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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 2024-01-16.

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
47%
23801
23%
74268
17%
23748
53%
23748
28%
46292

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
27%
950
19%
2648
10%
946
35%
946
23%
1788
January11th to 20thNight
24%
843
18%
2508
8%
843
34%
843
16%
1823
January21st to endNight
25%
792
25%
2390
11%
792
38%
792
24%
1557
February1st to 10thNight
24%
720
18%
2160
9%
720
32%
720
20%
1530
February11th to 20thNight
23%
703
18%
2099
8%
700
31%
700
19%
1473
February21st to endNight
21%
592
19%
1776
9%
592
29%
592
18%
1256
March1st to 10thNight
29%
720
20%
2160
10%
720
37%
720
23%
1402
March11th to 20thNight
32%
720
18%
2073
11%
720
38%
720
22%
1427
March21st to endNight
34%
680
20%
2066
12%
680
42%
680
24%
1354
April1st to 10thNight
41%
540
27%
1800
19%
540
52%
540
30%
1029
April11th to 20thNight
40%
533
28%
1775
18%
533
54%
533
30%
1028
April21st to endNight
42%
540
23%
1775
16%
540
52%
540
29%
1043
May1st to 10thNight
46%
540
23%
1620
14%
540
53%
540
32%
983
May11th to 20thNight
53%
531
18%
1593
13%
531
56%
531
30%
986
May21st to endNight
65%
582
18%
1744
14%
582
67%
582
34%
1055
June1st to 10thNight
64%
540
19%
1616
16%
540
66%
540
33%
959
June11th to 20thNight
76%
540
25%
1440
20%
540
78%
540
49%
800
June21st to endNight
73%
540
24%
1440
17%
540
76%
540
44%
843
July1st to 10thNight
71%
525
17%
1400
14%
525
71%
525
34%
886
July11th to 20thNight
73%
522
21%
1441
19%
522
74%
522
39%
855
July21st to endNight
73%
591
21%
1672
20%
558
74%
558
33%
1005
August1st to 10thNight
75%
537
21%
1724
22%
534
76%
534
34%
993
August11th to 20thNight
72%
534
18%
1776
20%
534
73%
534
33%
1016
August21st to endNight
72%
594
22%
1980
26%
594
72%
594
31%
1158
September1st to 10thNight
69%
544
26%
1804
28%
544
70%
544
32%
1046
September11th to 20thNight
66%
720
27%
1980
22%
720
68%
720
36%
1206
September21st to endNight
65%
720
31%
1980
24%
720
69%
720
42%
1133
October1st to 10thNight
63%
720
35%
1980
27%
720
68%
720
45%
1083
October11th to 20thNight
45%
720
30%
2019
21%
720
53%
720
32%
1242
October21st to endNight
45%
792
29%
2549
24%
792
55%
792
30%
1522
November1st to 10thNight
52%
740
29%
2406
28%
740
59%
740
33%
1345
November11th to 20thNight
42%
760
30%
2470
21%
760
55%
760
33%
1393
November21st to endNight
41%
760
26%
2470
20%
760
51%
760
27%
1490
December1st to 10thNight
31%
760
19%
2470
13%
760
40%
760
19%
1676
December11th to 20thNight
34%
759
26%
2917
17%
758
45%
758
21%
1761
December21st to endNight
27%
897
12%
4547
11%
888
35%
888
11%
3146

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
13%6%36%6%35%5%6%8%40%
75086
Night
13%7%35%5%3445%7%43%
74684
TransparencyDay
42%5%11%23%17%3
74799
Night
40%410%23%19%4
74491
SeeingDay
17%6%22%24%20%11%
14014
Night
16%6%23%31%20%3
23814

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
17%8%36%6%35%446%38%
1517
11th to 20thDay
21%10%37%5%4345%6%33%
1555
21st to endDay
15%7%46%5%2435%6%42%
1965
February1st to 10thDay
19%10%47%5%34447%35%
1800
11th to 20thDay
20%10%47%6%34345%34%
1748
21st to endDay
21%9%46%434445%36%
1480
March1st to 10thDay
14%10%36%6%345%46%40%
1800
11th to 20thDay
19%8%37%6%35%5%5%5%34%
1885
21st to endDay
15%8%37%6%46%5%6%6%33%
2305
April1st to 10thDay
12%5%35%5%35%447%47%
2160
11th to 20thDay
14%7%35%5%345%46%44%
2134
21st to endDay
13%7%36%6%3446%8%39%
2182
May1st to 10thDay
16%5%25%5%25%5%6%8%41%
2340
11th to 20thDay
14%7%37%5%4445%7%39%
2301
21st to endDay
8%5%36%6%46%5%6%10%39%
2531
June1st to 10thDay
9%5%26%6%35%7%7%8%41%
2340
11th to 20thDay
5%325%6%45%6%8%10%46%
2518
21st to endDay
5%325%6%47%8%8%11%41%
2520
July1st to 10thDay
9%5%36%7%47%8%8%10%34%
2520
11th to 20thDay
9%435%7%48%7%7%10%37%
2466
21st to endDay
6%426%7%47%9%9%11%35%
2547
August1st to 10thDay
6%5%35%8%5%8%7%8%12%34%
2199
11th to 20thDay
9%5%37%6%46%6%7%10%37%
2125
21st to endDay
10%6%25%6%46%7%7%10%38%
2376
September1st to 10thDay
10%5%26%6%46%6%7%8%40%
2138
11th to 20thDay
13%6%245%45%5%6%7%43%
1980
21st to endDay
11%4245%2445%7%53%
1980
October1st to 10thDay
11%5%24424346%55%
1980
11th to 20thDay
12%6%25%5%24346%52%
1938
21st to endDay
17%6%25%4235%45%46%
1805
November1st to 10thDay
13%5%13323346%58%
1672
11th to 20thDay
14%5%3432445%6%48%
1710
21st to endDay
14%7%35%424447%45%
1710
December1st to 10thDay
22%10%26%42445%5%35%
1710
11th to 20thDay
16%8%36%6%345%5%6%38%
2153
21st to endDay
16%11%47%7%35%5%5%7%30%
2996
January1st to 10thNight
18%9%36%6%23446%39%
2648
11th to 20thNight
19%11%47%5%35%5%45%31%
2508
21st to endNight
16%8%45%5%34446%41%
2390
February1st to 10thNight
20%8%47%7%3445%6%33%
2160
11th to 20thNight
21%9%46%5%2443437%
2098
21st to endNight
24%9%36%5%3345%5%32%
1776
March1st to 10thNight
16%7%36%5%3445%7%41%
2160
11th to 20thNight
18%7%46%6%345%47%37%
2073
21st to endNight
14%8%36%5%36%45%7%39%
2066
April1st to 10thNight
11%426%5%345%5%8%49%
1800
11th to 20thNight
15%6%23423446%49%
1775
21st to endNight
12%5%36%5%3445%10%44%
1775
May1st to 10thNight
10%6%26%5%25%45%6%48%
1620
11th to 20thNight
9%6%36%5%35%5%6%8%45%
1592
21st to endNight
6%426%7%45%6%7%10%43%
1744
June1st to 10thNight
8%6%245%35%5%6%9%46%
1616
11th to 20thNight
34235%25%5%6%10%55%
1440
21st to endNight
33245%35%5%8%12%49%
1440
July1st to 10thNight
8%435%436%7%6%12%41%
1440
11th to 20thNight
7%325%446%5%7%13%44%
1489
21st to endNight
5%325%7%46%7%8%11%43%
1771
August1st to 10thNight
6%425%5%35%5%7%11%46%
1735
11th to 20thNight
6%435%5%35%5%7%10%45%
1776
21st to endNight
8%425%6%35%6%6%11%44%
1980
September1st to 10thNight
11%5%245%345%5%7%49%
1804
11th to 20thNight
9%425%5%3446%7%48%
1980
21st to endNight
9%42342446%6%56%
1980
October1st to 10thNight
9%5%23323346%60%
1980
11th to 20thNight
14%6%2443335%6%48%
2019
21st to endNight
15%7%24423446%48%
2549
November1st to 10thNight
11%5%25%43444455%
2406
11th to 20thNight
13%5%3442445%8%49%
2470
21st to endNight
15%7%25%5%23446%45%
2470
December1st to 10thNight
20%10%45%5%3435%6%36%
2470
11th to 20thNight
15%8%36%424345%46%
3042
21st to endNight
16%11%5%8%6%45%5%5%6%29%
4642

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
48%37%23%16%3
1518
11th to 20thDay
54%37%21%14%1
1555
21st to endDay
43%38%26%18%2
1965
February1st to 10thDay
52%38%21%15%3
1800
11th to 20thDay
54%35%22%13%3
1758
21st to endDay
51%39%17%16%6%
1480
March1st to 10thDay
47%38%18%19%6%
1800
11th to 20thDay
52%48%18%15%2
1885
21st to endDay
50%5%10%21%13%1
2305
April1st to 10thDay
38%5%10%24%20%3
2160
11th to 20thDay
41%47%21%22%5%
2134
21st to endDay
42%49%26%17%2
2182
May1st to 10thDay
41%411%26%15%3
2340
11th to 20thDay
44%5%12%24%15%1
2305
21st to endDay
40%6%14%26%12%2
2531
June1st to 10thDay
38%6%11%25%18%2
2340
11th to 20thDay
31%5%17%27%18%3
2518
21st to endDay
33%8%16%23%16%4
2520
July1st to 10thDay
41%7%17%20%12%3
2451
11th to 20thDay
39%7%17%22%11%4
2391
21st to endDay
36%8%19%25%10%2
2405
August1st to 10thDay
39%7%17%24%11%1
2186
11th to 20thDay
40%7%13%23%15%2
2125
21st to endDay
40%5%14%24%13%3
2376
September1st to 10thDay
40%6%12%22%17%3
2138
11th to 20thDay
39%6%10%23%20%3
1980
21st to endDay
32%310%27%23%6%
1980
October1st to 10thDay
32%38%25%27%5%
1980
11th to 20thDay
35%37%22%25%8%
1938
21st to endDay
40%46%21%24%5%
1805
November1st to 10thDay
30%38%24%30%6%
1672
11th to 20thDay
37%36%23%25%6%
1710
21st to endDay
40%36%25%21%5%
1710
December1st to 10thDay
51%36%21%16%3
1710
11th to 20thDay
46%49%21%18%2
2150
21st to endDay
52%5%9%21%10%3
2996
January1st to 10thNight
47%39%22%17%2
2648
11th to 20thNight
56%36%20%13%3
2508
21st to endNight
45%37%24%18%3
2390
February1st to 10thNight
53%39%18%16%1
2160
11th to 20thNight
52%36%19%16%4
2099
21st to endNight
53%38%16%14%5%
1776
March1st to 10thNight
43%48%15%21%8%
2160
11th to 20thNight
48%49%21%16%2
2073
21st to endNight
44%5%10%25%14%2
2066
April1st to 10thNight
34%410%26%22%3
1800
11th to 20thNight
36%38%21%22%9%
1775
21st to endNight
38%311%27%19%2
1775
May1st to 10thNight
36%5%10%26%21%2
1620
11th to 20thNight
36%7%18%22%16%2
1593
21st to endNight
34%6%17%26%15%2
1745
June1st to 10thNight
33%6%15%25%18%3
1616
11th to 20thNight
23%5%18%34%17%3
1440
21st to endNight
25%7%18%32%15%4
1440
July1st to 10thNight
34%7%19%23%14%3
1400
11th to 20thNight
29%7%20%26%14%5%
1441
21st to endNight
31%8%17%28%13%2
1672
August1st to 10thNight
30%8%16%31%14%1
1724
11th to 20thNight
32%7%20%23%16%2
1776
21st to endNight
34%6%14%27%14%4
1980
September1st to 10thNight
35%5%12%26%18%4
1804
11th to 20thNight
34%411%22%26%2
1980
21st to endNight
28%5%9%25%26%7%
1980
October1st to 10thNight
26%38%25%29%9%
1980
11th to 20thNight
37%47%21%23%9%
2019
21st to endNight
38%3423%26%6%
2549
November1st to 10thNight
34%36%23%27%8%
2406
11th to 20thNight
34%36%22%28%7%
2470
21st to endNight
40%37%24%22%5%
2470
December1st to 10thNight
50%38%19%16%3
2470
11th to 20thNight
41%36%23%23%4
3044
21st to endNight
55%5%7%19%12%2
4642

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
22%15%41%14%7%
270
11th to 20thDay
29%15%35%15%42
255
21st to endDay
19%13%47%18%3
264
February1st to 10thDay
28%14%37%15%5%1
240
11th to 20thDay
35%15%37%11%2
240
21st to endDay
36%14%36%10%4
198
March1st to 10thDay
24%13%40%19%4
240
11th to 20thDay
27%13%34%18%7%1
325
21st to endDay
22%12%34%22%9%1
462
April1st to 10thDay
17%12%29%27%13%2
420
11th to 20thDay
19%11%28%27%13%2
412
21st to endDay
20%11%27%24%14%4
420
May1st to 10thDay
20%7%26%27%15%5%
423
11th to 20thDay
17%422%26%19%11%
447
21st to endDay
13%216%26%25%18%
485
June1st to 10thDay
14%116%21%26%22%
450
11th to 20thDay
6%114%28%33%18%
628
21st to endDay
7%216%33%25%18%
630
July1st to 10thDay
11%110%24%31%23%
621
11th to 20thDay
11%18%24%32%25%
564
21st to endDay
8%27%24%32%27%
488
August1st to 10thDay
9%17%25%37%22%
446
11th to 20thDay
13%16%29%35%16%
439
21st to endDay
15%1420%36%23%
495
September1st to 10thDay
12%19%26%34%18%
450
11th to 20thDay
16%18%23%31%22%
450
21st to endDay
14%413%27%28%13%
450
October1st to 10thDay
16%117%29%26%11%
450
11th to 20thDay
14%8%31%29%14%4
408
21st to endDay
26%7%26%27%10%2
297
November1st to 10thDay
18%6%29%29%14%4
270
11th to 20thDay
15%10%40%26%9%
270
21st to endDay
20%10%34%19%14%3
270
December1st to 10thDay
28%15%29%23%41
270
11th to 20thDay
19%14%38%19%10%
270
21st to endDay
23%16%36%21%4
297
January1st to 10thNight
23%13%32%27%5%
950
11th to 20thNight
27%13%31%24%5%
843
21st to endNight
21%10%41%26%3
792
February1st to 10thNight
24%10%36%27%4
720
11th to 20thNight
26%14%33%24%3
703
21st to endNight
30%12%34%22%2
592
March1st to 10thNight
21%11%34%28%6%
720
11th to 20thNight
21%10%32%28%9%1
720
21st to endNight
19%9%32%30%10%
680
April1st to 10thNight
14%9%32%33%11%
540
11th to 20thNight
16%10%31%33%9%2
533
21st to endNight
15%6%32%34%12%1
540
May1st to 10thNight
13%331%33%17%2
540
11th to 20thNight
12%223%35%23%5%
531
21st to endNight
9%212%37%34%6%
584
June1st to 10thNight
12%112%35%33%6%
540
11th to 20thNight
5%110%38%40%6%
540
21st to endNight
4111%37%39%8%
540
July1st to 10thNight
10%1430%44%11%
525
11th to 20thNight
10%16%27%43%13%
522
21st to endNight
6%16%28%50%9%
591
August1st to 10thNight
9%1328%50%10%
537
11th to 20thNight
7%16%40%39%7%
534
21st to endNight
10%1429%46%10%
594
September1st to 10thNight
12%27%29%45%5%
544
11th to 20thNight
12%110%30%41%6%
720
21st to endNight
11%213%32%36%5%
720
October1st to 10thNight
11%316%33%30%7%
720
11th to 20thNight
18%425%33%18%2
720
21st to endNight
18%5%26%32%16%2
792
November1st to 10thNight
13%5%23%38%17%3
740
11th to 20thNight
15%8%31%33%13%1
760
21st to endNight
20%8%27%33%11%1
760
December1st to 10thNight
26%9%28%29%7%1
760
11th to 20thNight
21%7%31%32%8%1
760
21st to endNight
26%9%31%28%5%
907
Page generated at 2024-01-13 00:38:11. Version ac07

Copyright 2024 Attilla Danko


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