Moab Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Moab Observatory clear sky chart from 2005-11-06 to 2024-01-11.

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
62%
24305
26%
74582
22%
24260
67%
24260
39%
40636

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
66%
756
23%
2457
23%
756
70%
756
35%
1381
January11th to 20thNight
63%
724
25%
2352
24%
724
67%
724
36%
1288
January21st to endNight
60%
792
25%
2574
25%
792
65%
792
31%
1506
February1st to 10thNight
59%
720
23%
2340
21%
720
66%
720
36%
1295
February11th to 20thNight
53%
700
21%
2273
18%
700
60%
700
32%
1316
February21st to endNight
50%
592
29%
1730
22%
592
58%
592
33%
1027
March1st to 10thNight
53%
720
25%
1980
19%
720
58%
720
35%
1201
March11th to 20thNight
57%
720
28%
1980
20%
720
63%
720
41%
1144
March21st to endNight
51%
792
22%
2178
14%
792
58%
792
32%
1367
April1st to 10thNight
46%
615
24%
1875
17%
615
54%
615
31%
1094
April11th to 20thNight
47%
533
25%
1777
17%
533
59%
533
31%
975
April21st to endNight
50%
540
28%
1695
20%
540
61%
540
34%
912
May1st to 10thNight
53%
540
26%
1620
19%
540
60%
540
35%
919
May11th to 20thNight
62%
531
25%
1595
20%
531
66%
531
39%
863
May21st to endNight
56%
582
25%
1702
17%
582
62%
582
41%
908
June1st to 10thNight
66%
540
32%
1440
23%
540
72%
540
54%
745
June11th to 20thNight
63%
540
31%
1440
23%
540
69%
540
52%
753
June21st to endNight
73%
540
31%
1463
25%
540
77%
540
60%
707
July1st to 10thNight
75%
525
21%
1575
18%
525
77%
525
47%
809
July11th to 20thNight
76%
522
20%
1566
18%
522
77%
522
40%
868
July21st to endNight
78%
591
21%
1674
19%
558
78%
558
34%
1004
August1st to 10thNight
77%
537
23%
1602
20%
534
78%
534
40%
867
August11th to 20thNight
77%
534
30%
1602
28%
534
79%
534
46%
827
August21st to endNight
77%
594
31%
1944
33%
594
79%
594
42%
991
September1st to 10thNight
77%
540
34%
1800
35%
540
81%
540
46%
865
September11th to 20thNight
71%
690
34%
1950
28%
690
76%
690
52%
994
September21st to endNight
70%
720
37%
1980
27%
720
76%
720
54%
987
October1st to 10thNight
64%
720
30%
2160
22%
720
71%
720
45%
1103
October11th to 20thNight
70%
720
37%
2160
27%
720
77%
720
57%
998
October21st to endNight
63%
792
38%
2376
27%
792
72%
792
50%
1163
November1st to 10thNight
65%
740
35%
2220
27%
740
72%
740
50%
1077
November11th to 20thNight
65%
802
35%
2482
28%
802
73%
802
48%
1205
November21st to endNight
60%
950
27%
2660
21%
950
65%
950
42%
1477
December1st to 10thNight
60%
950
23%
2660
18%
950
64%
950
38%
1564
December11th to 20thNight
55%
948
20%
3146
15%
948
60%
948
26%
1961
December21st to endNight
51%
953
10%
4554
14%
944
54%
944
19%
2475

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
44244345%6%8%58%
74621
Night
5%5%2442445%7%57%
75097
TransparencyDay
25%7%12%20%22%15%
74346
Night
26%6%11%21%22%13%
74893
SeeingDay
7%10%26%32%20%4
13959
Night
7%5%20%38%26%4
24327

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
5%6%26%6%37%8%9%13%36%
1708
11th to 20thDay
36%25%5%35%5%9%12%43%
1620
21st to endDay
7%5%245%35%6%6%9%48%
1782
February1st to 10thDay
46%25%5%345%8%10%47%
1620
11th to 20thDay
6%7%35%5%245%7%8%48%
1575
21st to endDay
7%7%34445%46%6%49%
1522
March1st to 10thDay
47%45%5%25%45%7%51%
1980
11th to 20thDay
45%25%5%345%8%10%50%
1980
21st to endDay
5%7%3443446%8%51%
2178
April1st to 10thDay
5%5%25%42335%6%58%
2083
11th to 20thDay
45%245%3445%7%56%
2131
21st to endDay
45%2442445%8%59%
2261
May1st to 10thDay
45%24435%5%6%9%53%
2340
11th to 20thDay
43243345%5%8%59%
2301
21st to endDay
43135%245%6%8%59%
2569
June1st to 10thDay
321322335%8%68%
2520
11th to 20thDay
231231334473%
2520
21st to endDay
1212223345%74%
2490
July1st to 10thDay
22233246%6%8%62%
2340
11th to 20thDay
33134446%7%9%56%
2340
21st to endDay
43145%46%7%9%11%46%
2545
August1st to 10thDay
33145%45%7%8%9%51%
2328
11th to 20thDay
23135%3446%8%61%
2299
21st to endDay
42134245%6%8%61%
2412
September1st to 10thDay
431332346%6%65%
2160
11th to 20thDay
321432435%6%67%
2007
21st to endDay
3212322335%73%
1979
October1st to 10thDay
5%41332345%6%65%
1800
11th to 20thDay
3213312246%73%
1800
21st to endDay
431332235%6%68%
1980
November1st to 10thDay
432332225%7%68%
1859
11th to 20thDay
5%312412347%67%
1671
21st to endDay
5%5%13323447%63%
1520
December1st to 10thDay
6%8%25%5%235%5%7%52%
1520
11th to 20thDay
6%7%36%5%45%6%7%12%38%
1926
21st to endDay
5%8%26%5%45%6%6%8%45%
2955
January1st to 10thNight
5%5%234345%5%9%53%
2457
11th to 20thNight
5%6%245%3345%8%56%
2352
21st to endNight
7%7%25%43445%7%50%
2574
February1st to 10thNight
36%243345%6%9%56%
2340
11th to 20thNight
6%7%25%435%36%7%52%
2272
21st to endNight
5%8%36%4345%5%8%49%
1730
March1st to 10thNight
7%7%34435%45%6%53%
1980
11th to 20thNight
46%25%424447%57%
1980
21st to endNight
5%7%26%435%6%6%7%48%
2178
April1st to 10thNight
5%7%36%435%5%5%6%53%
1875
11th to 20thNight
6%6%35%435%5%46%54%
1777
21st to endNight
6%4344345%6%7%55%
1695
May1st to 10thNight
6%424435%5%6%7%53%
1620
11th to 20thNight
45%24435%5%7%7%55%
1594
21st to endNight
5%3144245%6%6%61%
1702
June1st to 10thNight
23243235%6%8%63%
1440
11th to 20thNight
331342445%8%64%
1440
21st to endNight
221342345%6%68%
1463
July1st to 10thNight
2222435%6%7%9%57%
1620
11th to 20thNight
23245%47%7%7%10%50%
1620
21st to endNight
3326%6%36%6%9%12%44%
1773
August1st to 10thNight
3224445%7%8%10%52%
1611
11th to 20thNight
432442346%10%57%
1602
21st to endNight
2413425%5%7%8%58%
1944
September1st to 10thNight
4312315%46%7%63%
1800
11th to 20thNight
4223423447%65%
1950
21st to endNight
431231333472%
1980
October1st to 10thNight
7%213323347%65%
2160
11th to 20thNight
4312213345%73%
2160
21st to endNight
5%413322335%68%
2376
November1st to 10thNight
3323324247%67%
2220
11th to 20thNight
5%413313346%67%
2482
21st to endNight
6%6%24323346%61%
2660
December1st to 10thNight
7%6%24423347%57%
2660
11th to 20thNight
7%6%25%5%35%6%7%9%46%
3271
21st to endNight
6%8%36%5%2446%8%47%
4739

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
33%11%23%26%6%1
1709
11th to 20thDay
30%9%21%30%9%1
1620
21st to endDay
29%12%19%27%10%3
1782
February1st to 10thDay
31%9%21%21%16%3
1620
11th to 20thDay
34%7%15%23%19%3
1584
21st to endDay
34%7%9%25%20%4
1522
March1st to 10thDay
34%5%10%25%22%4
1980
11th to 20thDay
29%8%13%28%16%7%
1980
21st to endDay
31%7%13%25%19%5%
2178
April1st to 10thDay
28%5%9%23%23%12%
2083
11th to 20thDay
28%5%11%23%23%10%
2134
21st to endDay
25%5%10%22%30%8%
2261
May1st to 10thDay
27%7%10%18%27%10%
2340
11th to 20thDay
22%7%11%21%27%13%
2304
21st to endDay
22%7%11%15%29%16%
2569
June1st to 10thDay
15%46%16%32%28%
2520
11th to 20thDay
15%35%9%23%44%
2520
21st to endDay
13%36%10%23%45%
2490
July1st to 10thDay
20%6%10%12%16%36%
2276
11th to 20thDay
23%7%12%18%16%23%
2271
21st to endDay
26%11%16%19%13%15%
2404
August1st to 10thDay
25%11%13%15%15%21%
2313
11th to 20thDay
22%7%10%15%19%27%
2299
21st to endDay
22%6%10%19%21%22%
2412
September1st to 10thDay
20%5%8%13%22%31%
2160
11th to 20thDay
18%6%9%17%21%28%
2007
21st to endDay
17%37%13%39%21%
1979
October1st to 10thDay
22%7%10%22%25%16%
1800
11th to 20thDay
15%47%21%38%15%
1800
21st to endDay
19%6%9%28%31%8%
1980
November1st to 10thDay
19%312%28%30%8%
1859
11th to 20thDay
20%49%34%30%3
1671
21st to endDay
24%6%14%28%24%4
1520
December1st to 10thDay
32%7%17%26%14%4
1520
11th to 20thDay
38%10%21%21%9%
1924
21st to endDay
35%10%14%13%23%6%
2955
January1st to 10thNight
26%10%20%31%11%1
2457
11th to 20thNight
28%6%20%30%15%1
2352
21st to endNight
31%9%16%28%12%4
2574
February1st to 10thNight
26%9%18%27%17%3
2340
11th to 20thNight
30%8%13%24%21%4
2273
21st to endNight
32%6%10%26%20%5%
1730
March1st to 10thNight
32%6%9%24%26%4
1980
11th to 20thNight
28%5%9%27%24%8%
1980
21st to endNight
33%8%11%24%19%4
2178
April1st to 10thNight
32%6%8%18%24%12%
1875
11th to 20thNight
31%5%8%19%26%11%
1777
21st to endNight
27%6%9%20%29%10%
1695
May1st to 10thNight
29%6%9%16%29%10%
1620
11th to 20thNight
26%6%9%20%27%11%
1595
21st to endNight
22%7%11%16%30%14%
1702
June1st to 10thNight
18%46%14%31%27%
1440
11th to 20thNight
18%5%7%10%17%43%
1440
21st to endNight
15%47%10%20%44%
1463
July1st to 10thNight
21%6%10%13%14%36%
1575
11th to 20thNight
25%8%11%18%17%22%
1566
21st to endNight
29%10%17%18%14%12%
1674
August1st to 10thNight
24%8%13%18%17%19%
1602
11th to 20thNight
22%6%10%18%15%29%
1602
21st to endNight
22%7%10%16%21%25%
1944
September1st to 10thNight
20%5%8%13%18%36%
1800
11th to 20thNight
19%5%11%17%19%30%
1950
21st to endNight
17%46%11%34%28%
1980
October1st to 10thNight
21%6%8%20%25%20%
2160
11th to 20thNight
16%37%17%36%21%
2160
21st to endNight
20%37%26%33%11%
2376
November1st to 10thNight
20%39%23%32%13%
2220
11th to 20thNight
21%48%28%34%5%
2482
21st to endNight
26%5%9%22%29%9%
2660
December1st to 10thNight
28%8%13%27%19%5%
2660
11th to 20thNight
35%9%15%24%16%1
3272
21st to endNight
33%8%15%16%20%7%
4739

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%11%27%30%16%5%
270
11th to 20thDay
11%6%26%39%17%1
240
21st to endDay
6%432%37%18%3
264
February1st to 10thDay
8%8%33%37%13%3
240
11th to 20thDay
12%9%38%26%14%1
240
21st to endDay
10%20%30%29%10%1
307
March1st to 10thDay
10%16%31%31%12%1
420
11th to 20thDay
8%14%32%29%15%2
420
21st to endDay
15%19%34%24%6%
462
April1st to 10thDay
12%17%32%25%11%3
420
11th to 20thDay
13%19%37%22%7%2
412
21st to endDay
12%20%30%23%13%1
420
May1st to 10thDay
9%13%41%26%9%1
423
11th to 20thDay
6%13%30%30%16%4
448
21st to endDay
7%15%25%30%18%5%
524
June1st to 10thDay
48%24%32%29%3
630
11th to 20thDay
410%26%33%22%5%
630
21st to endDay
36%26%37%24%3
600
July1st to 10thDay
25%20%39%28%6%
446
11th to 20thDay
3118%37%35%6%
444
21st to endDay
3112%37%41%6%
487
August1st to 10thDay
5%417%42%28%5%
447
11th to 20thDay
3418%38%28%9%
437
21st to endDay
4321%36%29%7%
495
September1st to 10thDay
45%19%34%29%9%
450
11th to 20thDay
311%24%33%23%6%
450
21st to endDay
6%12%21%30%23%7%
449
October1st to 10thDay
12%9%21%26%24%9%
270
11th to 20thDay
6%12%21%30%25%6%
270
21st to endDay
8%13%26%29%23%2
297
November1st to 10thDay
8%14%26%29%19%4
270
11th to 20thDay
39%33%33%19%4
270
21st to endDay
8%10%25%32%22%2
270
December1st to 10thDay
9%10%27%34%19%2
270
11th to 20thDay
10%7%27%38%14%4
270
21st to endDay
11%12%28%36%12%2
297
January1st to 10thNight
8%5%18%41%24%5%
760
11th to 20thNight
7%421%39%26%4
724
21st to endNight
10%321%41%20%5%
792
February1st to 10thNight
6%327%43%18%3
720
11th to 20thNight
8%6%28%38%18%3
704
21st to endNight
8%8%28%41%14%1
592
March1st to 10thNight
9%8%25%40%16%2
720
11th to 20thNight
6%6%24%36%26%2
720
21st to endNight
7%10%28%37%16%2
792
April1st to 10thNight
10%10%29%35%15%1
615
11th to 20thNight
10%12%28%33%16%2
533
21st to endNight
8%14%25%31%17%5%
540
May1st to 10thNight
7%10%25%39%16%3
540
11th to 20thNight
6%5%21%39%25%4
531
21st to endNight
410%26%32%25%3
584
June1st to 10thNight
36%20%36%33%2
540
11th to 20thNight
5%7%21%38%26%3
540
21st to endNight
2316%41%34%3
540
July1st to 10thNight
2114%31%45%6%
525
11th to 20thNight
2110%34%47%7%
522
21st to endNight
417%32%49%8%
591
August1st to 10thNight
4110%36%42%6%
537
11th to 20thNight
4210%39%37%7%
534
21st to endNight
4210%39%37%9%
594
September1st to 10thNight
5%111%40%35%8%
540
11th to 20thNight
3415%36%35%7%
690
21st to endNight
5%5%15%33%31%11%
720
October1st to 10thNight
7%5%20%38%26%5%
720
11th to 20thNight
4419%38%29%6%
720
21st to endNight
7%5%20%33%29%6%
792
November1st to 10thNight
5%5%19%37%29%4
740
11th to 20thNight
5%422%41%22%5%
802
21st to endNight
9%6%20%36%23%5%
950
December1st to 10thNight
9%420%44%20%2
950
11th to 20thNight
12%5%21%39%22%2
950
21st to endNight
13%6%23%39%17%3
963
Page generated at 2024-01-08 09:14:21. Version ac07

Copyright 2024 Attilla Danko


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