Franklin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Franklin clear sky chart from 2005-11-05 to 2018-02-14.

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
38%
16691
17%
48799
10%
16649
44%
16649
23%
32765

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 15thNight
20%
975
13%
2716
4%
970
28%
970
18%
1971
January16th to endNight
21%
1040
11%
2906
3%
1040
27%
1040
17%
2154
February1st to 15thNight
23%
874
14%
2397
4%
874
31%
874
20%
1699
February16th to endNight
26%
631
18%
1893
7%
631
35%
631
19%
1322
March1st to 15thNight
30%
720
14%
2160
8%
720
35%
720
19%
1518
March16th to endNight
36%
630
16%
2015
13%
630
42%
630
20%
1401
April1st to 15thNight
32%
539
15%
1797
11%
539
40%
539
18%
1250
April16th to endNight
43%
540
19%
1716
14%
540
49%
540
24%
1131
May1st to 15thNight
43%
540
16%
1574
11%
540
48%
540
23%
1096
May16th to endNight
51%
562
17%
1498
11%
561
55%
561
30%
981
June1st to 15thNight
58%
540
15%
1440
10%
540
60%
540
33%
913
June16th to endNight
55%
540
16%
1440
9%
540
59%
540
32%
939
July1st to 15thNight
67%
510
17%
1360
12%
510
69%
510
41%
801
July16th to endNight
71%
564
19%
1417
15%
531
73%
531
41%
830
August1st to 15thNight
73%
539
23%
1528
21%
536
74%
536
42%
864
August16th to endNight
67%
573
21%
1910
21%
573
70%
573
34%
1071
September1st to 15thNight
63%
546
26%
1806
26%
546
67%
546
34%
988
September16th to endNight
57%
717
27%
1980
20%
717
62%
717
36%
1194
October1st to 15thNight
46%
720
21%
2073
17%
720
50%
720
28%
1315
October16th to endNight
32%
768
18%
2457
10%
768
42%
768
21%
1620
November1st to 15thNight
33%
760
21%
2471
15%
760
41%
760
23%
1570
November16th to endNight
25%
848
15%
2603
7%
848
34%
848
18%
1785
December1st to 15thNight
20%
975
10%
2730
4%
975
25%
975
15%
2048
December16th to endNight
16%
1040
11%
2912
2%
1040
25%
1040
13%
2304

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%7%36%5%3445%7%37%
49283
Night
14%7%35%42445%6%40%
48967
Cloud CoverDay
12%7%36%5%35%5%5%8%37%
49292
Night
14%7%35%5%2445%7%39%
48972
TransparencyDay
44%7%13%22%11%1
48969
Night
44%5%13%22%12%1
48799
SeeingDay
14%5%25%30%18%5%
6486
Night
17%7%28%29%14%2
16695

By Month

Percentage Cloud Cover NE (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 15thDay
11%13%5%5%5%35%5%47%32%
1552
16th to endDay
10%14%7%10%7%34446%25%
1667
February1st to 15thDay
12%14%5%6%5%245%45%32%
1766
16th to endDay
13%11%5%7%6%34445%31%
1580
March1st to 15thDay
15%9%5%7%6%345%36%32%
1790
16th to endDay
16%9%46%5%34447%31%
2217
April1st to 15thDay
18%9%5%6%5%245%5%7%29%
2151
16th to endDay
18%7%35%424447%37%
2244
May1st to 15thDay
17%8%36%5%35%5%5%7%30%
2376
16th to endDay
12%5%25%6%35%45%6%41%
2617
June1st to 15thDay
11%5%245%35%45%9%42%
2520
16th to endDay
9%5%25%5%35%5%5%9%42%
2520
July1st to 15thDay
7%315%5%25%5%6%9%47%
2520
16th to endDay
6%425%5%36%5%5%9%44%
2655
August1st to 15thDay
7%425%6%35%5%6%9%43%
2419
16th to endDay
9%5%25%435%5%6%8%43%
2292
September1st to 15thDay
12%31442445%7%48%
2142
16th to endDay
8%425%6%345%6%9%43%
1980
October1st to 15thDay
16%6%25%43345%7%40%
1886
16th to endDay
16%7%36%5%24446%36%
1765
November1st to 15thDay
12%8%47%5%3345%8%35%
1717
16th to endDay
17%8%26%5%24336%38%
1683
December1st to 15thDay
16%11%46%5%35%46%7%29%
1560
16th to endDay
18%13%5%7%5%3445%5%22%
1664
January1st to 15thNight
16%11%47%424345%35%
2716
16th to endNight
12%10%5%8%6%35%45%7%30%
2906
February1st to 15thNight
14%11%46%432346%37%
2395
16th to endNight
16%10%45%5%3345%6%34%
1893
March1st to 15thNight
15%10%45%5%34445%37%
2147
16th to endNight
17%8%36%425%45%6%35%
2015
April1st to 15thNight
18%8%35%5%345%5%6%34%
1797
16th to endNight
19%7%24324346%40%
1716
May1st to 15thNight
18%7%35%435%46%6%35%
1574
16th to endNight
11%435%43446%7%43%
1496
June1st to 15thNight
11%41442445%7%47%
1440
16th to endNight
8%3346%35%46%8%44%
1440
July1st to 15thNight
5%315%425%5%5%8%52%
1440
16th to endNight
6%2143246%7%9%51%
1513
August1st to 15thNight
5%3133236%7%10%52%
1537
16th to endNight
9%22343435%8%52%
1910
September1st to 15thNight
8%324424346%56%
1806
16th to endNight
8%5%24423346%52%
1980
October1st to 15thNight
13%5%25%424346%47%
2073
16th to endNight
17%7%24423446%40%
2457
November1st to 15thNight
13%8%35%424446%44%
2471
16th to endNight
17%9%35%43435%6%37%
2603
December1st to 15thNight
18%10%36%5%345%46%31%
2730
16th to endNight
21%13%47%6%24446%24%
2912

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 15thDay
11%12%5%7%5%345%5%8%30%
1552
16th to endDay
11%13%6%11%7%35%45%8%23%
1667
February1st to 15thDay
12%13%6%6%5%345%5%6%30%
1766
16th to endDay
12%10%6%8%6%35%45%7%29%
1580
March1st to 15thDay
15%8%47%6%345%47%31%
1800
16th to endDay
15%9%46%6%35%5%5%7%31%
2216
April1st to 15thDay
16%10%47%5%345%5%6%29%
2151
16th to endDay
17%6%25%5%24446%37%
2244
May1st to 15thDay
16%8%37%5%35%6%5%7%30%
2376
16th to endDay
11%6%25%5%35%46%7%41%
2617
June1st to 15thDay
10%5%25%5%345%6%8%43%
2520
16th to endDay
7%5%25%5%45%46%9%42%
2520
July1st to 15thDay
6%414435%46%10%47%
2520
16th to endDay
6%4245%36%5%6%9%44%
2655
August1st to 15thDay
6%425%6%35%5%7%9%43%
2419
16th to endDay
8%5%25%5%35%46%8%44%
2292
September1st to 15thDay
11%3234245%6%7%48%
2142
16th to endDay
7%425%5%45%5%7%9%42%
1980
October1st to 15thDay
15%6%3442346%6%40%
1886
16th to endDay
15%7%36%5%35%45%7%35%
1765
November1st to 15thDay
12%9%47%5%3445%8%35%
1717
16th to endDay
16%8%35%435%436%38%
1683
December1st to 15thDay
16%11%46%5%45%47%8%26%
1560
16th to endDay
18%13%5%8%6%36%5%5%6%20%
1664
January1st to 15thNight
16%11%46%6%24347%33%
2716
16th to endNight
12%10%6%8%6%3446%8%27%
2906
February1st to 15thNight
13%12%47%5%23347%36%
2388
16th to endNight
15%10%46%5%24447%33%
1893
March1st to 15thNight
15%9%45%5%34446%36%
2160
16th to endNight
16%8%45%5%25%45%6%34%
2015
April1st to 15thNight
18%8%35%43445%6%33%
1797
16th to endNight
19%7%2442435%5%39%
1716
May1st to 15thNight
18%8%345%15%5%6%7%34%
1573
16th to endNight
11%436%5%2445%8%42%
1496
June1st to 15thNight
11%4244245%5%7%46%
1440
16th to endNight
8%425%5%45%46%9%43%
1440
July1st to 15thNight
5%3144235%6%8%51%
1440
16th to endNight
5%3134245%7%9%51%
1513
August1st to 15thNight
5%3133245%6%10%52%
1537
16th to endNight
9%32442445%7%51%
1910
September1st to 15thNight
8%314434337%54%
1806
16th to endNight
9%424424447%50%
1980
October1st to 15thNight
14%425%42445%6%45%
2073
16th to endNight
17%7%25%5%2435%6%39%
2457
November1st to 15thNight
13%7%26%5%24345%43%
2471
16th to endNight
16%8%35%5%3345%6%36%
2603
December1st to 15thNight
18%10%46%5%35%5%46%29%
2730
16th to endNight
21%12%5%7%6%2346%6%23%
2912

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 15thDay
50%7%15%19%6%
1553
16th to endDay
58%6%13%15%5%
1667
February1st to 15thDay
52%6%13%19%7%1
1768
16th to endDay
52%7%12%18%7%1
1580
March1st to 15thDay
52%6%13%18%7%1
1800
16th to endDay
52%6%14%20%5%
2217
April1st to 15thDay
52%7%10%18%10%
2151
16th to endDay
46%6%12%20%11%2
2244
May1st to 15thDay
50%7%11%21%7%
2376
16th to endDay
40%8%11%24%13%1
2621
June1st to 15thDay
38%7%13%25%15%1
2520
16th to endDay
36%7%14%21%17%1
2520
July1st to 15thDay
30%8%12%29%16%2
2371
16th to endDay
34%9%14%24%14%3
2488
August1st to 15thDay
33%8%14%29%12%1
2404
16th to endDay
36%8%12%25%16%1
2292
September1st to 15thDay
32%7%12%27%18%1
2142
16th to endDay
35%7%13%30%12%
1980
October1st to 15thDay
41%5%13%25%12%1
1886
16th to endDay
48%5%12%23%9%
1765
November1st to 15thDay
46%5%13%23%10%1
1717
16th to endDay
49%416%23%5%
1683
December1st to 15thDay
54%7%17%14%6%
1560
16th to endDay
62%6%13%12%5%
1664
January1st to 15thNight
51%5%12%19%10%
2716
16th to endNight
53%5%18%15%6%
2906
February1st to 15thNight
49%5%12%20%11%1
2397
16th to endNight
49%5%12%20%9%2
1893
March1st to 15thNight
48%6%12%18%11%1
2160
16th to endNight
49%6%13%22%7%1
2015
April1st to 15thNight
49%6%7%19%16%
1797
16th to endNight
46%311%19%14%4
1716
May1st to 15thNight
47%5%11%23%11%
1574
16th to endNight
39%6%12%22%16%2
1498
June1st to 15thNight
34%7%11%26%17%1
1440
16th to endNight
37%6%11%24%17%2
1440
July1st to 15thNight
27%7%13%28%19%3
1360
16th to endNight
25%9%16%27%17%4
1417
August1st to 15thNight
25%7%14%32%18%1
1528
16th to endNight
30%6%11%30%17%2
1910
September1st to 15thNight
29%5%10%25%25%2
1806
16th to endNight
32%411%35%14%1
1980
October1st to 15thNight
38%5%12%24%17%1
2073
16th to endNight
45%5%14%23%10%
2457
November1st to 15thNight
42%412%23%14%2
2471
16th to endNight
48%5%17%20%7%
2603
December1st to 15thNight
54%6%13%17%6%
2730
16th to endNight
61%5%12%13%5%
2912

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 15thDay
16%12%31%31%8%
135
16th to endDay
18%435%29%10%
144
February1st to 15thDay
17%10%52%14%5%
130
16th to endDay
17%13%35%20%12%
81
March1st to 15thDay
25%13%36%18%41
90
16th to endDay
26%8%28%23%10%2
246
April1st to 15thDay
24%7%31%22%12%1
270
16th to endDay
18%8%28%24%14%4
270
May1st to 15thDay
21%6%28%29%10%3
333
16th to endDay
14%428%31%16%5%
517
June1st to 15thDay
10%323%35%21%4
495
16th to endDay
10%224%38%18%5%
495
July1st to 15thDay
7%121%36%24%8%
475
16th to endDay
7%220%37%23%8%
515
August1st to 15thDay
8%14%37%26%12%
415
16th to endDay
9%218%30%26%13%
332
September1st to 15thDay
9%215%29%26%15%
315
16th to endDay
9%319%28%28%11%
314
October1st to 15thDay
21%5%18%33%17%3
221
16th to endDay
15%10%33%30%10%
144
November1st to 15thDay
12%10%31%22%20%2
135
16th to endDay
22%10%39%19%8%
135
December1st to 15thDay
14%17%40%20%5%
135
16th to endDay
25%17%42%12%2
144
January1st to 15thNight
21%13%38%20%5%
975
16th to endNight
16%10%40%26%5%
1040
February1st to 15thNight
19%9%37%26%5%
877
16th to endNight
21%9%32%26%8%
631
March1st to 15thNight
18%8%34%27%10%
720
16th to endNight
19%5%31%31%10%2
630
April1st to 15thNight
23%6%31%28%9%
539
16th to endNight
23%324%33%13%2
540
May1st to 15thNight
21%424%35%13%1
540
16th to endNight
12%323%36%21%3
563
June1st to 15thNight
15%117%41%22%1
540
16th to endNight
10%25%36%23%3
540
July1st to 15thNight
6%15%40%31%4
510
16th to endNight
5%113%43%31%4
564
August1st to 15thNight
8%9%42%33%4
539
16th to endNight
8%116%32%35%5%
573
September1st to 15thNight
9%215%33%29%8%
546
16th to endNight
12%5%18%26%30%5%
717
October1st to 15thNight
17%6%22%31%18%2
720
16th to endNight
22%8%31%26%9%
768
November1st to 15thNight
19%8%34%24%12%1
760
16th to endNight
21%12%34%23%7%
848
December1st to 15thNight
22%14%36%22%4
975
16th to endNight
27%11%35%22%3
1040
Page generated at 2018-02-15 09:58:42. Version ac04

Copyright 2018 A. Danko


Franklin Clear Sky Chart |Charts Home