Dome Valley Observatory
Clear Sky Chart
History

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

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
55%
25007
29%
94963
21%
24802
66%
24802
35%
47271

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
54%
760
30%
4032
25%
741
69%
741
27%
1990
January11th to 20thNight
52%
757
39%
3944
26%
740
66%
740
33%
1521
January21st to endNight
52%
824
22%
4298
24%
814
66%
814
25%
2179
February1st to 10thNight
47%
760
32%
2462
21%
760
62%
760
44%
1194
February11th to 20thNight
42%
743
30%
2218
17%
740
56%
740
39%
1189
February21st to endNight
38%
628
37%
1884
18%
628
58%
628
45%
938
March1st to 10thNight
41%
756
40%
3409
16%
744
58%
744
34%
1429
March11th to 20thNight
45%
756
28%
3456
16%
740
57%
740
24%
1950
March21st to endNight
44%
771
24%
3544
15%
754
61%
754
30%
1596
April1st to 10thNight
35%
570
35%
1900
17%
570
59%
570
40%
884
April11th to 20thNight
38%
563
34%
1877
20%
563
58%
563
36%
913
April21st to endNight
36%
570
33%
1900
16%
570
59%
570
39%
895
May1st to 10thNight
43%
567
35%
2979
20%
559
62%
559
32%
1159
May11th to 20thNight
47%
553
20%
2913
18%
541
58%
541
23%
1396
May21st to endNight
49%
608
26%
2736
17%
593
64%
593
43%
961
June1st to 10thNight
60%
570
28%
1520
19%
570
66%
570
47%
825
June11th to 20thNight
59%
570
33%
1520
23%
570
66%
570
59%
750
June21st to endNight
64%
570
23%
1520
18%
570
67%
570
40%
894
July1st to 10thNight
68%
543
26%
2281
16%
535
70%
535
26%
1177
July11th to 20thNight
72%
540
16%
2458
16%
533
74%
533
21%
1416
July21st to endNight
70%
609
13%
2673
15%
569
71%
569
16%
1635
August1st to 10thNight
77%
553
14%
2730
16%
545
78%
545
18%
1768
August11th to 20thNight
70%
544
16%
2779
20%
543
72%
543
20%
1484
August21st to endNight
77%
607
16%
3366
27%
605
80%
605
19%
2062
September1st to 10thNight
72%
570
29%
1900
30%
570
77%
570
35%
1055
September11th to 20thNight
74%
570
36%
1900
33%
570
79%
570
43%
954
September21st to endNight
68%
641
34%
2123
28%
641
75%
641
49%
994
October1st to 10thNight
61%
760
34%
2280
24%
760
68%
760
45%
1186
October11th to 20thNight
65%
760
40%
2280
25%
760
75%
760
58%
1016
October21st to endNight
61%
836
41%
2508
24%
836
73%
836
55%
1159
November1st to 10thNight
66%
748
44%
2244
28%
748
77%
748
64%
966
November11th to 20thNight
61%
946
39%
2466
23%
946
69%
946
62%
1193
November21st to endNight
54%
950
36%
2470
21%
950
63%
950
47%
1363
December1st to 10thNight
54%
950
36%
2632
21%
950
64%
950
49%
1359
December11th to 20thNight
50%
948
31%
3113
19%
948
58%
948
37%
1664
December21st to endNight
44%
1036
21%
4648
18%
1026
55%
1026
29%
2157

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
231433446%8%61%
100840
Night
3425%44446%7%58%
98360
TransparencyDay
19%6%9%22%27%17%
100603
Night
23%7%9%21%26%15%
98187
SeeingDay
6%14%27%31%19%4
15039
Night
5%9%26%41%18%1
25165

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
15%36%33445%7%59%
2858
11th to 20thDay
15%1432335%7%66%
2860
21st to endDay
36%26%5%5%445%8%52%
3146
February1st to 10thDay
25%26%43435%6%59%
1715
11th to 20thDay
25%16%43335%8%60%
1849
21st to endDay
1425%43425%7%62%
1570
March1st to 10thDay
131423436%7%66%
3343
11th to 20thDay
25%25%45%5%47%9%52%
3490
21st to endDay
25%26%44445%7%59%
3930
April1st to 10thDay
231443425%7%67%
2280
11th to 20thDay
231433435%7%64%
2251
21st to endDay
231332435%7%67%
2280
May1st to 10thDay
111223335%7%73%
3800
11th to 20thDay
3213445%46%9%60%
3903
21st to endDay
1111122245%79%
4794
June1st to 10thDay
211333447%9%64%
2660
11th to 20thDay
111223335%6%72%
2660
21st to endDay
341434447%8%57%
2660
July1st to 10thDay
22133445%6%8%60%
4256
11th to 20thDay
1213445%6%11%13%50%
4110
21st to endDay
3315%5%5%7%7%11%12%42%
4454
August1st to 10thDay
221445%6%6%10%14%48%
4010
11th to 20thDay
121334446%12%60%
3726
21st to endDay
22145%5%6%6%9%11%47%
4180
September1st to 10thDay
432445%5%5%7%8%55%
2280
11th to 20thDay
4313335%37%7%61%
2280
21st to endDay
2213223347%70%
2052
October1st to 10thDay
431434436%6%62%
1900
11th to 20thDay
1213222245%75%
1900
21st to endDay
331323323474%
2090
November1st to 10thDay
211222335%7%73%
1860
11th to 20thDay
221323325%6%71%
1710
21st to endDay
2315%43435%5%65%
1710
December1st to 10thDay
241433335%7%65%
1544
11th to 20thDay
2426%45%446%8%55%
1926
21st to endDay
25%25%34235%7%63%
2803
January1st to 10thNight
16%5%6%44435%6%56%
4115
11th to 20thNight
3424443235%67%
4110
21st to endNight
37%26%445%36%9%52%
4521
February1st to 10thNight
26%24333347%64%
2462
11th to 20thNight
36%25%434346%59%
2218
21st to endNight
2415%333346%64%
1884
March1st to 10thNight
25%25%333345%65%
3523
11th to 20thNight
5%6%27%45%4447%50%
3490
21st to endNight
37%14333347%61%
3717
April1st to 10thNight
341432435%8%63%
1900
11th to 20thNight
3424334347%62%
1877
21st to endNight
331433335%7%64%
1900
May1st to 10thNight
1314444447%65%
3170
11th to 20thNight
45%26%445%47%8%53%
2998
21st to endNight
3213233345%71%
2776
June1st to 10thNight
2214445%48%11%55%
1520
11th to 20thNight
1213333447%68%
1520
21st to endNight
35%25%446%5%6%9%50%
1520
July1st to 10thNight
1215%5%5%6%6%7%8%54%
2694
11th to 20thNight
3325%6%6%7%6%10%12%40%
2860
21st to endNight
6%5%26%6%6%6%6%11%12%36%
3109
August1st to 10thNight
2438%7%8%8%7%10%13%30%
2929
11th to 20thNight
3325%5%7%7%6%10%11%44%
3113
21st to endNight
2326%6%8%9%7%11%12%32%
3487
September1st to 10thNight
3315%45%6%6%8%10%49%
1900
11th to 20thNight
4314345%36%8%59%
1900
21st to endNight
331333335%6%67%
2123
October1st to 10thNight
431433335%5%64%
2280
11th to 20thNight
2112222345%76%
2280
21st to endNight
3212223345%72%
2508
November1st to 10thNight
1212222345%77%
2244
11th to 20thNight
1213222345%73%
2466
21st to endNight
35%1433425%6%63%
2470
December1st to 10thNight
341333335%7%65%
2632
11th to 20thNight
2425%44446%8%57%
3271
21st to endNight
36%25%433345%61%
4873

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
21%8%7%34%26%3
2859
11th to 20thDay
16%7%13%36%24%4
2860
21st to endDay
27%9%8%25%26%5%
3146
February1st to 10thDay
24%49%27%26%10%
1715
11th to 20thDay
24%46%25%29%11%
1859
21st to endDay
22%4420%30%20%
1570
March1st to 10thDay
17%4419%37%18%
3343
11th to 20thDay
26%9%9%23%25%8%
3490
21st to endDay
20%8%5%20%34%12%
3930
April1st to 10thDay
17%5%6%16%35%20%
2280
11th to 20thDay
19%6%5%16%31%23%
2254
21st to endDay
16%5%6%20%35%18%
2280
May1st to 10thDay
11%5%5%16%36%28%
3800
11th to 20thDay
19%8%8%18%31%16%
3906
21st to endDay
9%35%11%22%49%
4794
June1st to 10thDay
14%6%9%18%28%25%
2660
11th to 20thDay
13%35%12%23%44%
2660
21st to endDay
22%5%8%20%21%24%
2660
July1st to 10thDay
19%8%11%15%20%28%
4192
11th to 20thDay
19%8%19%28%19%6%
4041
21st to endDay
26%9%18%31%13%2
4314
August1st to 10thDay
21%10%21%24%16%8%
3996
11th to 20thDay
17%6%12%26%24%15%
3762
21st to endDay
25%11%18%23%19%4
4179
September1st to 10thDay
25%7%10%20%26%13%
2280
11th to 20thDay
21%7%9%18%26%20%
2280
21st to endDay
15%37%21%33%21%
2052
October1st to 10thDay
22%6%6%19%26%21%
1900
11th to 20thDay
14%35%13%36%29%
1900
21st to endDay
15%37%20%37%18%
2090
November1st to 10thDay
12%45%22%40%17%
1860
11th to 20thDay
15%46%25%39%11%
1710
21st to endDay
21%5%422%34%14%
1710
December1st to 10thDay
19%5%9%33%24%10%
1544
11th to 20thDay
26%7%10%24%27%6%
1924
21st to endDay
20%5%9%23%31%13%
2803
January1st to 10thNight
24%10%7%28%24%6%
4115
11th to 20thNight
16%7%8%38%24%6%
4110
21st to endNight
26%9%9%24%26%5%
4521
February1st to 10thNight
21%410%24%29%11%
2462
11th to 20thNight
25%6%7%23%27%13%
2218
21st to endNight
21%45%17%34%20%
1884
March1st to 10thNight
20%5%416%38%17%
3523
11th to 20thNight
30%11%7%20%23%9%
3490
21st to endNight
19%9%5%22%34%11%
3717
April1st to 10thNight
20%46%16%33%22%
1900
11th to 20thNight
21%5%415%28%26%
1877
21st to endNight
19%6%7%16%34%18%
1900
May1st to 10thNight
14%9%8%12%28%29%
3170
11th to 20thNight
25%10%9%19%21%16%
2999
21st to endNight
14%47%9%16%49%
2776
June1st to 10thNight
20%8%13%16%19%25%
1520
11th to 20thNight
16%36%11%22%42%
1520
21st to endNight
28%7%12%13%16%24%
1520
July1st to 10thNight
25%8%11%17%12%28%
2650
11th to 20thNight
30%10%17%28%10%5%
2806
21st to endNight
34%11%17%28%10%1
3011
August1st to 10thNight
37%13%16%17%12%6%
2920
11th to 20thNight
28%10%15%17%17%13%
3143
21st to endNight
37%11%17%20%11%5%
3487
September1st to 10thNight
28%8%13%18%21%13%
1900
11th to 20thNight
22%6%12%16%21%23%
1900
21st to endNight
18%5%7%16%30%24%
2123
October1st to 10thNight
22%6%8%18%23%24%
2280
11th to 20thNight
13%4414%32%32%
2280
21st to endNight
15%45%18%38%20%
2508
November1st to 10thNight
11%35%21%41%19%
2244
11th to 20thNight
13%35%23%40%16%
2466
21st to endNight
23%35%19%34%16%
2470
December1st to 10thNight
19%5%8%30%30%8%
2632
11th to 20thNight
24%7%8%25%29%7%
3272
21st to endNight
22%8%6%23%31%9%
4873

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
416%37%34%9%
270
11th to 20thDay
11%19%29%32%10%
270
21st to endDay
314%34%35%12%2
297
February1st to 10thDay
6%22%36%25%11%
270
11th to 20thDay
7%23%41%26%4
270
21st to endDay
14%28%35%20%4
225
March1st to 10thDay
8%28%29%28%7%
393
11th to 20thDay
14%26%29%21%9%1
460
21st to endDay
14%33%31%15%7%
506
April1st to 10thDay
9%27%36%19%9%
460
11th to 20thDay
11%33%33%17%5%1
452
21st to endDay
8%29%36%22%41
460
May1st to 10thDay
8%25%40%21%5%1
463
11th to 20thDay
7%18%34%28%12%2
488
21st to endDay
5%16%32%33%13%1
716
June1st to 10thDay
26%25%42%23%2
680
11th to 20thDay
39%24%38%23%3
680
21st to endDay
5%6%24%35%27%4
680
July1st to 10thDay
3319%38%30%7%
580
11th to 20thDay
3110%31%39%17%
484
21st to endDay
418%33%41%14%
531
August1st to 10thDay
3111%34%39%11%
487
11th to 20thDay
4117%38%31%9%
477
21st to endDay
4116%38%34%8%
539
September1st to 10thDay
5%318%37%29%8%
490
11th to 20thDay
25%26%39%22%6%
490
21st to endDay
29%24%34%24%6%
338
October1st to 10thDay
411%26%27%25%6%
300
11th to 20thDay
6%12%27%30%21%4
300
21st to endDay
11%12%23%30%21%2
330
November1st to 10thDay
418%31%32%14%1
276
11th to 20thDay
311%30%36%19%
270
21st to endDay
6%23%29%28%12%2
270
December1st to 10thDay
7%16%30%36%10%
270
11th to 20thDay
9%16%31%37%7%
270
21st to endDay
13%21%31%31%4
297
January1st to 10thNight
47%32%42%15%1
765
11th to 20thNight
49%29%41%15%1
760
21st to endNight
411%29%40%15%1
836
February1st to 10thNight
6%10%35%38%11%1
760
11th to 20thNight
8%11%36%38%7%
744
21st to endNight
7%13%41%36%4
628
March1st to 10thNight
6%13%36%34%10%
760
11th to 20thNight
8%12%32%37%12%
760
21st to endNight
7%15%32%39%8%
776
April1st to 10thNight
6%16%39%33%5%
570
11th to 20thNight
7%21%31%34%7%
563
21st to endNight
6%16%38%33%6%
570
May1st to 10thNight
413%35%38%9%
570
11th to 20thNight
6%11%30%39%12%1
561
21st to endNight
410%32%43%11%
617
June1st to 10thNight
16%27%49%16%1
570
11th to 20thNight
15%30%47%16%1
570
21st to endNight
4420%48%24%1
570
July1st to 10thNight
3217%46%31%2
555
11th to 20thNight
3210%40%42%3
552
21st to endNight
328%36%45%6%
624
August1st to 10thNight
427%34%46%7%
567
11th to 20thNight
4212%45%33%3
564
21st to endNight
319%44%38%4
627
September1st to 10thNight
4215%47%30%1
570
11th to 20thNight
5%215%49%27%2
570
21st to endNight
4422%45%25%1
641
October1st to 10thNight
45%23%46%19%2
760
11th to 20thNight
37%22%46%20%1
760
21st to endNight
5%6%26%40%21%3
836
November1st to 10thNight
36%24%46%20%1
748
11th to 20thNight
38%25%45%17%2
946
21st to endNight
6%12%24%36%19%3
950
December1st to 10thNight
5%9%28%43%13%1
950
11th to 20thNight
7%10%28%43%12%
950
21st to endNight
7%12%30%41%9%
1045
Page generated at 2024-10-31 01:39:25. Version ac07

Copyright © 2024 Attilla Danko.


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