Fossil View Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fossil View Observatory clear sky chart from 2005-11-06 to 2024-01-22.

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%
23832
27%
74451
16%
23773
56%
23773
36%
41333

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
32%
949
31%
2458
12%
946
45%
946
40%
1448
January11th to 20thNight
32%
950
29%
2470
9%
950
45%
950
37%
1476
January21st to endNight
30%
800
34%
2400
14%
800
47%
800
32%
1396
February1st to 10thNight
29%
720
29%
2160
11%
720
45%
720
32%
1240
February11th to 20thNight
26%
704
24%
2098
9%
700
38%
700
30%
1215
February21st to endNight
18%
592
28%
1776
5%
592
38%
592
29%
1036
March1st to 10thNight
22%
645
26%
2085
9%
645
40%
645
28%
1228
March11th to 20thNight
29%
540
24%
1980
13%
540
44%
540
24%
1139
March21st to endNight
22%
594
28%
2178
10%
594
45%
594
32%
1137
April1st to 10thNight
23%
540
27%
1980
9%
540
47%
540
29%
1059
April11th to 20thNight
20%
533
25%
1807
10%
533
40%
533
28%
1043
April21st to endNight
22%
540
29%
1742
12%
540
45%
540
34%
971
May1st to 10thNight
26%
540
27%
1620
13%
540
44%
540
33%
947
May11th to 20thNight
36%
531
20%
1593
15%
531
46%
531
31%
973
May21st to endNight
38%
583
22%
1745
12%
582
53%
582
32%
1056
June1st to 10thNight
62%
540
23%
1620
20%
540
71%
540
51%
800
June11th to 20thNight
53%
540
25%
1620
19%
540
65%
540
51%
798
June21st to endNight
66%
540
25%
1620
26%
540
71%
540
43%
873
July1st to 10thNight
68%
525
17%
1575
18%
525
71%
525
34%
931
July11th to 20thNight
81%
522
30%
1566
31%
522
86%
522
54%
757
July21st to endNight
82%
591
28%
1673
29%
558
86%
558
55%
795
August1st to 10thNight
86%
537
29%
1727
34%
534
89%
534
61%
745
August11th to 20thNight
76%
534
26%
1778
31%
534
79%
534
36%
963
August21st to endNight
78%
594
21%
1993
24%
594
80%
594
35%
1102
September1st to 10thNight
72%
540
22%
1980
25%
540
74%
540
34%
1062
September11th to 20thNight
73%
540
22%
1980
24%
540
75%
540
29%
1115
September21st to endNight
68%
540
27%
1980
27%
540
71%
540
35%
1044
October1st to 10thNight
70%
540
34%
1980
32%
540
76%
540
44%
915
October11th to 20thNight
51%
564
35%
2004
25%
564
61%
564
36%
1046
October21st to endNight
44%
792
33%
2376
17%
792
55%
792
39%
1307
November1st to 10thNight
49%
792
30%
2272
15%
792
57%
792
40%
1278
November11th to 20thNight
45%
950
28%
2470
12%
950
53%
950
44%
1410
November21st to endNight
37%
950
29%
2470
12%
950
47%
950
33%
1543
December1st to 10thNight
41%
950
32%
2470
14%
950
51%
950
39%
1470
December11th to 20thNight
32%
950
27%
2901
11%
949
42%
949
29%
1801
December21st to endNight
33%
1040
19%
4304
11%
1026
44%
1026
27%
2214

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
8%5%244345%5%7%52%
74938
Night
8%42442445%8%56%
75022
TransparencyDay
32%6%11%20%21%11%
74663
Night
28%6%11%21%21%13%
74817
SeeingDay
10%8%26%32%19%5%
13745
Night
10%8%34%36%12%1
23839

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
9%6%25%313446%58%
1707
11th to 20thDay
13%5%34423346%53%
1726
21st to endDay
10%424424446%56%
1990
February1st to 10thDay
11%6%35%32335%6%54%
1800
11th to 20thDay
13%6%2342346%6%51%
1749
21st to endDay
12%5%2432445%7%54%
1480
March1st to 10thDay
12%7%25%5%2445%8%46%
1873
11th to 20thDay
11%5%345%34446%51%
1980
21st to endDay
9%5%24434446%55%
2178
April1st to 10thDay
10%5%25%4245%6%7%50%
1980
11th to 20thDay
11%6%35%334447%50%
2098
21st to endDay
9%5%25%5%34347%53%
2215
May1st to 10thDay
10%5%35%435%6%7%7%45%
2340
11th to 20thDay
11%6%36%6%35%5%5%8%43%
2302
21st to endDay
9%5%26%5%46%6%7%8%42%
2531
June1st to 10thDay
4314435%5%7%9%56%
2340
11th to 20thDay
33244345%7%11%56%
2340
21st to endDay
5%325%5%35%6%8%11%47%
2340
July1st to 10thDay
8%435%6%5%7%7%7%9%40%
2340
11th to 20thDay
32134346%6%10%58%
2340
21st to endDay
32235%36%5%6%10%55%
2546
August1st to 10thDay
1213334449%66%
2197
11th to 20thDay
6%326%6%36%6%6%9%48%
2123
21st to endDay
6%325%6%46%6%6%9%46%
2360
September1st to 10thDay
9%5%25%6%35%46%7%47%
1980
11th to 20thDay
10%5%35%6%46%6%6%7%43%
1980
21st to endDay
10%3244345%6%8%51%
1980
October1st to 10thDay
5%4134246%6%8%57%
1980
11th to 20thDay
10%414434446%56%
1936
21st to endDay
9%5%23323445%61%
1980
November1st to 10thDay
11%42342345%7%53%
1801
11th to 20thDay
7%5%233245%5%7%56%
1710
21st to endDay
11%5%35%5%33346%53%
1710
December1st to 10thDay
11%7%23324447%53%
1710
11th to 20thDay
9%7%25%44345%6%50%
2161
21st to endDay
9%6%24323335%59%
3135
January1st to 10thNight
11%424323236%58%
2458
11th to 20thNight
11%5%23323346%56%
2470
21st to endNight
12%5%24433446%53%
2400
February1st to 10thNight
9%6%25%423446%54%
2160
11th to 20thNight
13%5%24323346%54%
2098
21st to endNight
11%5%243245%5%8%52%
1776
March1st to 10thNight
10%6%25%4245%6%8%48%
2085
11th to 20thNight
10%425%5%35%5%5%6%50%
1980
21st to endNight
6%3234345%5%8%57%
2178
April1st to 10thNight
6%424435%5%6%8%54%
1980
11th to 20thNight
8%5%25%5%35%45%6%53%
1807
21st to endNight
8%32343346%8%57%
1742
May1st to 10thNight
6%5%244245%6%10%51%
1620
11th to 20thNight
8%425%425%6%7%8%49%
1593
21st to endNight
7%5%24325%47%11%49%
1745
June1st to 10thNight
22122245%6%12%62%
1620
11th to 20thNight
311232347%10%64%
1620
21st to endNight
42133245%7%9%58%
1620
July1st to 10thNight
5%3246%25%6%6%12%49%
1620
11th to 20thNight
22222346%10%67%
1620
21st to endNight
212221346%11%64%
1772
August1st to 10thNight
1111213349%73%
1737
11th to 20thNight
4323426%5%7%9%54%
1778
21st to endNight
43235%35%5%6%11%53%
1993
September1st to 10thNight
6%4234345%5%9%54%
1980
11th to 20thNight
9%5%234346%6%9%49%
1980
21st to endNight
8%3134335%5%8%56%
1980
October1st to 10thNight
5%21232345%9%65%
1980
11th to 20thNight
8%3245%23446%58%
2004
21st to endNight
10%42342333462%
2376
November1st to 10thNight
8%41432335%6%60%
2272
11th to 20thNight
7%31332346%7%60%
2470
21st to endNight
12%5%24424447%51%
2470
December1st to 10thNight
10%5%1432335%6%56%
2470
11th to 20thNight
9%7%35%5%335%5%6%50%
3036
21st to endNight
9%5%25%422336%59%
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
30%35%18%26%17%
1708
11th to 20thDay
33%46%16%24%17%
1726
21st to endDay
32%47%12%27%18%
1990
February1st to 10thDay
32%5%8%14%21%20%
1800
11th to 20thDay
35%48%18%19%16%
1759
21st to endDay
31%48%16%23%19%
1480
March1st to 10thDay
38%6%8%15%19%14%
1873
11th to 20thDay
36%5%8%15%18%18%
1980
21st to endDay
32%5%9%18%21%15%
2178
April1st to 10thDay
35%5%10%18%19%13%
1980
11th to 20thDay
35%6%7%16%22%14%
2098
21st to endDay
34%5%7%19%21%13%
2215
May1st to 10thDay
37%8%10%15%22%9%
2340
11th to 20thDay
40%7%10%18%20%4
2306
21st to endDay
39%9%12%20%17%2
2531
June1st to 10thDay
25%8%14%28%22%4
2340
11th to 20thDay
24%8%15%26%21%6%
2340
21st to endDay
31%10%14%23%18%5%
2340
July1st to 10thDay
37%11%16%25%10%1
2276
11th to 20thDay
21%9%17%28%22%3
2271
21st to endDay
21%8%24%33%14%1
2405
August1st to 10thDay
18%5%14%40%22%2
2183
11th to 20thDay
31%9%15%28%13%4
2123
21st to endDay
31%10%15%26%14%4
2360
September1st to 10thDay
37%7%11%19%18%8%
1980
11th to 20thDay
39%8%12%17%18%5%
1980
21st to endDay
30%8%11%21%19%11%
1980
October1st to 10thDay
24%8%12%20%25%10%
1980
11th to 20thDay
31%5%8%14%24%18%
1936
21st to endDay
28%46%15%27%20%
1980
November1st to 10thDay
33%410%20%21%12%
1801
11th to 20thDay
28%6%10%16%23%17%
1710
21st to endDay
35%46%17%23%15%
1710
December1st to 10thDay
32%5%9%19%25%10%
1710
11th to 20thDay
34%6%9%11%23%17%
2159
21st to endDay
29%4415%28%19%
3135
January1st to 10thNight
30%35%16%25%21%
2458
11th to 20thNight
31%46%18%23%19%
2470
21st to endNight
33%46%14%23%21%
2400
February1st to 10thNight
32%5%8%12%22%20%
2160
11th to 20thNight
33%47%17%21%18%
2098
21st to endNight
33%5%8%12%21%21%
1776
March1st to 10thNight
33%7%9%16%22%13%
2085
11th to 20thNight
35%6%8%14%18%18%
1980
21st to endNight
28%6%12%19%19%17%
2178
April1st to 10thNight
30%6%11%20%16%17%
1980
11th to 20thNight
33%6%10%15%19%17%
1807
21st to endNight
30%5%11%21%21%12%
1742
May1st to 10thNight
30%8%12%20%19%11%
1620
11th to 20thNight
32%9%13%23%17%5%
1594
21st to endNight
31%9%16%27%15%2
1746
June1st to 10thNight
16%9%18%32%22%3
1620
11th to 20thNight
16%7%17%30%22%7%
1620
21st to endNight
22%8%17%28%20%5%
1620
July1st to 10thNight
26%12%21%28%10%1
1575
11th to 20thNight
14%8%19%31%25%3
1566
21st to endNight
13%8%25%39%14%1
1673
August1st to 10thNight
11%6%19%41%22%1
1727
11th to 20thNight
24%10%19%28%15%4
1778
21st to endNight
25%11%21%26%15%3
1993
September1st to 10thNight
27%7%14%24%20%8%
1980
11th to 20thNight
31%9%17%22%16%5%
1980
21st to endNight
28%7%13%21%19%12%
1980
October1st to 10thNight
19%6%15%26%22%11%
1980
11th to 20thNight
28%5%10%17%23%18%
2004
21st to endNight
28%46%17%23%22%
2376
November1st to 10thNight
28%5%9%19%25%15%
2272
11th to 20thNight
25%6%9%21%22%18%
2470
21st to endNight
35%5%7%15%21%16%
2470
December1st to 10thNight
29%5%10%18%24%14%
2470
11th to 20thNight
36%5%6%13%19%21%
3037
21st to endNight
30%45%15%29%18%
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
16%16%41%23%31
270
11th to 20thDay
19%16%34%23%6%1
270
21st to endDay
10%18%48%20%4
267
February1st to 10thDay
19%17%37%21%5%
240
11th to 20thDay
24%13%42%18%21
240
21st to endDay
17%20%41%20%3
198
March1st to 10thDay
14%20%45%18%3
240
11th to 20thDay
15%19%38%20%7%
240
21st to endDay
14%19%47%16%31
264
April1st to 10thDay
15%19%45%20%2
240
11th to 20thDay
13%22%43%19%31
376
21st to endDay
12%18%46%20%4
475
May1st to 10thDay
11%13%46%26%5%
603
11th to 20thDay
17%9%33%30%9%2
625
21st to endDay
12%8%32%35%11%1
679
June1st to 10thDay
5%321%47%21%4
630
11th to 20thDay
4223%52%16%3
630
21st to endDay
4119%44%27%5%
630
July1st to 10thDay
5%213%42%30%8%
621
11th to 20thDay
216%46%38%7%
618
21st to endDay
36%43%36%12%
684
August1st to 10thDay
2443%42%9%
495
11th to 20thDay
7%17%33%38%14%
437
21st to endDay
7%25%32%41%14%
479
September1st to 10thDay
10%426%41%19%
270
11th to 20thDay
7%19%28%39%17%
270
21st to endDay
15%1332%34%13%
270
October1st to 10thDay
5%416%37%32%6%
270
11th to 20thDay
9%5%29%37%16%4
270
21st to endDay
18%13%29%27%11%1
297
November1st to 10thDay
18%436%29%10%3
270
11th to 20thDay
16%13%31%25%10%4
270
21st to endDay
19%22%29%21%7%2
270
December1st to 10thDay
14%9%36%30%9%3
270
11th to 20thDay
14%18%38%22%7%
270
21st to endDay
15%13%40%24%7%
297
January1st to 10thNight
14%11%40%29%6%1
950
11th to 20thNight
16%9%40%30%5%
950
21st to endNight
14%12%40%27%7%
800
February1st to 10thNight
13%14%41%27%4
720
11th to 20thNight
16%13%43%24%3
704
21st to endNight
16%16%49%19%1
592
March1st to 10thNight
13%15%47%23%2
645
11th to 20thNight
13%11%43%28%4
540
21st to endNight
9%12%56%20%3
594
April1st to 10thNight
6%14%55%22%3
540
11th to 20thNight
9%15%53%21%2
533
21st to endNight
10%10%56%19%5%
540
May1st to 10thNight
8%12%53%24%4
540
11th to 20thNight
10%8%43%31%8%
531
21st to endNight
7%8%43%33%9%
584
June1st to 10thNight
2132%48%16%1
540
11th to 20thNight
3140%47%8%
540
21st to endNight
3224%50%19%2
540
July1st to 10thNight
5%216%53%22%2
525
11th to 20thNight
312%61%22%1
522
21st to endNight
2110%63%22%2
591
August1st to 10thNight
19%63%25%2
537
11th to 20thNight
6%19%52%30%2
534
21st to endNight
418%49%34%4
594
September1st to 10thNight
7%211%47%29%4
540
11th to 20thNight
10%19%46%33%1
540
21st to endNight
9%116%47%26%1
540
October1st to 10thNight
4120%47%25%2
540
11th to 20thNight
10%5%29%41%13%1
564
21st to endNight
11%10%33%30%15%1
792
November1st to 10thNight
11%5%32%38%13%1
792
11th to 20thNight
9%8%35%33%13%1
950
21st to endNight
15%11%34%31%9%1
950
December1st to 10thNight
13%9%35%36%8%
950
11th to 20thNight
13%12%40%31%5%
950
21st to endNight
13%11%40%29%6%
1045
Page generated at 2024-01-19 08:28:32. Version ac07

Copyright 2024 Attilla Danko


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