Galena
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Galena clear sky chart from 2005-11-06 to 2024-02-25.

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
32%
24860
17%
80488
10%
24760
40%
24760
21%
54274

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
21%
940
10%
4395
5%
926
30%
926
11%
3172
January11th to 20thNight
18%
950
11%
4365
4%
930
24%
930
8%
3350
January21st to endNight
16%
1037
7%
4561
2%
1023
23%
1023
8%
3595
February1st to 10thNight
19%
950
14%
2470
4%
950
25%
950
18%
1827
February11th to 20thNight
22%
844
19%
2322
6%
843
31%
843
20%
1583
February21st to endNight
17%
611
18%
1831
5%
611
29%
611
17%
1287
March1st to 10thNight
19%
720
14%
2160
5%
720
27%
720
18%
1503
March11th to 20thNight
29%
559
20%
1999
12%
559
40%
559
20%
1237
March21st to endNight
19%
594
14%
2052
7%
594
29%
594
13%
1490
April1st to 10thNight
21%
540
16%
1800
8%
540
33%
540
18%
1194
April11th to 20thNight
29%
533
20%
1775
13%
533
42%
533
18%
1179
April21st to endNight
30%
540
16%
1800
9%
540
39%
540
19%
1196
May1st to 10thNight
29%
540
16%
1506
7%
540
38%
540
24%
1043
May11th to 20thNight
32%
531
19%
1417
9%
531
40%
531
24%
990
May21st to endNight
43%
584
17%
1551
8%
582
51%
582
32%
987
June1st to 10thNight
48%
540
17%
1440
8%
540
53%
540
35%
890
June11th to 20thNight
47%
540
20%
1440
10%
540
52%
540
37%
886
June21st to endNight
46%
540
19%
1440
9%
540
52%
540
32%
917
July1st to 10thNight
66%
525
18%
1400
12%
525
68%
525
44%
810
July11th to 20thNight
61%
522
23%
1392
14%
522
65%
522
45%
797
July21st to endNight
61%
591
23%
1487
17%
558
65%
558
43%
867
August1st to 10thNight
66%
537
23%
1548
20%
534
70%
534
41%
868
August11th to 20thNight
66%
534
24%
1689
25%
534
69%
534
38%
925
August21st to endNight
60%
594
24%
1980
25%
594
65%
594
37%
1054
September1st to 10thNight
56%
540
24%
1800
21%
540
63%
540
35%
976
September11th to 20thNight
55%
540
31%
1800
28%
540
63%
540
34%
1002
September21st to endNight
47%
720
26%
2002
15%
720
55%
720
34%
1192
October1st to 10thNight
43%
720
23%
2160
15%
720
49%
720
32%
1265
October11th to 20thNight
30%
720
21%
2160
10%
720
41%
720
25%
1376
October21st to endNight
25%
792
18%
2480
10%
792
34%
792
19%
1660
November1st to 10thNight
29%
740
25%
2406
15%
740
43%
740
26%
1429
November11th to 20thNight
22%
805
17%
2515
8%
805
31%
805
17%
1724
November21st to endNight
22%
950
18%
2660
8%
950
31%
950
21%
1818
December1st to 10thNight
19%
950
12%
2660
3%
950
26%
950
16%
1954
December11th to 20thNight
21%
949
13%
3194
4%
948
28%
948
13%
2296
December21st to endNight
14%
1038
7%
4831
3%
1026
23%
1026
6%
3935

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%9%47%6%345%5%7%36%
78386
Night
14%10%47%5%3445%6%38%
80955
TransparencyDay
48%412%23%12%1
78086
Night
48%411%23%13%2
80775
SeeingDay
18%14%31%23%10%3
14824
Night
18%12%31%27%10%1
24889

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
11%12%11%14%7%34435%26%
2527
11th to 20thDay
11%10%5%13%9%46%11%5%5%20%
2530
21st to endDay
17%21%9%11%5%24345%20%
3053
February1st to 10thDay
12%14%6%8%6%35%5%5%6%30%
1710
11th to 20thDay
14%10%46%5%35%45%6%36%
1744
21st to endDay
15%12%49%7%33346%33%
1520
March1st to 10thDay
16%10%6%6%6%3445%7%34%
1800
11th to 20thDay
13%9%46%5%3445%8%38%
1975
21st to endDay
21%11%46%5%3446%7%27%
2303
April1st to 10thDay
18%12%47%6%3445%6%31%
2160
11th to 20thDay
17%11%46%6%345%5%5%34%
2134
21st to endDay
22%9%36%5%35%346%34%
2160
May1st to 10thDay
17%9%47%6%46%5%6%7%29%
2450
11th to 20thDay
20%8%36%6%345%5%6%33%
2479
21st to endDay
15%7%37%6%36%45%7%35%
2725
June1st to 10thDay
11%5%35%5%35%5%6%8%43%
2520
11th to 20thDay
11%6%35%5%35%5%5%8%44%
2520
21st to endDay
12%6%36%5%45%6%6%8%39%
2520
July1st to 10thDay
9%5%245%345%6%10%47%
2520
11th to 20thDay
8%5%245%35%6%6%10%46%
2520
21st to endDay
6%5%25%6%45%6%7%10%45%
2743
August1st to 10thDay
6%5%35%6%47%7%8%10%40%
2378
11th to 20thDay
11%6%35%6%345%6%7%45%
2212
21st to endDay
10%5%245%345%6%7%48%
2376
September1st to 10thDay
14%5%25%6%3445%7%44%
2160
11th to 20thDay
13%424424447%52%
2142
21st to endDay
14%6%25%42445%7%45%
1955
October1st to 10thDay
14%8%35%5%24346%45%
1800
11th to 20thDay
21%9%35%6%24445%37%
1800
21st to endDay
20%9%36%433445%40%
1874
November1st to 10thDay
12%8%36%5%25%447%45%
1672
11th to 20thDay
15%12%48%6%34446%34%
1663
21st to endDay
15%12%47%5%23436%38%
1520
December1st to 10thDay
15%13%410%6%45%445%32%
1520
11th to 20thDay
14%13%5%9%6%35%5%5%6%29%
1918
21st to endDay
20%24%9%9%6%3343415%
2783
January1st to 10thNight
12%12%7%12%8%44445%29%
4428
11th to 20thNight
12%17%7%11%8%347%6%420%
4440
21st to endNight
17%18%8%9%8%3434422%
4599
February1st to 10thNight
12%12%6%8%7%45%445%32%
2470
11th to 20thNight
11%9%48%6%3445%5%40%
2321
21st to endNight
16%13%5%7%434445%35%
1831
March1st to 10thNight
17%12%46%434445%36%
2160
11th to 20thNight
12%8%45%6%345%48%41%
1999
21st to endNight
20%11%48%6%34446%29%
2052
April1st to 10thNight
17%9%46%5%24446%39%
1800
11th to 20thNight
18%10%35%5%3435%6%38%
1775
21st to endNight
18%8%26%5%36%45%6%37%
1800
May1st to 10thNight
16%7%35%435%5%6%9%35%
1506
11th to 20thNight
16%9%36%43446%7%37%
1416
21st to endNight
10%6%35%4345%7%10%42%
1551
June1st to 10thNight
8%5%345%446%5%9%48%
1440
11th to 20thNight
10%6%24335%5%6%10%46%
1440
21st to endNight
10%5%25%435%5%6%8%46%
1440
July1st to 10thNight
6%4144235%6%11%53%
1440
11th to 20thNight
6%32343345%9%57%
1440
21st to endNight
7%315%4346%6%9%52%
1575
August1st to 10thNight
6%3245%35%5%5%9%53%
1557
11th to 20thNight
8%4245%3435%8%55%
1689
21st to endNight
9%4245%23447%56%
1980
September1st to 10thNight
10%5%245%23447%54%
1800
11th to 20thNight
11%42444445%8%51%
1800
21st to endNight
10%5%245%35%5%46%52%
2002
October1st to 10thNight
12%6%24433446%52%
2160
11th to 20thNight
17%8%25%42345%6%44%
2160
21st to endNight
19%8%36%5%34346%39%
2480
November1st to 10thNight
12%7%35%423346%50%
2406
11th to 20thNight
15%10%48%7%35%345%36%
2515
21st to endNight
17%8%47%5%2345%5%38%
2660
December1st to 10thNight
14%11%5%9%7%3445%6%30%
2660
11th to 20thNight
14%13%5%9%6%35%45%6%31%
3279
21st to endNight
21%18%7%11%5%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
63%311%16%6%
2528
11th to 20thDay
63%413%12%8%1
2530
21st to endDay
68%210%14%4
3053
February1st to 10thDay
55%312%19%10%1
1710
11th to 20thDay
48%412%25%10%2
1753
21st to endDay
54%49%22%9%1
1520
March1st to 10thDay
51%315%21%9%1
1800
11th to 20thDay
45%414%24%12%1
1975
21st to endDay
56%5%10%20%7%1
2303
April1st to 10thDay
54%410%22%10%
2160
11th to 20thDay
51%5%8%22%12%2
2134
21st to endDay
52%49%21%12%2
2160
May1st to 10thDay
53%5%12%21%8%
2450
11th to 20thDay
51%5%10%21%12%
2483
21st to endDay
49%5%11%19%14%2
2725
June1st to 10thDay
38%6%12%27%16%1
2520
11th to 20thDay
39%5%12%23%19%2
2520
21st to endDay
41%7%13%25%13%1
2520
July1st to 10thDay
33%7%15%29%15%2
2451
11th to 20thDay
32%6%17%27%15%2
2445
21st to endDay
33%6%16%27%14%3
2591
August1st to 10thDay
36%7%15%29%11%1
2363
11th to 20thDay
37%5%14%26%17%2
2212
21st to endDay
34%6%12%28%17%3
2376
September1st to 10thDay
40%5%9%27%18%2
2160
11th to 20thDay
33%411%35%15%2
2142
21st to endDay
39%410%29%17%1
1955
October1st to 10thDay
41%410%29%16%1
1800
11th to 20thDay
49%311%22%14%1
1800
21st to endDay
47%412%23%13%1
1874
November1st to 10thDay
42%313%25%14%2
1672
11th to 20thDay
52%313%20%10%1
1663
21st to endDay
49%417%23%7%1
1520
December1st to 10thDay
56%414%17%8%2
1520
11th to 20thDay
55%418%14%8%1
1915
21st to endDay
75%39%9%4
2783
January1st to 10thNight
60%311%19%8%
4428
11th to 20thNight
65%310%14%8%
4440
21st to endNight
68%28%15%5%1
4599
February1st to 10thNight
55%310%19%12%1
2470
11th to 20thNight
46%411%24%13%1
2322
21st to endNight
52%310%21%11%3
1831
March1st to 10thNight
51%313%22%10%1
2160
11th to 20thNight
43%413%22%16%2
1999
21st to endNight
58%310%19%8%2
2052
April1st to 10thNight
47%410%24%13%2
1800
11th to 20thNight
48%48%20%17%4
1775
21st to endNight
48%411%21%14%2
1800
May1st to 10thNight
45%6%14%23%12%1
1506
11th to 20thNight
46%6%10%23%14%1
1417
21st to endNight
36%6%14%25%17%2
1552
June1st to 10thNight
33%6%14%26%20%2
1440
11th to 20thNight
34%5%12%25%22%4
1440
21st to endNight
36%6%14%24%16%4
1440
July1st to 10thNight
27%5%14%34%16%4
1400
11th to 20thNight
26%5%12%33%21%4
1392
21st to endNight
27%6%18%27%18%4
1487
August1st to 10thNight
28%5%16%34%15%3
1548
11th to 20thNight
30%413%32%20%1
1689
21st to endNight
29%312%30%20%5%
1980
September1st to 10thNight
31%411%28%25%2
1800
11th to 20thNight
33%310%33%18%3
1800
21st to endNight
33%5%8%32%20%2
2002
October1st to 10thNight
35%310%27%22%2
2160
11th to 20thNight
42%311%24%19%2
2160
21st to endNight
48%310%24%13%1
2480
November1st to 10thNight
38%411%27%18%3
2406
11th to 20thNight
51%312%21%12%1
2515
21st to endNight
48%312%26%10%1
2660
December1st to 10thNight
56%312%20%8%1
2660
11th to 20thNight
55%314%20%7%1
3281
21st to endNight
71%37%14%5%
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
21%17%32%21%8%1
270
11th to 20thDay
24%21%39%12%31
270
21st to endDay
25%21%37%13%31
297
February1st to 10thDay
21%27%36%14%3
270
11th to 20thDay
23%29%31%14%3
270
21st to endDay
30%22%38%9%1
210
March1st to 10thDay
20%28%38%12%2
240
11th to 20thDay
21%25%34%14%42
240
21st to endDay
32%20%28%14%5%1
389
April1st to 10thDay
28%21%31%15%4
420
11th to 20thDay
28%19%26%17%8%2
412
21st to endDay
26%18%30%17%9%1
420
May1st to 10thDay
21%17%36%19%6%2
543
11th to 20thDay
25%14%30%22%8%2
625
21st to endDay
17%14%29%25%11%4
679
June1st to 10thDay
10%9%33%30%13%4
630
11th to 20thDay
14%11%36%27%10%3
630
21st to endDay
14%11%33%27%11%4
630
July1st to 10thDay
9%5%25%31%19%10%
621
11th to 20thDay
9%9%30%32%15%6%
618
21st to endDay
8%7%30%34%15%5%
684
August1st to 10thDay
8%326%35%22%6%
626
11th to 20thDay
15%5%22%25%23%10%
526
21st to endDay
11%7%25%32%19%7%
495
September1st to 10thDay
15%10%28%26%15%5%
450
11th to 20thDay
13%426%31%19%6%
450
21st to endDay
17%15%26%25%14%3
425
October1st to 10thDay
21%12%31%25%10%1
270
11th to 20thDay
27%26%29%14%4
270
21st to endDay
31%18%31%16%4
297
November1st to 10thDay
19%22%35%18%5%2
270
11th to 20thDay
21%24%36%14%41
270
21st to endDay
26%16%40%14%3
270
December1st to 10thDay
20%22%36%15%5%1
270
11th to 20thDay
17%21%34%21%5%1
270
21st to endDay
28%22%36%13%1
297
January1st to 10thNight
17%19%35%24%6%1
950
11th to 20thNight
19%17%36%23%5%
950
21st to endNight
22%14%36%23%5%
1045
February1st to 10thNight
21%16%36%22%5%
950
11th to 20thNight
17%20%35%25%4
847
21st to endNight
26%17%36%18%3
611
March1st to 10thNight
24%16%34%20%5%
720
11th to 20thNight
18%13%35%26%7%
559
21st to endNight
25%16%35%19%5%1
594
April1st to 10thNight
21%17%35%22%4
540
11th to 20thNight
25%15%27%26%7%1
533
21st to endNight
22%12%31%26%8%1
540
May1st to 10thNight
19%11%36%27%5%1
540
11th to 20thNight
21%9%33%29%9%
531
21st to endNight
13%7%32%32%15%1
584
June1st to 10thNight
10%6%31%40%13%1
540
11th to 20thNight
12%6%31%39%11%1
540
21st to endNight
13%6%28%37%15%1
540
July1st to 10thNight
8%317%39%28%5%
525
11th to 20thNight
7%424%39%23%2
522
21st to endNight
9%222%43%24%1
591
August1st to 10thNight
6%217%44%28%3
537
11th to 20thNight
9%316%37%31%5%
534
21st to endNight
11%320%40%22%4
594
September1st to 10thNight
11%5%22%35%21%5%
540
11th to 20thNight
12%424%31%24%4
540
21st to endNight
13%9%27%33%17%1
720
October1st to 10thNight
16%9%29%28%17%1
720
11th to 20thNight
22%13%30%27%8%
720
21st to endNight
23%16%31%22%6%1
792
November1st to 10thNight
17%15%34%24%8%1
740
11th to 20thNight
21%20%34%21%4
805
21st to endNight
21%16%34%21%7%
950
December1st to 10thNight
22%18%33%22%5%1
950
11th to 20thNight
22%15%34%23%6%
950
21st to endNight
28%16%33%20%2
1045
Page generated at 2024-02-22 05:05:43. Version ac07

Copyright 2024 Attilla Danko


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