Big Trout Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Big Trout Lake clear sky chart from 2005-11-06 to 2024-02-05.

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
28%
24235
7%
81162
4%
24141
31%
24141
11%
64120

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
26%
944
5%
5044
4%
926
30%
926
4%
4263
January11th to 20thNight
25%
935
5%
4787
3%
930
28%
930
5%
3838
January21st to endNight
30%
1039
5%
5050
5%
1023
32%
1023
5%
4366
February1st to 10thNight
33%
923
9%
2583
4%
923
36%
923
12%
2110
February11th to 20thNight
34%
876
11%
2302
6%
874
36%
874
16%
1794
February21st to endNight
38%
686
16%
1870
7%
686
45%
686
16%
1414
March1st to 10thNight
34%
717
10%
2160
7%
717
38%
717
13%
1666
March11th to 20thNight
27%
630
14%
2070
7%
630
36%
630
15%
1516
March21st to endNight
36%
594
17%
2016
16%
594
42%
594
15%
1460
April1st to 10thNight
34%
540
16%
1800
12%
540
41%
540
18%
1266
April11th to 20thNight
37%
533
16%
1648
11%
533
43%
533
21%
1158
April21st to endNight
39%
540
16%
1440
7%
540
45%
540
27%
966
May1st to 10thNight
26%
540
6%
1440
2%
540
28%
540
16%
1119
May11th to 20thNight
30%
470
5%
1355
3%
470
33%
470
19%
971
May21st to endNight
29%
389
0%
1181
0%
388
29%
388
17%
856
June1st to 10thNight
31%
360
0%
1080
0%
360
31%
360
18%
766
June11th to 20thNight
37%
360
0%
1080
0%
360
37%
360
19%
755
June21st to endNight
36%
360
0%
1080
0%
360
36%
360
21%
744
July1st to 10thNight
39%
350
0%
1050
0%
350
39%
350
20%
720
July11th to 20thNight
42%
367
0%
1063
0%
367
42%
367
23%
716
July21st to endNight
45%
591
3%
1353
3%
558
47%
558
26%
975
August1st to 10thNight
43%
537
6%
1423
3%
534
45%
534
21%
1045
August11th to 20thNight
42%
534
10%
1422
5%
534
45%
534
23%
992
August21st to endNight
38%
594
12%
1790
8%
594
42%
594
20%
1284
September1st to 10thNight
29%
540
10%
1800
5%
540
35%
540
16%
1248
September11th to 20thNight
27%
540
7%
1800
6%
540
29%
540
12%
1385
September21st to endNight
25%
715
9%
2027
4%
715
29%
715
15%
1565
October1st to 10thNight
20%
720
10%
2160
5%
720
25%
720
10%
1743
October11th to 20thNight
21%
720
5%
2267
3%
720
23%
720
7%
1929
October21st to endNight
13%
825
3%
2607
1%
825
15%
825
5%
2305
November1st to 10thNight
15%
925
4%
2591
2%
925
18%
925
5%
2317
November11th to 20thNight
12%
950
4%
2797
1%
950
14%
950
4%
2535
November21st to endNight
12%
950
4%
2850
1%
950
14%
950
4%
2552
December1st to 10thNight
18%
950
4%
3025
1%
950
22%
950
6%
2610
December11th to 20thNight
28%
950
7%
3723
4%
949
33%
949
8%
3082
December21st to endNight
25%
1041
5%
5428
5%
1026
30%
1026
5%
4089

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%11%5%9%7%46%6%6%7%26%
77354
Night
13%12%6%11%9%5%7%6%6%5%20%
81533
TransparencyDay
57%7%11%17%7%1
77029
Night
64%6%10%15%6%
81392
SeeingDay
20%12%31%25%10%2
14737
Night
19%10%32%28%10%2
24272

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 10thDay
6%9%5%16%15%8%12%8%7%6%9%
1899
11th to 20thDay
5%7%7%18%13%7%10%8%8%5%11%
2167
21st to endDay
12%18%8%11%9%5%6%7%8%7%8%
2598
February1st to 10thDay
29%5%9%8%7%11%14%11%8%15%
1472
11th to 20thDay
49%410%8%5%10%9%13%8%20%
1542
21st to endDay
39%6%9%8%5%10%10%10%8%22%
1386
March1st to 10thDay
6%9%5%12%9%5%8%8%5%7%26%
1798
11th to 20thDay
8%12%5%7%9%5%7%7%7%6%26%
1903
21st to endDay
8%10%5%10%9%5%7%7%5%7%27%
2339
April1st to 10thDay
9%11%410%7%47%5%5%6%32%
2160
11th to 20thDay
10%10%49%9%46%46%6%33%
2258
21st to endDay
9%9%47%6%46%5%5%7%38%
2520
May1st to 10thDay
14%13%410%8%445%6%7%26%
2520
11th to 20thDay
16%10%47%6%445%6%8%32%
2540
21st to endDay
20%9%37%6%35%5%5%7%32%
3092
June1st to 10thDay
18%8%36%6%46%5%6%7%30%
2880
11th to 20thDay
17%6%36%6%35%5%6%8%34%
2880
21st to endDay
17%6%36%6%36%6%6%7%35%
2880
July1st to 10thDay
14%6%37%6%46%6%7%8%32%
2880
11th to 20thDay
17%6%36%5%45%6%7%7%33%
2858
21st to endDay
15%6%25%6%36%6%6%9%35%
2885
August1st to 10thDay
15%6%36%6%45%5%5%8%36%
2507
11th to 20thDay
17%7%36%6%45%5%6%6%32%
2479
21st to endDay
20%6%38%7%36%5%5%7%30%
2565
September1st to 10thDay
22%9%37%5%445%5%7%30%
2160
11th to 20thDay
26%11%38%6%3445%5%25%
2147
21st to endDay
20%12%46%6%3445%6%30%
1926
October1st to 10thDay
25%20%6%6%435%45%5%19%
1800
11th to 20thDay
23%20%7%10%6%34445%13%
1692
21st to endDay
21%24%8%11%7%4333412%
1746
November1st to 10thDay
17%20%10%16%9%4443410%
1487
11th to 20thDay
16%19%7%14%13%6%5%5%439%
1382
21st to endDay
11%20%9%17%9%6%7%5%438%
1330
December1st to 10thDay
10%16%7%14%11%6%7%6%6%5%12%
1150
11th to 20thDay
8%14%5%12%9%6%7%9%7%8%14%
1436
21st to endDay
9%10%6%10%10%7%7%7%7%6%20%
2090
January1st to 10thNight
5%10%6%16%12%7%13%12%8%5%8%
5057
11th to 20thNight
5%9%7%20%15%5%7%7%10%411%
4800
21st to endNight
11%17%8%15%10%5%7%7%7%49%
5067
February1st to 10thNight
5%8%6%11%9%7%15%12%8%5%15%
2583
11th to 20thNight
410%5%10%10%7%10%11%9%6%19%
2301
21st to endNight
5%9%5%9%7%7%10%10%8%7%22%
1870
March1st to 10thNight
6%10%6%11%10%7%9%7%6%6%23%
2149
11th to 20thNight
9%13%48%8%6%7%6%6%6%27%
2069
21st to endNight
9%10%5%10%9%5%6%6%5%6%29%
2016
April1st to 10thNight
11%9%7%9%8%45%5%5%5%32%
1800
11th to 20thNight
13%12%37%8%35%35%6%36%
1648
21st to endNight
10%9%45%6%345%5%7%41%
1440
May1st to 10thNight
17%12%6%10%6%45%5%46%26%
1440
11th to 20thNight
19%11%36%5%345%5%7%32%
1355
21st to endNight
19%11%35%5%347%5%7%30%
1181
June1st to 10thNight
18%8%5%6%6%445%7%7%30%
1080
11th to 20thNight
17%8%47%5%45%5%5%8%34%
1080
21st to endNight
17%6%36%6%445%5%9%34%
1080
July1st to 10thNight
15%5%38%6%46%5%5%8%34%
1080
11th to 20thNight
16%5%26%6%45%6%6%9%35%
1099
21st to endNight
15%7%26%6%445%7%7%38%
1432
August1st to 10thNight
17%7%36%6%46%5%6%6%34%
1432
11th to 20thNight
16%5%25%6%45%5%7%8%36%
1422
21st to endNight
22%7%36%5%3445%6%35%
1790
September1st to 10thNight
20%8%36%6%435%48%33%
1800
11th to 20thNight
22%12%48%6%345%46%26%
1800
21st to endNight
23%13%37%5%34445%29%
2027
October1st to 10thNight
28%17%5%6%6%33245%21%
2160
11th to 20thNight
23%21%7%8%7%34445%15%
2267
21st to endNight
21%25%8%12%6%3333411%
2607
November1st to 10thNight
19%20%8%13%9%5%434410%
2591
11th to 20thNight
14%18%10%15%12%6%5%43310%
2797
21st to endNight
12%20%10%18%10%5%6%5%339%
2850
December1st to 10thNight
8%16%7%15%12%7%6%8%6%5%10%
3025
11th to 20thNight
8%12%6%12%13%7%9%9%7%5%12%
3761
21st to endNight
8%11%5%14%10%6%9%6%6%5%20%
5577

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
72%5%11%11%2
1900
11th to 20thDay
69%6%9%13%2
2167
21st to endDay
72%5%7%12%4
2598
February1st to 10thDay
57%9%10%17%7%
1472
11th to 20thDay
53%7%12%21%7%
1551
21st to endDay
53%8%11%16%12%
1386
March1st to 10thDay
57%6%11%18%8%1
1800
11th to 20thDay
54%6%13%19%8%1
1903
21st to endDay
56%6%10%18%9%2
2339
April1st to 10thDay
53%5%13%18%11%
2160
11th to 20thDay
52%6%10%21%10%1
2258
21st to endDay
45%6%11%22%15%1
2520
May1st to 10thDay
57%6%12%18%7%
2520
11th to 20thDay
51%6%9%20%14%1
2544
21st to endDay
52%7%9%20%12%1
3092
June1st to 10thDay
53%7%8%19%13%
2880
11th to 20thDay
47%7%10%22%12%1
2880
21st to endDay
46%9%11%20%13%1
2880
July1st to 10thDay
47%8%14%24%6%
2801
11th to 20thDay
47%9%13%22%8%1
2771
21st to endDay
45%10%16%22%7%
2725
August1st to 10thDay
46%9%17%24%3
2492
11th to 20thDay
49%10%16%21%4
2479
21st to endDay
53%8%17%17%5%
2565
September1st to 10thDay
54%8%15%17%6%
2160
11th to 20thDay
62%6%12%19%1
2147
21st to endDay
55%7%15%18%5%
1926
October1st to 10thDay
68%5%11%12%41
1800
11th to 20thDay
73%7%9%8%3
1692
21st to endDay
79%5%8%6%2
1746
November1st to 10thDay
81%47%6%1
1487
11th to 20thDay
79%6%9%5%1
1382
21st to endDay
80%47%6%2
1330
December1st to 10thDay
73%5%9%10%4
1150
11th to 20thDay
64%410%16%6%
1436
21st to endDay
62%6%9%15%8%1
2090
January1st to 10thNight
72%8%10%9%2
5057
11th to 20thNight
70%5%12%11%2
4800
21st to endNight
76%5%5%10%4
5067
February1st to 10thNight
65%7%8%15%6%
2583
11th to 20thNight
58%7%10%20%5%
2302
21st to endNight
56%5%10%17%12%
1870
March1st to 10thNight
61%5%12%15%7%1
2160
11th to 20thNight
57%5%9%21%7%1
2070
21st to endNight
55%6%8%18%12%2
2016
April1st to 10thNight
52%5%8%22%13%
1800
11th to 20thNight
51%48%21%14%2
1648
21st to endNight
43%5%10%21%21%1
1440
May1st to 10thNight
59%5%8%19%9%
1440
11th to 20thNight
50%7%8%18%13%4
1356
21st to endNight
52%6%9%19%12%1
1181
June1st to 10thNight
51%6%11%18%13%1
1080
11th to 20thNight
48%8%9%20%15%1
1080
21st to endNight
46%7%12%22%12%1
1080
July1st to 10thNight
46%8%14%21%10%
1050
11th to 20thNight
42%9%15%26%7%1
1063
21st to endNight
43%10%16%23%8%
1353
August1st to 10thNight
47%10%16%22%5%
1423
11th to 20thNight
43%9%17%26%4
1422
21st to endNight
50%7%17%21%5%
1790
September1st to 10thNight
50%7%18%20%5%1
1800
11th to 20thNight
59%8%15%16%1
1800
21st to endNight
59%6%13%18%5%
2027
October1st to 10thNight
67%49%15%4
2160
11th to 20thNight
72%6%11%9%2
2267
21st to endNight
78%5%9%6%2
2607
November1st to 10thNight
79%5%8%6%2
2591
11th to 20thNight
82%5%7%6%1
2797
21st to endNight
81%36%8%2
2850
December1st to 10thNight
74%6%8%10%2
3025
11th to 20thNight
70%5%9%12%3
3760
21st to endNight
64%48%18%6%
5577

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
10%13%39%33%41
180
11th to 20thDay
9%12%36%29%12%1
258
21st to endDay
16%10%26%34%11%2
297
February1st to 10thDay
410%38%39%8%2
252
11th to 20thDay
8%13%44%22%10%3
240
21st to endDay
5%18%32%28%13%4
198
March1st to 10thDay
11%7%32%30%14%6%
240
11th to 20thDay
9%17%44%20%9%2
240
21st to endDay
13%14%32%26%11%4
425
April1st to 10thDay
17%12%33%27%7%3
420
11th to 20thDay
17%12%31%25%12%3
468
21st to endDay
15%13%29%25%15%4
600
May1st to 10thDay
22%12%31%24%10%1
603
11th to 20thDay
21%13%34%22%8%2
625
21st to endDay
23%15%32%23%6%1
679
June1st to 10thDay
25%14%30%20%8%2
630
11th to 20thDay
20%16%27%23%12%2
630
21st to endDay
21%10%28%26%14%1
630
July1st to 10thDay
15%12%30%31%11%1
621
11th to 20thDay
20%10%30%23%13%3
618
21st to endDay
18%7%29%25%17%4
684
August1st to 10thDay
19%11%27%27%14%3
626
11th to 20thDay
19%13%26%25%15%3
615
21st to endDay
26%9%26%27%9%3
613
September1st to 10thDay
29%14%30%21%5%1
450
11th to 20thDay
29%12%27%22%9%1
450
21st to endDay
25%12%34%22%5%2
396
October1st to 10thDay
32%15%29%15%8%1
270
11th to 20thDay
30%13%23%23%10%1
270
21st to endDay
30%17%28%18%7%1
297
November1st to 10thDay
23%16%37%17%7%1
270
11th to 20thDay
24%14%33%22%6%1
204
21st to endDay
22%18%33%21%5%2
180
December1st to 10thDay
18%15%31%28%7%1
180
11th to 20thDay
17%11%37%24%9%1
180
21st to endDay
14%12%29%29%11%5%
198
January1st to 10thNight
13%9%38%29%9%2
950
11th to 20thNight
14%12%32%31%10%1
950
21st to endNight
13%7%31%35%13%1
1045
February1st to 10thNight
8%9%37%34%10%1
923
11th to 20thNight
9%8%36%30%13%4
879
21st to endNight
9%7%31%31%16%5%
686
March1st to 10thNight
10%8%31%29%19%2
720
11th to 20thNight
14%12%38%24%10%1
630
21st to endNight
15%10%30%29%12%3
594
April1st to 10thNight
15%9%34%31%9%1
540
11th to 20thNight
19%7%29%31%12%2
533
21st to endNight
13%9%32%30%14%1
540
May1st to 10thNight
23%9%33%28%7%
540
11th to 20thNight
26%9%30%26%9%1
470
21st to endNight
25%10%31%27%7%
389
June1st to 10thNight
20%9%33%26%10%2
360
11th to 20thNight
18%9%30%30%12%1
360
21st to endNight
18%9%31%32%10%1
360
July1st to 10thNight
17%6%31%33%12%1
350
11th to 20thNight
17%7%28%33%14%
367
21st to endNight
15%6%26%32%18%3
591
August1st to 10thNight
22%6%22%36%14%1
537
11th to 20thNight
19%5%27%29%16%2
534
21st to endNight
26%8%25%29%11%2
594
September1st to 10thNight
25%8%34%26%7%1
540
11th to 20thNight
30%9%27%25%10%
540
21st to endNight
29%9%29%24%8%1
715
October1st to 10thNight
37%12%24%22%5%1
720
11th to 20thNight
32%12%23%22%9%2
720
21st to endNight
35%11%29%18%7%1
825
November1st to 10thNight
29%14%27%21%8%1
925
11th to 20thNight
23%11%37%20%8%1
950
21st to endNight
23%16%33%20%5%3
950
December1st to 10thNight
15%13%38%27%6%1
950
11th to 20thNight
13%11%34%27%12%2
950
21st to endNight
14%9%34%28%12%3
1045
Page generated at 2024-02-02 04:20:27. Version ac07

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