Pelican Lake Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pelican Lake Observatory clear sky chart from 2005-11-06 to 2024-01-14.

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
35%
24945
15%
74646
8%
24888
41%
24888
21%
51796

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
30%
950
12%
2837
6%
946
36%
946
17%
2055
January11th to 20thNight
24%
918
8%
2661
4%
918
27%
918
14%
2049
January21st to endNight
23%
990
12%
2578
4%
990
30%
990
15%
2035
February1st to 10thNight
27%
900
14%
2340
3%
900
34%
900
21%
1672
February11th to 20thNight
28%
879
18%
2274
6%
875
35%
875
23%
1591
February21st to endNight
28%
740
16%
1924
5%
740
37%
740
19%
1445
March1st to 10thNight
30%
576
13%
2016
9%
576
36%
576
17%
1371
March11th to 20thNight
28%
540
18%
1980
11%
540
40%
540
21%
1280
March21st to endNight
35%
594
15%
2178
13%
594
41%
594
16%
1500
April1st to 10thNight
29%
540
14%
1801
10%
540
37%
540
19%
1240
April11th to 20thNight
33%
533
17%
1681
13%
533
41%
533
19%
1191
April21st to endNight
33%
540
15%
1620
9%
540
39%
540
21%
1139
May1st to 10thNight
33%
540
15%
1516
8%
540
37%
540
24%
1039
May11th to 20thNight
41%
531
16%
1417
7%
531
46%
531
28%
958
May21st to endNight
45%
584
12%
1552
5%
582
47%
582
27%
1052
June1st to 10thNight
49%
540
11%
1326
4%
540
52%
540
35%
877
June11th to 20thNight
44%
540
13%
1260
5%
540
48%
540
35%
839
June21st to endNight
53%
540
14%
1260
7%
540
54%
540
36%
829
July1st to 10thNight
64%
525
16%
1225
8%
525
66%
525
48%
737
July11th to 20thNight
55%
522
19%
1254
8%
522
58%
522
43%
760
July21st to endNight
65%
591
20%
1494
9%
558
68%
558
48%
831
August1st to 10thNight
66%
537
18%
1601
13%
534
69%
534
38%
911
August11th to 20thNight
59%
534
21%
1600
19%
534
64%
534
33%
950
August21st to endNight
56%
594
23%
1831
22%
594
63%
594
37%
1028
September1st to 10thNight
56%
540
20%
1800
20%
540
61%
540
32%
1015
September11th to 20thNight
50%
540
21%
1867
17%
540
58%
540
30%
1068
September21st to endNight
39%
580
22%
2020
15%
580
49%
580
26%
1186
October1st to 10thNight
38%
720
18%
2160
12%
720
43%
720
25%
1411
October11th to 20thNight
29%
720
18%
2160
9%
720
37%
720
20%
1488
October21st to endNight
28%
806
15%
2409
7%
806
35%
806
17%
1732
November1st to 10thNight
31%
925
17%
2591
9%
925
39%
925
20%
1833
November11th to 20thNight
25%
950
13%
2660
5%
950
31%
950
16%
2014
November21st to endNight
25%
950
13%
2660
5%
950
31%
950
18%
1942
December1st to 10thNight
26%
950
9%
2660
4%
950
30%
950
13%
2089
December11th to 20thNight
18%
949
10%
3274
3%
949
26%
949
11%
2508
December21st to endNight
17%
1037
6%
5159
3%
1026
25%
1026
6%
4131

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%9%47%6%35%5%5%7%36%
74807
Night
13%9%47%6%35%45%7%36%
74960
TransparencyDay
46%8%14%22%9%1
74497
Night
46%7%13%22%10%1
74790
SeeingDay
15%9%31%27%14%4
14914
Night
16%8%32%32%11%1
24954

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
8%11%8%10%9%5%6%45%8%27%
1328
11th to 20thDay
10%14%7%13%11%45%6%47%20%
1369
21st to endDay
8%13%7%14%10%5%6%6%5%9%17%
1775
February1st to 10thDay
7%14%5%10%7%46%5%6%7%30%
1620
11th to 20thDay
8%10%5%8%7%5%5%6%6%5%34%
1574
21st to endDay
10%12%5%11%8%46%45%6%30%
1332
March1st to 10thDay
12%11%5%9%7%45%5%5%7%30%
1960
11th to 20thDay
14%10%48%6%35%5%5%7%34%
1980
21st to endDay
19%11%37%5%35%447%31%
2178
April1st to 10thDay
17%11%37%6%44446%33%
2158
11th to 20thDay
18%13%46%5%35%45%6%31%
2226
21st to endDay
22%9%36%6%34445%33%
2340
May1st to 10thDay
19%9%36%5%3445%6%35%
2443
11th to 20thDay
17%8%25%5%345%6%8%38%
2479
21st to endDay
16%6%35%5%35%5%6%8%38%
2725
June1st to 10thDay
12%5%26%5%35%6%6%9%41%
2630
11th to 20thDay
15%6%25%6%45%5%5%7%39%
2700
21st to endDay
10%5%25%6%47%6%7%10%38%
2700
July1st to 10thDay
7%3244346%7%8%51%
2700
11th to 20thDay
10%5%25%435%5%7%8%46%
2660
21st to endDay
6%424435%5%6%10%51%
2734
August1st to 10thDay
9%5%25%5%35%5%6%8%46%
2328
11th to 20thDay
12%6%25%5%35%46%8%44%
2301
21st to endDay
12%5%25%5%345%5%8%48%
2524
September1st to 10thDay
11%5%25%5%345%6%8%45%
2160
11th to 20thDay
13%5%36%6%445%6%7%41%
2089
21st to endDay
16%7%26%5%345%5%6%40%
1922
October1st to 10thDay
18%9%35%5%3445%7%37%
1800
11th to 20thDay
17%13%5%6%6%25%345%35%
1800
21st to endDay
19%12%5%7%5%245%46%31%
1941
November1st to 10thDay
12%11%6%9%7%35%45%6%32%
1487
11th to 20thDay
13%15%6%12%8%3435%5%25%
1520
21st to endDay
13%11%6%9%9%45%5%6%7%25%
1520
December1st to 10thDay
10%15%6%11%9%5%6%5%46%23%
1520
11th to 20thDay
10%13%7%12%8%46%6%5%5%24%
1842
21st to endDay
21%17%7%11%9%4433418%
2442
January1st to 10thNight
8%8%5%10%10%46%5%7%7%29%
2837
11th to 20thNight
10%13%6%11%9%45%5%5%8%24%
2661
21st to endNight
12%13%6%12%8%46%5%6%7%22%
2578
February1st to 10thNight
5%9%6%9%8%45%6%6%8%33%
2340
11th to 20thNight
7%10%48%7%36%5%6%8%37%
2273
21st to endNight
11%11%6%8%6%5%5%45%6%32%
1924
March1st to 10thNight
11%11%47%8%35%46%6%35%
2016
11th to 20thNight
12%11%46%5%34446%40%
1980
21st to endNight
16%11%47%6%3445%6%34%
2178
April1st to 10thNight
16%11%46%6%35%446%36%
1801
11th to 20thNight
19%11%46%5%35%345%36%
1681
21st to endNight
19%10%47%42445%6%36%
1620
May1st to 10thNight
17%9%37%433346%41%
1516
11th to 20thNight
16%5%35%335%5%7%7%40%
1416
21st to endNight
13%5%247%46%5%6%7%41%
1551
June1st to 10thNight
11%4245%345%8%9%45%
1326
11th to 20thNight
10%425%6%445%6%9%46%
1260
21st to endNight
11%5%244245%6%7%48%
1260
July1st to 10thNight
4324425%5%7%9%57%
1260
11th to 20thNight
6%42433345%7%57%
1296
21st to endNight
4313425%6%5%9%58%
1582
August1st to 10thNight
7%4145%3447%9%52%
1611
11th to 20thNight
11%424425%45%5%53%
1600
21st to endNight
11%42332345%8%54%
1831
September1st to 10thNight
9%4235%35%6%48%51%
1800
11th to 20thNight
10%425%5%3435%8%50%
1867
21st to endNight
15%5%35%5%22347%48%
2020
October1st to 10thNight
16%7%25%5%3436%6%42%
2160
11th to 20thNight
15%10%47%6%3445%6%37%
2160
21st to endNight
19%10%5%7%5%3446%6%33%
2409
November1st to 10thNight
14%9%47%6%35%5%5%7%35%
2591
11th to 20thNight
15%11%5%10%7%35%5%5%6%28%
2660
21st to endNight
12%9%5%9%8%445%6%7%31%
2660
December1st to 10thNight
9%13%6%12%9%5%6%5%5%6%24%
2660
11th to 20thNight
11%14%6%11%8%45%5%6%7%24%
3350
21st to endNight
22%18%6%10%6%34345%19%
5225

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
56%6%11%20%7%
1329
11th to 20thDay
64%7%8%14%7%
1369
21st to endDay
63%7%11%12%7%
1775
February1st to 10thDay
52%5%11%21%9%1
1620
11th to 20thDay
50%7%14%19%8%2
1583
21st to endDay
55%6%11%16%12%1
1332
March1st to 10thDay
52%8%15%19%7%
1960
11th to 20thDay
49%7%14%21%9%
1980
21st to endDay
54%6%12%21%7%1
2178
April1st to 10thDay
52%5%11%19%11%2
2158
11th to 20thDay
53%7%12%17%10%1
2226
21st to endDay
52%6%10%20%11%
2340
May1st to 10thDay
50%6%12%21%9%2
2443
11th to 20thDay
45%7%13%25%8%2
2483
21st to endDay
43%9%14%23%10%1
2725
June1st to 10thDay
37%9%18%27%9%1
2630
11th to 20thDay
42%8%14%22%13%1
2700
21st to endDay
37%11%18%26%8%1
2700
July1st to 10thDay
28%9%17%31%15%1
2626
11th to 20thDay
32%10%16%26%13%2
2579
21st to endDay
27%9%19%28%15%1
2582
August1st to 10thDay
34%8%17%29%10%2
2314
11th to 20thDay
36%9%18%27%9%1
2301
21st to endDay
34%8%14%29%14%1
2524
September1st to 10thDay
35%8%14%32%11%
2160
11th to 20thDay
40%9%19%25%8%
2089
21st to endDay
43%7%13%30%7%
1922
October1st to 10thDay
46%8%15%23%7%1
1800
11th to 20thDay
51%6%11%22%9%2
1800
21st to endDay
54%7%12%20%7%
1941
November1st to 10thDay
52%7%12%18%10%1
1487
11th to 20thDay
61%5%13%13%7%1
1520
21st to endDay
54%9%14%16%5%2
1520
December1st to 10thDay
61%7%13%14%5%
1520
11th to 20thDay
60%8%11%17%4
1839
21st to endDay
70%6%6%12%5%
2442
January1st to 10thNight
52%7%12%21%8%1
2837
11th to 20thNight
58%7%13%13%7%1
2661
21st to endNight
60%6%10%16%8%1
2578
February1st to 10thNight
48%6%12%22%11%1
2340
11th to 20thNight
45%7%13%23%11%1
2274
21st to endNight
52%7%8%20%11%1
1924
March1st to 10thNight
49%6%16%19%9%1
2016
11th to 20thNight
45%6%14%22%13%1
1980
21st to endNight
51%6%13%21%7%2
2178
April1st to 10thNight
49%6%11%18%15%1
1801
11th to 20thNight
51%6%8%19%16%1
1681
21st to endNight
49%6%11%20%12%2
1620
May1st to 10thNight
44%7%13%24%11%1
1516
11th to 20thNight
40%8%15%22%12%2
1417
21st to endNight
40%8%13%21%16%2
1552
June1st to 10thNight
32%10%21%27%9%2
1326
11th to 20thNight
33%9%17%24%16%2
1260
21st to endNight
33%8%17%29%12%2
1260
July1st to 10thNight
20%10%20%33%16%1
1225
11th to 20thNight
26%8%16%30%16%5%
1254
21st to endNight
21%8%20%32%17%3
1494
August1st to 10thNight
27%8%18%33%10%4
1601
11th to 20thNight
31%8%16%30%14%1
1600
21st to endNight
28%7%15%31%18%1
1831
September1st to 10thNight
30%7%16%33%13%1
1800
11th to 20thNight
32%8%17%31%12%
1867
21st to endNight
36%6%13%34%11%
2020
October1st to 10thNight
42%7%13%27%11%1
2160
11th to 20thNight
46%8%12%24%10%
2160
21st to endNight
51%7%12%21%8%
2409
November1st to 10thNight
48%6%12%23%9%1
2591
11th to 20thNight
55%7%13%15%8%1
2660
21st to endNight
50%8%17%19%5%1
2660
December1st to 10thNight
59%7%13%15%41
2660
11th to 20thNight
58%7%12%15%6%1
3352
21st to endNight
68%5%8%13%5%
5225

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
11%9%36%32%9%3
270
11th to 20thDay
18%9%29%35%9%
249
21st to endDay
13%8%40%23%14%2
264
February1st to 10thDay
16%14%44%21%5%
240
11th to 20thDay
19%15%33%23%8%2
240
21st to endDay
12%12%39%33%41
198
March1st to 10thDay
15%13%38%25%7%2
240
11th to 20thDay
18%6%34%26%13%3
240
21st to endDay
22%14%28%19%14%3
264
April1st to 10thDay
24%12%33%22%8%1
418
11th to 20thDay
26%11%26%25%11%1
504
21st to endDay
24%11%29%23%13%1
600
May1st to 10thDay
20%14%30%23%11%2
603
11th to 20thDay
20%10%30%25%12%3
625
21st to endDay
16%9%26%32%13%3
679
June1st to 10thDay
12%6%30%31%18%4
630
11th to 20thDay
16%8%35%27%11%2
630
21st to endDay
11%7%32%28%18%5%
630
July1st to 10thDay
7%424%29%28%8%
621
11th to 20thDay
9%6%31%26%19%8%
618
21st to endDay
6%426%32%24%8%
684
August1st to 10thDay
10%423%30%27%6%
626
11th to 20thDay
11%6%22%31%23%7%
615
21st to endDay
11%9%23%32%20%6%
643
September1st to 10thDay
11%6%28%32%19%4
450
11th to 20thDay
12%7%29%30%17%5%
379
21st to endDay
20%12%33%21%11%3
270
October1st to 10thDay
21%10%28%24%10%6%
270
11th to 20thDay
16%13%39%25%7%1
270
21st to endDay
26%12%39%16%6%1
297
November1st to 10thDay
17%13%36%25%9%1
270
11th to 20thDay
19%14%43%19%4
270
21st to endDay
21%11%42%21%5%
270
December1st to 10thDay
15%9%41%26%9%1
270
11th to 20thDay
17%17%35%27%4
270
21st to endDay
24%10%34%24%6%1
297
January1st to 10thNight
12%11%36%31%9%2
950
11th to 20thNight
17%9%36%30%8%1
918
21st to endNight
18%10%37%27%8%1
990
February1st to 10thNight
10%9%40%31%9%1
900
11th to 20thNight
11%10%42%25%10%1
879
21st to endNight
17%8%36%27%10%1
740
March1st to 10thNight
14%11%35%29%9%1
576
11th to 20thNight
16%8%42%27%6%1
540
21st to endNight
21%10%26%30%11%2
594
April1st to 10thNight
20%9%37%29%6%
540
11th to 20thNight
24%7%30%29%9%1
533
21st to endNight
23%6%30%30%9%1
540
May1st to 10thNight
18%10%35%28%8%1
540
11th to 20thNight
16%8%31%36%9%1
531
21st to endNight
14%8%27%38%13%
584
June1st to 10thNight
12%5%29%39%15%1
540
11th to 20thNight
10%434%42%9%
540
21st to endNight
13%6%22%41%17%1
540
July1st to 10thNight
4223%43%26%2
525
11th to 20thNight
7%328%42%19%1
522
21st to endNight
4323%45%23%2
591
August1st to 10thNight
8%315%50%22%2
537
11th to 20thNight
11%420%38%25%2
534
21st to endNight
12%5%23%38%21%2
594
September1st to 10thNight
10%5%23%41%19%1
540
11th to 20thNight
12%6%29%32%20%1
540
21st to endNight
16%7%34%28%14%2
580
October1st to 10thNight
19%9%30%30%11%1
720
11th to 20thNight
20%10%34%29%6%1
720
21st to endNight
23%11%32%28%6%
806
November1st to 10thNight
18%9%33%31%9%
925
11th to 20thNight
19%12%35%25%8%1
950
21st to endNight
17%12%39%25%6%
950
December1st to 10thNight
15%11%33%31%8%1
950
11th to 20thNight
20%10%37%26%7%1
950
21st to endNight
25%11%33%25%5%1
1045
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Copyright 2024 Attilla Danko


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