Cargeena 2 Astronomy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cargeena 2 Astronomy clear sky chart from 2005-11-06 to 2024-01-15.

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
61%
24656
20%
74519
17%
24606
65%
24606
29%
47075

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
51%
758
22%
2459
18%
757
60%
757
31%
1430
January11th to 20thNight
49%
737
25%
2393
19%
737
60%
737
31%
1392
January21st to endNight
46%
792
24%
2491
18%
792
55%
792
28%
1519
February1st to 10thNight
49%
720
23%
2160
17%
720
55%
720
30%
1347
February11th to 20thNight
52%
700
27%
2098
19%
699
62%
699
39%
1156
February21st to endNight
55%
592
31%
1642
22%
592
63%
592
42%
922
March1st to 10thNight
57%
720
32%
1980
21%
720
66%
720
47%
1058
March11th to 20thNight
57%
720
30%
1980
20%
720
65%
720
42%
1122
March21st to endNight
59%
792
30%
2178
22%
792
65%
792
45%
1198
April1st to 10thNight
60%
720
24%
1980
19%
720
65%
720
45%
1080
April11th to 20thNight
58%
711
21%
1924
16%
711
63%
711
39%
1134
April21st to endNight
60%
720
30%
1800
18%
720
65%
720
45%
1063
May1st to 10thNight
69%
673
28%
1753
20%
673
72%
673
49%
976
May11th to 20thNight
70%
531
15%
1592
12%
531
72%
531
32%
999
May21st to endNight
74%
582
21%
1744
18%
582
75%
582
32%
1109
June1st to 10thNight
68%
540
13%
1620
12%
540
68%
540
21%
1163
June11th to 20thNight
71%
540
10%
1620
9%
540
71%
540
24%
1156
June21st to endNight
72%
540
8%
1620
8%
540
72%
540
21%
1180
July1st to 10thNight
70%
525
5%
1575
4%
525
70%
525
20%
1187
July11th to 20thNight
78%
522
5%
1566
6%
522
78%
522
20%
1174
July21st to endNight
72%
591
7%
1672
7%
558
72%
558
20%
1258
August1st to 10thNight
75%
537
5%
1600
4%
534
75%
534
22%
1148
August11th to 20thNight
72%
602
5%
1734
5%
602
72%
602
21%
1248
August21st to endNight
59%
792
6%
2178
6%
792
59%
792
17%
1673
September1st to 10thNight
64%
720
5%
1980
5%
720
65%
720
17%
1510
September11th to 20thNight
58%
720
7%
1980
7%
720
58%
720
18%
1473
September21st to endNight
59%
720
14%
1980
13%
720
60%
720
20%
1432
October1st to 10thNight
62%
720
21%
2002
20%
720
64%
720
27%
1326
October11th to 20thNight
66%
720
26%
2160
27%
720
69%
720
32%
1311
October21st to endNight
63%
792
27%
2376
26%
792
67%
792
35%
1379
November1st to 10thNight
58%
740
25%
2221
21%
740
65%
740
34%
1290
November11th to 20thNight
58%
760
29%
2280
26%
760
64%
760
33%
1366
November21st to endNight
56%
760
29%
2308
24%
760
63%
760
33%
1368
December1st to 10thNight
60%
760
28%
2470
25%
760
68%
760
34%
1397
December11th to 20thNight
57%
758
24%
2938
23%
758
62%
758
25%
1696
December21st to endNight
55%
829
15%
4465
22%
817
61%
817
16%
2835

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
8%5%37%7%5%6%6%7%9%37%
74875
Night
8%5%36%6%35%5%6%9%43%
74899
TransparencyDay
41%8%15%18%13%5%
74598
Night
35%9%16%20%14%5%
74695
SeeingDay
8%313%24%26%25%
14536
Night
9%315%34%29%10%
24672

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
8%6%26%5%45%48%9%43%
1706
11th to 20thDay
7%425%435%5%7%11%46%
1656
21st to endDay
12%436%6%45%5%6%7%44%
1861
February1st to 10thDay
11%5%35%5%445%5%8%45%
1800
11th to 20thDay
5%325%5%35%5%6%7%54%
1748
21st to endDay
7%5%25%6%35%45%7%49%
1612
March1st to 10thDay
4324445%5%6%8%56%
1980
11th to 20thDay
6%3246%35%5%6%9%51%
1980
21st to endDay
6%3245%45%5%6%7%53%
2178
April1st to 10thDay
5%415%6%45%6%7%9%48%
1980
11th to 20thDay
7%5%26%7%5%7%6%7%8%41%
1982
21st to endDay
5%4245%37%6%7%10%48%
2160
May1st to 10thDay
5%3245%45%5%5%9%53%
2219
11th to 20thDay
8%6%36%7%47%6%8%10%37%
2301
21st to endDay
7%6%37%8%5%7%6%7%9%33%
2531
June1st to 10thDay
12%10%49%9%5%8%7%7%8%21%
2340
11th to 20thDay
7%7%39%8%6%9%8%8%9%25%
2340
21st to endDay
8%7%48%9%6%8%8%7%10%24%
2340
July1st to 10thDay
9%7%48%9%6%9%8%8%10%23%
2340
11th to 20thDay
6%6%410%9%7%8%7%8%11%24%
2340
21st to endDay
8%6%39%9%6%9%9%8%10%22%
2547
August1st to 10thDay
6%5%29%9%6%9%9%9%12%24%
2327
11th to 20thDay
5%6%38%9%5%9%9%9%11%25%
2140
21st to endDay
11%7%38%9%5%8%8%8%10%21%
2178
September1st to 10thDay
7%6%49%9%5%9%7%7%11%25%
1980
11th to 20thDay
9%7%410%9%6%7%8%8%10%22%
1980
21st to endDay
9%7%38%8%5%6%8%8%10%27%
1980
October1st to 10thDay
10%6%27%7%46%7%7%9%36%
1958
11th to 20thDay
6%5%37%6%5%5%6%6%9%42%
1800
21st to endDay
8%425%6%45%6%5%10%45%
1980
November1st to 10thDay
7%5%36%5%45%5%6%9%46%
1857
11th to 20thDay
9%5%37%6%45%6%6%8%42%
1900
21st to endDay
8%5%36%5%35%5%6%9%44%
1867
December1st to 10thDay
7%435%6%45%5%6%8%47%
1710
11th to 20thDay
10%6%36%6%36%45%8%44%
2153
21st to endDay
10%7%38%8%46%6%6%7%35%
3124
January1st to 10thNight
9%5%25%5%4447%9%45%
2459
11th to 20thNight
9%5%25%6%25%46%10%46%
2393
21st to endNight
11%5%35%436%5%6%7%44%
2491
February1st to 10thNight
9%7%36%5%35%5%5%8%44%
2160
11th to 20thNight
8%42442345%8%54%
2098
21st to endNight
6%425%5%2446%9%54%
1642
March1st to 10thNight
3324435%36%8%59%
1980
11th to 20thNight
6%424425%45%8%57%
1980
21st to endNight
44244245%6%8%57%
2178
April1st to 10thNight
4325%33445%9%57%
1980
11th to 20thNight
5%425%5%35%6%6%10%49%
1924
21st to endNight
5%424425%45%8%57%
1800
May1st to 10thNight
43245%34348%61%
1753
11th to 20thNight
7%425%6%46%6%6%9%47%
1592
21st to endNight
6%5%36%6%46%6%6%10%43%
1744
June1st to 10thNight
10%7%38%6%46%7%7%11%32%
1620
11th to 20thNight
7%5%37%7%5%7%7%8%13%30%
1620
21st to endNight
6%6%28%9%47%7%8%11%33%
1620
July1st to 10thNight
9%8%37%8%46%7%8%13%28%
1620
11th to 20thNight
6%5%36%8%5%8%9%7%11%31%
1620
21st to endNight
6%6%38%8%49%7%8%12%28%
1771
August1st to 10thNight
5%5%36%7%5%7%7%9%12%33%
1611
11th to 20thNight
6%5%37%7%5%6%8%9%13%32%
1734
21st to endNight
9%8%38%8%5%6%7%8%10%29%
2178
September1st to 10thNight
6%6%47%8%5%8%9%8%11%28%
1980
11th to 20thNight
8%7%49%9%5%6%6%7%10%29%
1980
21st to endNight
11%7%37%7%5%6%6%6%9%32%
1980
October1st to 10thNight
10%6%26%6%45%5%7%9%39%
2002
11th to 20thNight
7%7%25%6%3436%7%48%
2160
21st to endNight
9%5%25%5%235%5%10%49%
2376
November1st to 10thNight
9%4346%3445%8%50%
2221
11th to 20thNight
7%5%26%6%445%5%7%48%
2280
21st to endNight
9%5%35%4345%6%10%45%
2308
December1st to 10thNight
7%425%435%6%5%8%50%
2470
11th to 20thNight
12%6%25%43445%7%48%
3042
21st to endNight
11%7%37%7%46%6%6%7%36%
4532

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
36%5%9%22%20%8%
1707
11th to 20thDay
31%5%10%25%22%7%
1656
21st to endDay
39%47%20%20%9%
1861
February1st to 10thDay
36%5%10%20%20%9%
1800
11th to 20thDay
27%5%9%24%22%12%
1758
21st to endDay
34%5%10%17%26%9%
1612
March1st to 10thDay
25%6%10%26%25%9%
1980
11th to 20thDay
28%6%11%27%19%8%
1980
21st to endDay
29%5%9%25%23%9%
2178
April1st to 10thDay
30%7%16%24%18%6%
1980
11th to 20thDay
38%8%12%18%19%5%
1982
21st to endDay
29%7%10%22%24%8%
2160
May1st to 10thDay
27%5%13%21%25%9%
2219
11th to 20thDay
39%9%15%19%16%1
2305
21st to endDay
45%9%12%20%14%1
2531
June1st to 10thDay
58%9%17%13%4
2340
11th to 20thDay
50%10%21%16%2
2340
21st to endDay
52%11%22%12%21
2340
July1st to 10thDay
54%13%25%7%2
2275
11th to 20thDay
52%12%25%10%1
2271
21st to endDay
50%13%24%11%1
2405
August1st to 10thDay
45%15%31%8%1
2314
11th to 20thDay
46%15%28%10%1
2140
21st to endDay
54%14%21%9%2
2178
September1st to 10thDay
49%14%22%13%1
1980
11th to 20thDay
53%13%19%11%3
1980
21st to endDay
49%13%16%13%8%1
1980
October1st to 10thDay
42%8%14%19%12%6%
1958
11th to 20thDay
38%7%10%22%20%4
1800
21st to endDay
33%6%11%20%20%10%
1980
November1st to 10thDay
35%413%19%18%12%
1857
11th to 20thDay
38%6%9%21%18%7%
1900
21st to endDay
35%6%11%21%20%6%
1867
December1st to 10thDay
34%6%14%24%17%5%
1710
11th to 20thDay
37%6%9%20%16%11%
2150
21st to endDay
45%6%11%18%15%4
3124
January1st to 10thNight
34%5%12%22%19%7%
2459
11th to 20thNight
34%5%9%28%17%6%
2393
21st to endNight
37%5%10%22%17%8%
2491
February1st to 10thNight
37%6%11%19%18%9%
2160
11th to 20thNight
28%5%9%24%24%10%
2099
21st to endNight
27%5%13%21%28%6%
1642
March1st to 10thNight
22%5%12%30%24%8%
1980
11th to 20thNight
26%6%12%31%18%7%
1980
21st to endNight
23%6%13%27%23%8%
2178
April1st to 10thNight
24%5%19%29%16%7%
1980
11th to 20thNight
27%8%17%23%21%5%
1924
21st to endNight
26%6%11%27%24%6%
1800
May1st to 10thNight
22%6%12%28%23%9%
1753
11th to 20thNight
33%9%21%23%13%1
1593
21st to endNight
33%10%16%22%18%1
1745
June1st to 10thNight
45%12%21%18%5%
1620
11th to 20thNight
42%12%25%17%3
1620
21st to endNight
42%15%25%13%5%
1620
July1st to 10thNight
45%14%28%11%1
1575
11th to 20thNight
43%16%29%11%1
1566
21st to endNight
44%16%28%12%
1672
August1st to 10thNight
39%16%34%11%
1600
11th to 20thNight
38%18%34%8%1
1734
21st to endNight
48%16%25%10%1
2178
September1st to 10thNight
44%19%24%11%2
1980
11th to 20thNight
47%13%22%15%2
1980
21st to endNight
46%11%17%16%9%1
1980
October1st to 10thNight
39%9%15%19%13%5%
2002
11th to 20thNight
34%7%12%21%22%4
2160
21st to endNight
31%6%13%19%21%10%
2376
November1st to 10thNight
33%5%12%20%21%9%
2221
11th to 20thNight
33%7%10%26%16%8%
2280
21st to endNight
33%6%10%23%22%6%
2308
December1st to 10thNight
31%6%12%30%16%6%
2470
11th to 20thNight
35%6%9%21%16%12%
3044
21st to endNight
44%8%12%17%14%5%
4532

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
9%6%37%30%14%3
270
11th to 20thDay
6%7%33%34%14%6%
252
21st to endDay
15%8%38%27%13%
264
February1st to 10thDay
9%7%26%34%20%5%
240
11th to 20thDay
5%428%33%22%8%
240
21st to endDay
8%422%35%24%7%
330
March1st to 10thDay
5%428%38%23%3
420
11th to 20thDay
8%426%29%27%6%
420
21st to endDay
5%422%32%29%7%
462
April1st to 10thDay
5%425%36%24%5%
420
11th to 20thDay
7%5%19%38%23%8%
412
21st to endDay
5%215%35%28%14%
420
May1st to 10thDay
5%213%26%37%16%
423
11th to 20thDay
9%212%25%30%23%
447
21st to endDay
10%26%18%32%32%
485
June1st to 10thDay
15%38%15%28%31%
450
11th to 20thDay
9%1212%29%46%
450
21st to endDay
7%2210%24%57%
450
July1st to 10thDay
9%17%20%62%
445
11th to 20thDay
5%28%24%60%
444
21st to endDay
7%1113%22%56%
488
August1st to 10thDay
6%229%26%56%
446
11th to 20thDay
5%17%28%60%
439
21st to endDay
11%3215%25%44%
495
September1st to 10thDay
8%3312%24%51%
450
11th to 20thDay
10%2315%27%42%
450
21st to endDay
11%1215%35%36%
450
October1st to 10thDay
12%18%31%32%15%
450
11th to 20thDay
7%12%33%34%14%
450
21st to endDay
8%214%30%35%11%
495
November1st to 10thDay
9%418%28%31%10%
455
11th to 20thDay
14%220%36%24%5%
460
21st to endDay
11%219%37%26%5%
427
December1st to 10thDay
6%5%26%33%19%11%
270
11th to 20thDay
9%6%24%35%21%5%
270
21st to endDay
9%325%36%20%6%
297
January1st to 10thNight
11%5%24%41%18%
760
11th to 20thNight
10%5%28%42%15%1
737
21st to endNight
14%6%28%41%12%1
792
February1st to 10thNight
12%5%25%42%15%1
720
11th to 20thNight
11%426%43%16%1
703
21st to endNight
8%325%48%15%1
592
March1st to 10thNight
45%29%46%15%1
720
11th to 20thNight
8%424%44%20%1
720
21st to endNight
6%226%47%18%1
792
April1st to 10thNight
4324%49%19%
720
11th to 20thNight
6%325%46%18%2
711
21st to endNight
7%224%44%23%
720
May1st to 10thNight
5%116%49%26%2
673
11th to 20thNight
8%9%44%34%5%
531
21st to endNight
8%15%33%46%7%
584
June1st to 10thNight
12%1327%47%10%
540
11th to 20thNight
7%2216%48%25%
540
21st to endNight
7%1113%47%31%
540
July1st to 10thNight
10%216%47%35%
525
11th to 20thNight
5%28%45%40%
522
21st to endNight
8%27%46%37%
591
August1st to 10thNight
6%218%46%37%
537
11th to 20thNight
7%118%45%38%
602
21st to endNight
11%3418%37%27%
792
September1st to 10thNight
9%2315%41%30%
720
11th to 20thNight
11%2319%45%20%
720
21st to endNight
14%3422%42%16%
720
October1st to 10thNight
14%29%37%32%7%
720
11th to 20thNight
11%29%37%36%5%
720
21st to endNight
12%115%39%30%3
792
November1st to 10thNight
10%220%40%26%3
740
11th to 20thNight
10%219%43%24%2
760
21st to endNight
12%221%46%19%1
760
December1st to 10thNight
9%320%40%27%2
760
11th to 20thNight
10%419%40%25%2
760
21st to endNight
10%323%40%23%1
836
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