Mont-Tremblant
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mont-Tremblant clear sky chart from 2005-11-06 to 2024-01-16.

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
27%
22492
12%
74766
7%
22451
34%
22451
14%
54819

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
10%
760
7%
2649
1%
757
17%
757
6%
2196
January11th to 20thNight
15%
744
9%
2602
3%
744
23%
744
7%
2065
January21st to endNight
20%
792
12%
2772
7%
792
27%
792
11%
2051
February1st to 10thNight
13%
720
10%
2354
3%
720
22%
720
9%
1856
February11th to 20thNight
15%
703
11%
2230
4%
700
25%
700
9%
1717
February21st to endNight
21%
592
13%
1776
6%
592
30%
592
13%
1340
March1st to 10thNight
19%
720
14%
2160
8%
720
27%
720
12%
1653
March11th to 20thNight
19%
720
14%
2048
5%
720
28%
720
13%
1547
March21st to endNight
26%
792
20%
2014
7%
792
34%
792
19%
1450
April1st to 10thNight
22%
720
14%
1800
4%
720
26%
720
17%
1369
April11th to 20thNight
28%
711
16%
1775
5%
711
34%
711
22%
1271
April21st to endNight
25%
581
15%
1661
7%
581
31%
581
17%
1200
May1st to 10thNight
31%
360
16%
1440
12%
360
43%
360
15%
965
May11th to 20thNight
31%
354
19%
1416
18%
354
44%
354
18%
914
May21st to endNight
31%
389
12%
1551
9%
388
42%
388
17%
999
June1st to 10thNight
33%
360
9%
1440
7%
360
42%
360
14%
984
June11th to 20thNight
38%
360
10%
1440
12%
360
44%
360
16%
933
June21st to endNight
44%
360
9%
1440
13%
360
48%
360
16%
968
July1st to 10thNight
48%
350
11%
1400
16%
350
54%
350
22%
823
July11th to 20thNight
50%
348
13%
1392
19%
348
53%
348
21%
851
July21st to endNight
51%
394
12%
1486
14%
372
55%
372
21%
910
August1st to 10thNight
52%
358
13%
1422
14%
356
56%
356
19%
881
August11th to 20thNight
52%
514
16%
1578
12%
514
55%
514
27%
1035
August21st to endNight
43%
792
16%
1980
8%
792
47%
792
28%
1362
September1st to 10thNight
43%
720
15%
1800
5%
720
47%
720
30%
1227
September11th to 20thNight
49%
720
19%
1840
11%
720
52%
720
31%
1213
September21st to endNight
42%
720
21%
1980
14%
720
47%
720
26%
1330
October1st to 10thNight
34%
720
18%
2150
11%
720
42%
720
18%
1516
October11th to 20thNight
26%
720
12%
2171
7%
720
32%
720
14%
1631
October21st to endNight
23%
792
11%
2574
6%
792
29%
792
12%
1969
November1st to 10thNight
25%
740
13%
2407
8%
740
32%
740
13%
1769
November11th to 20thNight
19%
760
14%
2612
8%
760
26%
760
11%
1993
November21st to endNight
18%
760
8%
2660
5%
760
22%
760
7%
2150
December1st to 10thNight
12%
760
7%
2660
3%
760
17%
760
6%
2237
December11th to 20thNight
14%
760
10%
3246
4%
759
21%
759
6%
2548
December21st to endNight
11%
826
6%
4840
3%
817
18%
817
4%
3896

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
19%11%48%6%3445%6%29%
74769
Night
18%12%5%8%6%3445%6%29%
75023
TransparencyDay
55%6%10%18%9%1
74474
Night
56%6%10%18%9%1
74852
SeeingDay
27%17%29%18%7%2
13372
Night
25%14%27%24%9%1
22502

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
18%20%8%13%9%35%32316%
1517
11th to 20thDay
18%18%5%12%8%23447%19%
1480
21st to endDay
12%14%9%9%8%4446%6%24%
1584
February1st to 10thDay
11%19%6%13%9%35%446%20%
1604
11th to 20thDay
13%19%6%12%7%34345%24%
1617
21st to endDay
16%18%6%9%7%4445%5%23%
1480
March1st to 10thDay
15%14%6%9%8%34446%27%
1797
11th to 20thDay
16%13%5%10%6%44447%27%
1908
21st to endDay
19%10%47%6%34445%33%
2341
April1st to 10thDay
21%15%5%8%5%33345%28%
2160
11th to 20thDay
22%10%46%6%34445%32%
2134
21st to endDay
22%11%48%6%345%35%30%
2310
May1st to 10thDay
22%10%46%5%245%45%31%
2520
11th to 20thDay
21%8%36%7%335%5%5%34%
2478
21st to endDay
20%8%36%5%35%45%7%33%
2725
June1st to 10thDay
25%9%36%6%35%6%6%7%25%
2520
11th to 20thDay
17%6%36%7%46%5%6%7%33%
2520
21st to endDay
23%8%37%6%46%6%5%7%27%
2520
July1st to 10thDay
16%7%35%5%45%5%6%9%35%
2520
11th to 20thDay
16%6%35%6%46%6%7%8%33%
2520
21st to endDay
14%8%36%6%46%6%6%8%32%
2744
August1st to 10thDay
16%8%46%6%46%6%6%8%30%
2506
11th to 20thDay
16%7%35%6%45%6%7%8%34%
2302
21st to endDay
18%6%36%6%45%5%5%7%36%
2376
September1st to 10thDay
19%5%25%5%45%45%6%40%
2160
11th to 20thDay
18%7%35%4345%7%6%40%
2119
21st to endDay
22%7%35%43345%8%38%
1980
October1st to 10thDay
24%10%26%434347%31%
1805
11th to 20thDay
29%13%38%6%33445%23%
1788
21st to endDay
27%15%46%5%34445%23%
1782
November1st to 10thDay
18%13%48%5%2446%6%29%
1671
11th to 20thDay
21%16%7%9%7%34445%20%
1563
21st to endDay
23%15%6%11%7%3433420%
1520
December1st to 10thDay
24%19%6%9%6%34345%15%
1520
11th to 20thDay
21%17%7%11%8%3444418%
1906
21st to endDay
22%20%6%10%6%2434418%
2772
January1st to 10thNight
17%20%9%12%8%34435%15%
2649
11th to 20thNight
18%18%7%10%8%445%5%418%
2602
21st to endNight
11%15%6%9%9%46%5%5%6%25%
2772
February1st to 10thNight
13%17%6%11%9%45%5%45%22%
2354
11th to 20thNight
14%15%8%11%9%44345%24%
2228
21st to endNight
15%15%6%10%5%35%5%5%5%26%
1776
March1st to 10thNight
16%13%5%9%7%45%45%427%
2150
11th to 20thNight
18%14%5%8%7%34345%29%
2047
21st to endNight
16%10%46%5%3435%5%37%
2014
April1st to 10thNight
23%12%46%6%3435%5%30%
1800
11th to 20thNight
21%8%35%43446%6%37%
1775
21st to endNight
20%11%47%5%3435%6%33%
1661
May1st to 10thNight
19%9%37%5%3445%6%35%
1440
11th to 20thNight
19%7%36%5%34447%38%
1415
21st to endNight
17%6%35%6%35%45%6%39%
1550
June1st to 10thNight
19%6%37%5%35%5%6%8%31%
1440
11th to 20thNight
17%8%36%5%246%6%8%36%
1440
21st to endNight
20%7%35%5%35%5%5%6%36%
1440
July1st to 10thNight
13%6%36%5%3445%8%42%
1440
11th to 20thNight
13%6%35%5%35%5%7%8%41%
1440
21st to endNight
13%5%25%6%345%8%9%40%
1574
August1st to 10thNight
12%6%35%6%35%5%6%9%40%
1432
11th to 20thNight
13%6%26%6%4447%6%43%
1578
21st to endNight
17%6%25%435%45%8%41%
1980
September1st to 10thNight
16%8%3443445%6%43%
1800
11th to 20thNight
18%6%2442445%7%45%
1840
21st to endNight
18%7%25%424449%41%
1980
October1st to 10thNight
22%8%26%434446%36%
2150
11th to 20thNight
25%12%36%5%34445%28%
2171
21st to endNight
26%12%37%6%34445%25%
2574
November1st to 10thNight
21%12%46%5%35%45%6%28%
2407
11th to 20thNight
19%15%6%8%7%34446%23%
2612
21st to endNight
23%17%6%10%6%35%34419%
2660
December1st to 10thNight
22%20%8%11%7%3344415%
2660
11th to 20thNight
22%17%6%9%8%3433421%
3288
21st to endNight
23%22%5%10%7%3333417%
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
74%45%12%5%
1518
11th to 20thDay
67%38%11%9%1
1480
21st to endDay
61%49%15%10%1
1584
February1st to 10thDay
66%46%15%7%2
1604
11th to 20thDay
63%49%12%10%1
1626
21st to endDay
64%46%15%9%1
1480
March1st to 10thDay
59%5%8%16%11%2
1800
11th to 20thDay
58%5%9%13%12%2
1908
21st to endDay
53%5%8%18%13%4
2341
April1st to 10thDay
58%49%15%11%3
2160
11th to 20thDay
54%5%8%19%12%2
2134
21st to endDay
57%5%7%14%12%4
2310
May1st to 10thDay
55%5%6%19%12%3
2520
11th to 20thDay
51%5%8%18%15%2
2482
21st to endDay
51%6%10%18%13%2
2725
June1st to 10thDay
56%7%10%16%10%1
2520
11th to 20thDay
48%8%11%20%11%3
2520
21st to endDay
56%8%10%17%9%
2520
July1st to 10thDay
43%8%14%25%10%
2450
11th to 20thDay
45%8%13%24%9%
2445
21st to endDay
47%9%15%21%8%
2591
August1st to 10thDay
50%9%15%22%5%
2492
11th to 20thDay
44%9%17%22%8%1
2302
21st to endDay
45%7%13%23%11%1
2376
September1st to 10thDay
44%6%12%25%12%
2160
11th to 20thDay
42%7%12%28%11%1
2119
21st to endDay
46%6%12%26%9%
1980
October1st to 10thDay
53%6%11%20%10%1
1805
11th to 20thDay
63%5%11%15%5%1
1788
21st to endDay
64%5%10%14%6%1
1782
November1st to 10thDay
53%7%13%20%7%1
1671
11th to 20thDay
66%5%9%11%8%1
1563
21st to endDay
68%6%11%11%41
1520
December1st to 10thDay
72%6%8%10%4
1520
11th to 20thDay
69%5%9%12%5%
1906
21st to endDay
71%46%13%6%
2772
January1st to 10thNight
72%48%11%4
2649
11th to 20thNight
67%49%10%8%1
2602
21st to endNight
58%5%9%14%12%2
2772
February1st to 10thNight
64%5%8%15%7%1
2354
11th to 20thNight
63%410%15%8%1
2230
21st to endNight
59%49%16%10%2
1776
March1st to 10thNight
60%5%8%16%9%2
2160
11th to 20thNight
58%49%14%12%2
2048
21st to endNight
50%49%18%14%4
2014
April1st to 10thNight
56%48%17%13%2
1800
11th to 20thNight
47%5%10%21%14%2
1775
21st to endNight
53%49%18%13%3
1661
May1st to 10thNight
50%5%8%19%15%3
1440
11th to 20thNight
46%6%9%18%17%3
1416
21st to endNight
44%8%11%21%14%2
1551
June1st to 10thNight
49%9%11%21%10%
1440
11th to 20thNight
45%8%10%22%12%3
1440
21st to endNight
48%8%11%21%12%1
1440
July1st to 10thNight
38%7%15%26%13%1
1400
11th to 20thNight
38%9%14%28%10%1
1392
21st to endNight
38%10%17%25%10%
1486
August1st to 10thNight
38%11%17%26%8%
1422
11th to 20thNight
39%8%17%26%10%
1578
21st to endNight
39%8%15%27%10%
1980
September1st to 10thNight
40%7%13%27%13%1
1800
11th to 20thNight
38%6%14%32%9%1
1840
21st to endNight
42%6%12%29%10%
1980
October1st to 10thNight
49%7%9%24%11%1
2150
11th to 20thNight
57%5%12%18%7%
2171
21st to endNight
61%5%12%15%7%1
2574
November1st to 10thNight
56%6%13%18%7%
2407
11th to 20thNight
61%5%11%15%7%1
2612
21st to endNight
68%5%9%13%5%
2660
December1st to 10thNight
73%5%8%10%4
2660
11th to 20thNight
68%37%14%6%1
3288
21st to endNight
72%46%13%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
23%22%37%16%3
180
11th to 20thDay
28%24%28%14%6%1
170
21st to endDay
24%22%32%15%42
176
February1st to 10thDay
37%29%27%5%1
234
11th to 20thDay
29%32%30%9%
284
21st to endDay
34%21%30%13%2
346
March1st to 10thDay
28%20%33%16%3
420
11th to 20thDay
31%22%29%15%31
420
21st to endDay
32%20%24%16%6%1
462
April1st to 10thDay
32%17%31%14%5%1
420
11th to 20thDay
34%17%22%16%9%2
412
21st to endDay
32%19%29%15%41
420
May1st to 10thDay
30%21%30%14%41
423
11th to 20thDay
27%18%31%18%6%1
447
21st to endDay
25%20%31%18%6%1
485
June1st to 10thDay
29%19%31%15%6%
450
11th to 20thDay
21%19%30%18%10%1
450
21st to endDay
26%14%31%19%8%1
450
July1st to 10thDay
18%11%34%25%9%2
445
11th to 20thDay
16%12%36%27%7%1
444
21st to endDay
17%10%36%26%9%2
488
August1st to 10thDay
18%12%27%29%11%2
446
11th to 20thDay
18%7%27%27%13%7%
439
21st to endDay
20%17%26%19%12%6%
495
September1st to 10thDay
22%9%31%19%12%6%
450
11th to 20thDay
18%14%26%21%14%8%
450
21st to endDay
22%17%24%21%10%6%
450
October1st to 10thDay
31%17%20%18%12%2
450
11th to 20thDay
35%20%23%15%7%1
444
21st to endDay
38%13%27%17%5%
396
November1st to 10thDay
35%15%25%19%41
365
11th to 20thDay
31%23%27%12%6%
223
21st to endDay
32%27%29%12%11
180
December1st to 10thDay
36%19%29%12%4
180
11th to 20thDay
31%29%29%9%11
180
21st to endDay
37%22%27%10%32
198
January1st to 10thNight
29%16%34%16%3
760
11th to 20thNight
31%18%27%18%5%
744
21st to endNight
20%16%35%21%6%1
792
February1st to 10thNight
21%21%34%19%41
720
11th to 20thNight
24%21%32%19%3
703
21st to endNight
25%19%29%24%4
592
March1st to 10thNight
26%17%31%21%4
720
11th to 20thNight
27%19%30%19%41
720
21st to endNight
26%14%29%24%6%1
792
April1st to 10thNight
31%15%27%23%5%
720
11th to 20thNight
27%15%28%24%7%
711
21st to endNight
28%17%27%20%9%
581
May1st to 10thNight
26%11%27%25%9%2
360
11th to 20thNight
22%10%31%29%8%
354
21st to endNight
19%10%35%27%9%
389
June1st to 10thNight
23%7%31%30%9%1
360
11th to 20thNight
20%7%28%31%12%1
360
21st to endNight
21%6%21%36%17%
360
July1st to 10thNight
14%6%26%38%15%1
350
11th to 20thNight
15%5%25%38%18%1
348
21st to endNight
13%5%26%39%16%1
394
August1st to 10thNight
14%321%42%20%1
358
11th to 20thNight
13%5%20%35%24%2
514
21st to endNight
18%6%25%31%17%2
792
September1st to 10thNight
19%7%27%32%15%1
720
11th to 20thNight
22%6%19%32%20%1
720
21st to endNight
21%10%23%27%18%1
720
October1st to 10thNight
25%11%25%26%13%1
720
11th to 20thNight
32%12%24%23%8%1
720
21st to endNight
32%13%25%24%5%
792
November1st to 10thNight
29%14%27%23%7%1
740
11th to 20thNight
28%18%29%14%9%1
760
21st to endNight
34%18%25%18%6%1
760
December1st to 10thNight
33%19%26%17%4
760
11th to 20thNight
31%20%28%16%5%1
760
21st to endNight
37%16%28%16%3
836
Page generated at 2024-01-13 09:37:59. Version ac07

Copyright 2024 Attilla Danko


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