Nocturne Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nocturne Observatory clear sky chart from 2005-11-06 to 2024-03-06.

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
60%
24129
20%
79936
19%
24055
63%
24055
27%
49925

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
50%
742
12%
4045
12%
736
52%
736
11%
2798
January11th to 20thNight
48%
754
9%
4102
14%
740
50%
740
10%
3094
January21st to endNight
44%
826
7%
4515
10%
814
47%
814
8%
3671
February1st to 10thNight
46%
760
10%
2470
10%
760
49%
760
16%
1818
February11th to 20thNight
51%
741
15%
2337
16%
740
54%
740
23%
1554
February21st to endNight
48%
628
18%
1884
16%
628
52%
628
23%
1281
March1st to 10thNight
52%
742
16%
2123
15%
742
55%
742
22%
1489
March11th to 20thNight
60%
720
21%
1980
17%
720
64%
720
31%
1278
March21st to endNight
51%
792
15%
2178
12%
792
54%
792
26%
1490
April1st to 10thNight
52%
705
17%
1960
13%
705
55%
705
27%
1289
April11th to 20thNight
53%
533
23%
1601
18%
533
57%
533
28%
1020
April21st to endNight
61%
540
26%
1620
21%
540
64%
540
35%
963
May1st to 10thNight
60%
540
21%
1620
17%
540
62%
540
31%
987
May11th to 20thNight
64%
531
23%
1595
19%
531
66%
531
34%
936
May21st to endNight
61%
582
15%
1746
15%
582
63%
582
29%
1099
June1st to 10thNight
69%
540
21%
1445
19%
540
72%
540
47%
800
June11th to 20thNight
63%
402
28%
1302
27%
402
70%
402
44%
644
June21st to endNight
79%
360
34%
1304
41%
360
85%
360
54%
535
July1st to 10thNight
76%
350
25%
1400
35%
350
79%
350
43%
613
July11th to 20thNight
75%
492
26%
1536
28%
492
77%
492
50%
752
July21st to endNight
83%
591
29%
1674
28%
558
84%
558
52%
820
August1st to 10thNight
76%
537
29%
1602
25%
534
78%
534
46%
847
August11th to 20thNight
78%
534
35%
1602
28%
534
80%
534
51%
797
August21st to endNight
77%
594
39%
1782
32%
594
79%
594
51%
882
September1st to 10thNight
78%
670
33%
1920
28%
670
81%
670
55%
941
September11th to 20thNight
79%
720
34%
1980
30%
720
81%
720
55%
1005
September21st to endNight
74%
720
36%
1980
28%
720
77%
720
53%
1029
October1st to 10thNight
70%
720
28%
2060
22%
720
73%
720
44%
1124
October11th to 20thNight
68%
720
32%
2160
28%
720
72%
720
42%
1171
October21st to endNight
69%
792
30%
2427
27%
792
73%
792
41%
1318
November1st to 10thNight
64%
740
23%
2405
24%
740
66%
740
31%
1417
November11th to 20thNight
61%
760
22%
2470
21%
760
64%
760
31%
1442
November21st to endNight
60%
921
19%
2631
16%
921
62%
921
30%
1668
December1st to 10thNight
49%
950
12%
2660
9%
950
51%
950
23%
1863
December11th to 20thNight
46%
948
10%
3193
8%
948
47%
948
15%
2396
December21st to endNight
39%
932
7%
4627
9%
927
41%
927
9%
3094

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%8%35%5%3445%7%48%
79204
Night
9%9%36%5%345%5%7%45%
80361
TransparencyDay
35%6%11%20%18%10%
78922
Night
38%6%12%20%15%8%
80164
SeeingDay
11%5%19%32%24%8%
14270
Night
13%212%44%26%3
24184

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
9%17%6%10%8%5%5%44427%
2858
11th to 20thDay
11%18%6%9%6%445%45%29%
2860
21st to endDay
13%17%5%10%8%35%446%24%
3146
February1st to 10thDay
14%14%47%6%335%5%6%34%
1710
11th to 20thDay
12%12%49%6%335%5%7%34%
1726
21st to endDay
7%15%5%8%6%45%5%6%6%33%
1570
March1st to 10thDay
9%11%47%7%25%45%7%39%
1952
11th to 20thDay
8%8%46%6%447%7%9%39%
1980
21st to endDay
12%12%5%7%7%35%45%8%33%
2178
April1st to 10thDay
11%10%36%5%45%5%6%7%40%
1997
11th to 20thDay
10%9%36%5%35%5%5%7%42%
2307
21st to endDay
9%7%35%6%35%45%7%45%
2340
May1st to 10thDay
7%5%35%6%35%6%6%9%44%
2340
11th to 20thDay
8%5%25%435%5%7%10%46%
2301
21st to endDay
8%6%26%5%46%6%7%8%42%
2530
June1st to 10thDay
5%3234246%6%9%57%
2510
11th to 20thDay
5%32443445%8%59%
2651
21st to endDay
1213223446%72%
2649
July1st to 10thDay
221222445%8%68%
2520
11th to 20thDay
331232435%6%68%
2368
21st to endDay
331332345%8%63%
2545
August1st to 10thDay
4223424448%63%
2328
11th to 20thDay
3212322447%69%
2299
21st to endDay
4313323348%66%
2574
September1st to 10thDay
3313323445%70%
2037
11th to 20thDay
5%22322345%6%66%
1980
21st to endDay
8%312223445%68%
1980
October1st to 10thDay
10%5%244345%5%5%53%
1900
11th to 20thDay
8%424433447%58%
1800
21st to endDay
6%6%25%32445%7%56%
1926
November1st to 10thDay
11%9%35%6%44446%44%
1674
11th to 20thDay
12%7%2433345%8%49%
1710
21st to endDay
10%10%45%6%3345%7%43%
1526
December1st to 10thDay
11%12%5%8%7%44446%34%
1520
11th to 20thDay
13%12%5%9%7%46%5%5%7%26%
1926
21st to endDay
8%12%5%9%7%45%5%6%6%32%
2986
January1st to 10thNight
11%15%5%8%6%35%6%5%7%29%
4097
11th to 20thNight
14%17%7%9%6%34446%26%
4110
21st to endNight
16%17%5%12%11%34435%20%
4521
February1st to 10thNight
14%15%47%6%345%5%6%31%
2470
11th to 20thNight
11%11%36%6%345%5%5%40%
2337
21st to endNight
7%13%5%7%6%445%5%7%36%
1884
March1st to 10thNight
12%12%46%6%35%5%6%7%34%
2123
11th to 20thNight
8%8%346%45%6%6%8%43%
1980
21st to endNight
11%10%37%6%345%6%6%39%
2178
April1st to 10thNight
10%9%46%5%345%5%7%43%
1960
11th to 20thNight
9%7%37%6%35%45%5%44%
1601
21st to endNight
10%6%25%43445%6%51%
1620
May1st to 10thNight
8%6%36%5%3445%8%46%
1620
11th to 20thNight
8%425%5%346%6%9%47%
1594
21st to endNight
11%5%25%6%35%6%6%8%43%
1746
June1st to 10thNight
5%225%4245%6%9%57%
1445
11th to 20thNight
6%31432345%7%60%
1302
21st to endNight
321222345%7%70%
1304
July1st to 10thNight
3213435%5%5%8%62%
1440
11th to 20thNight
431442445%6%62%
1588
21st to endNight
22234335%6%8%62%
1773
August1st to 10thNight
43244345%6%8%57%
1611
11th to 20thNight
331343346%7%63%
1602
21st to endNight
332342445%7%64%
1782
September1st to 10thNight
3213423346%68%
1920
11th to 20thNight
5%313313446%67%
1980
21st to endNight
7%41232333468%
1980
October1st to 10thNight
8%42432445%6%58%
2060
11th to 20thNight
8%5%24423335%60%
2160
21st to endNight
7%5%243245%47%57%
2427
November1st to 10thNight
11%7%25%5%34447%49%
2405
11th to 20thNight
10%7%3443445%7%49%
2470
21st to endNight
8%8%35%5%35%5%6%6%46%
2631
December1st to 10thNight
12%11%48%5%34446%38%
2660
11th to 20thNight
13%12%48%7%5%6%6%5%6%27%
3271
21st to endNight
11%12%48%7%46%5%5%7%31%
4709

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
57%11%15%15%2
2859
11th to 20thDay
58%8%17%13%31
2860
21st to endDay
58%13%12%11%5%
3146
February1st to 10thDay
52%7%19%16%5%1
1710
11th to 20thDay
49%7%15%21%7%1
1735
21st to endDay
51%6%15%20%6%1
1570
March1st to 10thDay
45%6%15%25%7%2
1952
11th to 20thDay
39%7%18%24%12%1
1980
21st to endDay
51%5%17%19%8%1
2178
April1st to 10thDay
45%5%13%22%12%3
1997
11th to 20thDay
41%410%25%17%2
2310
21st to endDay
38%411%26%20%2
2340
May1st to 10thDay
36%5%11%24%20%4
2340
11th to 20thDay
32%5%11%28%17%7%
2304
21st to endDay
38%6%11%25%17%3
2530
June1st to 10thDay
23%5%12%25%29%6%
2510
11th to 20thDay
24%5%9%18%26%19%
2651
21st to endDay
13%4414%31%35%
2649
July1st to 10thDay
16%3416%27%35%
2451
11th to 20thDay
17%3412%27%38%
2297
21st to endDay
18%45%12%28%33%
2404
August1st to 10thDay
20%45%17%23%31%
2313
11th to 20thDay
16%3315%34%29%
2299
21st to endDay
18%3415%33%26%
2574
September1st to 10thDay
17%3415%30%30%
2037
11th to 20thDay
20%46%19%30%21%
1980
21st to endDay
19%37%22%38%11%
1980
October1st to 10thDay
33%5%9%25%22%7%
1900
11th to 20thDay
27%413%30%23%4
1800
21st to endDay
29%416%33%17%1
1926
November1st to 10thDay
42%5%14%24%14%1
1674
11th to 20thDay
35%5%20%27%11%1
1710
21st to endDay
41%5%18%25%10%1
1526
December1st to 10thDay
51%8%14%17%8%1
1520
11th to 20thDay
54%10%18%17%2
1924
21st to endDay
48%11%14%20%6%
2986
January1st to 10thNight
51%9%15%21%31
4097
11th to 20thNight
60%8%16%13%31
4110
21st to endNight
57%17%12%9%41
4521
February1st to 10thNight
54%7%15%19%5%
2470
11th to 20thNight
45%6%13%24%11%1
2338
21st to endNight
47%5%13%25%9%1
1884
March1st to 10thNight
49%6%13%25%7%1
2123
11th to 20thNight
39%6%14%25%15%2
1980
21st to endNight
45%5%15%23%10%2
2178
April1st to 10thNight
42%5%13%22%11%7%
1960
11th to 20thNight
41%49%24%20%2
1601
21st to endNight
34%49%28%21%3
1620
May1st to 10thNight
35%6%10%23%22%5%
1620
11th to 20thNight
31%7%8%28%18%8%
1595
21st to endNight
38%7%13%23%18%2
1746
June1st to 10thNight
23%6%13%23%29%8%
1445
11th to 20thNight
23%5%7%20%28%17%
1302
21st to endNight
15%4314%29%36%
1304
July1st to 10thNight
21%45%14%25%31%
1400
11th to 20thNight
21%3313%25%35%
1536
21st to endNight
18%5%5%14%23%35%
1674
August1st to 10thNight
23%5%6%15%20%30%
1602
11th to 20thNight
20%3312%31%30%
1602
21st to endNight
19%5%5%12%29%30%
1782
September1st to 10thNight
19%3414%24%36%
1920
11th to 20thNight
20%37%15%31%24%
1980
21st to endNight
21%35%19%34%18%
1980
October1st to 10thNight
27%310%23%29%8%
2060
11th to 20thNight
28%37%32%25%6%
2160
21st to endNight
27%411%33%21%3
2427
November1st to 10thNight
36%5%13%27%16%3
2405
11th to 20thNight
35%5%16%29%14%1
2470
21st to endNight
39%5%16%29%11%1
2631
December1st to 10thNight
48%6%19%18%8%2
2660
11th to 20thNight
53%9%17%19%2
3272
21st to endNight
50%9%16%18%6%
4709

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
25%315%34%16%7%
270
11th to 20thDay
19%5%16%35%20%5%
270
21st to endDay
18%415%35%21%6%
297
February1st to 10thDay
25%326%30%14%3
270
11th to 20thDay
18%6%26%31%14%5%
331
21st to endDay
12%8%36%29%13%3
382
March1st to 10thDay
18%8%24%35%13%3
441
11th to 20thDay
12%5%28%33%19%3
420
21st to endDay
19%8%28%32%10%2
462
April1st to 10thDay
16%11%25%27%18%3
420
11th to 20thDay
13%15%30%27%13%3
412
21st to endDay
15%9%25%28%17%6%
420
May1st to 10thDay
7%10%26%32%23%3
423
11th to 20thDay
13%7%19%28%24%8%
448
21st to endDay
8%5%20%29%26%12%
485
June1st to 10thDay
5%5%17%31%32%10%
620
11th to 20thDay
9%5%19%36%24%6%
630
21st to endDay
3219%39%30%7%
579
July1st to 10thDay
3318%38%30%9%
446
11th to 20thDay
4218%40%31%6%
444
21st to endDay
5%110%37%38%10%
487
August1st to 10thDay
6%214%38%31%10%
447
11th to 20thDay
4210%31%41%12%
437
21st to endDay
5%312%31%37%12%
495
September1st to 10thDay
36%12%30%33%16%
450
11th to 20thDay
6%220%27%30%14%
450
21st to endDay
9%319%24%34%11%
450
October1st to 10thDay
12%417%25%25%17%
370
11th to 20thDay
9%321%24%24%19%
270
21st to endDay
9%321%36%25%6%
297
November1st to 10thDay
23%215%33%17%11%
270
11th to 20thDay
13%320%32%23%9%
270
21st to endDay
18%310%35%26%8%
270
December1st to 10thDay
17%216%34%23%8%
270
11th to 20thDay
19%5%10%43%21%3
270
21st to endDay
20%317%38%16%6%
297
January1st to 10thNight
21%19%42%22%4
760
11th to 20thNight
21%311%38%21%5%
760
21st to endNight
23%39%38%22%4
836
February1st to 10thNight
20%115%44%18%2
760
11th to 20thNight
18%114%46%18%3
744
21st to endNight
14%417%47%15%3
628
March1st to 10thNight
19%313%48%14%3
742
11th to 20thNight
13%313%50%19%3
720
21st to endNight
18%315%44%19%1
792
April1st to 10thNight
14%417%44%19%1
705
11th to 20thNight
14%318%45%18%2
533
21st to endNight
14%215%42%24%3
540
May1st to 10thNight
11%414%46%22%2
540
11th to 20thNight
11%212%37%34%4
531
21st to endNight
14%412%35%30%4
584
June1st to 10thNight
6%5%12%39%36%2
540
11th to 20thNight
9%218%44%24%3
402
21st to endNight
3113%48%32%4
360
July1st to 10thNight
419%43%40%3
350
11th to 20thNight
5%211%48%34%1
492
21st to endNight
31446%42%4
591
August1st to 10thNight
6%17%48%36%2
537
11th to 20thNight
5%18%47%37%2
534
21st to endNight
5%110%44%37%4
594
September1st to 10thNight
5%18%42%39%5%
670
11th to 20thNight
7%17%41%38%6%
720
21st to endNight
8%211%39%32%9%
720
October1st to 10thNight
9%111%44%30%4
720
11th to 20thNight
12%111%40%32%4
720
21st to endNight
10%212%45%26%4
792
November1st to 10thNight
15%29%44%26%4
740
11th to 20thNight
15%111%50%20%3
760
21st to endNight
12%213%44%24%5%
921
December1st to 10thNight
18%314%44%21%1
950
11th to 20thNight
23%210%44%18%2
950
21st to endNight
23%314%42%16%1
946
Page generated at 2024-03-03 04:28:54. Version ac07

Copyright © 2024 Attilla Danko.


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