This page made possible by the sponsorship of: Dr. John Sohl.

Ogden
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ogden clear sky chart from 2005-11-06 to 2024-01-16.

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
56%
24119
21%
74521
18%
24073
59%
24073
30%
45579

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
45%
756
12%
2457
10%
756
48%
756
17%
1780
January11th to 20thNight
47%
740
12%
2405
12%
740
48%
740
18%
1707
January21st to endNight
45%
792
12%
2574
12%
792
48%
792
16%
1887
February1st to 10thNight
43%
720
12%
2340
12%
720
46%
720
18%
1664
February11th to 20thNight
46%
701
16%
2210
15%
700
49%
700
23%
1465
February21st to endNight
39%
592
18%
1776
15%
592
44%
592
20%
1248
March1st to 10thNight
47%
720
17%
2047
15%
720
50%
720
22%
1439
March11th to 20thNight
51%
720
20%
1980
15%
720
56%
720
30%
1294
March21st to endNight
44%
792
16%
2178
11%
792
48%
792
25%
1517
April1st to 10thNight
47%
702
18%
1962
13%
702
51%
702
28%
1286
April11th to 20thNight
45%
533
23%
1615
16%
533
51%
533
27%
1027
April21st to endNight
54%
540
24%
1620
19%
540
57%
540
32%
980
May1st to 10thNight
52%
540
20%
1620
15%
540
56%
540
28%
1009
May11th to 20thNight
59%
531
21%
1595
18%
531
62%
531
34%
926
May21st to endNight
57%
582
16%
1746
14%
582
59%
582
27%
1101
June1st to 10thNight
66%
540
23%
1481
19%
540
71%
540
44%
813
June11th to 20thNight
63%
517
27%
1417
22%
517
70%
517
51%
742
June21st to endNight
69%
360
32%
1348
38%
360
78%
360
55%
527
July1st to 10thNight
72%
418
23%
1468
25%
418
77%
418
46%
669
July11th to 20thNight
74%
522
24%
1566
22%
522
77%
522
48%
810
July21st to endNight
80%
591
27%
1674
24%
558
81%
558
48%
841
August1st to 10thNight
75%
537
28%
1602
23%
534
77%
534
46%
832
August11th to 20thNight
77%
534
33%
1602
26%
534
79%
534
49%
803
August21st to endNight
76%
594
36%
1786
30%
594
78%
594
49%
884
September1st to 10thNight
72%
666
32%
1926
27%
666
76%
666
53%
935
September11th to 20thNight
73%
720
33%
1980
28%
720
76%
720
52%
1025
September21st to endNight
69%
720
35%
1980
27%
720
74%
720
54%
1014
October1st to 10thNight
63%
720
27%
2064
21%
720
67%
720
41%
1157
October11th to 20thNight
63%
720
32%
2160
26%
720
69%
720
42%
1182
October21st to endNight
60%
792
32%
2402
27%
792
66%
792
41%
1297
November1st to 10thNight
59%
740
24%
2405
23%
740
62%
740
30%
1420
November11th to 20thNight
55%
760
22%
2470
20%
760
59%
760
30%
1461
November21st to endNight
53%
902
19%
2612
17%
902
56%
902
29%
1660
December1st to 10thNight
45%
950
13%
2660
10%
950
47%
950
24%
1851
December11th to 20thNight
43%
949
11%
3200
8%
948
45%
948
16%
2295
December21st to endNight
33%
906
7%
4593
8%
898
36%
898
9%
3031

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%8%35%43445%7%49%
74922
Night
10%8%35%5%3445%6%48%
74870
TransparencyDay
34%7%11%18%19%11%
74646
Night
36%6%12%20%17%9%
74667
SeeingDay
11%8%23%35%21%3
14012
Night
14%419%40%22%2
24140

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
18%15%36%435%5%5%6%31%
1708
11th to 20thDay
13%16%5%7%5%46%45%5%31%
1665
21st to endDay
12%18%6%7%6%345%6%6%27%
1782
February1st to 10thDay
15%15%47%4345%6%6%31%
1620
11th to 20thDay
13%14%5%7%6%3445%6%32%
1633
21st to endDay
11%16%7%8%6%3445%6%29%
1480
March1st to 10thDay
11%13%5%7%5%345%5%7%36%
1912
11th to 20thDay
9%10%35%6%45%6%7%9%36%
1980
21st to endDay
16%12%47%445%5%5%7%32%
2178
April1st to 10thDay
15%9%35%6%345%5%7%39%
1998
11th to 20thDay
12%10%36%5%445%5%7%40%
2289
21st to endDay
10%9%36%43445%7%45%
2340
May1st to 10thDay
9%7%36%5%45%6%6%8%41%
2340
11th to 20thDay
9%5%245%25%6%7%10%45%
2301
21st to endDay
12%425%5%35%6%7%8%42%
2530
June1st to 10thDay
5%42443346%9%56%
2470
11th to 20thDay
6%42432345%8%59%
2532
21st to endDay
3213322345%72%
2604
July1st to 10thDay
321332335%7%67%
2440
11th to 20thDay
4313223346%67%
2340
21st to endDay
42133235%7%7%62%
2545
August1st to 10thDay
43134335%5%7%63%
2328
11th to 20thDay
3213423446%68%
2299
21st to endDay
421332345%7%66%
2570
September1st to 10thDay
4212323335%71%
2032
11th to 20thDay
4213433445%66%
1980
21st to endDay
7%313222345%67%
1980
October1st to 10thDay
12%5%24434446%54%
1895
11th to 20thDay
9%5%2342345%7%57%
1800
21st to endDay
7%6%25%4335%46%55%
1949
November1st to 10thDay
13%10%35%5%235%47%44%
1674
11th to 20thDay
16%7%25%324349%45%
1710
21st to endDay
11%11%45%5%3345%6%43%
1545
December1st to 10thDay
12%13%47%5%35%446%37%
1520
11th to 20thDay
16%13%48%5%345%5%8%28%
1926
21st to endDay
10%13%5%7%6%45%5%6%7%32%
3027
January1st to 10thNight
17%11%37%6%34447%34%
2457
11th to 20thNight
15%13%47%5%3345%7%35%
2405
21st to endNight
14%17%37%5%3345%6%33%
2574
February1st to 10thNight
13%14%45%6%345%5%6%34%
2340
11th to 20thNight
12%11%47%43345%6%41%
2209
21st to endNight
10%15%5%8%6%335%5%5%35%
1776
March1st to 10thNight
14%12%46%6%3445%6%36%
2047
11th to 20thNight
10%9%36%5%345%5%8%42%
1980
21st to endNight
12%13%46%5%25%446%38%
2178
April1st to 10thNight
14%10%35%5%24445%45%
1962
11th to 20thNight
11%8%46%6%3445%5%45%
1615
21st to endNight
11%7%26%42345%6%49%
1620
May1st to 10thNight
11%6%25%6%35%5%6%6%44%
1620
11th to 20thNight
9%5%244345%6%8%50%
1594
21st to endNight
12%6%26%5%35%6%6%7%43%
1746
June1st to 10thNight
6%4243245%6%8%56%
1481
11th to 20thNight
7%313322347%64%
1417
21st to endNight
3213322347%70%
1348
July1st to 10thNight
442442446%9%59%
1512
11th to 20thNight
34243345%5%7%59%
1620
21st to endNight
34243245%7%8%59%
1773
August1st to 10thNight
43144345%5%8%58%
1611
11th to 20thNight
341443445%7%61%
1602
21st to endNight
332343445%6%63%
1786
September1st to 10thNight
4322423345%68%
1926
11th to 20thNight
6%313323445%66%
1980
21st to endNight
7%31331233469%
1980
October1st to 10thNight
9%423423445%58%
2064
11th to 20thNight
10%5%23323346%60%
2160
21st to endNight
8%5%24423446%59%
2402
November1st to 10thNight
13%8%2442335%6%49%
2405
11th to 20thNight
12%7%25%42345%7%47%
2470
21st to endNight
11%9%346%34446%46%
2612
December1st to 10thNight
13%11%47%42335%7%40%
2660
11th to 20thNight
16%12%47%5%345%5%7%32%
3271
21st to endNight
12%12%48%7%3445%7%34%
4667

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
52%11%18%15%41
1709
11th to 20thDay
53%8%19%14%41
1665
21st to endDay
56%10%17%11%31
1782
February1st to 10thDay
53%9%16%15%7%1
1620
11th to 20thDay
50%8%15%17%9%1
1642
21st to endDay
54%8%13%16%7%1
1480
March1st to 10thDay
46%8%14%23%8%1
1912
11th to 20thDay
41%10%15%21%12%2
1980
21st to endDay
51%7%14%19%8%2
2178
April1st to 10thDay
44%8%12%19%14%4
1998
11th to 20thDay
42%8%10%21%18%2
2292
21st to endDay
38%6%10%24%21%2
2340
May1st to 10thDay
37%7%11%22%20%3
2340
11th to 20thDay
32%8%9%25%20%6%
2304
21st to endDay
36%9%11%24%17%3
2530
June1st to 10thDay
24%5%11%23%30%8%
2470
11th to 20thDay
23%5%7%18%27%20%
2532
21st to endDay
15%2411%30%37%
2604
July1st to 10thDay
16%36%15%24%36%
2375
11th to 20thDay
17%36%12%26%36%
2271
21st to endDay
19%6%8%12%26%30%
2404
August1st to 10thDay
20%48%16%23%29%
2313
11th to 20thDay
16%46%12%34%28%
2299
21st to endDay
18%46%15%32%25%
2570
September1st to 10thDay
16%46%15%29%31%
2032
11th to 20thDay
20%5%7%19%31%19%
1980
21st to endDay
19%48%20%37%11%
1980
October1st to 10thDay
32%5%8%23%24%7%
1895
11th to 20thDay
27%5%11%30%23%4
1800
21st to endDay
29%7%15%31%18%1
1949
November1st to 10thDay
40%7%14%21%16%1
1674
11th to 20thDay
38%6%18%25%12%
1710
21st to endDay
41%7%18%21%12%1
1545
December1st to 10thDay
48%11%16%15%8%1
1520
11th to 20thDay
55%7%20%14%4
1924
21st to endDay
48%11%16%14%10%1
3027
January1st to 10thNight
51%9%18%18%41
2457
11th to 20thNight
49%8%19%16%6%1
2405
21st to endNight
51%10%18%14%6%2
2574
February1st to 10thNight
50%8%16%20%6%
2340
11th to 20thNight
45%6%13%22%14%1
2210
21st to endNight
49%7%12%22%9%2
1776
March1st to 10thNight
48%6%12%24%10%
2047
11th to 20thNight
39%6%13%25%15%2
1980
21st to endNight
46%6%14%23%9%2
2178
April1st to 10thNight
43%313%20%14%7%
1962
11th to 20thNight
39%7%9%24%20%2
1615
21st to endNight
35%5%11%24%22%3
1620
May1st to 10thNight
37%7%10%20%22%5%
1620
11th to 20thNight
30%8%10%25%21%7%
1595
21st to endNight
37%8%12%21%20%2
1746
June1st to 10thNight
24%6%11%22%31%7%
1481
11th to 20thNight
21%48%19%28%20%
1417
21st to endNight
16%26%12%27%38%
1348
July1st to 10thNight
21%38%12%23%32%
1468
11th to 20thNight
22%46%12%23%32%
1566
21st to endNight
20%5%9%13%22%30%
1674
August1st to 10thNight
23%5%8%14%22%28%
1602
11th to 20thNight
21%47%11%26%30%
1602
21st to endNight
20%47%12%28%28%
1786
September1st to 10thNight
19%37%13%23%35%
1926
11th to 20thNight
21%46%15%30%25%
1980
21st to endNight
20%36%17%34%19%
1980
October1st to 10thNight
27%5%8%22%29%8%
2064
11th to 20thNight
28%47%31%26%6%
2160
21st to endNight
27%5%10%33%23%3
2402
November1st to 10thNight
36%5%12%26%19%4
2405
11th to 20thNight
37%414%28%15%1
2470
21st to endNight
40%5%14%26%13%2
2612
December1st to 10thNight
46%6%17%20%9%2
2660
11th to 20thNight
50%9%19%16%6%
3272
21st to endNight
50%8%17%14%10%1
4667

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
19%11%25%29%13%4
270
11th to 20thDay
20%11%18%32%16%2
255
21st to endDay
21%5%26%33%13%2
264
February1st to 10thDay
23%8%29%28%10%2
240
11th to 20thDay
16%9%35%28%10%1
298
21st to endDay
14%12%36%29%8%1
346
March1st to 10thDay
17%10%32%31%9%1
420
11th to 20thDay
12%9%30%35%14%
420
21st to endDay
20%13%32%26%8%
462
April1st to 10thDay
16%12%28%28%15%1
420
11th to 20thDay
15%17%32%25%10%1
412
21st to endDay
14%13%31%22%18%2
420
May1st to 10thDay
9%13%31%31%15%1
423
11th to 20thDay
11%10%24%32%20%3
448
21st to endDay
9%9%22%34%22%4
485
June1st to 10thDay
5%6%22%38%26%4
580
11th to 20thDay
7%7%23%40%22%2
630
21st to endDay
4422%42%24%4
534
July1st to 10thDay
1218%47%30%2
446
11th to 20thDay
3316%48%26%4
444
21st to endDay
419%48%33%4
487
August1st to 10thDay
4415%47%26%4
447
11th to 20thDay
3313%43%34%5%
437
21st to endDay
4215%40%34%5%
495
September1st to 10thDay
45%16%33%34%8%
450
11th to 20thDay
6%422%34%29%6%
450
21st to endDay
7%6%19%31%33%4
450
October1st to 10thDay
12%7%24%27%25%6%
365
11th to 20thDay
7%8%25%26%25%8%
270
21st to endDay
8%10%22%38%20%1
297
November1st to 10thDay
20%7%21%29%16%6%
270
11th to 20thDay
13%9%17%40%16%4
270
21st to endDay
15%7%20%30%22%6%
270
December1st to 10thDay
16%8%21%36%13%6%
270
11th to 20thDay
19%7%25%39%10%1
270
21st to endDay
22%9%22%33%11%2
297
January1st to 10thNight
20%419%36%19%2
760
11th to 20thNight
21%418%39%16%3
740
21st to endNight
22%418%38%14%4
792
February1st to 10thNight
21%324%39%12%1
720
11th to 20thNight
17%325%40%15%1
704
21st to endNight
15%7%28%37%13%1
592
March1st to 10thNight
19%6%21%41%12%2
720
11th to 20thNight
13%322%44%16%1
720
21st to endNight
20%5%23%39%13%1
792
April1st to 10thNight
19%7%23%39%13%1
702
11th to 20thNight
13%8%29%35%16%
533
21st to endNight
13%5%22%37%22%1
540
May1st to 10thNight
12%424%39%19%1
540
11th to 20thNight
11%320%33%30%2
531
21st to endNight
13%5%17%36%28%2
584
June1st to 10thNight
6%6%18%39%30%1
540
11th to 20thNight
8%6%19%43%24%
517
21st to endNight
3220%40%32%3
360
July1st to 10thNight
5%114%45%33%2
418
11th to 20thNight
5%115%49%30%1
522
21st to endNight
5%7%45%41%1
591
August1st to 10thNight
5%111%49%33%1
537
11th to 20thNight
3112%46%37%1
534
21st to endNight
6%312%40%38%2
594
September1st to 10thNight
5%314%41%35%3
666
11th to 20thNight
7%314%42%32%4
720
21st to endNight
8%317%34%31%7%
720
October1st to 10thNight
10%417%41%26%2
720
11th to 20thNight
13%316%37%28%2
720
21st to endNight
10%322%38%24%2
792
November1st to 10thNight
15%417%41%20%3
740
11th to 20thNight
14%420%44%16%3
760
21st to endNight
14%422%37%20%3
902
December1st to 10thNight
18%423%39%14%1
950
11th to 20thNight
22%5%20%39%13%1
950
21st to endNight
26%6%22%36%9%1
917
Page generated at 2024-01-12 23:38:13. Version ac07

Copyright 2024 Attilla Danko


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