Corona
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Corona clear sky chart from 2005-11-05 to 2017-09-16.

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
80%
15968
33%
46669
31%
15922
82%
15922
53%
23035

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
71%
719
29%
2315
30%
716
75%
716
42%
1174
January16th to endNight
67%
768
32%
2304
28%
768
73%
768
39%
1273
February1st to 15thNight
72%
697
34%
2102
34%
697
77%
697
47%
1084
February16th to endNight
66%
632
28%
1895
30%
632
69%
632
36%
1097
March1st to 15thNight
76%
720
30%
2160
32%
720
79%
720
46%
1105
March16th to endNight
77%
768
29%
2020
25%
768
79%
768
50%
1096
April1st to 15thNight
72%
719
28%
1799
20%
719
74%
719
49%
1032
April16th to endNight
78%
720
31%
1800
20%
720
79%
720
57%
949
May1st to 15thNight
79%
594
30%
1674
22%
594
80%
594
55%
856
May16th to endNight
82%
561
28%
1685
23%
561
83%
561
53%
832
June1st to 15thNight
86%
540
29%
1620
26%
540
86%
540
58%
764
June16th to endNight
95%
380
40%
1460
47%
380
95%
380
77%
458
July1st to 15thNight
94%
376
34%
1396
37%
376
94%
376
63%
515
July16th to endNight
91%
641
31%
1664
24%
602
91%
602
61%
803
August1st to 15thNight
93%
717
36%
1790
24%
713
93%
713
77%
820
August16th to endNight
93%
764
42%
1910
29%
764
93%
764
78%
876
September1st to 15thNight
88%
720
38%
1848
32%
720
89%
720
69%
892
September16th to endNight
89%
660
44%
1826
43%
660
90%
660
75%
780
October1st to 15thNight
84%
660
37%
1815
37%
660
85%
660
59%
883
October16th to endNight
81%
704
38%
2135
39%
704
83%
704
53%
1023
November1st to 15thNight
83%
700
35%
2275
39%
700
86%
700
55%
1006
November16th to endNight
78%
720
35%
2340
39%
720
81%
720
47%
1129
December1st to 15thNight
70%
720
32%
2340
33%
720
75%
720
38%
1250
December16th to endNight
62%
768
32%
2496
30%
768
69%
768
37%
1338

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
3212312346%68%
48062
Night
3212213346%67%
46874
TransparencyDay
18%37%16%27%27%
47757
Night
18%47%16%25%27%
46680
SeeingDay
45%18%37%25%8%
5937
Night
5%18%32%41%10%
15979

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 15thDay
5%212422346%61%
1620
16th to endDay
8%31332335%5%58%
1920
February1st to 15thDay
5%313223345%63%
1751
16th to endDay
8%5%246%13437%52%
1579
March1st to 15thDay
32133235%5%9%59%
1800
16th to endDay
3212425%45%8%61%
2199
April1st to 15thDay
4212424447%60%
2149
16th to endDay
2213213236%69%
2160
May1st to 15thDay
2313312346%66%
2274
16th to endDay
2423312346%65%
2429
June1st to 15thDay
3423212236%66%
2340
16th to endDay
1111112383%
2493
July1st to 15thDay
1211212435%72%
2475
16th to endDay
1112212346%71%
2386
August1st to 15thDay
1111222480%
2160
16th to endDay
1121223478%
2292
September1st to 15thDay
111111235%79%
2110
16th to endDay
1121122480%
1823
October1st to 15thDay
3112323346%68%
1815
16th to endDay
3312212235%70%
1735
November1st to 15thDay
3112212236%71%
1584
16th to endDay
4214322346%65%
1620
December1st to 15thDay
5%21342445%8%57%
1620
16th to endDay
8%423313347%57%
1728
January1st to 15thNight
5%413324346%60%
2315
16th to endNight
7%414323345%58%
2304
February1st to 15thNight
5%313313245%64%
2101
16th to endNight
11%32342345%5%53%
1895
March1st to 15thNight
331332435%9%59%
2160
16th to endNight
321232345%8%61%
2020
April1st to 15thNight
5%423323347%60%
1799
16th to endNight
3312213345%68%
1800
May1st to 15thNight
2413222337%66%
1674
16th to endNight
1213312346%68%
1684
June1st to 15thNight
1212122347%70%
1620
16th to endNight
111112384%
1460
July1st to 15thNight
111212236%74%
1479
16th to endNight
212223347%69%
1778
August1st to 15thNight
11112235%79%
1800
16th to endNight
1111123481%
1910
September1st to 15thNight
11221222476%
1848
16th to endNight
211111383%
1826
October1st to 15thNight
3112223245%70%
1815
16th to endNight
332312335%69%
2135
November1st to 15thNight
2222212335%71%
2275
16th to endNight
4213223336%65%
2340
December1st to 15thNight
5%314424446%57%
2340
16th to endNight
9%424322335%59%
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
24%47%12%24%26%
1621
16th to endDay
27%48%13%19%27%
1920
February1st to 15thDay
23%45%14%24%27%
1751
16th to endDay
33%46%17%26%11%
1579
March1st to 15thDay
21%49%20%21%23%
1800
16th to endDay
21%5%11%24%20%15%
2199
April1st to 15thDay
24%49%24%24%12%
2149
16th to endDay
16%39%22%27%19%
2160
May1st to 15thDay
18%49%19%27%19%
2274
16th to endDay
20%48%26%29%11%
2432
June1st to 15thDay
18%28%17%31%21%
2340
16th to endDay
7%138%30%48%
2493
July1st to 15thDay
13%35%11%26%39%
2329
16th to endDay
13%47%22%30%21%
2237
August1st to 15thDay
8%1312%36%36%
2146
16th to endDay
10%2311%37%34%
2292
September1st to 15thDay
9%35%10%32%38%
2110
16th to endDay
9%1312%33%39%
1823
October1st to 15thDay
18%35%18%26%26%
1815
16th to endDay
17%4411%20%40%
1735
November1st to 15thDay
16%37%15%23%34%
1584
16th to endDay
21%35%13%22%33%
1620
December1st to 15thDay
24%410%16%18%24%
1620
16th to endDay
29%47%17%20%20%
1728
January1st to 15thNight
24%46%12%21%29%
2315
16th to endNight
28%47%13%15%29%
2304
February1st to 15thNight
23%37%16%21%27%
2112
16th to endNight
32%47%16%23%15%
1895
March1st to 15thNight
22%48%20%22%21%
2160
16th to endNight
20%5%12%21%22%16%
2020
April1st to 15thNight
24%410%24%21%14%
1799
16th to endNight
17%410%23%24%19%
1800
May1st to 15thNight
17%5%12%22%22%19%
1675
16th to endNight
16%6%12%28%23%12%
1685
June1st to 15thNight
13%5%10%19%29%20%
1620
16th to endNight
5%15%11%28%46%
1460
July1st to 15thNight
10%25%12%28%39%
1396
16th to endNight
13%49%22%29%20%
1664
August1st to 15thNight
8%15%14%39%29%
1790
16th to endNight
7%25%11%35%37%
1910
September1st to 15thNight
11%25%11%33%35%
1848
16th to endNight
9%1313%32%40%
1826
October1st to 15thNight
16%26%18%32%23%
1815
16th to endNight
18%4411%21%40%
2135
November1st to 15thNight
16%25%15%23%36%
2275
16th to endNight
20%46%14%19%34%
2340
December1st to 15thNight
27%5%7%14%19%25%
2340
16th to endNight
28%48%14%24%20%
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
18%316%39%22%1
99
16th to endDay
12%7%27%34%15%2
288
February1st to 15thDay
6%7%28%32%19%5%
266
16th to endDay
11%13%26%29%15%2
238
March1st to 15thDay
412%24%32%19%6%
270
16th to endDay
5%9%30%34%14%5%
288
April1st to 15thDay
5%14%29%33%11%5%
269
16th to endDay
111%41%32%8%4
270
May1st to 15thDay
49%26%39%15%4
288
16th to endDay
46%26%40%16%4
330
June1st to 15thDay
6%319%40%21%8%
315
16th to endDay
19%39%32%16%
315
July1st to 15thDay
36%34%36%17%
305
16th to endDay
1334%40%19%
327
August1st to 15thDay
26%42%38%9%
315
16th to endDay
1237%42%16%
332
September1st to 15thDay
27%53%27%8%
315
16th to endDay
1113%46%26%10%
258
October1st to 15thDay
26%20%40%25%4
255
16th to endDay
5%121%32%29%9%
228
November1st to 15thDay
2212%23%32%27%
90
16th to endDay
2426%30%30%6%
90
December1st to 15thDay
15%13%28%42%8%
90
16th to endDay
8%7%21%34%25%3
96
January1st to 15thNight
7%112%40%27%10%
720
16th to endNight
9%214%36%29%8%
768
February1st to 15thNight
6%211%40%28%10%
704
16th to endNight
12%311%40%24%7%
632
March1st to 15thNight
5%13%43%29%7%
720
16th to endNight
4110%40%35%7%
768
April1st to 15thNight
7%211%41%33%4
719
16th to endNight
428%41%35%7%
720
May1st to 15thNight
4110%35%41%6%
595
16th to endNight
111%38%42%4
563
June1st to 15thNight
127%38%46%4
540
16th to endNight
123%68%5%
380
July1st to 15thNight
215%69%11%
376
16th to endNight
2112%69%13%
641
August1st to 15thNight
116%64%16%
717
16th to endNight
111%64%22%
764
September1st to 15thNight
3218%56%19%
720
16th to endNight
2324%54%14%
660
October1st to 15thNight
36%36%42%9%
660
16th to endNight
416%29%41%16%
704
November1st to 15thNight
47%36%37%14%
700
16th to endNight
6%18%33%36%13%
720
December1st to 15thNight
7%39%37%31%10%
720
16th to endNight
12%215%36%25%7%
768
Page generated at 2017-09-17 09:05:40. Version ac04

Copyright 2017 A. Danko


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