Site d'observation de St-Félix d'Otis
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Site d'observation de St-Félix d'Otis 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
22%
22746
8%
74956
5%
22698
26%
22698
9%
59446

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%
810
4%
2753
1%
807
14%
807
3%
2449
January11th to 20thNight
14%
744
7%
2602
3%
744
19%
744
6%
2149
January21st to endNight
16%
792
8%
2772
4%
792
23%
792
7%
2210
February1st to 10thNight
15%
720
7%
2520
4%
720
20%
720
7%
2002
February11th to 20thNight
14%
702
6%
2181
2%
700
19%
700
7%
1794
February21st to endNight
16%
592
10%
1776
4%
592
24%
592
11%
1406
March1st to 10thNight
17%
720
10%
2160
6%
720
23%
720
10%
1736
March11th to 20thNight
19%
720
10%
2052
6%
720
23%
720
11%
1633
March21st to endNight
21%
792
13%
2070
5%
792
26%
792
13%
1619
April1st to 10thNight
17%
720
10%
1800
3%
720
22%
720
12%
1480
April11th to 20thNight
24%
579
14%
1643
7%
579
29%
579
16%
1225
April21st to endNight
26%
540
14%
1620
8%
540
33%
540
17%
1157
May1st to 10thNight
26%
482
10%
1562
8%
482
31%
482
14%
1162
May11th to 20thNight
34%
354
14%
1416
15%
354
42%
354
16%
950
May21st to endNight
29%
389
9%
1361
7%
388
35%
388
12%
994
June1st to 10thNight
29%
360
5%
1260
4%
360
31%
360
13%
934
June11th to 20thNight
43%
360
8%
1260
6%
360
46%
360
17%
854
June21st to endNight
35%
360
5%
1260
3%
360
37%
360
13%
912
July1st to 10thNight
35%
350
6%
1225
5%
350
39%
350
16%
875
July11th to 20thNight
43%
348
7%
1344
9%
348
45%
348
13%
946
July21st to endNight
39%
394
7%
1486
10%
372
41%
372
11%
1084
August1st to 10thNight
47%
358
10%
1422
11%
356
50%
356
15%
986
August11th to 20thNight
37%
514
9%
1578
7%
514
39%
514
15%
1183
August21st to endNight
35%
631
11%
1819
7%
631
37%
631
17%
1367
September1st to 10thNight
34%
720
11%
1800
5%
720
36%
720
21%
1333
September11th to 20thNight
31%
720
8%
1974
4%
720
34%
720
16%
1495
September21st to endNight
32%
720
15%
1980
10%
720
35%
720
17%
1456
October1st to 10thNight
29%
720
15%
1992
9%
720
35%
720
17%
1489
October11th to 20thNight
20%
720
7%
2326
4%
720
23%
720
8%
1929
October21st to endNight
18%
792
7%
2574
4%
792
22%
792
8%
2114
November1st to 10thNight
17%
740
8%
2407
4%
740
21%
740
7%
1982
November11th to 20thNight
18%
811
7%
2599
4%
811
20%
811
7%
2192
November21st to endNight
12%
850
3%
2850
2%
850
14%
850
4%
2529
December1st to 10thNight
11%
850
3%
2850
1%
850
12%
850
4%
2575
December11th to 20thNight
14%
850
5%
3499
2%
848
16%
848
3%
3035
December21st to endNight
12%
922
4%
5163
2%
906
15%
906
2%
4210

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%12%5%8%7%45%5%5%6%24%
74589
Night
18%14%5%9%7%45%5%5%5%22%
75223
TransparencyDay
59%8%12%15%6%1
74285
Night
63%7%11%13%5%1
75062
SeeingDay
28%18%28%19%7%1
14369
Night
26%16%27%23%7%1
22760

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
13%19%9%13%10%5%7%6%6%49%
1407
11th to 20thDay
13%16%7%12%10%46%8%7%5%12%
1486
21st to endDay
7%11%6%12%11%6%8%11%8%5%15%
1584
February1st to 10thDay
6%11%8%11%10%9%10%8%5%6%16%
1440
11th to 20thDay
11%15%6%14%9%6%7%7%5%6%13%
1666
21st to endDay
8%15%7%9%10%5%8%8%6%6%19%
1480
March1st to 10thDay
15%14%8%11%6%46%6%5%5%20%
1797
11th to 20thDay
14%16%6%9%9%5%45%35%22%
1908
21st to endDay
16%17%6%10%5%34445%26%
2283
April1st to 10thDay
18%16%7%9%7%33446%22%
2160
11th to 20thDay
19%14%47%5%34445%31%
2266
21st to endDay
19%13%47%5%345%6%5%29%
2340
May1st to 10thDay
22%10%36%43445%6%32%
2413
11th to 20thDay
17%10%36%6%35%45%7%33%
2478
21st to endDay
21%8%26%5%46%5%5%7%31%
2915
June1st to 10thDay
22%8%36%6%45%5%5%8%27%
2700
11th to 20thDay
19%7%37%6%45%5%6%8%31%
2700
21st to endDay
22%8%47%6%45%6%5%6%28%
2700
July1st to 10thDay
22%8%37%5%46%5%6%7%27%
2700
11th to 20thDay
17%8%47%7%5%7%6%6%8%26%
2568
21st to endDay
17%8%47%7%45%6%6%8%29%
2744
August1st to 10thDay
20%9%46%8%46%6%7%7%23%
2506
11th to 20thDay
19%8%36%6%36%5%6%8%29%
2304
21st to endDay
21%8%46%6%4446%8%30%
2534
September1st to 10thDay
21%8%36%5%45%5%5%7%31%
2160
11th to 20thDay
22%8%36%43445%6%35%
1985
21st to endDay
23%10%26%5%3445%6%32%
1980
October1st to 10thDay
21%12%47%7%3445%6%28%
1967
11th to 20thDay
27%17%47%6%4445%5%16%
1631
21st to endDay
25%22%6%8%42323419%
1782
November1st to 10thDay
21%18%7%9%6%34445%19%
1671
11th to 20thDay
18%20%6%12%8%34445%16%
1575
21st to endDay
17%20%8%13%9%5%345%5%12%
1330
December1st to 10thDay
18%20%7%13%12%5%445%48%
1330
11th to 20thDay
17%17%8%13%9%5%7%44414%
1668
21st to endDay
19%17%5%10%12%5%6%445%14%
2431
January1st to 10thNight
13%19%9%14%11%5%8%6%5%37%
2753
11th to 20thNight
13%15%7%14%9%5%6%8%6%412%
2602
21st to endNight
9%12%6%11%10%7%10%9%7%5%15%
2772
February1st to 10thNight
8%11%6%11%11%8%9%6%6%5%17%
2520
11th to 20thNight
12%16%7%14%8%5%7%6%4416%
2178
21st to endNight
10%17%7%12%9%5%6%5%5%421%
1776
March1st to 10thNight
13%16%8%10%8%46%45%5%20%
2150
11th to 20thNight
14%16%6%11%9%45%436%22%
2051
21st to endNight
15%17%6%9%6%34445%27%
2070
April1st to 10thNight
22%17%5%9%6%3444422%
1800
11th to 20thNight
21%13%46%5%3445%6%30%
1643
21st to endNight
21%11%36%43445%6%34%
1620
May1st to 10thNight
25%13%5%5%42445%5%28%
1562
11th to 20thNight
20%9%26%6%35%5%5%6%33%
1415
21st to endNight
25%9%45%5%45%46%6%28%
1360
June1st to 10thNight
19%9%47%7%36%5%6%7%27%
1260
11th to 20thNight
19%8%36%5%35%5%47%35%
1260
21st to endNight
20%7%37%8%36%5%6%8%27%
1260
July1st to 10thNight
20%7%37%7%35%6%6%6%29%
1260
11th to 20thNight
15%7%38%6%46%7%8%8%28%
1389
21st to endNight
20%7%47%6%45%6%7%8%28%
1574
August1st to 10thNight
16%7%36%7%45%6%7%9%30%
1432
11th to 20thNight
21%7%37%7%46%6%6%6%29%
1578
21st to endNight
22%9%45%5%35%5%5%8%29%
1819
September1st to 10thNight
22%7%36%6%345%6%5%34%
1800
11th to 20thNight
23%7%46%5%45%45%5%32%
1974
21st to endNight
22%8%36%5%34445%35%
1980
October1st to 10thNight
21%10%36%6%3346%7%32%
1992
11th to 20thNight
29%16%46%6%34445%20%
2326
21st to endNight
27%17%46%5%34446%19%
2574
November1st to 10thNight
24%19%7%8%5%34345%20%
2407
11th to 20thNight
18%19%8%11%7%3444417%
2599
21st to endNight
17%20%7%14%11%3443412%
2850
December1st to 10thNight
19%18%8%14%10%5%5%4449%
2850
11th to 20thNight
18%16%7%14%10%5%6%5%3411%
3531
21st to endNight
17%20%6%12%10%45%43217%
5236

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
75%7%9%7%2
1408
11th to 20thDay
69%6%9%10%5%1
1486
21st to endDay
60%9%10%12%8%
1584
February1st to 10thDay
65%8%12%9%5%1
1440
11th to 20thDay
69%6%12%8%5%
1674
21st to endDay
62%7%10%14%6%1
1480
March1st to 10thDay
64%7%10%11%8%1
1800
11th to 20thDay
65%5%9%12%8%
1908
21st to endDay
61%6%9%15%8%1
2283
April1st to 10thDay
65%5%10%12%6%2
2160
11th to 20thDay
56%5%12%19%8%1
2266
21st to endDay
55%7%11%15%11%1
2340
May1st to 10thDay
53%6%12%15%12%1
2413
11th to 20thDay
50%6%11%22%10%1
2482
21st to endDay
52%8%10%20%10%
2915
June1st to 10thDay
55%8%10%16%11%1
2700
11th to 20thDay
51%7%14%18%9%1
2700
21st to endDay
56%8%12%16%8%1
2700
July1st to 10thDay
53%9%15%19%5%
2625
11th to 20thDay
54%9%15%16%5%
2490
21st to endDay
54%10%15%18%4
2591
August1st to 10thDay
56%13%15%14%2
2492
11th to 20thDay
52%11%16%17%4
2304
21st to endDay
53%8%16%19%4
2534
September1st to 10thDay
51%8%14%20%6%
2160
11th to 20thDay
50%7%16%20%6%
1985
21st to endDay
53%9%13%18%7%
1980
October1st to 10thDay
58%7%13%14%8%
1967
11th to 20thDay
69%9%9%11%1
1631
21st to endDay
70%6%10%10%31
1782
November1st to 10thDay
68%7%12%10%3
1671
11th to 20thDay
71%9%9%9%2
1575
21st to endDay
75%9%11%5%1
1330
December1st to 10thDay
79%7%7%6%1
1330
11th to 20thDay
73%5%10%9%3
1668
21st to endDay
69%7%10%9%4
2431
January1st to 10thNight
78%7%7%7%2
2753
11th to 20thNight
68%7%10%10%4
2602
21st to endNight
64%8%10%12%5%
2772
February1st to 10thNight
64%7%12%11%6%
2520
11th to 20thNight
69%6%11%10%5%
2181
21st to endNight
64%5%9%15%6%
1776
March1st to 10thNight
64%6%10%13%7%1
2160
11th to 20thNight
64%5%10%14%7%1
2052
21st to endNight
59%6%9%17%7%1
2070
April1st to 10thNight
66%49%11%8%2
1800
11th to 20thNight
55%5%8%18%12%1
1643
21st to endNight
52%6%10%21%10%2
1620
May1st to 10thNight
56%6%10%14%12%1
1562
11th to 20thNight
50%6%13%19%11%1
1416
21st to endNight
56%6%8%17%11%1
1361
June1st to 10thNight
56%8%11%17%6%2
1260
11th to 20thNight
48%7%11%19%11%3
1260
21st to endNight
53%9%13%17%7%
1260
July1st to 10thNight
50%9%16%20%4
1225
11th to 20thNight
49%12%14%19%6%
1344
21st to endNight
53%11%13%17%5%
1486
August1st to 10thNight
47%12%19%18%3
1422
11th to 20thNight
52%11%17%15%5%
1578
21st to endNight
53%9%14%20%4
1819
September1st to 10thNight
49%9%14%20%9%
1800
11th to 20thNight
53%9%15%17%6%
1974
21st to endNight
51%8%12%22%7%1
1980
October1st to 10thNight
52%8%12%18%9%1
1992
11th to 20thNight
68%7%9%13%3
2326
21st to endNight
68%6%9%12%41
2574
November1st to 10thNight
67%7%10%11%4
2407
11th to 20thNight
69%8%10%9%3
2599
21st to endNight
76%8%8%5%2
2850
December1st to 10thNight
78%7%7%5%1
2850
11th to 20thNight
76%7%7%7%3
3532
21st to endNight
71%7%9%10%3
5236

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%27%31%17%2
180
11th to 20thDay
22%28%30%17%31
172
21st to endDay
16%27%32%19%5%1
176
February1st to 10thDay
21%28%39%9%31
160
11th to 20thDay
26%25%31%13%4
373
21st to endDay
26%23%28%18%41
346
March1st to 10thDay
28%20%32%15%5%
420
11th to 20thDay
32%21%26%14%6%1
420
21st to endDay
32%19%26%16%7%1
462
April1st to 10thDay
33%23%28%12%31
420
11th to 20thDay
32%17%31%15%5%1
412
21st to endDay
27%22%29%17%41
420
May1st to 10thDay
32%19%27%16%5%1
423
11th to 20thDay
21%17%36%18%7%2
447
21st to endDay
29%16%27%21%8%1
675
June1st to 10thDay
28%15%28%24%5%1
630
11th to 20thDay
24%15%25%24%11%1
630
21st to endDay
25%15%27%23%9%1
630
July1st to 10thDay
24%13%27%26%8%1
620
11th to 20thDay
24%11%28%26%9%2
489
21st to endDay
20%14%31%23%11%1
488
August1st to 10thDay
24%11%27%25%10%3
446
11th to 20thDay
22%11%29%25%11%3
439
21st to endDay
28%12%24%21%11%3
495
September1st to 10thDay
26%17%24%18%10%4
450
11th to 20thDay
26%18%29%17%8%2
450
21st to endDay
28%17%24%19%10%3
450
October1st to 10thDay
26%19%26%18%8%3
444
11th to 20thDay
38%18%23%13%8%1
360
21st to endDay
40%18%23%15%31
396
November1st to 10thDay
38%19%22%16%31
365
11th to 20thDay
30%23%26%14%6%1
343
21st to endDay
38%24%24%11%2
180
December1st to 10thDay
27%24%31%14%31
180
11th to 20thDay
32%26%32%8%31
180
21st to endDay
33%26%25%10%6%1
198
January1st to 10thNight
25%22%31%18%4
810
11th to 20thNight
22%22%30%20%6%1
744
21st to endNight
17%18%37%21%6%1
792
February1st to 10thNight
16%24%32%21%5%1
720
11th to 20thNight
24%23%30%17%6%
703
21st to endNight
23%18%33%20%5%1
592
March1st to 10thNight
23%17%34%22%4
720
11th to 20thNight
26%20%29%16%8%1
720
21st to endNight
25%18%27%24%5%1
792
April1st to 10thNight
32%16%28%19%41
720
11th to 20thNight
28%14%28%23%6%1
579
21st to endNight
29%13%28%24%6%
540
May1st to 10thNight
30%9%28%28%5%
482
11th to 20thNight
21%9%27%31%11%
354
21st to endNight
29%12%26%25%8%
389
June1st to 10thNight
22%8%30%32%8%1
360
11th to 20thNight
21%8%23%34%13%1
360
21st to endNight
19%9%26%36%10%1
360
July1st to 10thNight
23%8%27%31%10%1
350
11th to 20thNight
16%9%21%42%11%1
348
21st to endNight
24%7%21%36%11%1
394
August1st to 10thNight
16%8%20%41%16%1
358
11th to 20thNight
23%10%22%28%17%2
514
21st to endNight
24%10%24%29%12%2
631
September1st to 10thNight
24%12%24%28%11%1
720
11th to 20thNight
28%9%25%24%11%3
720
21st to endNight
25%13%23%26%11%2
720
October1st to 10thNight
28%13%25%26%8%1
720
11th to 20thNight
38%15%21%17%8%1
720
21st to endNight
38%16%23%17%5%1
792
November1st to 10thNight
34%18%24%18%5%1
740
11th to 20thNight
29%24%24%17%6%1
811
21st to endNight
29%22%28%16%41
850
December1st to 10thNight
30%20%29%16%5%1
850
11th to 20thNight
30%20%27%16%6%
850
21st to endNight
29%20%27%18%6%1
935
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