Ferrum
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ferrum clear sky chart from 2005-11-06 to 2024-02-15.

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
40%
24437
21%
79650
12%
24339
50%
24339
24%
49358

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
20%
755
26%
3995
7%
737
40%
737
14%
2048
January11th to 20thNight
22%
758
27%
3952
9%
740
39%
740
13%
2193
January21st to endNight
20%
830
16%
4451
8%
814
41%
814
14%
2695
February1st to 10thNight
24%
760
21%
2470
11%
760
39%
760
22%
1553
February11th to 20thNight
13%
719
19%
2282
4%
718
31%
718
16%
1473
February21st to endNight
19%
592
25%
1700
8%
592
36%
592
21%
1116
March1st to 10thNight
23%
720
26%
1980
10%
720
38%
720
28%
1215
March11th to 20thNight
24%
720
19%
1980
6%
720
36%
720
22%
1328
March21st to endNight
26%
792
19%
2178
9%
792
35%
792
22%
1460
April1st to 10thNight
26%
720
19%
1918
5%
720
37%
720
25%
1243
April11th to 20thNight
31%
711
23%
1775
8%
711
41%
711
31%
1144
April21st to endNight
34%
626
24%
1706
8%
626
44%
626
30%
1090
May1st to 10thNight
34%
540
16%
1620
6%
540
41%
540
24%
1052
May11th to 20thNight
40%
531
14%
1593
8%
531
46%
531
22%
1099
May21st to endNight
59%
582
14%
1745
11%
582
61%
582
28%
1130
June1st to 10thNight
65%
540
17%
1620
16%
540
66%
540
28%
1049
June11th to 20thNight
64%
540
15%
1620
12%
540
67%
540
31%
1024
June21st to endNight
67%
540
17%
1620
15%
540
70%
540
30%
1009
July1st to 10thNight
68%
525
13%
1575
11%
525
70%
525
26%
1045
July11th to 20thNight
75%
522
15%
1566
14%
522
76%
522
32%
979
July21st to endNight
71%
591
16%
1672
13%
558
73%
558
30%
1071
August1st to 10thNight
61%
537
14%
1600
11%
534
63%
534
23%
1114
August11th to 20thNight
64%
534
19%
1598
16%
534
66%
534
26%
1059
August21st to endNight
66%
756
16%
1944
12%
756
67%
756
30%
1328
September1st to 10thNight
62%
720
23%
1831
16%
720
64%
720
31%
1224
September11th to 20thNight
59%
720
22%
1980
19%
720
61%
720
27%
1315
September21st to endNight
43%
720
19%
1980
14%
720
49%
720
22%
1384
October1st to 10thNight
48%
720
21%
2146
18%
720
54%
720
29%
1330
October11th to 20thNight
44%
720
27%
2160
20%
720
57%
720
31%
1276
October21st to endNight
43%
792
30%
2376
20%
792
57%
792
32%
1360
November1st to 10thNight
42%
740
28%
2221
18%
740
54%
740
31%
1309
November11th to 20thNight
38%
760
27%
2413
16%
760
53%
760
29%
1368
November21st to endNight
35%
760
26%
2470
16%
760
50%
760
27%
1410
December1st to 10thNight
25%
760
23%
2564
9%
760
42%
760
19%
1613
December11th to 20thNight
26%
759
26%
2936
9%
758
45%
758
20%
1709
December21st to endNight
25%
825
15%
4413
9%
817
40%
817
12%
2543

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%5%25%5%35%5%6%8%42%
78593
Night
14%5%2443445%7%46%
80445
TransparencyDay
39%9%13%20%16%4
78315
Night
37%8%12%22%18%4
80242
SeeingDay
19%14%25%23%14%5%
14209
Night
17%11%26%28%16%2
24467

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%5%24433347%50%
2836
11th to 20thDay
13%6%25%5%44446%47%
2840
21st to endDay
20%8%36%5%34345%40%
3124
February1st to 10thDay
12%6%27%5%35%5%5%6%43%
1710
11th to 20thDay
18%7%344245%6%6%41%
1654
21st to endDay
17%7%26%5%3345%5%41%
1556
March1st to 10thDay
13%4245%2446%7%50%
1980
11th to 20thDay
17%6%35%43445%8%40%
1980
21st to endDay
16%7%36%4445%5%6%40%
2178
April1st to 10thDay
10%424435%5%6%9%50%
2042
11th to 20thDay
13%6%25%5%2445%8%47%
2134
21st to endDay
16%6%25%6%445%46%41%
2268
May1st to 10thDay
14%6%346%45%6%6%9%38%
2340
11th to 20thDay
17%5%36%6%46%5%7%8%34%
2301
21st to endDay
13%5%25%6%46%6%6%9%37%
2531
June1st to 10thDay
11%425%5%36%6%8%10%40%
2340
11th to 20thDay
8%435%7%46%6%8%11%38%
2340
21st to endDay
9%426%6%47%7%8%9%38%
2340
July1st to 10thDay
10%5%25%6%48%7%8%10%33%
2340
11th to 20thDay
6%426%6%47%9%9%12%35%
2340
21st to endDay
9%5%37%8%5%7%8%8%10%31%
2547
August1st to 10thDay
11%6%36%6%47%7%9%10%32%
2327
11th to 20thDay
12%5%26%6%5%7%6%8%10%32%
2303
21st to endDay
11%6%35%5%46%6%6%10%38%
2393
September1st to 10thDay
14%5%244345%6%7%46%
2124
11th to 20thDay
15%6%26%435%6%6%7%41%
1980
21st to endDay
23%6%26%43445%5%37%
1980
October1st to 10thDay
18%424323347%50%
1813
11th to 20thDay
16%42332345%6%52%
1800
21st to endDay
13%5%35%423346%52%
1980
November1st to 10thDay
12%42333345%5%56%
1857
11th to 20thDay
14%5%23334347%52%
1763
21st to endDay
13%5%135%2345%7%50%
1710
December1st to 10thDay
14%8%25%5%45%5%5%7%41%
1565
11th to 20thDay
15%423324446%55%
2153
21st to endDay
20%7%24435%5%6%7%37%
3124
January1st to 10thNight
14%6%24424446%50%
4109
11th to 20thNight
14%7%25%424445%48%
4120
21st to endNight
23%6%24424345%42%
4532
February1st to 10thNight
14%7%35%43445%7%45%
2470
11th to 20thNight
20%6%25%5%25%345%43%
2282
21st to endNight
14%7%345%345%5%6%43%
1700
March1st to 10thNight
13%42432436%6%52%
1980
11th to 20thNight
17%5%25%435%46%8%40%
1980
21st to endNight
16%4245%35%5%6%7%44%
2178
April1st to 10thNight
14%6%244345%48%46%
1918
11th to 20thNight
13%5%244335%5%7%50%
1775
21st to endNight
17%31442445%8%47%
1706
May1st to 10thNight
13%5%25%5%45%46%8%44%
1620
11th to 20thNight
17%6%35%6%35%46%7%39%
1592
21st to endNight
16%42443446%10%42%
1744
June1st to 10thNight
10%424446%7%7%11%42%
1620
11th to 20thNight
10%6%243345%6%11%46%
1620
21st to endNight
8%3245%35%6%7%12%45%
1620
July1st to 10thNight
8%5%35%5%36%7%7%10%42%
1620
11th to 20thNight
44245%36%7%8%13%44%
1620
21st to endNight
6%4245%46%7%8%13%41%
1771
August1st to 10thNight
12%6%26%6%46%5%6%9%38%
1611
11th to 20thNight
11%436%5%35%6%6%10%40%
1598
21st to endNight
10%426%5%46%6%7%10%40%
1944
September1st to 10thNight
12%5%35%42446%7%47%
1831
11th to 20thNight
15%435%5%3445%7%44%
1980
21st to endNight
22%7%35%5%34346%40%
1980
October1st to 10thNight
16%5%25%423347%47%
2146
11th to 20thNight
14%5%24424445%53%
2160
21st to endNight
14%424423335%56%
2376
November1st to 10thNight
14%6%24323435%54%
2221
11th to 20thNight
13%5%2332445%6%54%
2413
21st to endNight
13%42442445%7%50%
2470
December1st to 10thNight
15%7%345%25%45%6%44%
2564
11th to 20thNight
14%6%24434445%49%
3042
21st to endNight
19%5%245%345%6%7%39%
4532

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
33%7%9%26%19%6%
2837
11th to 20thDay
38%6%8%19%25%5%
2840
21st to endDay
46%6%8%19%18%3
3124
February1st to 10thDay
41%6%12%21%18%3
1710
11th to 20thDay
41%7%9%23%16%4
1663
21st to endDay
45%6%12%14%17%6%
1556
March1st to 10thDay
34%5%11%24%21%5%
1980
11th to 20thDay
42%8%11%18%16%6%
1980
21st to endDay
44%8%10%21%14%4
2178
April1st to 10thDay
30%8%13%23%18%8%
2042
11th to 20thDay
35%6%13%22%18%6%
2134
21st to endDay
44%6%12%21%14%3
2268
May1st to 10thDay
40%10%18%16%12%3
2340
11th to 20thDay
46%10%13%19%10%1
2305
21st to endDay
40%12%16%23%9%
2531
June1st to 10thDay
37%12%16%23%12%1
2340
11th to 20thDay
37%12%16%18%14%2
2340
21st to endDay
37%13%17%19%13%2
2340
July1st to 10thDay
40%13%16%17%11%2
2275
11th to 20thDay
36%14%20%17%12%1
2271
21st to endDay
42%13%18%18%9%1
2405
August1st to 10thDay
42%13%17%20%7%1
2314
11th to 20thDay
42%14%17%18%8%1
2303
21st to endDay
39%11%19%17%11%3
2393
September1st to 10thDay
36%9%14%20%18%3
2124
11th to 20thDay
41%8%11%21%17%2
1980
21st to endDay
48%7%11%16%17%2
1980
October1st to 10thDay
36%5%12%23%20%4
1813
11th to 20thDay
33%5%12%24%20%6%
1800
21st to endDay
34%5%8%25%21%7%
1980
November1st to 10thDay
30%6%10%20%27%6%
1857
11th to 20thDay
34%48%22%23%7%
1763
21st to endDay
34%5%10%22%25%4
1710
December1st to 10thDay
43%7%10%18%17%4
1565
11th to 20thDay
32%5%10%23%23%8%
2150
21st to endDay
41%9%12%22%14%2
3124
January1st to 10thNight
33%6%10%23%22%5%
4109
11th to 20thNight
37%7%9%18%24%5%
4120
21st to endNight
43%6%8%21%16%6%
4532
February1st to 10thNight
39%6%10%23%19%3
2470
11th to 20thNight
43%5%9%19%17%6%
2284
21st to endNight
41%6%11%22%14%5%
1700
March1st to 10thNight
33%6%10%24%21%6%
1980
11th to 20thNight
41%7%11%21%17%3
1980
21st to endNight
40%8%10%21%17%4
2178
April1st to 10thNight
38%6%12%20%21%4
1918
11th to 20thNight
34%6%12%21%21%6%
1775
21st to endNight
36%7%12%25%17%3
1706
May1st to 10thNight
37%10%15%23%13%2
1620
11th to 20thNight
45%8%13%21%11%2
1593
21st to endNight
37%10%19%24%10%1
1745
June1st to 10thNight
33%13%16%25%13%1
1620
11th to 20thNight
31%12%19%22%14%2
1620
21st to endNight
29%14%17%23%14%4
1620
July1st to 10thNight
34%15%17%19%12%4
1575
11th to 20thNight
30%13%21%23%11%2
1566
21st to endNight
31%14%21%25%10%
1672
August1st to 10thNight
41%12%17%19%11%1
1600
11th to 20thNight
37%12%17%22%11%1
1598
21st to endNight
36%11%17%23%10%3
1944
September1st to 10thNight
36%10%13%22%15%5%
1831
11th to 20thNight
38%9%11%21%19%2
1980
21st to endNight
47%6%9%19%16%3
1980
October1st to 10thNight
38%5%10%22%22%4
2146
11th to 20thNight
34%5%10%25%20%5%
2160
21st to endNight
32%5%9%23%25%8%
2376
November1st to 10thNight
34%5%9%20%25%7%
2221
11th to 20thNight
31%5%9%21%24%9%
2413
21st to endNight
33%5%10%24%22%6%
2470
December1st to 10thNight
42%6%9%23%18%4
2564
11th to 20thNight
36%7%8%21%22%7%
3044
21st to endNight
39%8%13%20%17%2
4532

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
30%28%27%12%2
270
11th to 20thDay
33%25%34%7%1
270
21st to endDay
25%34%32%9%1
297
February1st to 10thDay
25%30%29%13%3
270
11th to 20thDay
41%30%25%41
252
21st to endDay
32%28%26%12%2
274
March1st to 10thDay
25%22%32%17%4
420
11th to 20thDay
26%25%30%15%31
420
21st to endDay
23%21%34%16%5%
462
April1st to 10thDay
20%24%30%18%8%
420
11th to 20thDay
19%20%29%19%10%3
412
21st to endDay
25%17%28%18%10%2
420
May1st to 10thDay
21%17%34%18%6%3
423
11th to 20thDay
17%10%28%27%12%6%
447
21st to endDay
18%6%21%29%20%7%
485
June1st to 10thDay
14%7%26%31%16%6%
450
11th to 20thDay
9%10%21%33%18%8%
450
21st to endDay
11%6%27%31%20%5%
450
July1st to 10thDay
11%316%31%29%10%
445
11th to 20thDay
5%316%34%32%10%
444
21st to endDay
9%319%31%24%13%
488
August1st to 10thDay
14%322%26%22%13%
446
11th to 20thDay
11%318%26%25%16%
439
21st to endDay
12%315%31%23%16%
495
September1st to 10thDay
17%315%24%27%14%
450
11th to 20thDay
17%5%14%25%29%10%
450
21st to endDay
26%10%20%26%14%5%
450
October1st to 10thDay
22%7%21%28%17%5%
450
11th to 20thDay
16%15%25%23%18%2
450
21st to endDay
17%15%28%29%8%2
495
November1st to 10thDay
19%14%28%25%12%3
455
11th to 20thDay
21%24%26%21%7%1
323
21st to endDay
20%20%31%23%5%1
270
December1st to 10thDay
23%32%29%14%31
200
11th to 20thDay
23%23%34%15%5%
270
21st to endDay
29%21%33%11%6%
297
January1st to 10thNight
19%23%34%21%3
760
11th to 20thNight
19%22%33%24%2
760
21st to endNight
19%19%40%21%2
836
February1st to 10thNight
19%18%36%24%3
760
11th to 20thNight
26%21%37%16%
722
21st to endNight
21%19%39%19%2
592
March1st to 10thNight
18%18%39%22%3
720
11th to 20thNight
21%18%34%20%6%1
720
21st to endNight
19%17%35%25%4
792
April1st to 10thNight
18%20%34%21%7%
720
11th to 20thNight
16%15%34%23%10%1
711
21st to endNight
19%7%35%28%9%
626
May1st to 10thNight
15%11%34%27%12%1
540
11th to 20thNight
19%6%27%28%19%1
531
21st to endNight
17%315%31%31%3
584
June1st to 10thNight
11%216%40%30%2
540
11th to 20thNight
11%315%34%31%5%
540
21st to endNight
8%213%44%28%4
540
July1st to 10thNight
10%28%35%39%6%
525
11th to 20thNight
6%18%34%43%7%
522
21st to endNight
7%112%39%36%5%
591
August1st to 10thNight
15%211%36%32%4
537
11th to 20thNight
13%29%35%37%4
534
21st to endNight
11%110%32%37%9%
756
September1st to 10thNight
13%312%30%35%8%
720
11th to 20thNight
17%413%30%31%5%
720
21st to endNight
26%7%17%28%22%2
720
October1st to 10thNight
19%8%20%25%24%5%
720
11th to 20thNight
17%10%26%29%17%2
720
21st to endNight
16%12%25%33%12%1
792
November1st to 10thNight
18%9%26%31%14%2
740
11th to 20thNight
16%15%28%31%9%1
760
21st to endNight
16%15%30%28%11%1
760
December1st to 10thNight
20%17%34%23%6%
760
11th to 20thNight
16%14%40%25%5%
760
21st to endNight
22%17%29%27%4
836
Page generated at 2024-02-12 06:35:32. Version ac07

Copyright 2024 Attilla Danko


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