%
720
60%
953
October21st to endNight
79%
792
39%
2448
40%
792
82%
792
56%
1122
November1st to 10thNight
81%
740
36%
2405
39%
740
85%
740
56%
1045
November11th to 20thNight
81%
760
38%
2470
40%
760
85%
760
53%
1118
November21st to endNight
73%
760
33%
2470
35%
760
76%
760
42%
1252
December1st to 10thNight
68%
760
32%
2470
32%
760
73%
760
40%
1283
December11th to 20thNight
64%
759
29%
2961
32%
758
69%
758
28%
1692
December21st to endNight
63%
822
20%
4427
29%
817
70%
817
20%
2538

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
3313323446%67%
75256
Night
431332345%6%65%
74484
TransparencyDay
19%47%16%26%28%
74983
Night
20%48%16%24%28%
74279
SeeingDay
46%18%35%26%11%
14596
Night
5%210%35%39%9%
24575

By Month

Percentage Cloud Cover SW (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
7%324433449%57%
1708
11th to 20thDay
6%3224245%5%7%60%
1733
21st to endDay
8%424423346%60%
1980
February1st to 10thDay
6%424323345%64%
1800
11th to 20thDay
6%31332345%7%62%
1750
21st to endDay
6%5%347%24437%57%
1480
March1st to 10thDay
5%425%5%45%7%6%8%52%
1800
11th to 20thDay
5%33343445%9%57%
1854
21st to endDay
4312425%5%5%8%60%
2344
April1st to 10thDay
4323425%45%7%60%
2160
11th to 20thDay
321342445%6%66%
2129
21st to endDay
3314323346%68%
2160
May1st to 10thDay
342432336%7%62%
2254
11th to 20thDay
24245%23446%65%
2301
21st to endDay
35%2432345%7%62%
2530
June1st to 10thDay
3423323447%65%
2340
11th to 20thDay
1313322236%75%
2391
21st to endDay
121232233478%
2520
July1st to 10thDay
1212213335%76%
2520
11th to 20thDay
1212213345%75%
2366
21st to endDay
211222346%8%70%
2423
August1st to 10thDay
1212212235%80%
2149
11th to 20thDay
1111113235%82%
2122
21st to endDay
122222345%78%
2376
September1st to 10thDay
2212211345%78%
2160
11th to 20thDay
121221223481%
1997
21st to endDay
1112212335%80%
1980
October1st to 10thDay
321332335%6%69%
1980
11th to 20thDay
331222333475%
1922
21st to endDay
3312222246%73%
1908
November1st to 10thDay
3212223337%72%
1674
11th to 20thDay
311332335%6%70%
1710
21st to endDay
4225%5%24447%62%
1710
December1st to 10thDay
5%42442445%8%59%
1710
11th to 20thDay
9%5%25%5%35%46%10%45%
2169
21st to endDay
8%5%26%6%5%6%6%5%6%44%
3146
January1st to 10thNight
7%4244245%5%7%57%
2457
11th to 20thNight
5%423425%45%7%59%
2251
21st to endNight
7%5%25%323346%61%
2376
February1st to 10thNight
6%424423346%64%
2160
11th to 20thNight
6%31332345%5%63%
2098
21st to endNight
8%4245%3445%5%56%
1776
March1st to 10thNight
43245%45%5%6%10%51%
2160
11th to 20thNight
6%4243335%6%9%57%
2104
21st to endNight
5%41343446%7%59%
2008
April1st to 10thNight
6%42432346%9%57%
1800
11th to 20thNight
45%1332335%6%66%
1779
21st to endNight
442332436%6%65%
1800
May1st to 10thNight
36%13423447%63%
1705
11th to 20thNight
23143245%5%8%63%
1594
21st to endNight
3423322347%68%
1746
June1st to 10thNight
231322345%7%68%
1620
11th to 20thNight
1222222245%76%
1560
21st to endNight
111211225%479%
1440
July1st to 10thNight
112112346%79%
1440
11th to 20thNight
111232335%6%75%
1588
21st to endNight
211232435%7%70%
1890
August1st to 10thNight
2212112245%78%
1790
11th to 20thNight
111112236%81%
1780
21st to endNight
112211245%80%
1980
September1st to 10thNight
2213322335%75%
1800
11th to 20thNight
121221122482%
1962
21st to endNight
131221222481%
1980
October1st to 10thNight
221232435%6%69%
1980
11th to 20thNight
3213322235%73%
2035
21st to endNight
2313223445%72%
2448
November1st to 10thNight
3213223446%70%
2405
11th to 20thNight
2223323346%70%
2470
21st to endNight
5%3244245%5%8%59%
2470
December1st to 10thNight
6%4145%2445%8%56%
2470
11th to 20thNight
9%5%25%5%345%6%7%48%
3041
21st to endNight
8%7%36%6%46%5%6%8%42%
4521

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
27%48%17%24%20%
1709
11th to 20thDay
23%5%7%14%25%27%
1733
21st to endDay
27%37%15%19%28%
1980
February1st to 10thDay
24%45%13%24%30%
1800
11th to 20thDay
23%4416%26%26%
1760
21st to endDay
30%47%15%23%21%
1480
March1st to 10thDay
28%5%9%17%18%22%
1800
11th to 20thDay
24%5%9%20%24%18%
1854
21st to endDay
22%6%12%22%22%17%
2344
April1st to 10thDay
24%5%11%24%23%14%
2160
11th to 20thDay
19%48%22%28%20%
2132
21st to endDay
18%49%21%34%15%
2160
May1st to 10thDay
21%6%10%19%27%18%
2254
11th to 20thDay
19%410%21%31%15%
2304
21st to endDay
22%5%10%26%27%9%
2530
June1st to 10thDay
17%410%22%31%17%
2340
11th to 20thDay
13%26%14%30%36%
2391
21st to endDay
11%3410%27%46%
2520
July1st to 10thDay
12%25%11%23%48%
2451
11th to 20thDay
11%46%18%31%31%
2295
21st to endDay
13%5%9%23%33%18%
2288
August1st to 10thDay
10%2412%33%40%
2135
11th to 20thDay
7%2416%32%39%
2122
21st to endDay
11%2310%35%38%
2376
September1st to 10thDay
10%36%8%32%41%
2160
11th to 20thDay
10%249%35%41%
1997
21st to endDay
10%2315%32%37%
1980
October1st to 10thDay
17%36%18%23%33%
1980
11th to 20thDay
15%3413%27%38%
1922
21st to endDay
15%45%10%22%45%
1908
November1st to 10thDay
15%36%15%26%35%
1674
11th to 20thDay
16%47%14%20%39%
1710
21st to endDay
23%37%12%22%33%
1710
December1st to 10thDay
25%48%16%19%28%
1710
11th to 20thDay
35%6%10%14%17%19%
2168
21st to endDay
40%5%7%19%16%13%
3146
January1st to 10thNight
26%48%15%24%23%
2457
11th to 20thNight
24%5%6%14%22%29%
2251
21st to endNight
27%48%15%15%31%
2376
February1st to 10thNight
23%37%14%23%29%
2160
11th to 20thNight
24%47%16%21%28%
2099
21st to endNight
30%47%16%20%23%
1776
March1st to 10thNight
28%6%9%19%18%19%
2160
11th to 20thNight
24%5%11%17%24%19%
2104
21st to endNight
24%6%11%22%22%14%
2008
April1st to 10thNight
24%6%12%23%18%16%
1800
11th to 20thNight
19%5%11%22%23%20%
1779
21st to endNight
19%5%12%22%27%15%
1800
May1st to 10thNight
20%5%15%21%19%20%
1705
11th to 20thNight
19%6%15%23%25%13%
1595
21st to endNight
18%6%15%27%24%10%
1746
June1st to 10thNight
15%6%14%21%27%17%
1620
11th to 20thNight
11%39%17%27%33%
1560
21st to endNight
8%27%13%26%44%
1440
July1st to 10thNight
7%26%15%23%47%
1400
11th to 20thNight
10%47%20%30%29%
1536
21st to endNight
14%410%22%33%17%
1785
August1st to 10thNight
10%25%15%33%35%
1780
11th to 20thNight
6%16%14%35%37%
1780
21st to endNight
8%25%13%31%42%
1980
September1st to 10thNight
13%35%10%28%40%
1800
11th to 20thNight
9%26%12%29%43%
1962
21st to endNight
11%2413%33%37%
1980
October1st to 10thNight
16%37%19%25%30%
1980
11th to 20thNight
16%36%14%27%35%
2035
21st to endNight
16%45%9%21%46%
2448
November1st to 10thNight
16%37%14%24%36%
2405
11th to 20thNight
17%36%13%20%40%
2470
21st to endNight
24%5%7%14%18%32%
2470
December1st to 10thNight
26%5%7%14%19%30%
2470
11th to 20thNight
34%5%9%14%20%17%
3041
21st to endNight
36%8%10%17%16%13%
4521

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
10%6%17%41%22%4
270
11th to 20thDay
9%10%20%34%22%5%
347
21st to endDay
9%10%26%32%19%3
462
February1st to 10thDay
9%10%23%33%18%8%
420
11th to 20thDay
8%11%30%31%18%3
415
21st to endDay
9%15%25%34%15%2
346
March1st to 10thDay
8%16%26%33%14%3
420
11th to 20thDay
7%11%29%33%15%5%
420
21st to endDay
6%13%31%32%15%3
462
April1st to 10thDay
6%9%27%32%20%6%
420
11th to 20thDay
211%34%33%15%6%
412
21st to endDay
311%28%32%17%10%
420
May1st to 10thDay
5%9%27%35%18%6%
423
11th to 20thDay
36%25%39%21%6%
448
21st to endDay
5%7%23%37%21%7%
485
June1st to 10thDay
4415%37%27%13%
450
11th to 20thDay
2217%35%29%15%
450
21st to endDay
2111%37%33%16%
450
July1st to 10thDay
315%32%38%21%
446
11th to 20thDay
1432%37%26%
444
21st to endDay
11333%39%23%
487
August1st to 10thDay
26%38%36%18%
447
11th to 20thDay
2433%39%22%
437
21st to endDay
11434%38%21%
495
September1st to 10thDay
218%42%31%15%
450
11th to 20thDay
3110%44%31%12%
450
21st to endDay
1217%33%30%17%
450
October1st to 10thDay
3418%37%29%10%
450
11th to 20thDay
25%18%34%30%11%
450
21st to endDay
5%318%32%27%15%
423
November1st to 10thDay
4416%33%32%11%
270
11th to 20thDay
2316%36%30%13%
270
21st to endDay
47%17%33%27%11%
270
December1st to 10thDay
7%6%14%36%29%9%
270
11th to 20thDay
46%18%33%29%10%
270
21st to endDay
10%11%21%33%20%5%
297
January1st to 10thNight
9%315%40%25%9%
760
11th to 20thNight
6%215%42%28%6%
726
21st to endNight
9%317%40%25%5%
792
February1st to 10thNight
7%315%41%26%9%
720
11th to 20thNight
7%316%41%25%7%
704
21st to endNight
11%6%16%41%21%6%
592
March1st to 10thNight
6%216%49%22%5%
720
11th to 20thNight
6%413%39%29%8%
720
21st to endNight
6%316%42%29%4
792
April1st to 10thNight
8%310%42%33%4
720
11th to 20thNight
5%215%41%32%5%
711
21st to endNight
5%39%41%35%6%
720
May1st to 10thNight
6%311%39%36%5%
625
11th to 20thNight
2114%35%42%6%
531
21st to endNight
4212%41%37%4
584
June1st to 10thNight
1210%37%44%5%
540
11th to 20thNight
126%36%51%4
480
21st to endNight
11326%61%8%
360
July1st to 10thNight
116%71%12%
350
11th to 20thNight
2120%66%11%
492
21st to endNight
2114%67%15%
708
August1st to 10thNight
31121%58%16%
716
11th to 20thNight
1114%66%18%
712
21st to endNight
116%61%21%
792
September1st to 10thNight
3320%55%18%
720
11th to 20thNight
2427%55%13%
720
21st to endNight
316%29%49%13%
720
October1st to 10thNight
316%40%43%7%
720
11th to 20thNight
417%34%43%11%
720
21st to endNight
3211%34%36%14%
792
November1st to 10thNight
429%37%37%12%
740
11th to 20thNight
419%41%35%11%
760
21st to endNight
6%211%41%33%7%
760
December1st to 10thNight
8%313%39%29%8%
760
11th to 20thNight
11%315%40%25%6%
760
21st to endNight
8%5%18%39%23%7%
836
Page generated at 2024-01-09 04:14:45. Version ac07

Copyright 2024 Attilla Danko


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