Franklin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Franklin clear sky chart from 2005-11-06 to 2024-01-27.

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
42%
24353
19%
74761
14%
24303
48%
24303
24%
49467

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
24%
950
15%
2648
7%
946
32%
946
17%
1979
January11th to 20thNight
21%
950
12%
2660
6%
950
26%
950
15%
2065
January21st to endNight
23%
921
14%
2757
7%
921
30%
921
16%
2051
February1st to 10thNight
21%
720
12%
2160
6%
720
27%
720
15%
1626
February11th to 20thNight
25%
701
16%
2099
8%
700
33%
700
19%
1469
February21st to endNight
22%
592
16%
1776
7%
592
30%
592
16%
1298
March1st to 10thNight
28%
720
17%
2160
9%
720
33%
720
21%
1467
March11th to 20thNight
30%
720
17%
2044
9%
720
37%
720
23%
1409
March21st to endNight
31%
724
16%
2110
9%
724
38%
724
20%
1502
April1st to 10thNight
35%
540
20%
1800
12%
540
45%
540
24%
1116
April11th to 20thNight
38%
533
21%
1775
17%
533
46%
533
25%
1113
April21st to endNight
32%
540
19%
1648
8%
540
43%
540
24%
1082
May1st to 10thNight
35%
540
14%
1620
8%
540
41%
540
21%
1131
May11th to 20thNight
47%
531
18%
1593
12%
531
51%
531
26%
1033
May21st to endNight
59%
582
18%
1721
13%
582
64%
582
32%
1062
June1st to 10thNight
61%
540
19%
1440
15%
540
64%
540
37%
888
June11th to 20thNight
61%
540
22%
1440
16%
540
65%
540
36%
870
June21st to endNight
65%
540
22%
1440
17%
540
68%
540
41%
847
July1st to 10thNight
71%
525
18%
1400
16%
525
72%
525
36%
865
July11th to 20thNight
73%
522
22%
1392
17%
522
74%
522
44%
793
July21st to endNight
69%
591
25%
1582
21%
558
71%
558
39%
933
August1st to 10thNight
73%
537
23%
1600
22%
534
74%
534
36%
925
August11th to 20thNight
71%
534
24%
1693
23%
534
74%
534
37%
947
August21st to endNight
74%
594
25%
1980
27%
594
77%
594
40%
1022
September1st to 10thNight
67%
558
24%
1818
22%
558
70%
558
32%
1044
September11th to 20thNight
70%
720
32%
1980
27%
720
73%
720
43%
1113
September21st to endNight
58%
720
28%
1980
21%
720
62%
720
36%
1197
October1st to 10thNight
58%
720
29%
1980
21%
720
64%
720
41%
1135
October11th to 20thNight
43%
720
25%
2104
17%
720
52%
720
29%
1325
October21st to endNight
36%
792
21%
2574
16%
792
44%
792
23%
1667
November1st to 10thNight
45%
740
25%
2406
21%
740
53%
740
29%
1411
November11th to 20thNight
35%
760
25%
2470
15%
760
48%
760
25%
1542
November21st to endNight
33%
760
19%
2470
13%
760
41%
760
18%
1711
December1st to 10thNight
25%
760
15%
2470
9%
760
33%
760
17%
1760
December11th to 20thNight
28%
882
16%
3120
9%
881
33%
881
16%
2175
December21st to endNight
21%
1034
7%
4851
6%
1026
27%
1026
7%
3894

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
14%8%36%6%35%5%5%7%38%
74983
Night
15%8%46%5%3445%7%39%
75075
TransparencyDay
46%411%23%14%2
74691
Night
46%310%23%15%3
74888
SeeingDay
17%6%23%26%19%9%
14415
Night
18%6%25%33%16%2
24369

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
16%12%7%9%7%35%45%6%26%
1517
11th to 20thDay
17%12%6%10%7%44445%25%
1520
21st to endDay
14%15%5%9%7%35%45%7%26%
1735
February1st to 10thDay
18%12%7%9%6%34446%27%
1800
11th to 20thDay
16%10%5%9%6%45%45%6%30%
1748
21st to endDay
17%13%5%9%5%34446%31%
1480
March1st to 10thDay
17%9%47%7%34446%34%
1800
11th to 20thDay
19%9%46%5%345%5%6%34%
1916
21st to endDay
19%11%48%6%3446%6%27%
2261
April1st to 10thDay
14%8%46%6%445%5%8%36%
2160
11th to 20thDay
16%8%35%6%345%6%7%38%
2134
21st to endDay
19%8%36%5%3445%8%35%
2312
May1st to 10thDay
18%7%36%7%35%5%5%8%34%
2340
11th to 20thDay
19%8%36%6%345%6%7%35%
2301
21st to endDay
9%5%37%6%46%7%9%8%37%
2551
June1st to 10thDay
11%5%346%36%5%6%8%43%
2520
11th to 20thDay
9%5%25%5%35%5%6%9%46%
2520
21st to endDay
9%5%35%5%36%5%7%10%41%
2520
July1st to 10thDay
11%5%26%6%35%6%6%11%41%
2520
11th to 20thDay
7%424436%6%6%10%47%
2520
21st to endDay
9%4245%36%6%7%10%42%
2640
August1st to 10thDay
8%425%5%45%7%7%10%44%
2327
11th to 20thDay
10%5%36%5%35%6%7%10%39%
2204
21st to endDay
7%425%5%35%6%6%9%48%
2376
September1st to 10thDay
13%5%25%6%35%5%5%8%43%
2124
11th to 20thDay
11%6%24435%5%6%8%48%
1980
21st to endDay
12%4245%34447%51%
1980
October1st to 10thDay
13%5%25%5%34447%48%
1980
11th to 20thDay
13%6%25%445%46%7%45%
1850
21st to endDay
19%9%37%6%3445%5%35%
1782
November1st to 10thDay
8%6%335%25%446%53%
1672
11th to 20thDay
16%8%46%5%3445%7%38%
1710
21st to endDay
19%10%46%5%24346%36%
1710
December1st to 10thDay
19%12%6%7%5%44446%29%
1710
11th to 20thDay
14%15%7%9%5%34445%30%
1980
21st to endDay
22%19%7%8%6%34445%18%
2783
January1st to 10thNight
17%10%6%9%6%45%45%5%29%
2648
11th to 20thNight
17%13%7%9%7%44445%25%
2660
21st to endNight
17%13%5%8%7%35%45%428%
2757
February1st to 10thNight
21%10%5%10%6%34445%27%
2160
11th to 20thNight
15%10%5%7%6%445%5%6%32%
2098
21st to endNight
20%11%49%6%2345%6%30%
1776
March1st to 10thNight
16%10%38%6%345%45%37%
2160
11th to 20thNight
17%8%37%435%5%5%7%37%
2044
21st to endNight
19%9%38%5%345%47%34%
2110
April1st to 10thNight
13%7%46%5%345%6%7%40%
1800
11th to 20thNight
15%8%36%43445%7%41%
1775
21st to endNight
17%6%27%5%35%46%7%38%
1648
May1st to 10thNight
18%8%36%7%36%5%5%7%33%
1620
11th to 20thNight
16%5%36%5%3445%8%41%
1592
21st to endNight
8%6%36%5%36%6%7%11%41%
1720
June1st to 10thNight
9%5%35%5%345%5%8%48%
1440
11th to 20thNight
9%426%5%35%46%9%48%
1440
21st to endNight
6%3345%35%5%7%10%50%
1440
July1st to 10thNight
8%6%244346%7%10%46%
1440
11th to 20thNight
7%4234335%7%9%53%
1440
21st to endNight
9%5%25%5%2445%7%53%
1675
August1st to 10thNight
7%425%5%35%6%6%8%51%
1611
11th to 20thNight
6%4245%35%6%7%8%50%
1693
21st to endNight
6%32443446%9%54%
1980
September1st to 10thNight
12%425%6%345%5%8%48%
1818
11th to 20thNight
8%41432445%7%56%
1980
21st to endNight
11%5%245%34347%52%
1980
October1st to 10thNight
9%42443335%7%56%
1980
11th to 20thNight
16%6%25%44435%6%45%
2104
21st to endNight
18%7%36%5%35%446%40%
2574
November1st to 10thNight
11%6%35%43445%6%48%
2406
11th to 20thNight
15%8%35%5%2445%8%41%
2470
21st to endNight
18%11%47%6%3445%6%34%
2470
December1st to 10thNight
18%10%5%8%6%35%45%5%31%
2470
11th to 20thNight
18%11%48%5%3435%6%32%
3212
21st to endNight
23%17%6%8%7%35%44418%
4884

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
59%47%18%12%1
1518
11th to 20thDay
63%310%17%7%
1520
21st to endDay
60%211%20%5%1
1735
February1st to 10thDay
60%39%18%10%1
1800
11th to 20thDay
55%410%21%9%1
1758
21st to endDay
56%39%21%9%2
1480
March1st to 10thDay
53%38%23%12%1
1800
11th to 20thDay
51%313%20%11%2
1916
21st to endDay
59%312%19%6%1
2261
April1st to 10thDay
48%311%23%14%1
2160
11th to 20thDay
46%311%24%13%3
2134
21st to endDay
49%311%22%13%3
2312
May1st to 10thDay
49%5%13%23%9%1
2340
11th to 20thDay
49%412%21%13%1
2305
21st to endDay
41%6%15%22%15%2
2551
June1st to 10thDay
39%411%26%16%3
2520
11th to 20thDay
36%412%25%20%2
2520
21st to endDay
38%5%16%23%14%4
2520
July1st to 10thDay
38%5%15%23%16%3
2451
11th to 20thDay
31%5%16%30%16%2
2445
21st to endDay
35%5%17%24%16%3
2493
August1st to 10thDay
34%5%14%30%14%2
2314
11th to 20thDay
39%5%14%26%16%2
2204
21st to endDay
31%5%13%26%17%7%
2376
September1st to 10thDay
39%410%27%16%4
2124
11th to 20thDay
34%310%28%20%3
1980
21st to endDay
34%38%27%26%2
1980
October1st to 10thDay
37%311%25%22%3
1980
11th to 20thDay
39%29%25%22%3
1850
21st to endDay
51%29%23%14%1
1782
November1st to 10thDay
33%311%30%18%4
1672
11th to 20thDay
46%39%23%16%4
1710
21st to endDay
51%29%23%13%1
1710
December1st to 10thDay
59%39%19%10%
1710
11th to 20thDay
58%36%21%10%1
1977
21st to endDay
70%39%12%6%
2783
January1st to 10thNight
58%37%20%12%
2648
11th to 20thNight
63%210%17%7%
2660
21st to endNight
59%210%18%9%1
2757
February1st to 10thNight
61%211%18%7%1
2160
11th to 20thNight
53%311%21%12%1
2099
21st to endNight
57%211%18%10%2
1776
March1st to 10thNight
50%28%24%14%2
2160
11th to 20thNight
48%412%22%13%2
2044
21st to endNight
53%310%24%8%2
2110
April1st to 10thNight
42%312%27%13%2
1800
11th to 20thNight
44%210%20%18%5%
1775
21st to endNight
46%410%23%14%4
1648
May1st to 10thNight
51%411%21%10%3
1620
11th to 20thNight
42%5%13%22%15%2
1593
21st to endNight
36%6%17%22%14%5%
1721
June1st to 10thNight
34%411%26%22%3
1440
11th to 20thNight
34%412%26%21%4
1440
21st to endNight
29%5%17%25%20%4
1440
July1st to 10thNight
34%5%15%23%17%6%
1400
11th to 20thNight
28%415%31%19%4
1392
21st to endNight
32%312%31%18%4
1582
August1st to 10thNight
32%5%14%29%17%3
1600
11th to 20thNight
30%5%15%29%20%2
1693
21st to endNight
27%414%28%21%7%
1980
September1st to 10thNight
35%311%25%18%7%
1818
11th to 20thNight
28%49%31%25%4
1980
21st to endNight
35%38%25%24%4
1980
October1st to 10thNight
30%311%27%26%4
1980
11th to 20thNight
41%36%25%22%3
2104
21st to endNight
46%39%24%16%3
2574
November1st to 10thNight
37%38%25%22%4
2406
11th to 20thNight
44%29%24%19%3
2470
21st to endNight
53%39%22%12%1
2470
December1st to 10thNight
56%310%21%10%1
2470
11th to 20thNight
55%29%21%13%1
3214
21st to endNight
71%28%12%6%
4884

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
23%13%30%26%7%1
270
11th to 20thDay
23%15%33%24%5%
270
21st to endDay
28%11%35%21%5%
282
February1st to 10thDay
26%10%40%18%6%
240
11th to 20thDay
24%14%35%21%6%
240
21st to endDay
28%7%40%21%41
198
March1st to 10thDay
20%17%39%20%5%
240
11th to 20thDay
27%9%34%21%8%1
356
21st to endDay
29%12%32%17%9%1
462
April1st to 10thDay
18%12%31%26%11%2
420
11th to 20thDay
19%12%28%22%15%5%
412
21st to endDay
23%10%35%20%9%4
420
May1st to 10thDay
21%10%27%26%11%4
423
11th to 20thDay
25%325%25%15%7%
447
21st to endDay
14%220%26%22%15%
505
June1st to 10thDay
13%320%31%22%10%
630
11th to 20thDay
11%319%30%24%12%
630
21st to endDay
12%222%28%24%11%
630
July1st to 10thDay
14%19%28%27%22%
621
11th to 20thDay
9%112%33%29%16%
618
21st to endDay
10%210%29%32%17%
581
August1st to 10thDay
10%28%23%36%21%
446
11th to 20thDay
15%28%29%30%17%
439
21st to endDay
8%29%26%33%21%
495
September1st to 10thDay
13%211%26%34%14%
450
11th to 20thDay
11%210%23%34%20%
450
21st to endDay
13%5%19%25%24%14%
450
October1st to 10thDay
12%320%37%19%9%
450
11th to 20thDay
11%9%36%27%14%2
396
21st to endDay
30%7%33%25%5%1
297
November1st to 10thDay
12%12%29%29%14%4
270
11th to 20thDay
17%15%30%22%14%1
270
21st to endDay
24%7%34%24%10%1
270
December1st to 10thDay
21%13%36%22%6%3
270
11th to 20thDay
20%10%36%26%7%1
270
21st to endDay
26%14%32%22%5%1
297
January1st to 10thNight
22%11%33%29%5%
950
11th to 20thNight
25%9%34%26%5%
950
21st to endNight
23%9%34%29%4
921
February1st to 10thNight
27%8%36%26%3
720
11th to 20thNight
20%12%36%29%3
703
21st to endNight
26%10%35%26%3
592
March1st to 10thNight
21%10%34%28%6%
720
11th to 20thNight
21%8%34%29%8%1
720
21st to endNight
24%6%30%33%6%1
724
April1st to 10thNight
16%8%35%32%9%
540
11th to 20thNight
18%5%32%31%13%1
533
21st to endNight
21%438%28%8%1
540
May1st to 10thNight
20%431%33%10%1
540
11th to 20thNight
18%421%33%21%3
531
21st to endNight
10%317%40%28%2
584
June1st to 10thNight
11%117%45%24%2
540
11th to 20thNight
11%116%44%26%2
540
21st to endNight
7%116%41%31%3
540
July1st to 10thNight
10%25%37%37%9%
525
11th to 20thNight
8%19%41%35%6%
522
21st to endNight
11%28%40%36%3
591
August1st to 10thNight
10%15%38%42%4
537
11th to 20thNight
7%19%39%39%5%
534
21st to endNight
7%29%33%43%7%
594
September1st to 10thNight
14%19%35%36%5%
558
11th to 20thNight
10%210%34%39%6%
720
21st to endNight
14%316%36%27%3
720
October1st to 10thNight
11%320%37%24%5%
720
11th to 20thNight
19%6%27%32%16%1
720
21st to endNight
22%5%32%31%9%1
792
November1st to 10thNight
14%7%27%35%15%2
740
11th to 20thNight
18%10%31%29%10%1
760
21st to endNight
24%9%26%33%7%1
760
December1st to 10thNight
24%7%34%28%6%1
760
11th to 20thNight
25%6%31%30%7%1
883
21st to endNight
29%10%29%27%4
1045
Page generated at 2024-01-24 09:37:29. Version ac07

Copyright 2024 Attilla Danko


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