Morin-Heights
Clear Sky Chart
History

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

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
26%
22495
14%
74690
7%
22456
34%
22456
16%
52539

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
14%
760
9%
2649
3%
757
21%
757
8%
2070
January11th to 20thNight
15%
724
10%
2532
3%
724
23%
724
10%
1917
January21st to endNight
19%
792
14%
2772
7%
792
29%
792
13%
1969
February1st to 10thNight
14%
720
11%
2362
2%
720
25%
720
12%
1780
February11th to 20thNight
15%
703
13%
2211
4%
700
26%
700
13%
1591
February21st to endNight
18%
592
15%
1776
6%
592
31%
592
14%
1294
March1st to 10thNight
17%
720
15%
2160
8%
720
27%
720
13%
1594
March11th to 20thNight
20%
720
15%
2066
4%
720
30%
720
15%
1495
March21st to endNight
24%
792
21%
2002
6%
792
34%
792
21%
1422
April1st to 10thNight
21%
720
16%
1800
4%
720
27%
720
18%
1344
April11th to 20thNight
25%
711
17%
1775
5%
711
32%
711
22%
1259
April21st to endNight
23%
590
17%
1670
6%
590
31%
590
18%
1193
May1st to 10thNight
24%
370
16%
1450
10%
370
36%
370
15%
967
May11th to 20thNight
28%
354
20%
1416
15%
354
44%
354
17%
899
May21st to endNight
27%
389
13%
1551
8%
388
41%
388
19%
977
June1st to 10thNight
28%
360
10%
1440
7%
360
39%
360
16%
950
June11th to 20thNight
34%
360
10%
1440
11%
360
42%
360
17%
907
June21st to endNight
39%
360
10%
1440
12%
360
45%
360
17%
950
July1st to 10thNight
45%
350
13%
1400
15%
350
55%
350
23%
808
July11th to 20thNight
46%
348
14%
1392
18%
348
52%
348
22%
828
July21st to endNight
48%
394
13%
1486
15%
372
54%
372
22%
889
August1st to 10thNight
53%
358
15%
1422
13%
356
60%
356
22%
852
August11th to 20thNight
49%
520
17%
1584
11%
520
54%
520
29%
1018
August21st to endNight
43%
792
18%
1980
8%
792
47%
792
31%
1314
September1st to 10thNight
44%
720
16%
1800
6%
720
48%
720
32%
1206
September11th to 20thNight
45%
720
21%
1854
11%
720
51%
720
34%
1192
September21st to endNight
42%
720
22%
1980
14%
720
48%
720
28%
1288
October1st to 10thNight
33%
720
19%
2131
11%
720
43%
720
21%
1442
October11th to 20thNight
25%
720
15%
2182
7%
720
35%
720
17%
1551
October21st to endNight
21%
792
11%
2574
5%
792
29%
792
14%
1869
November1st to 10thNight
24%
740
15%
2407
7%
740
34%
740
15%
1689
November11th to 20thNight
20%
760
16%
2586
9%
760
29%
760
14%
1800
November21st to endNight
18%
760
11%
2660
5%
760
25%
760
10%
1968
December1st to 10thNight
13%
760
9%
2660
3%
760
20%
760
8%
2098
December11th to 20thNight
15%
760
11%
3244
4%
759
25%
759
8%
2427
December21st to endNight
11%
824
7%
4836
3%
817
19%
817
5%
3722

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
18%10%47%6%35%5%5%6%31%
74739
Night
16%11%47%6%3445%6%33%
74953
TransparencyDay
52%6%12%19%10%1
74444
Night
51%6%12%20%10%1
74782
SeeingDay
24%17%31%19%7%2
13400
Night
22%14%31%24%8%1
22507

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
16%17%7%12%9%35%44421%
1517
11th to 20thDay
16%19%5%9%7%34445%25%
1440
21st to endDay
10%15%6%9%8%35%5%5%5%28%
1584
February1st to 10thDay
12%17%5%11%9%35%446%23%
1594
11th to 20thDay
12%18%6%10%6%45%45%5%26%
1636
21st to endDay
15%16%7%9%7%35%445%25%
1480
March1st to 10thDay
14%13%6%11%7%44445%28%
1797
11th to 20thDay
15%14%49%7%35%45%6%29%
1890
21st to endDay
18%12%37%6%2445%6%34%
2353
April1st to 10thDay
21%12%47%6%23445%31%
2160
11th to 20thDay
21%9%36%5%34446%34%
2134
21st to endDay
22%10%47%5%34446%30%
2295
May1st to 10thDay
20%9%47%6%36%445%32%
2520
11th to 20thDay
20%8%46%6%3445%6%34%
2478
21st to endDay
20%7%35%5%46%5%46%34%
2725
June1st to 10thDay
22%8%36%6%45%6%6%7%27%
2520
11th to 20thDay
16%6%36%7%36%5%6%7%34%
2520
21st to endDay
23%8%38%6%45%5%5%7%27%
2520
July1st to 10thDay
14%5%35%6%47%5%6%7%38%
2520
11th to 20thDay
15%6%36%6%46%6%6%9%33%
2520
21st to endDay
13%7%36%6%46%6%7%8%33%
2744
August1st to 10thDay
14%6%36%7%46%6%7%7%34%
2506
11th to 20thDay
13%6%36%6%46%6%8%8%35%
2296
21st to endDay
15%5%36%6%45%45%9%39%
2376
September1st to 10thDay
16%6%25%5%345%6%7%40%
2160
11th to 20thDay
15%5%35%43445%7%44%
2105
21st to endDay
19%6%35%43445%6%40%
1980
October1st to 10thDay
22%8%26%5%345%5%6%34%
1828
11th to 20thDay
23%10%47%7%35%5%46%26%
1778
21st to endDay
25%12%46%5%34446%26%
1782
November1st to 10thDay
15%10%47%6%35%5%6%6%33%
1671
11th to 20thDay
19%12%5%9%5%345%6%6%26%
1592
21st to endDay
21%13%6%8%6%35%5%5%6%23%
1520
December1st to 10thDay
21%18%6%9%7%34435%19%
1520
11th to 20thDay
19%14%6%11%6%34445%24%
1906
21st to endDay
22%19%7%9%5%3444421%
2772
January1st to 10thNight
14%16%7%11%8%45%446%20%
2649
11th to 20thNight
14%17%7%10%7%34345%24%
2532
21st to endNight
10%12%5%10%7%45%5%5%6%31%
2772
February1st to 10thNight
12%13%6%11%7%46%5%5%6%25%
2362
11th to 20thNight
11%13%6%10%7%45%45%6%29%
2209
21st to endNight
13%13%5%10%7%25%45%6%30%
1776
March1st to 10thNight
14%11%5%9%7%46%445%29%
2150
11th to 20thNight
15%13%5%8%5%445%6%6%30%
2065
21st to endNight
15%10%36%5%44435%40%
2002
April1st to 10thNight
22%10%46%6%34346%32%
1800
11th to 20thNight
18%7%26%6%35%45%5%38%
1775
21st to endNight
21%8%27%5%35%45%6%35%
1670
May1st to 10thNight
19%9%36%7%34446%35%
1450
11th to 20thNight
18%8%36%5%34447%39%
1415
21st to endNight
16%7%25%5%3445%8%40%
1550
June1st to 10thNight
20%8%35%5%336%5%10%32%
1440
11th to 20thNight
18%6%35%6%345%5%8%38%
1440
21st to endNight
19%7%246%45%5%5%7%37%
1440
July1st to 10thNight
11%6%25%6%3446%8%45%
1440
11th to 20thNight
12%6%25%6%35%5%6%9%42%
1440
21st to endNight
12%5%35%6%35%5%7%7%43%
1574
August1st to 10thNight
11%6%25%426%5%6%10%42%
1432
11th to 20thNight
10%6%36%5%3446%7%46%
1584
21st to endNight
14%5%25%5%4445%7%46%
1980
September1st to 10thNight
11%6%26%5%345%5%6%47%
1800
11th to 20thNight
14%5%2443346%7%47%
1854
21st to endNight
18%5%2432445%7%44%
1980
October1st to 10thNight
17%7%36%5%4445%5%39%
2131
11th to 20thNight
21%9%36%5%35%446%34%
2182
21st to endNight
23%10%36%6%3445%6%29%
2574
November1st to 10thNight
17%9%5%7%6%35%46%7%30%
2407
11th to 20thNight
17%10%48%6%35%5%5%6%31%
2586
21st to endNight
19%14%5%8%6%3345%5%27%
2660
December1st to 10thNight
17%16%6%10%7%45%45%7%20%
2660
11th to 20thNight
20%14%6%8%7%34446%25%
3288
21st to endNight
23%19%5%8%6%3334422%
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
65%5%8%16%5%
1518
11th to 20thDay
62%311%13%10%1
1440
21st to endDay
56%5%9%17%11%1
1584
February1st to 10thDay
61%5%7%17%8%2
1594
11th to 20thDay
59%5%11%14%9%1
1645
21st to endDay
62%38%15%9%2
1480
March1st to 10thDay
58%5%8%17%10%2
1800
11th to 20thDay
55%312%15%12%3
1890
21st to endDay
51%5%8%18%14%4
2353
April1st to 10thDay
56%49%17%12%3
2160
11th to 20thDay
50%49%22%13%2
2134
21st to endDay
56%5%8%16%12%4
2295
May1st to 10thDay
53%47%20%13%3
2520
11th to 20thDay
49%5%10%17%16%3
2482
21st to endDay
49%6%10%20%14%2
2725
June1st to 10thDay
53%6%11%17%11%2
2520
11th to 20thDay
46%7%12%20%12%3
2520
21st to endDay
56%8%11%16%9%1
2520
July1st to 10thDay
41%9%14%26%10%1
2450
11th to 20thDay
43%8%14%24%10%
2445
21st to endDay
45%8%16%22%9%
2591
August1st to 10thDay
45%9%16%23%7%
2492
11th to 20thDay
42%10%16%23%9%1
2296
21st to endDay
42%7%15%23%13%1
2376
September1st to 10thDay
41%6%14%26%13%
2160
11th to 20thDay
37%6%14%29%12%1
2105
21st to endDay
43%6%15%26%11%
1980
October1st to 10thDay
49%5%12%23%11%1
1828
11th to 20thDay
57%7%13%17%6%1
1778
21st to endDay
59%414%14%7%1
1782
November1st to 10thDay
49%7%14%20%9%1
1671
11th to 20thDay
56%415%15%9%
1592
21st to endDay
60%6%15%14%41
1520
December1st to 10thDay
67%6%11%11%5%
1520
11th to 20thDay
61%413%15%6%
1906
21st to endDay
68%5%8%13%6%
2772
January1st to 10thNight
64%5%10%14%5%
2649
11th to 20thNight
61%5%12%11%8%2
2532
21st to endNight
53%6%10%17%12%2
2772
February1st to 10thNight
59%5%10%18%7%1
2362
11th to 20thNight
54%6%13%18%9%1
2211
21st to endNight
56%39%17%12%2
1776
March1st to 10thNight
57%49%17%10%2
2160
11th to 20thNight
54%5%11%16%12%3
2066
21st to endNight
48%48%20%15%4
2002
April1st to 10thNight
53%48%19%14%2
1800
11th to 20thNight
47%5%9%23%15%2
1775
21st to endNight
51%5%8%20%13%3
1670
May1st to 10thNight
51%47%19%14%4
1450
11th to 20thNight
45%6%9%18%18%4
1416
21st to endNight
43%7%11%21%16%3
1551
June1st to 10thNight
48%6%13%22%11%1
1440
11th to 20thNight
45%6%10%23%13%3
1440
21st to endNight
46%9%12%21%13%
1440
July1st to 10thNight
35%9%15%26%14%1
1400
11th to 20thNight
39%7%14%29%10%
1392
21st to endNight
38%8%17%25%12%
1486
August1st to 10thNight
36%10%18%26%10%
1422
11th to 20thNight
36%9%16%27%11%
1584
21st to endNight
37%8%16%27%12%
1980
September1st to 10thNight
36%8%14%26%15%1
1800
11th to 20thNight
36%6%14%33%11%1
1854
21st to endNight
39%6%12%30%13%
1980
October1st to 10thNight
46%5%11%24%13%1
2131
11th to 20thNight
50%6%15%21%8%
2182
21st to endNight
55%6%14%17%8%1
2574
November1st to 10thNight
51%6%15%21%7%1
2407
11th to 20thNight
52%5%15%18%8%2
2586
21st to endNight
57%6%13%17%6%1
2660
December1st to 10thNight
64%6%12%13%4
2660
11th to 20thNight
60%5%10%16%7%1
3288
21st to endNight
66%5%8%15%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%20%39%17%4
180
11th to 20thDay
28%17%38%12%6%1
160
21st to endDay
21%22%37%15%5%1
176
February1st to 10thDay
37%28%30%5%
229
11th to 20thDay
24%28%37%10%1
303
21st to endDay
28%23%31%15%2
346
March1st to 10thDay
28%20%32%17%3
420
11th to 20thDay
24%25%32%14%41
420
21st to endDay
29%21%27%15%7%1
462
April1st to 10thDay
32%16%30%14%7%
420
11th to 20thDay
32%19%25%15%7%1
412
21st to endDay
30%20%30%14%41
420
May1st to 10thDay
26%19%34%15%5%1
423
11th to 20thDay
24%18%32%20%41
447
21st to endDay
23%21%32%19%5%
485
June1st to 10thDay
26%18%34%16%6%1
450
11th to 20thDay
19%19%33%19%9%2
450
21st to endDay
27%12%32%19%8%2
450
July1st to 10thDay
14%10%36%27%11%2
445
11th to 20thDay
16%11%36%27%8%2
444
21st to endDay
15%9%35%29%11%1
488
August1st to 10thDay
15%10%31%29%13%2
446
11th to 20thDay
13%9%30%29%13%6%
439
21st to endDay
18%14%29%20%13%6%
495
September1st to 10thDay
17%10%33%24%10%5%
450
11th to 20thDay
13%12%29%25%15%6%
450
21st to endDay
21%14%26%23%12%4
450
October1st to 10thDay
25%19%24%21%10%1
450
11th to 20thDay
26%16%31%19%7%1
439
21st to endDay
33%14%30%18%5%
396
November1st to 10thDay
28%18%29%19%41
365
11th to 20thDay
25%24%32%15%4
252
21st to endDay
27%24%32%15%2
180
December1st to 10thDay
29%17%32%18%41
180
11th to 20thDay
29%24%33%12%11
180
21st to endDay
34%25%24%12%41
198
January1st to 10thNight
24%17%34%22%3
760
11th to 20thNight
23%19%32%20%4
724
21st to endNight
17%16%39%22%6%1
792
February1st to 10thNight
20%18%38%20%41
720
11th to 20thNight
21%18%39%17%41
703
21st to endNight
22%17%34%24%3
592
March1st to 10thNight
23%19%35%21%3
720
11th to 20thNight
24%17%34%19%6%
720
21st to endNight
22%16%33%23%6%1
792
April1st to 10thNight
27%17%28%24%4
720
11th to 20thNight
24%14%33%23%5%
711
21st to endNight
26%15%33%19%7%1
590
May1st to 10thNight
24%13%34%21%6%2
370
11th to 20thNight
21%12%32%27%7%1
354
21st to endNight
20%8%40%25%7%
389
June1st to 10thNight
26%8%31%28%7%
360
11th to 20thNight
24%7%29%29%11%1
360
21st to endNight
20%7%26%32%14%1
360
July1st to 10thNight
11%9%31%34%14%1
350
11th to 20thNight
11%6%27%41%14%
348
21st to endNight
14%426%42%12%2
394
August1st to 10thNight
14%5%21%42%16%2
358
11th to 20thNight
11%6%26%33%23%3
520
21st to endNight
15%6%29%31%17%2
792
September1st to 10thNight
13%8%30%35%13%1
720
11th to 20thNight
16%8%26%30%18%2
720
21st to endNight
20%9%25%28%16%2
720
October1st to 10thNight
23%11%29%27%10%1
720
11th to 20thNight
25%12%29%24%8%1
720
21st to endNight
27%15%31%22%5%
792
November1st to 10thNight
24%17%29%23%7%1
740
11th to 20thNight
23%16%34%19%8%1
760
21st to endNight
28%19%28%19%5%1
760
December1st to 10thNight
27%18%33%17%5%
760
11th to 20thNight
28%20%29%18%41
760
21st to endNight
32%18%31%16%4
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