Waning Moon II Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Waning Moon II Observatory clear sky chart from 2005-11-05 to 2018-11-30.

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
59%
16487
23%
51705
19%
16444
64%
16444
30%
31044

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
42%
780
26%
2328
14%
776
53%
776
30%
1415
January16th to endNight
39%
832
26%
2496
15%
832
48%
832
27%
1576
February1st to 15thNight
41%
764
25%
2292
13%
761
50%
761
29%
1434
February16th to endNight
36%
683
24%
2049
13%
683
44%
683
28%
1298
March1st to 15thNight
42%
692
24%
2252
15%
692
50%
692
26%
1387
March16th to endNight
54%
624
24%
2195
20%
624
61%
624
31%
1208
April1st to 15thNight
50%
584
25%
1947
20%
584
59%
584
29%
1135
April16th to endNight
59%
579
27%
1928
25%
579
66%
579
37%
1008
May1st to 15thNight
68%
584
23%
1949
24%
584
72%
584
35%
1071
May16th to endNight
73%
609
20%
2030
22%
609
75%
609
31%
1166
June1st to 15thNight
80%
585
14%
1788
16%
585
80%
585
33%
1075
June16th to endNight
76%
585
14%
1743
14%
585
76%
585
31%
1098
July1st to 15thNight
82%
555
13%
1680
15%
555
83%
555
30%
1049
July16th to endNight
77%
612
10%
1932
12%
579
77%
579
24%
1260
August1st to 15thNight
85%
575
12%
1906
16%
572
85%
572
29%
1165
August16th to endNight
76%
621
12%
2070
15%
621
77%
621
23%
1341
September1st to 15thNight
71%
585
20%
1950
22%
585
73%
585
26%
1242
September16th to endNight
72%
754
26%
2122
23%
754
73%
754
33%
1318
October1st to 15thNight
73%
780
33%
2229
28%
780
75%
780
45%
1195
October16th to endNight
60%
832
34%
2496
28%
832
66%
832
40%
1369
November1st to 15thNight
60%
820
31%
2487
27%
820
65%
820
35%
1424
November16th to endNight
53%
840
30%
2729
25%
840
62%
840
36%
1480
December1st to 15thNight
49%
780
24%
2535
19%
780
55%
780
26%
1559
December16th to endNight
37%
832
19%
2572
12%
832
43%
832
21%
1771

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
10%5%25%5%35%5%6%8%38%
52539
Night
9%42442446%8%47%
51918
TransparencyDay
38%9%12%17%15%6%
52255
Night
33%7%13%19%17%7%
51707
SeeingDay
12%214%24%29%16%
6749
Night
11%417%30%27%9%
16490

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 15thDay
13%5%25%5%2446%5%43%
1940
16th to endDay
18%5%2442334445%
2080
February1st to 15thDay
14%6%25%42335%6%44%
1900
16th to endDay
15%5%26%5%33447%40%
1710
March1st to 15thDay
16%6%24424446%43%
2047
16th to endDay
10%5%34425%46%8%43%
2377
April1st to 15thDay
12%5%25%5%3446%7%40%
2331
16th to endDay
10%5%145%3446%9%42%
2307
May1st to 15thDay
10%424435%6%6%8%42%
2331
16th to endDay
8%426%6%46%7%8%8%37%
2436
June1st to 15thDay
6%426%8%48%8%8%10%29%
2490
16th to endDay
5%5%36%7%5%8%8%10%11%25%
2527
July1st to 15thDay
7%5%38%8%5%9%8%7%10%25%
2516
16th to endDay
7%6%37%8%5%8%8%9%10%23%
2468
August1st to 15thDay
7%5%37%8%5%9%8%8%12%25%
2295
16th to endDay
10%7%27%8%5%6%8%7%9%25%
2484
September1st to 15thDay
10%6%26%6%37%8%7%9%31%
2340
16th to endDay
8%5%26%5%46%6%7%8%38%
2155
October1st to 15thDay
5%32443345%8%53%
2057
16th to endDay
7%314423337%57%
2080
November1st to 15thDay
10%42432445%7%51%
2028
16th to endDay
8%5%23324347%54%
1886
December1st to 15thDay
15%6%246%24446%43%
1755
16th to endDay
21%7%35%5%34446%33%
1999
January1st to 15thNight
13%5%2432335%7%46%
2328
16th to endNight
18%5%2432444445%
2496
February1st to 15thNight
14%6%24423446%46%
2283
16th to endNight
17%7%3331345%6%43%
2049
March1st to 15thNight
14%424425%45%7%43%
2252
16th to endNight
11%423324447%51%
2195
April1st to 15thNight
11%5%3442345%6%48%
1947
16th to endNight
7%31342336%8%53%
1928
May1st to 15thNight
6%3244245%5%10%50%
1949
16th to endNight
5%2335%345%6%10%49%
2029
June1st to 15thNight
4414445%6%9%12%42%
1788
16th to endNight
5%335%5%445%7%11%43%
1743
July1st to 15thNight
3324426%7%7%13%43%
1771
16th to endNight
4325%7%37%5%9%14%35%
2052
August1st to 15thNight
2314436%8%10%12%41%
1918
16th to endNight
7%325%5%35%5%9%13%37%
2070
September1st to 15thNight
7%5%15%5%36%5%7%10%40%
1950
16th to endNight
6%5%25%44447%8%47%
2122
October1st to 15thNight
4413224347%61%
2229
16th to endNight
9%313323345%58%
2496
November1st to 15thNight
10%5%24423346%53%
2487
16th to endNight
8%4145%24345%55%
2729
December1st to 15thNight
13%5%25%424446%45%
2535
16th to endNight
19%8%345%2445%6%35%
2572

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
41%5%8%15%20%9%
1941
16th to endDay
42%46%16%21%10%
2080
February1st to 15thDay
39%5%9%15%20%9%
1902
16th to endDay
41%5%10%17%18%7%
1710
March1st to 15thDay
39%6%8%19%19%6%
2047
16th to endDay
37%6%11%18%21%5%
2379
April1st to 15thDay
37%7%9%18%18%8%
2331
16th to endDay
34%8%11%22%18%4
2307
May1st to 15thDay
34%8%11%21%16%7%
2331
16th to endDay
35%11%13%22%15%1
2440
June1st to 15thDay
40%13%13%20%10%1
2490
16th to endDay
42%14%17%18%7%
2527
July1st to 15thDay
44%15%18%15%4
2378
16th to endDay
46%14%19%16%2
2325
August1st to 15thDay
43%16%19%15%4
2283
16th to endDay
47%14%15%13%6%1
2484
September1st to 15thDay
41%13%16%15%9%4
2340
16th to endDay
36%9%13%17%16%5%
2155
October1st to 15thDay
25%7%11%19%21%13%
2057
16th to endDay
26%47%16%27%17%
2080
November1st to 15thDay
31%5%8%19%27%7%
2028
16th to endDay
29%48%18%24%15%
1886
December1st to 15thDay
40%5%9%19%17%7%
1755
16th to endDay
50%5%8%16%14%4
1999
January1st to 15thNight
37%48%16%21%11%
2328
16th to endNight
41%27%13%22%11%
2496
February1st to 15thNight
38%48%18%19%10%
2292
16th to endNight
39%5%8%17%18%11%
2049
March1st to 15thNight
38%6%9%16%21%8%
2252
16th to endNight
31%5%13%19%22%6%
2195
April1st to 15thNight
34%5%10%21%16%10%
1947
16th to endNight
26%5%13%24%22%8%
1928
May1st to 15thNight
28%6%12%25%20%5%
1950
16th to endNight
28%10%16%26%16%1
2031
June1st to 15thNight
29%10%21%26%11%
1788
16th to endNight
31%11%22%23%9%
1743
July1st to 15thNight
28%15%29%22%4
1680
16th to endNight
33%15%26%20%3
1932
August1st to 15thNight
25%17%30%20%5%
1906
16th to endNight
34%15%25%15%6%2
2070
September1st to 15thNight
35%11%18%16%11%5%
1950
16th to endNight
33%8%15%20%16%6%
2122
October1st to 15thNight
22%6%11%23%20%15%
2229
16th to endNight
28%36%15%26%19%
2496
November1st to 15thNight
33%39%18%25%10%
2487
16th to endNight
29%47%18%23%17%
2729
December1st to 15thNight
38%5%9%20%17%7%
2535
16th to endNight
48%48%17%14%6%
2572

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
17%7%37%25%9%2
135
16th to endDay
20%13%38%23%3
144
February1st to 15thDay
17%11%32%30%6%
135
16th to endDay
10%6%45%30%7%
120
March1st to 15thDay
18%5%45%29%
135
16th to endDay
13%7%30%28%20%
235
April1st to 15thDay
15%6%26%32%18%1
330
16th to endDay
11%321%35%23%3
319
May1st to 15thDay
9%318%33%28%6%
348
16th to endDay
9%212%27%30%18%
395
June1st to 15thDay
12%5%22%33%25%
375
16th to endDay
8%5%20%38%25%
537
July1st to 15thDay
6%316%40%32%
532
16th to endDay
9%311%40%34%
390
August1st to 15thDay
10%311%37%36%
358
16th to endDay
9%15%13%37%33%
396
September1st to 15thDay
11%6%22%35%22%
375
16th to endDay
11%6%21%41%18%
374
October1st to 15thDay
5%110%33%35%13%
287
16th to endDay
12%314%38%25%5%
192
November1st to 15thDay
22%220%32%18%3
180
16th to endDay
9%5%29%34%16%4
178
December1st to 15thDay
26%328%25%14%1
135
16th to endDay
30%7%28%25%8%
144
January1st to 15thNight
16%7%29%37%8%
780
16th to endNight
21%8%27%33%9%
832
February1st to 15thNight
17%7%29%33%10%
764
16th to endNight
19%7%32%32%7%
683
March1st to 15thNight
16%6%29%35%11%
692
16th to endNight
12%423%37%20%1
624
April1st to 15thNight
12%5%24%35%20%1
584
16th to endNight
9%322%40%22%2
579
May1st to 15thNight
7%115%44%29%2
585
16th to endNight
6%19%32%39%10%
611
June1st to 15thNight
5%424%51%12%
585
16th to endNight
5%1419%46%22%
585
July1st to 15thNight
4210%49%33%
555
16th to endNight
4211%49%31%
612
August1st to 15thNight
419%47%36%
575
16th to endNight
9%214%43%30%
621
September1st to 15thNight
9%1416%41%26%
585
16th to endNight
9%1429%46%9%
754
October1st to 15thNight
6%112%33%37%8%
780
16th to endNight
11%418%31%28%5%
832
November1st to 15thNight
12%417%38%22%4
820
16th to endNight
10%5%23%37%21%1
840
December1st to 15thNight
16%6%23%33%18%1
780
16th to endNight
23%6%26%31%11%
832
Page generated at 2018-12-01 10:35:38. Version ac04

Copyright 2018 A. Danko


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