USAO JMOERC Habitat Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the USAO JMOERC Habitat Area clear sky chart from 2005-11-06 to 2024-11-11.

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
45%
25080
28%
94831
18%
24803
57%
24803
33%
47595

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
35%
943
30%
4004
12%
926
49%
926
27%
2210
January11th to 20thNight
37%
948
32%
3963
12%
930
48%
930
32%
1698
January21st to endNight
36%
1039
23%
4458
13%
1023
50%
1023
26%
2512
February1st to 10thNight
29%
834
28%
2354
11%
834
41%
834
33%
1396
February11th to 20thNight
29%
743
26%
2218
11%
740
42%
740
33%
1254
February21st to endNight
25%
628
30%
1884
10%
628
40%
628
31%
1064
March1st to 10thNight
33%
629
36%
3463
14%
621
49%
621
22%
1556
March11th to 20thNight
30%
566
34%
3390
16%
550
47%
550
23%
1336
March21st to endNight
27%
623
17%
3662
13%
605
43%
605
19%
1830
April1st to 10thNight
26%
570
28%
2090
14%
570
49%
570
32%
1026
April11th to 20thNight
26%
563
26%
1877
13%
563
44%
563
32%
1003
April21st to endNight
33%
570
28%
1710
14%
570
51%
570
35%
967
May1st to 10thNight
30%
568
29%
2812
14%
559
50%
559
21%
1568
May11th to 20thNight
42%
550
17%
2756
18%
541
51%
541
23%
1442
May21st to endNight
47%
608
17%
3073
18%
593
61%
593
27%
1456
June1st to 10thNight
60%
570
26%
1710
22%
570
67%
570
48%
864
June11th to 20thNight
55%
570
24%
1710
21%
570
61%
570
47%
867
June21st to endNight
64%
570
29%
1710
25%
570
72%
570
55%
820
July1st to 10thNight
71%
544
25%
2572
22%
535
75%
535
29%
1256
July11th to 20thNight
80%
540
27%
2347
32%
533
85%
533
48%
922
July21st to endNight
82%
608
27%
2686
36%
569
86%
569
44%
1031
August1st to 10thNight
76%
551
40%
2447
33%
544
82%
544
44%
930
August11th to 20thNight
69%
550
26%
2383
31%
543
75%
543
32%
1139
August21st to endNight
82%
609
24%
2996
34%
605
84%
605
40%
1158
September1st to 10thNight
71%
570
28%
2090
33%
570
74%
570
39%
1022
September11th to 20thNight
57%
570
28%
2090
26%
570
64%
570
32%
1110
September21st to endNight
64%
570
37%
2090
34%
570
73%
570
44%
956
October1st to 10thNight
57%
570
34%
2119
30%
550
67%
550
37%
1031
October11th to 20thNight
46%
745
32%
2426
18%
725
58%
725
39%
1276
October21st to endNight
41%
836
31%
2685
17%
814
53%
814
36%
1461
November1st to 10thNight
45%
885
34%
2445
15%
885
57%
885
49%
1268
November11th to 20thNight
44%
953
32%
2477
14%
953
54%
953
47%
1335
November21st to endNight
37%
950
31%
2470
13%
950
48%
950
39%
1442
December1st to 10thNight
40%
950
34%
2470
14%
950
53%
950
43%
1382
December11th to 20thNight
33%
949
33%
2857
12%
948
46%
948
32%
1646
December21st to endNight
34%
1038
21%
4337
13%
1026
48%
1026
25%
2361

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
9%5%25%33435%7%54%
101207
Night
9%5%2433335%7%58%
98074
TransparencyDay
30%39%26%25%7%
104976
Night
27%39%25%27%9%
102432
SeeingDay
12%8%26%31%19%5%
15359
Night
11%8%31%35%14%1
25229

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%7%27%44335%6%51%
2847
11th to 20thDay
7%6%13223345%64%
2850
21st to endDay
16%9%45%32223449%
3135
February1st to 10thDay
10%9%26%333245%52%
1843
11th to 20thDay
11%6%25%33425%5%54%
1849
21st to endDay
12%8%35%333335%52%
1570
March1st to 10thDay
12%6%24223236%58%
3336
11th to 20thDay
10%6%35%33435%6%54%
3480
21st to endDay
12%10%37%44435%7%42%
3814
April1st to 10thDay
9%5%2443335%7%55%
2090
11th to 20thDay
12%5%26%33335%6%51%
2247
21st to endDay
13%5%2443335%6%50%
2470
May1st to 10thDay
17%8%26%433346%43%
4082
11th to 20thDay
11%6%26%44445%7%49%
4082
21st to endDay
12%7%26%5%4436%6%44%
4477
June1st to 10thDay
6%5%25%445%47%9%50%
2470
11th to 20thDay
6%41433446%8%56%
2470
21st to endDay
5%31434435%8%61%
2470
July1st to 10thDay
7%415%5%45%5%7%9%48%
4120
11th to 20thDay
431434447%9%57%
4120
21st to endDay
331334446%9%58%
4465
August1st to 10thDay
4324445%45%9%58%
4104
11th to 20thDay
432434436%10%57%
4041
21st to endDay
331333446%9%63%
4155
September1st to 10thDay
9%415%34435%6%58%
2090
11th to 20thDay
11%425%45%4347%50%
2090
21st to endDay
7%42433325%6%60%
2090
October1st to 10thDay
8%324433346%61%
2085
11th to 20thDay
10%31332223468%
1900
21st to endDay
12%5%1323223462%
2090
November1st to 10thDay
9%5%13234246%61%
1849
11th to 20thDay
7%413222245%67%
1710
21st to endDay
12%423323345%60%
1710
December1st to 10thDay
9%425%444336%56%
1710
11th to 20thDay
12%6%25%344445%51%
2161
21st to endDay
12%7%36%45%435%6%44%
3135
January1st to 10thNight
12%7%25%333345%52%
4108
11th to 20thNight
5%42433335%6%63%
4120
21st to endNight
16%9%24223245%52%
4532
February1st to 10thNight
12%8%35%33224454%
2354
11th to 20thNight
10%7%25%332347%54%
2218
21st to endNight
10%6%35%33335%6%54%
1884
March1st to 10thNight
8%6%25%334246%57%
3520
11th to 20thNight
9%414223246%62%
3480
21st to endNight
9%6%26%44446%7%49%
3817
April1st to 10thNight
9%5%1433235%6%60%
2090
11th to 20thNight
12%423434347%54%
1877
21st to endNight
13%32433435%6%55%
1710
May1st to 10thNight
16%7%25%433245%49%
2823
11th to 20thNight
12%5%25%34435%7%49%
2823
21st to endNight
9%5%1433435%7%55%
3090
June1st to 10thNight
5%21333436%9%59%
1710
11th to 20thNight
5%31433445%9%59%
1710
21st to endNight
331322335%10%65%
1710
July1st to 10thNight
6%415%43447%9%53%
2850
11th to 20thNight
121322336%11%65%
2850
21st to endNight
421322336%8%66%
3098
August1st to 10thNight
111333436%10%65%
2836
11th to 20thNight
4314435%47%9%56%
2798
21st to endNight
321323335%11%65%
3503
September1st to 10thNight
6%414334346%61%
2090
11th to 20thNight
11%5%25%424346%53%
2090
21st to endNight
7%42322325%6%63%
2090
October1st to 10thNight
7%213333346%63%
2090
11th to 20thNight
8%423222235%65%
2265
21st to endNight
11%5%22222235%64%
2508
November1st to 10thNight
8%313232245%66%
2445
11th to 20thNight
5%424333235%65%
2477
21st to endNight
11%5%24333345%57%
2470
December1st to 10thNight
9%41323335%6%60%
2470
11th to 20thNight
10%6%27%333346%55%
3036
21st to endNight
13%6%2433335%5%52%
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%27%25%26%5%
2848
11th to 20thDay
25%112%24%33%5%
2850
21st to endDay
41%15%24%24%5%
3135
February1st to 10thDay
37%37%24%25%5%
1843
11th to 20thDay
33%26%28%24%7%
1859
21st to endDay
38%1418%28%10%
1570
March1st to 10thDay
31%26%18%26%17%
3336
11th to 20thDay
34%210%25%25%5%
3480
21st to endDay
44%28%24%17%5%
3814
April1st to 10thDay
30%311%26%21%10%
2090
11th to 20thDay
35%38%23%22%9%
2247
21st to endDay
35%39%27%22%4
2470
May1st to 10thDay
44%29%19%18%7%
4120
11th to 20thDay
36%313%28%17%3
4086
21st to endDay
41%211%21%17%7%
4489
June1st to 10thDay
30%418%28%16%4
2470
11th to 20thDay
25%412%29%25%5%
2470
21st to endDay
22%5%13%28%25%7%
2470
July1st to 10thDay
31%5%12%30%18%4
4056
11th to 20thDay
22%48%34%27%4
4051
21st to endDay
21%5%13%32%27%2
4325
August1st to 10thDay
22%410%25%28%11%
4090
11th to 20thDay
24%413%32%22%5%
4080
21st to endDay
19%5%12%40%21%4
4154
September1st to 10thDay
27%48%23%26%12%
2090
11th to 20thDay
35%48%22%24%7%
2090
21st to endDay
25%37%26%31%8%
2090
October1st to 10thDay
17%16%14%41%20%
3462
11th to 20thDay
18%26%23%33%17%
3140
21st to endDay
21%26%30%32%8%
3428
November1st to 10thDay
26%27%24%30%11%
1849
11th to 20thDay
21%26%28%31%10%
1710
21st to endDay
29%25%26%27%11%
1710
December1st to 10thDay
31%210%26%26%5%
1710
11th to 20thDay
37%17%19%29%7%
2159
21st to endDay
41%26%23%24%4
3135
January1st to 10thNight
36%25%24%28%6%
4108
11th to 20thNight
23%214%22%30%7%
4120
21st to endNight
38%17%20%27%7%
4532
February1st to 10thNight
36%27%22%25%8%
2354
11th to 20thNight
32%37%24%24%10%
2218
21st to endNight
33%25%20%25%15%
1884
March1st to 10thNight
30%35%19%23%21%
3520
11th to 20thNight
26%26%32%26%8%
3480
21st to endNight
35%39%27%22%4
3817
April1st to 10thNight
27%39%23%24%14%
2090
11th to 20thNight
30%410%24%20%13%
1877
21st to endNight
31%411%27%23%5%
1710
May1st to 10thNight
40%39%18%23%7%
2850
11th to 20thNight
35%413%28%18%3
2824
21st to endNight
30%412%23%20%11%
3099
June1st to 10thNight
21%417%35%18%5%
1710
11th to 20thNight
22%414%28%24%7%
1710
21st to endNight
17%411%29%29%9%
1710
July1st to 10thNight
27%412%34%19%3
2805
11th to 20thNight
14%310%41%29%4
2796
21st to endNight
16%314%34%31%2
2999
August1st to 10thNight
15%311%26%36%9%
2826
11th to 20thNight
23%410%34%25%4
2825
21st to endNight
16%414%39%22%5%
3503
September1st to 10thNight
26%48%23%27%12%
2090
11th to 20thNight
32%48%20%26%10%
2090
21st to endNight
23%36%25%31%12%
2090
October1st to 10thNight
16%26%15%38%23%
3480
11th to 20thNight
18%26%19%36%20%
3764
21st to endNight
19%25%29%34%11%
4120
November1st to 10thNight
22%27%23%31%14%
2445
11th to 20thNight
24%27%24%32%11%
2477
21st to endNight
31%26%21%27%13%
2470
December1st to 10thNight
26%39%28%26%9%
2470
11th to 20thNight
33%25%21%30%8%
3037
21st to endNight
35%36%23%25%9%
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
11%17%36%24%11%1
270
11th to 20thDay
19%17%34%24%5%1
270
21st to endDay
14%12%42%21%10%1
297
February1st to 10thDay
20%14%39%22%4
270
11th to 20thDay
15%20%43%19%3
270
21st to endDay
23%19%37%18%2
225
March1st to 10thDay
18%16%39%21%5%
270
11th to 20thDay
20%17%39%17%6%1
270
21st to endDay
18%17%41%18%5%1
297
April1st to 10thDay
16%18%34%24%9%
270
11th to 20thDay
19%18%38%22%3
445
21st to endDay
19%15%32%25%7%2
650
May1st to 10thDay
14%10%39%28%8%1
653
11th to 20thDay
16%7%32%28%15%2
675
21st to endDay
14%6%34%25%17%4
734
June1st to 10thDay
8%320%39%24%6%
680
11th to 20thDay
6%325%43%18%4
680
21st to endDay
4218%47%23%6%
680
July1st to 10thDay
5%112%35%35%11%
671
11th to 20thDay
4113%38%35%9%
668
21st to endDay
427%37%37%14%
739
August1st to 10thDay
5%19%42%36%7%
676
11th to 20thDay
9%212%34%35%9%
665
21st to endDay
6%26%35%38%13%
527
September1st to 10thDay
9%19%32%33%15%
300
11th to 20thDay
6%13%41%30%11%
300
21st to endDay
12%413%39%22%10%
300
October1st to 10thDay
8%5%26%34%19%9%
300
11th to 20thDay
10%10%29%37%13%1
300
21st to endDay
21%10%30%26%12%2
330
November1st to 10thDay
18%7%33%29%11%2
300
11th to 20thDay
13%10%37%26%10%3
270
21st to endDay
18%11%38%22%10%1
270
December1st to 10thDay
10%13%38%26%11%1
270
11th to 20thDay
16%13%36%24%10%1
270
21st to endDay
23%13%34%24%6%
297
January1st to 10thNight
11%10%39%31%7%1
950
11th to 20thNight
14%14%32%35%6%
950
21st to endNight
12%10%38%33%6%
1045
February1st to 10thNight
16%12%40%27%5%
834
11th to 20thNight
15%14%39%27%5%
744
21st to endNight
16%15%41%25%3
628
March1st to 10thNight
11%13%39%33%4
637
11th to 20thNight
16%12%38%27%6%
570
21st to endNight
11%15%42%25%5%
627
April1st to 10thNight
12%15%44%23%5%
570
11th to 20thNight
14%12%45%25%5%
563
21st to endNight
15%10%41%27%7%1
570
May1st to 10thNight
12%10%42%28%7%
570
11th to 20thNight
12%7%35%33%13%1
561
21st to endNight
6%5%35%36%15%3
617
June1st to 10thNight
7%324%43%21%2
570
11th to 20thNight
6%329%50%12%
570
21st to endNight
3126%48%20%2
570
July1st to 10thNight
5%113%46%32%2
555
11th to 20thNight
2112%49%34%3
552
21st to endNight
48%51%34%3
624
August1st to 10thNight
2113%50%32%2
567
11th to 20thNight
6%214%44%31%2
564
21st to endNight
219%46%39%3
627
September1st to 10thNight
9%213%45%30%2
570
11th to 20thNight
13%218%37%27%3
570
21st to endNight
9%319%44%22%3
570
October1st to 10thNight
8%5%25%37%22%1
570
11th to 20thNight
11%7%33%37%12%
745
21st to endNight
15%8%32%31%12%1
836
November1st to 10thNight
11%6%35%35%12%1
885
11th to 20thNight
8%12%34%35%11%
953
21st to endNight
15%11%34%31%9%
950
December1st to 10thNight
12%11%34%36%8%
950
11th to 20thNight
16%9%37%30%7%
950
21st to endNight
14%11%36%31%7%
1045
Page generated at 2024-11-08 05:44:45. Version ac07

Copyright © 2024 Attilla Danko.


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