Fossil Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fossil Falls clear sky chart from 2005-11-06 to 2024-10-24.

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
59%
24870
38%
92580
26%
24635
73%
24635
55%
34913

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
51%
756
40%
4262
21%
736
68%
736
37%
1376
January11th to 20thNight
52%
758
36%
4206
25%
740
70%
740
34%
1551
January21st to endNight
45%
831
26%
4028
22%
814
66%
814
30%
1770
February1st to 10thNight
50%
760
38%
2280
24%
760
67%
760
49%
1072
February11th to 20thNight
51%
740
40%
2218
26%
740
70%
740
52%
995
February21st to endNight
43%
628
36%
1884
22%
628
64%
628
52%
846
March1st to 10thNight
41%
757
40%
3652
17%
744
64%
744
38%
1228
March11th to 20thNight
45%
757
33%
3673
18%
740
63%
740
34%
1402
March21st to endNight
42%
833
26%
3285
15%
814
61%
814
44%
1265
April1st to 10thNight
43%
760
39%
1900
14%
760
60%
760
54%
950
April11th to 20thNight
45%
751
39%
1879
13%
751
59%
751
60%
896
April21st to endNight
50%
760
39%
1900
13%
760
63%
760
68%
873
May1st to 10thNight
46%
609
51%
2692
19%
602
59%
602
65%
713
May11th to 20thNight
57%
549
37%
2696
24%
541
69%
541
66%
658
May21st to endNight
56%
602
28%
3054
21%
593
68%
593
68%
699
June1st to 10thNight
69%
413
40%
1553
36%
413
80%
413
68%
514
June11th to 20thNight
63%
380
41%
1520
37%
380
79%
380
68%
477
June21st to endNight
71%
380
41%
1520
39%
380
85%
380
78%
447
July1st to 10thNight
80%
368
50%
2067
43%
360
92%
360
75%
439
July11th to 20thNight
85%
365
38%
1898
45%
359
91%
359
56%
568
July21st to endNight
81%
584
36%
2236
32%
543
86%
543
64%
717
August1st to 10thNight
76%
744
43%
2510
22%
733
80%
733
69%
936
August11th to 20thNight
82%
745
38%
2467
23%
731
86%
731
87%
791
August21st to endNight
80%
825
43%
2811
28%
814
84%
814
83%
905
September1st to 10thNight
80%
760
46%
1900
30%
760
85%
760
80%
849
September11th to 20thNight
71%
760
47%
2042
31%
760
83%
760
78%
847
September21st to endNight
70%
760
48%
2090
33%
760
85%
760
81%
830
October1st to 10thNight
69%
760
46%
2090
32%
760
83%
760
74%
881
October11th to 20thNight
67%
760
44%
2223
35%
760
80%
760
71%
896
October21st to endNight
66%
804
45%
2506
37%
804
81%
804
67%
974
November1st to 10thNight
66%
740
41%
2405
34%
740
82%
740
65%
915
November11th to 20thNight
65%
760
40%
2470
31%
760
80%
760
64%
978
November21st to endNight
56%
760
40%
2470
31%
760
71%
760
57%
1024
December1st to 10thNight
52%
760
35%
2470
22%
760
69%
760
48%
1113
December11th to 20thNight
53%
759
32%
3007
23%
758
70%
758
35%
1442
December21st to endNight
45%
832
22%
4716
21%
817
64%
817
25%
2076

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
2212222246%78%
100869
Night
1212222245%78%
98129
TransparencyDay
10%46%15%27%38%
100620
Night
10%46%18%29%33%
97967
SeeingDay
5%17%36%30%10%3
15301
Night
39%27%35%21%6%
24973

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
321222325%8%71%
2539
11th to 20thDay
221343435%9%65%
2608
21st to endDay
5%41323336%9%61%
3341
February1st to 10thDay
4212233247%71%
1900
11th to 20thDay
32122223410%69%
1850
21st to endDay
321222326%7%70%
1570
March1st to 10thDay
121323336%9%67%
3138
11th to 20thDay
341322335%8%67%
3257
21st to endDay
321323336%8%66%
4165
April1st to 10thDay
2312223347%73%
2280
11th to 20thDay
1212112345%78%
2249
21st to endDay
111121225%7%78%
2280
May1st to 10thDay
111111225%83%
4039
11th to 20thDay
111122246%79%
4071
21st to endDay
11111223485%
4477
June1st to 10thDay
1112122246%79%
2621
11th to 20thDay
11111235%84%
2660
21st to endDay
111111112387%
2660
July1st to 10thDay
1111112388%
4420
11th to 20thDay
111212323479%
4420
21st to endDay
112222235%80%
4482
August1st to 10thDay
211212212483%
3783
11th to 20thDay
1111111391%
3724
21st to endDay
1111112291%
4180
September1st to 10thDay
1112112235%81%
2280
11th to 20thDay
111112389%
2138
21st to endDay
1111112388%
2090
October1st to 10thDay
111111235%82%
2090
11th to 20thDay
21111212483%
1952
21st to endDay
111211123483%
1916
November1st to 10thDay
111122246%80%
1674
11th to 20thDay
112122245%79%
1710
21st to endDay
31221235%6%75%
1710
December1st to 10thDay
221322335%8%70%
1710
11th to 20thDay
341423336%8%61%
2091
21st to endDay
6%425%22335%9%58%
2794
January1st to 10thNight
2213123236%74%
4406
11th to 20thNight
131323336%10%64%
4352
21st to endNight
441433335%8%62%
4329
February1st to 10thNight
2313233446%69%
2280
11th to 20thNight
221222335%6%73%
2218
21st to endNight
4212222247%72%
1884
March1st to 10thNight
121322235%7%73%
3736
11th to 20thNight
221323336%8%68%
3720
21st to endNight
121323335%7%69%
3488
April1st to 10thNight
2112223247%74%
1900
11th to 20thNight
1111212235%80%
1879
21st to endNight
11122245%81%
1900
May1st to 10thNight
1111136%87%
2929
11th to 20thNight
1111135%86%
2834
21st to endNight
111112390%
3110
June1st to 10thNight
111111236%83%
1553
11th to 20thNight
111111112288%
1520
21st to endNight
111122389%
1520
July1st to 10thNight
11111391%
2540
11th to 20thNight
111221222483%
2540
21st to endNight
111111122386%
3061
August1st to 10thNight
11211222484%
3166
11th to 20thNight
11112392%
3126
21st to endNight
11111293%
3498
September1st to 10thNight
11211112486%
1900
11th to 20thNight
111113289%
2042
21st to endNight
11113489%
2090
October1st to 10thNight
11111123485%
2090
11th to 20thNight
11111123484%
2223
21st to endNight
11111135%84%
2506
November1st to 10thNight
112111235%82%
2405
11th to 20thNight
112122246%78%
2470
21st to endNight
221222225%6%75%
2470
December1st to 10thNight
2213332247%70%
2470
11th to 20thNight
242433436%8%62%
3112
21st to endNight
6%31433346%7%59%
4862

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
12%5%8%25%37%12%
2539
11th to 20thDay
17%7%17%24%23%12%
2608
21st to endDay
21%7%11%25%27%10%
3341
February1st to 10thDay
15%5%7%22%30%21%
1900
11th to 20thDay
13%5%8%22%31%21%
1860
21st to endDay
14%6%10%25%30%15%
1570
March1st to 10thDay
13%6%9%24%30%17%
3138
11th to 20thDay
15%7%9%28%26%15%
3257
21st to endDay
13%8%11%26%27%15%
4165
April1st to 10thDay
13%49%24%31%20%
2280
11th to 20thDay
10%46%21%35%24%
2252
21st to endDay
8%47%21%39%21%
2280
May1st to 10thDay
6%45%15%37%33%
4039
11th to 20thDay
6%46%11%45%29%
4074
21st to endDay
7%3310%45%32%
4477
June1st to 10thDay
8%35%13%29%42%
2621
11th to 20thDay
5%249%20%60%
2660
21st to endDay
6%12418%68%
2660
July1st to 10thDay
5%2237%81%
4351
11th to 20thDay
9%337%13%65%
4345
21st to endDay
8%3411%21%52%
4340
August1st to 10thDay
8%225%24%59%
3770
11th to 20thDay
322315%75%
3760
21st to endDay
411415%74%
4179
September1st to 10thDay
8%337%18%60%
2280
11th to 20thDay
4237%28%56%
2138
21st to endDay
5%127%36%49%
2090
October1st to 10thDay
8%3313%30%44%
2090
11th to 20thDay
8%339%35%42%
1952
21st to endDay
8%3311%35%40%
1916
November1st to 10thDay
9%35%15%40%28%
1674
11th to 20thDay
9%37%20%35%26%
1710
21st to endDay
12%48%19%31%27%
1710
December1st to 10thDay
14%6%9%26%25%20%
1710
11th to 20thDay
21%8%9%22%26%13%
2090
21st to endDay
24%7%13%27%20%10%
2794
January1st to 10thNight
14%47%25%37%13%
4406
11th to 20thNight
16%6%13%32%22%10%
4352
21st to endNight
21%6%13%27%25%9%
4329
February1st to 10thNight
17%48%23%28%20%
2280
11th to 20thNight
14%46%22%33%23%
2219
21st to endNight
13%48%24%34%17%
1884
March1st to 10thNight
11%6%9%26%26%22%
3736
11th to 20thNight
13%9%9%27%28%14%
3720
21st to endNight
11%6%8%30%33%11%
3488
April1st to 10thNight
12%5%7%26%33%18%
1900
11th to 20thNight
10%36%25%32%24%
1879
21st to endNight
7%35%23%43%18%
1900
May1st to 10thNight
325%14%45%30%
2929
11th to 20thNight
42315%49%26%
2835
21st to endNight
32414%49%28%
3110
June1st to 10thNight
7%2416%33%38%
1553
11th to 20thNight
6%2211%26%53%
1520
21st to endNight
5%115%20%68%
1520
July1st to 10thNight
31139%83%
2500
11th to 20thNight
7%336%14%68%
2492
21st to endNight
7%2210%23%56%
2965
August1st to 10thNight
7%227%24%57%
3156
11th to 20thNight
212415%76%
3156
21st to endNight
311318%73%
3498
September1st to 10thNight
6%236%20%64%
1900
11th to 20thNight
4328%27%56%
2042
21st to endNight
4227%31%54%
2090
October1st to 10thNight
6%3412%29%46%
2090
11th to 20thNight
7%2311%35%41%
2223
21st to endNight
7%349%36%40%
2506
November1st to 10thNight
8%35%16%40%28%
2405
11th to 20thNight
9%48%18%31%30%
2470
21st to endNight
12%36%20%31%27%
2470
December1st to 10thNight
15%6%8%22%27%21%
2470
11th to 20thNight
19%9%11%24%24%13%
3112
21st to endNight
22%8%10%26%24%10%
4862

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
9%17%42%23%9%1
180
11th to 20thDay
9%24%27%25%12%2
222
21st to endDay
11%19%31%30%8%2
463
February1st to 10thDay
6%26%36%23%7%2
460
11th to 20thDay
10%24%38%22%6%1
455
21st to endDay
9%25%43%18%4
382
March1st to 10thDay
11%28%35%20%5%1
460
11th to 20thDay
10%28%39%17%5%1
460
21st to endDay
11%30%41%16%3
506
April1st to 10thDay
11%25%37%20%6%1
460
11th to 20thDay
8%29%36%21%5%1
452
21st to endDay
5%25%38%22%7%3
460
May1st to 10thDay
8%25%40%21%42
463
11th to 20thDay
323%36%27%7%3
488
21st to endDay
5%18%37%29%9%3
529
June1st to 10thDay
311%36%35%10%4
490
11th to 20thDay
315%37%31%11%3
490
21st to endDay
113%35%36%10%4
490
July1st to 10thDay
26%35%39%14%5%
486
11th to 20thDay
1427%44%17%7%
484
21st to endDay
2429%44%16%6%
531
August1st to 10thDay
27%35%36%14%6%
487
11th to 20thDay
27%30%38%15%7%
477
21st to endDay
15%35%40%14%5%
539
September1st to 10thDay
19%34%39%16%1
490
11th to 20thDay
213%36%37%10%1
490
21st to endDay
312%39%32%13%1
490
October1st to 10thDay
314%37%36%10%
490
11th to 20thDay
412%36%35%11%1
490
21st to endDay
414%34%32%15%1
413
November1st to 10thDay
7%14%27%37%12%2
270
11th to 20thDay
316%36%27%16%3
270
21st to endDay
5%12%36%30%14%2
270
December1st to 10thDay
6%16%38%31%9%1
270
11th to 20thDay
418%35%27%14%2
246
21st to endDay
13%22%33%23%8%2
198
January1st to 10thNight
412%30%26%21%7%
760
11th to 20thNight
310%31%35%16%4
760
21st to endNight
7%12%32%29%15%5%
836
February1st to 10thNight
411%32%29%18%6%
760
11th to 20thNight
5%11%30%32%16%5%
744
21st to endNight
6%14%36%28%13%3
628
March1st to 10thNight
416%35%29%12%4
760
11th to 20thNight
5%15%32%25%16%6%
760
21st to endNight
415%37%30%12%2
836
April1st to 10thNight
316%35%29%14%3
760
11th to 20thNight
217%34%28%16%3
751
21st to endNight
114%33%30%17%4
760
May1st to 10thNight
213%37%33%13%2
613
11th to 20thNight
110%30%38%19%2
561
21st to endNight
212%28%40%17%1
617
June1st to 10thNight
16%23%48%20%2
413
11th to 20thNight
26%28%41%21%3
380
21st to endNight
1324%47%22%3
380
July1st to 10thNight
1116%49%29%5%
370
11th to 20thNight
110%49%36%3
368
21st to endNight
1113%47%35%4
592
August1st to 10thNight
2116%45%29%6%
756
11th to 20thNight
1114%43%34%8%
752
21st to endNight
1116%40%32%10%
836
September1st to 10thNight
1314%37%36%9%
760
11th to 20thNight
5%21%36%29%9%
760
21st to endNight
6%22%33%28%10%
760
October1st to 10thNight
16%23%46%18%6%
760
11th to 20thNight
36%22%38%21%10%
760
21st to endNight
28%22%30%26%11%
804
November1st to 10thNight
29%21%34%24%9%
740
11th to 20thNight
16%24%36%24%8%
760
21st to endNight
48%30%33%19%6%
760
December1st to 10thNight
49%31%31%20%5%
760
11th to 20thNight
48%32%35%16%5%
760
21st to endNight
415%32%28%16%5%
836
Page generated at 2024-10-20 23:20:05. Version ac07

Copyright © 2024 Attilla Danko.


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