Outback Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Outback Observatory clear sky chart from 2005-11-06 to 2024-11-02.

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
30%
25726
16%
95444
8%
25497
39%
25497
18%
62264

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
18%
942
14%
4357
4%
926
29%
926
11%
3012
January11th to 20thNight
18%
948
13%
4370
4%
930
26%
930
9%
3183
January21st to endNight
17%
1035
8%
4841
3%
1023
25%
1023
8%
3630
February1st to 10thNight
20%
950
17%
2480
4%
950
30%
950
19%
1771
February11th to 20thNight
20%
831
20%
2306
5%
827
31%
827
18%
1588
February21st to endNight
19%
628
17%
1884
4%
628
30%
628
17%
1325
March1st to 10thNight
26%
757
24%
3699
8%
745
34%
745
16%
1957
March11th to 20thNight
24%
686
22%
3628
10%
671
37%
671
14%
2135
March21st to endNight
29%
625
12%
3425
13%
605
40%
605
11%
2391
April1st to 10thNight
22%
570
16%
1900
7%
570
35%
570
17%
1328
April11th to 20thNight
28%
563
17%
1875
11%
563
38%
563
19%
1244
April21st to endNight
29%
570
16%
1768
7%
570
39%
570
21%
1215
May1st to 10thNight
27%
566
17%
2567
6%
559
33%
559
14%
1595
May11th to 20thNight
32%
553
16%
2440
8%
541
40%
541
18%
1335
May21st to endNight
42%
609
10%
2714
6%
593
47%
593
18%
1692
June1st to 10thNight
43%
570
13%
1520
5%
570
48%
570
32%
969
June11th to 20thNight
39%
570
12%
1520
5%
570
43%
570
28%
1016
June21st to endNight
47%
570
15%
1520
7%
570
51%
570
35%
939
July1st to 10thNight
56%
542
12%
2409
9%
535
60%
535
25%
1426
July11th to 20thNight
50%
539
16%
2142
8%
533
56%
533
32%
1025
July21st to endNight
51%
606
16%
2441
12%
569
58%
569
28%
1374
August1st to 10thNight
51%
556
20%
2346
13%
544
57%
544
23%
1423
August11th to 20thNight
54%
551
17%
2609
15%
543
63%
543
22%
1471
August21st to endNight
52%
615
15%
3223
19%
605
58%
605
19%
1875
September1st to 10thNight
52%
570
25%
1900
21%
570
61%
570
33%
1053
September11th to 20thNight
48%
622
26%
1952
20%
622
56%
622
35%
1113
September21st to endNight
40%
760
21%
2090
12%
760
46%
760
31%
1300
October1st to 10thNight
37%
760
24%
2228
13%
760
46%
760
29%
1348
October11th to 20thNight
26%
760
18%
2302
7%
760
37%
760
20%
1519
October21st to endNight
26%
836
14%
2717
8%
836
35%
836
17%
1886
November1st to 10thNight
25%
745
22%
2420
10%
745
40%
745
22%
1518
November11th to 20thNight
19%
830
17%
2540
5%
830
30%
830
17%
1750
November21st to endNight
22%
950
17%
2660
6%
950
32%
950
18%
1869
December1st to 10thNight
18%
950
12%
2660
3%
950
26%
950
16%
1915
December11th to 20thNight
17%
950
13%
3199
3%
948
26%
948
12%
2335
December21st to endNight
13%
1041
9%
4792
3%
1026
23%
1026
7%
3739

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%9%38%5%45%45%7%37%
101508
Night
13%10%48%5%4435%7%38%
97549
TransparencyDay
47%412%25%12%1
101302
Night
47%412%24%12%1
97425
SeeingDay
19%14%31%22%10%3
16008
Night
18%12%32%27%10%1
25860

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
11%15%5%12%6%5%5%35%5%27%
2527
11th to 20thDay
9%13%5%12%8%7%9%5%6%7%20%
2530
21st to endDay
13%18%7%14%5%4435%5%22%
2783
February1st to 10thDay
9%12%49%6%46%446%34%
1699
11th to 20thDay
10%12%48%5%5%5%45%7%36%
1761
21st to endDay
11%13%49%6%4445%6%33%
1570
March1st to 10thDay
12%10%37%343346%45%
3120
11th to 20thDay
8%9%411%6%45%46%7%36%
3310
21st to endDay
19%12%412%5%44345%28%
4151
April1st to 10thDay
15%13%38%6%5%445%6%31%
2280
11th to 20thDay
20%10%47%44445%6%32%
2254
21st to endDay
17%11%37%6%5%446%5%31%
2410
May1st to 10thDay
16%7%27%6%4435%7%39%
4305
11th to 20thDay
13%7%36%44435%7%44%
4399
21st to endDay
14%8%37%5%5%5%45%6%37%
4824
June1st to 10thDay
12%6%26%5%5%436%9%42%
2660
11th to 20thDay
14%7%27%5%5%5%37%7%38%
2660
21st to endDay
11%6%27%46%5%47%9%38%
2660
July1st to 10thDay
14%425%5%5%5%47%10%38%
4440
11th to 20thDay
5%325%345%5%7%9%51%
4440
21st to endDay
8%6%26%45%5%46%8%46%
4813
August1st to 10thDay
11%5%27%5%5%6%5%6%8%39%
4423
11th to 20thDay
13%5%15%5%45%46%7%46%
3964
21st to endDay
13%8%38%5%4446%7%39%
4180
September1st to 10thDay
13%7%25%44435%7%45%
2280
11th to 20thDay
13%6%26%435%35%8%45%
2209
21st to endDay
13%7%37%45%5%5%6%8%38%
2090
October1st to 10thDay
16%8%26%43436%9%41%
1948
11th to 20thDay
19%11%37%5%4445%6%31%
1877
21st to endDay
19%11%47%5%4435%5%33%
1881
November1st to 10thDay
14%9%36%45%5%45%8%38%
1681
11th to 20thDay
13%13%6%10%6%45%46%6%28%
1638
21st to endDay
14%12%5%8%5%445%6%6%32%
1520
December1st to 10thDay
12%13%5%10%5%5%446%5%29%
1520
11th to 20thDay
14%15%5%10%6%5%5%47%7%22%
1918
21st to endDay
20%24%5%10%5%3324419%
2783
January1st to 10thNight
12%14%7%11%5%44246%31%
4428
11th to 20thNight
10%13%5%12%8%6%6%46%7%23%
4440
21st to endNight
12%17%8%12%5%5%4345%24%
4884
February1st to 10thNight
8%13%5%9%5%5%445%6%35%
2480
11th to 20thNight
9%11%49%5%5%5%45%6%38%
2305
21st to endNight
14%13%49%6%4435%5%34%
1884
March1st to 10thNight
11%8%36%44425%6%46%
3733
11th to 20thNight
9%10%39%45%5%46%7%38%
3679
21st to endNight
18%11%412%5%44346%30%
3479
April1st to 10thNight
18%12%48%43435%7%32%
1900
11th to 20thNight
21%9%35%5%4445%5%37%
1875
21st to endNight
18%9%28%44446%7%35%
1768
May1st to 10thNight
17%8%38%5%4446%8%35%
2583
11th to 20thNight
12%6%26%5%4445%7%45%
2506
21st to endNight
16%7%37%44436%7%38%
2743
June1st to 10thNight
12%6%16%45%435%7%46%
1520
11th to 20thNight
11%7%28%5%45%5%7%7%39%
1520
21st to endNight
10%5%35%4445%6%9%46%
1520
July1st to 10thNight
14%5%15%44435%8%46%
2530
11th to 20thNight
5%31433346%9%57%
2530
21st to endNight
9%6%36%43335%7%51%
2750
August1st to 10thNight
11%5%37%6%4436%8%44%
2517
11th to 20thNight
12%6%25%34435%8%49%
2867
21st to endNight
12%7%26%44435%5%47%
3476
September1st to 10thNight
9%5%26%33435%7%53%
1900
11th to 20thNight
11%6%26%33435%6%52%
1952
21st to endNight
13%7%26%43336%8%46%
2090
October1st to 10thNight
13%6%2444445%8%47%
2228
11th to 20thNight
14%9%37%5%4446%7%38%
2302
21st to endNight
19%10%47%5%4445%7%32%
2717
November1st to 10thNight
14%10%36%44335%7%41%
2420
11th to 20thNight
13%11%5%9%5%34447%34%
2540
21st to endNight
14%11%38%5%5%5%45%8%33%
2660
December1st to 10thNight
13%13%49%5%45%46%6%32%
2660
11th to 20thNight
11%16%5%10%5%5%5%346%30%
3279
21st to endNight
23%19%6%9%43323423%
4884

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
60%311%20%6%1
2528
11th to 20thDay
63%410%15%7%1
2530
21st to endDay
65%212%16%5%
2783
February1st to 10thDay
50%5%11%20%13%1
1699
11th to 20thDay
48%411%25%11%2
1770
21st to endDay
51%412%21%10%2
1570
March1st to 10thDay
42%211%23%19%3
3120
11th to 20thDay
47%412%24%13%1
3310
21st to endDay
60%39%19%9%1
4151
April1st to 10thDay
53%410%19%13%1
2280
11th to 20thDay
54%38%21%12%2
2254
21st to endDay
54%49%20%12%2
2410
May1st to 10thDay
46%39%27%15%
4344
11th to 20thDay
41%310%32%14%1
4403
21st to endDay
47%49%23%15%1
4837
June1st to 10thDay
40%413%30%12%1
2660
11th to 20thDay
44%413%25%13%1
2660
21st to endDay
40%5%17%26%11%1
2660
July1st to 10thDay
41%416%28%10%1
4371
11th to 20thDay
27%5%15%37%15%2
4365
21st to endDay
35%5%11%30%18%1
4662
August1st to 10thDay
41%5%14%25%13%1
4408
11th to 20thDay
36%6%13%33%12%
4006
21st to endDay
42%6%13%25%13%1
4179
September1st to 10thDay
39%413%29%14%1
2280
11th to 20thDay
39%317%31%9%1
2209
21st to endDay
43%5%13%29%10%
2090
October1st to 10thDay
41%314%31%10%1
1948
11th to 20thDay
53%5%11%21%9%1
1877
21st to endDay
53%413%22%9%
1881
November1st to 10thDay
45%5%12%25%12%1
1681
11th to 20thDay
57%312%19%8%1
1638
21st to endDay
52%415%23%41
1520
December1st to 10thDay
55%410%24%6%
1520
11th to 20thDay
61%314%14%7%1
1915
21st to endDay
70%27%15%7%
2783
January1st to 10thNight
56%39%23%8%1
4428
11th to 20thNight
61%310%20%6%
4440
21st to endNight
64%39%18%6%
4884
February1st to 10thNight
51%39%23%12%2
2480
11th to 20thNight
47%5%10%24%12%2
2306
21st to endNight
53%310%22%9%2
1884
March1st to 10thNight
39%315%27%14%2
3733
11th to 20thNight
45%310%26%15%1
3679
21st to endNight
58%28%21%11%1
3479
April1st to 10thNight
52%47%18%18%1
1900
11th to 20thNight
48%410%21%14%3
1875
21st to endNight
48%5%10%22%15%1
1768
May1st to 10thNight
48%314%19%14%1
2608
11th to 20thNight
39%411%31%14%2
2507
21st to endNight
45%415%18%16%2
2751
June1st to 10thNight
37%414%29%15%1
1520
11th to 20thNight
43%314%22%17%1
1520
21st to endNight
35%416%31%11%3
1520
July1st to 10thNight
37%5%17%24%13%3
2490
11th to 20thNight
23%5%17%37%16%2
2482
21st to endNight
32%412%28%21%2
2662
August1st to 10thNight
39%415%23%17%2
2508
11th to 20thNight
33%6%15%29%15%2
2891
21st to endNight
38%5%14%24%18%1
3476
September1st to 10thNight
31%411%35%17%1
1900
11th to 20thNight
34%314%36%13%
1952
21st to endNight
37%414%32%12%1
2090
October1st to 10thNight
37%312%33%13%1
2228
11th to 20thNight
46%413%26%10%1
2302
21st to endNight
53%412%21%11%
2717
November1st to 10thNight
43%312%26%15%1
2420
11th to 20thNight
51%414%18%13%1
2540
21st to endNight
50%414%24%6%1
2660
December1st to 10thNight
52%414%23%6%
2660
11th to 20thNight
57%312%19%8%1
3281
21st to endNight
67%27%18%6%
4884

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
20%18%33%23%6%1
270
11th to 20thDay
24%20%34%18%31
270
21st to endDay
22%17%40%17%4
297
February1st to 10thDay
15%26%38%15%5%1
270
11th to 20thDay
20%32%32%11%4
270
21st to endDay
22%27%42%8%1
225
March1st to 10thDay
24%23%37%13%3
270
11th to 20thDay
24%20%33%16%6%1
270
21st to endDay
26%17%31%18%7%1
492
April1st to 10thDay
26%18%32%20%4
460
11th to 20thDay
32%16%27%16%7%2
452
21st to endDay
25%15%30%18%9%2
460
May1st to 10thDay
22%17%36%17%6%2
596
11th to 20thDay
21%14%34%21%8%3
675
21st to endDay
17%13%32%22%11%4
734
June1st to 10thDay
13%13%34%26%12%3
680
11th to 20thDay
19%11%31%25%10%3
680
21st to endDay
15%10%31%24%15%4
680
July1st to 10thDay
10%6%27%33%18%6%
671
11th to 20thDay
11%10%29%29%14%7%
668
21st to endDay
8%7%29%32%17%7%
739
August1st to 10thDay
12%6%28%31%18%6%
676
11th to 20thDay
17%6%20%30%20%7%
566
21st to endDay
17%8%25%25%19%6%
539
September1st to 10thDay
17%10%27%24%16%6%
490
11th to 20thDay
15%6%28%31%16%4
490
21st to endDay
18%15%26%23%15%3
490
October1st to 10thDay
22%15%26%24%12%1
348
11th to 20thDay
24%24%31%18%3
300
21st to endDay
30%22%35%11%2
330
November1st to 10thDay
19%16%40%19%41
273
11th to 20thDay
23%21%37%16%31
270
21st to endDay
21%24%37%13%41
270
December1st to 10thDay
21%19%43%10%6%
270
11th to 20thDay
27%23%33%13%41
270
21st to endDay
31%19%34%14%1
297
January1st to 10thNight
17%16%39%24%4
950
11th to 20thNight
21%15%37%20%6%1
950
21st to endNight
18%14%37%25%6%
1045
February1st to 10thNight
14%19%36%24%6%1
950
11th to 20thNight
16%20%35%23%6%
831
21st to endNight
24%13%37%22%4
628
March1st to 10thNight
19%15%35%23%9%1
760
11th to 20thNight
18%15%39%22%6%1
691
21st to endNight
22%10%32%26%9%1
627
April1st to 10thNight
26%12%34%22%5%1
570
11th to 20thNight
29%10%27%27%5%1
563
21st to endNight
23%10%33%26%8%1
570
May1st to 10thNight
22%11%34%26%7%1
570
11th to 20thNight
21%8%32%30%8%1
561
21st to endNight
14%8%31%34%13%1
617
June1st to 10thNight
13%8%28%38%11%
570
11th to 20thNight
16%7%29%39%8%1
570
21st to endNight
13%5%28%38%16%1
570
July1st to 10thNight
10%324%40%21%1
555
11th to 20thNight
10%329%37%20%1
552
21st to endNight
9%328%39%19%3
624
August1st to 10thNight
11%226%38%22%2
567
11th to 20thNight
13%320%35%25%4
564
21st to endNight
15%5%22%36%21%1
627
September1st to 10thNight
12%6%25%33%19%4
570
11th to 20thNight
13%5%29%32%17%4
622
21st to endNight
17%9%27%28%17%1
760
October1st to 10thNight
17%11%30%26%15%1
760
11th to 20thNight
20%16%32%26%6%
760
21st to endNight
26%11%29%23%10%1
836
November1st to 10thNight
21%11%38%21%7%2
745
11th to 20thNight
20%16%38%20%6%
830
21st to endNight
20%19%32%23%5%
950
December1st to 10thNight
21%18%34%20%6%
950
11th to 20thNight
21%17%33%23%5%1
950
21st to endNight
28%15%34%20%3
1045
Page generated at 2024-10-30 00:22:55. Version ac07

Copyright © 2024 Attilla Danko.


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