"Flying F" Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the "Flying F" 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
46%
24386
29%
74439
16%
24333
59%
24333
39%
38232

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
39%
873
31%
2570
15%
869
56%
869
44%
1264
January11th to 20thNight
39%
724
33%
2352
21%
724
57%
724
43%
1085
January21st to endNight
39%
792
35%
2574
20%
792
59%
792
41%
1252
February1st to 10thNight
30%
720
28%
2340
12%
720
51%
720
38%
1151
February11th to 20thNight
31%
702
31%
2184
14%
700
52%
700
41%
1070
February21st to endNight
27%
592
35%
1776
12%
592
52%
592
38%
927
March1st to 10thNight
35%
720
31%
2032
14%
720
51%
720
41%
1013
March11th to 20thNight
39%
720
29%
1980
14%
720
51%
720
41%
1075
March21st to endNight
31%
752
29%
2138
10%
752
48%
752
38%
1134
April1st to 10thNight
29%
540
28%
1800
12%
540
50%
540
35%
846
April11th to 20thNight
30%
533
27%
1777
12%
533
50%
533
30%
903
April21st to endNight
34%
540
30%
1800
13%
540
56%
540
34%
895
May1st to 10thNight
36%
540
26%
1740
14%
540
51%
540
36%
869
May11th to 20thNight
45%
531
23%
1516
14%
531
53%
531
33%
859
May21st to endNight
42%
584
27%
1552
13%
582
54%
582
39%
832
June1st to 10thNight
60%
540
30%
1440
18%
540
67%
540
52%
719
June11th to 20thNight
53%
540
34%
1440
23%
540
60%
540
55%
693
June21st to endNight
65%
540
29%
1440
21%
540
71%
540
49%
757
July1st to 10thNight
69%
525
18%
1400
16%
525
70%
525
34%
864
July11th to 20thNight
76%
522
18%
1516
15%
522
77%
522
37%
857
July21st to endNight
69%
591
11%
1674
11%
558
71%
558
24%
1108
August1st to 10thNight
69%
537
15%
1602
13%
534
71%
534
28%
985
August11th to 20thNight
70%
534
21%
1719
21%
534
74%
534
34%
955
August21st to endNight
67%
594
21%
1980
21%
594
70%
594
30%
1167
September1st to 10thNight
66%
540
26%
1800
23%
540
73%
540
33%
1011
September11th to 20thNight
63%
540
34%
1800
28%
540
73%
540
37%
944
September21st to endNight
63%
661
33%
2037
24%
661
72%
661
48%
990
October1st to 10thNight
49%
720
27%
2160
14%
720
59%
720
36%
1186
October11th to 20thNight
50%
720
39%
2160
18%
720
67%
720
55%
959
October21st to endNight
48%
792
39%
2376
19%
792
64%
792
48%
1132
November1st to 10thNight
49%
794
37%
2274
18%
794
62%
794
53%
1048
November11th to 20thNight
43%
950
39%
2470
17%
950
58%
950
58%
1181
November21st to endNight
43%
950
33%
2608
17%
950
55%
950
45%
1344
December1st to 10thNight
34%
950
28%
2660
10%
950
49%
950
44%
1360
December11th to 20thNight
35%
949
30%
3098
13%
948
48%
948
36%
1566
December21st to endNight
30%
1034
18%
4654
12%
1026
44%
1026
26%
2231

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
46%36%6%35%5%5%7%49%
74686
Night
242442445%8%60%
75029
TransparencyDay
34%49%23%22%8%
74404
Night
24%412%27%26%8%
74833
SeeingDay
18%21%24%21%13%3
14161
Night
8%11%29%32%17%2
24400

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
327%5%335%6%9%58%
1612
11th to 20thDay
336%5%4445%8%58%
1620
21st to endDay
437%6%2345%7%57%
1782
February1st to 10thDay
5%310%5%3435%8%55%
1620
11th to 20thDay
16%36%7%25%5%6%9%51%
1664
21st to endDay
4410%7%345%6%9%47%
1480
March1st to 10thDay
16%46%7%35%5%5%8%49%
1926
11th to 20thDay
29%47%5%35%45%8%50%
1980
21st to endDay
28%6%7%6%45%45%8%44%
2218
April1st to 10thDay
28%36%6%36%45%8%50%
2160
11th to 20thDay
211%47%6%45%5%6%7%44%
2131
21st to endDay
38%46%7%35%5%5%7%45%
2160
May1st to 10thDay
49%38%6%37%5%5%7%44%
2217
11th to 20thDay
6%10%47%7%46%5%5%8%39%
2375
21st to endDay
6%7%26%5%35%5%6%6%50%
2724
June1st to 10thDay
5%5%245%36%6%5%8%52%
2520
11th to 20thDay
44245%35%5%5%6%59%
2520
21st to endDay
45%36%6%46%6%6%6%48%
2520
July1st to 10thDay
8%7%37%8%5%7%5%6%6%38%
2520
11th to 20thDay
8%7%49%9%5%7%7%6%7%33%
2389
21st to endDay
11%8%49%9%6%8%7%7%7%24%
2545
August1st to 10thDay
13%8%48%9%5%6%5%6%6%29%
2328
11th to 20thDay
9%7%47%7%47%7%6%7%35%
2179
21st to endDay
9%8%47%8%6%5%6%6%6%35%
2376
September1st to 10thDay
8%7%37%8%45%5%6%6%40%
2160
11th to 20thDay
7%6%38%6%45%5%5%6%47%
2160
21st to endDay
6%6%35%5%34445%55%
1919
October1st to 10thDay
8%9%26%5%33445%52%
1800
11th to 20thDay
35%1332334469%
1800
21st to endDay
35%35%322345%64%
1980
November1st to 10thDay
1423322437%70%
1783
11th to 20thDay
1322323446%72%
1710
21st to endDay
435%5%24447%63%
1568
December1st to 10thDay
1435%5%3335%8%60%
1520
11th to 20thDay
4345%345%6%9%56%
1926
21st to endDay
5%36%42345%8%59%
2794
January1st to 10thNight
225%5%3345%7%65%
2570
11th to 20thNight
325%333346%66%
2352
21st to endNight
336%32445%7%63%
2574
February1st to 10thNight
335%5%335%47%62%
2340
11th to 20thNight
325%5%345%5%7%62%
2183
21st to endNight
336%5%35%35%8%59%
1776
March1st to 10thNight
325%32346%8%63%
2032
11th to 20thNight
15%36%42445%8%58%
1980
21st to endNight
15%3443435%8%59%
2138
April1st to 10thNight
15%2433446%8%63%
1800
11th to 20thNight
17%34436%46%8%53%
1777
21st to endNight
15%334245%5%7%60%
1800
May1st to 10thNight
25%345%3445%8%58%
1740
11th to 20thNight
47%35%43345%8%53%
1516
21st to endNight
5%41342445%6%61%
1552
June1st to 10thNight
221222446%8%66%
1440
11th to 20thNight
231232335%6%71%
1440
21st to endNight
2323325%6%6%8%61%
1440
July1st to 10thNight
45%25%6%47%6%6%10%45%
1440
11th to 20thNight
3423435%7%8%11%50%
1567
21st to endNight
5%6%36%6%36%7%9%12%37%
1773
August1st to 10thNight
5%326%6%36%6%9%10%44%
1611
11th to 20thNight
5%5%25%5%345%9%9%48%
1719
21st to endNight
5%5%35%5%36%6%6%10%46%
1980
September1st to 10thNight
5%5%25%6%35%6%7%9%48%
1800
11th to 20thNight
5%4245%35%46%8%55%
1800
21st to endNight
431432235%5%66%
2037
October1st to 10thNight
6%5%25%43445%6%57%
2160
11th to 20thNight
2312223347%72%
2160
21st to endNight
25%24322336%68%
2376
November1st to 10thNight
1322213447%70%
2274
11th to 20thNight
212213347%74%
2470
21st to endNight
15%3443345%6%64%
2608
December1st to 10thNight
424434448%63%
2660
11th to 20thNight
425%4245%6%9%58%
3271
21st to endNight
5%36%5%3445%7%58%
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
23%316%30%23%6%
1613
11th to 20thDay
25%311%31%25%5%
1620
21st to endDay
28%38%30%23%8%
1782
February1st to 10thDay
29%413%27%18%10%
1620
11th to 20thDay
30%48%25%25%9%
1673
21st to endDay
35%47%21%23%10%
1480
March1st to 10thDay
31%49%26%23%6%
1926
11th to 20thDay
33%39%29%22%5%
1980
21st to endDay
37%310%26%20%4
2218
April1st to 10thDay
31%49%24%22%10%
2160
11th to 20thDay
37%38%24%22%7%
2134
21st to endDay
37%38%29%20%3
2160
May1st to 10thDay
37%39%25%23%3
2217
11th to 20thDay
42%410%25%16%3
2379
21st to endDay
33%47%22%26%8%
2724
June1st to 10thDay
30%39%26%22%10%
2520
11th to 20thDay
24%37%19%28%19%
2520
21st to endDay
34%46%18%24%14%
2520
July1st to 10thDay
44%6%9%14%15%12%
2451
11th to 20thDay
47%6%15%16%10%5%
2317
21st to endDay
55%8%18%11%7%1
2404
August1st to 10thDay
54%6%11%10%12%6%
2313
11th to 20thDay
46%5%12%16%16%6%
2179
21st to endDay
47%5%10%19%16%3
2376
September1st to 10thDay
44%49%14%20%8%
2160
11th to 20thDay
39%37%18%24%9%
2160
21st to endDay
29%35%24%32%7%
1919
October1st to 10thDay
34%26%22%24%11%
1800
11th to 20thDay
21%3322%39%12%
1800
21st to endDay
23%26%28%31%9%
1980
November1st to 10thDay
16%38%27%35%11%
1783
11th to 20thDay
14%28%33%33%10%
1710
21st to endDay
22%38%26%28%13%
1568
December1st to 10thDay
24%314%28%23%8%
1520
11th to 20thDay
24%5%11%28%25%6%
1924
21st to endDay
26%38%21%25%17%
2794
January1st to 10thNight
20%313%31%26%7%
2570
11th to 20thNight
20%214%29%29%6%
2352
21st to endNight
21%47%34%26%7%
2574
February1st to 10thNight
23%314%27%24%9%
2340
11th to 20thNight
21%310%29%27%9%
2184
21st to endNight
26%27%26%30%9%
1776
March1st to 10thNight
19%312%29%31%5%
2032
11th to 20thNight
26%211%33%22%6%
1980
21st to endNight
24%412%30%26%4
2138
April1st to 10thNight
19%5%14%28%27%7%
1800
11th to 20thNight
28%210%29%26%6%
1777
21st to endNight
24%412%36%21%4
1800
May1st to 10thNight
25%311%32%24%5%
1740
11th to 20thNight
32%314%27%21%2
1517
21st to endNight
24%311%29%25%8%
1552
June1st to 10thNight
18%313%27%29%10%
1440
11th to 20thNight
15%36%24%32%21%
1440
21st to endNight
21%49%22%26%18%
1440
July1st to 10thNight
36%414%14%18%14%
1400
11th to 20thNight
27%8%22%22%12%9%
1516
21st to endNight
38%12%28%15%5%2
1674
August1st to 10thNight
34%9%17%17%14%9%
1602
11th to 20thNight
31%5%19%19%18%8%
1719
21st to endNight
35%6%15%22%19%4
1980
September1st to 10thNight
32%5%15%18%22%8%
1800
11th to 20thNight
28%411%21%27%10%
1800
21st to endNight
20%36%31%34%6%
2037
October1st to 10thNight
30%39%20%28%11%
2160
11th to 20thNight
14%36%24%41%12%
2160
21st to endNight
19%26%34%32%7%
2376
November1st to 10thNight
14%311%32%31%9%
2274
11th to 20thNight
12%39%35%33%8%
2470
21st to endNight
22%37%28%31%10%
2608
December1st to 10thNight
21%316%27%24%8%
2660
11th to 20thNight
22%5%12%27%28%6%
3272
21st to endNight
28%38%21%26%13%
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
17%18%33%20%10%1
270
11th to 20thDay
16%23%27%25%7%1
240
21st to endDay
9%24%37%24%7%
264
February1st to 10thDay
22%27%31%18%21
240
11th to 20thDay
23%30%27%15%41
240
21st to endDay
30%28%22%18%2
198
March1st to 10thDay
26%29%27%13%4
366
11th to 20thDay
25%29%26%15%5%1
420
21st to endDay
33%32%26%6%3
462
April1st to 10thDay
27%32%25%12%31
420
11th to 20thDay
33%36%18%8%4
412
21st to endDay
32%32%21%11%3
420
May1st to 10thDay
25%34%25%10%5%1
423
11th to 20thDay
18%28%26%16%9%2
522
21st to endDay
21%24%21%21%12%2
679
June1st to 10thDay
9%21%23%26%18%3
630
11th to 20thDay
11%23%25%23%13%4
630
21st to endDay
8%20%21%23%22%6%
630
July1st to 10thDay
9%9%16%31%27%7%
621
11th to 20thDay
11%7%19%30%26%8%
490
21st to endDay
14%8%15%31%24%8%
487
August1st to 10thDay
19%9%21%28%19%5%
447
11th to 20thDay
14%10%22%32%18%5%
437
21st to endDay
13%9%25%28%21%4
495
September1st to 10thDay
12%13%25%23%22%5%
450
11th to 20thDay
12%22%28%22%13%2
450
21st to endDay
17%16%23%20%20%3
334
October1st to 10thDay
19%17%23%19%17%5%
270
11th to 20thDay
15%21%25%20%17%2
270
21st to endDay
18%24%23%20%12%3
297
November1st to 10thDay
21%19%23%25%10%1
270
11th to 20thDay
14%20%27%26%10%2
270
21st to endDay
16%19%30%20%13%3
270
December1st to 10thDay
17%20%32%18%9%3
270
11th to 20thDay
17%19%32%20%10%1
270
21st to endDay
21%22%32%19%6%1
297
January1st to 10thNight
6%15%35%33%10%2
873
11th to 20thNight
6%13%36%33%11%1
724
21st to endNight
5%12%40%34%7%2
792
February1st to 10thNight
5%15%44%29%6%1
720
11th to 20thNight
8%14%43%28%8%
704
21st to endNight
9%15%45%28%3
592
March1st to 10thNight
9%21%33%30%7%
720
11th to 20thNight
6%13%37%32%13%1
720
21st to endNight
9%16%40%30%5%
752
April1st to 10thNight
10%19%37%29%4
540
11th to 20thNight
13%19%35%26%8%
533
21st to endNight
9%19%35%27%10%1
540
May1st to 10thNight
8%13%36%31%12%1
540
11th to 20thNight
10%11%24%37%16%2
531
21st to endNight
11%15%26%30%17%2
584
June1st to 10thNight
5%8%23%36%26%1
540
11th to 20thNight
5%9%29%36%19%2
540
21st to endNight
38%17%39%30%2
540
July1st to 10thNight
5%49%37%42%4
525
11th to 20thNight
6%26%33%47%7%
522
21st to endNight
8%2326%52%8%
591
August1st to 10thNight
7%36%29%48%6%
537
11th to 20thNight
6%29%37%41%5%
534
21st to endNight
7%411%35%39%5%
594
September1st to 10thNight
6%314%38%35%4
540
11th to 20thNight
9%417%39%28%3
540
21st to endNight
6%8%17%37%27%4
661
October1st to 10thNight
9%9%26%36%18%2
720
11th to 20thNight
6%8%32%36%15%3
720
21st to endNight
8%12%26%34%17%3
792
November1st to 10thNight
6%13%29%35%14%2
794
11th to 20thNight
8%11%36%32%11%2
950
21st to endNight
9%13%32%33%12%1
950
December1st to 10thNight
8%14%40%29%8%1
950
11th to 20thNight
9%17%35%29%9%1
950
21st to endNight
10%13%41%29%6%1
1045
Page generated at 2024-01-08 09:14:17. Version ac07

Copyright 2024 Attilla Danko


"Flying F" Observatory Clear Sky Chart |Charts Home