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 2005-11-05 to 2017-10-06.

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
23%
14632
8%
47028
5%
14601
27%
14601
10%
37447

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 15thNight
11%
731
6%
2571
2%
727
15%
727
4%
2224
January16th to endNight
15%
768
7%
2688
2%
768
21%
768
6%
2193
February1st to 15thNight
18%
703
6%
2404
5%
701
22%
701
8%
1909
February16th to endNight
15%
631
7%
1893
2%
631
20%
631
8%
1562
March1st to 15thNight
20%
720
12%
2148
7%
720
26%
720
11%
1674
March16th to endNight
22%
768
14%
2040
6%
768
28%
768
14%
1553
April1st to 15thNight
21%
688
12%
1766
5%
688
25%
688
14%
1407
April16th to endNight
28%
540
14%
1620
8%
540
33%
540
18%
1150
May1st to 15thNight
27%
441
9%
1521
8%
441
31%
441
13%
1123
May16th to endNight
30%
375
9%
1369
9%
374
34%
374
10%
1032
June1st to 15thNight
33%
360
5%
1260
3%
360
36%
360
13%
925
June16th to endNight
39%
360
4%
1260
3%
360
40%
360
13%
924
July1st to 15thNight
38%
340
6%
1215
6%
340
40%
340
13%
895
July16th to endNight
38%
376
6%
1418
9%
354
41%
354
11%
1021
August1st to 15thNight
45%
407
9%
1478
9%
405
47%
405
13%
1079
August16th to endNight
34%
598
9%
1744
5%
598
36%
598
16%
1312
September1st to 15thNight
33%
720
8%
1857
4%
720
35%
720
19%
1390
September16th to endNight
30%
717
13%
1980
9%
717
34%
717
17%
1468
October1st to 15thNight
26%
684
12%
1990
7%
684
30%
684
14%
1548
October16th to endNight
16%
704
5%
2288
4%
704
18%
704
6%
1958
November1st to 15thNight
19%
701
10%
2283
7%
701
23%
701
7%
1882
November16th to endNight
18%
750
5%
2655
3%
750
21%
750
6%
2234
December1st to 15thNight
10%
750
2%
2700
1%
750
11%
750
3%
2428
December16th to endNight
13%
800
5%
2880
3%
800
16%
800
3%
2556

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%47%6%35%5%45%23%
48183
Night
18%13%5%8%7%35%5%45%21%
47190
TransparencyDay
61%7%11%14%5%
47863
Night
63%7%10%13%5%
47028
SeeingDay
29%14%25%19%8%1
6326
Night
26%15%27%22%7%
14633

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 15thDay
13%15%8%10%9%6%8%6%6%410%
1364
16th to endDay
9%13%6%11%10%5%8%11%6%412%
1536
February1st to 15thDay
7%11%7%11%10%7%9%8%45%15%
1457
16th to endDay
9%18%7%11%9%46%6%45%15%
1580
March1st to 15thDay
16%12%7%9%5%46%6%4421%
1802
16th to endDay
14%15%5%9%6%3433427%
2182
April1st to 15thDay
19%15%7%6%5%23445%25%
2182
16th to endDay
20%11%36%5%24445%32%
2340
May1st to 15thDay
22%9%35%435%446%31%
2440
16th to endDay
23%8%35%6%36%5%5%7%26%
2746
June1st to 15thDay
22%8%36%6%35%5%5%7%26%
2700
16th to endDay
20%7%47%6%45%5%5%5%26%
2700
July1st to 15thDay
22%8%37%5%47%5%6%7%22%
2671
16th to endDay
19%7%36%6%46%5%5%6%27%
2654
August1st to 15thDay
21%9%45%7%36%5%6%7%22%
2460
16th to endDay
22%7%36%5%3445%8%27%
2456
September1st to 15thDay
25%7%26%424345%31%
2103
16th to endDay
22%8%25%43445%6%32%
1980
October1st to 15thDay
22%13%47%6%34446%23%
1766
16th to endDay
28%22%47%5%2323315%
1584
November1st to 15thDay
20%18%6%9%5%24446%18%
1573
16th to endDay
20%19%7%8%6%42445%15%
1303
December1st to 15thDay
20%20%5%10%10%5%5%34410%
1260
16th to endDay
16%19%7%11%9%5%7%44310%
1344
January1st to 15thNight
15%15%7%13%9%48%6%5%39%
2571
16th to endNight
10%14%6%11%9%6%9%9%6%412%
2688
February1st to 15thNight
7%11%6%11%10%7%10%6%6%417%
2403
16th to endNight
12%17%7%13%8%45%43317%
1893
March1st to 15thNight
15%15%6%8%6%35%446%22%
2135
16th to endNight
12%15%6%9%6%24435%29%
2040
April1st to 15thNight
24%13%47%5%3334425%
1766
16th to endNight
20%10%25%334346%34%
1620
May1st to 15thNight
23%11%46%42445%428%
1521
16th to endNight
24%10%45%5%35%345%26%
1367
June1st to 15thNight
21%7%36%6%36%346%28%
1260
16th to endNight
18%7%36%7%36%6%6%8%26%
1260
July1st to 15thNight
19%7%36%6%46%6%6%5%27%
1287
16th to endNight
17%7%37%6%35%5%6%7%28%
1514
August1st to 15thNight
18%7%36%6%45%5%7%7%28%
1488
16th to endNight
22%7%35%6%3445%8%27%
1744
September1st to 15thNight
23%7%25%5%335%5%433%
1857
16th to endNight
23%7%35%423445%34%
1980
October1st to 15thNight
21%11%35%5%335%5%6%27%
1990
16th to endNight
29%18%46%5%3333415%
2288
November1st to 15thNight
24%17%7%7%5%2333419%
2283
16th to endNight
19%17%6%10%8%24445%16%
2655
December1st to 15thNight
20%18%8%12%9%46%3348%
2700
16th to endNight
16%16%9%13%9%47%5%3310%
2880

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 15thDay
72%7%10%8%2
1365
16th to endDay
65%8%9%10%5%
1536
February1st to 15thDay
66%7%12%8%3
1460
16th to endDay
68%5%8%11%5%
1580
March1st to 15thDay
62%6%8%11%9%
1812
16th to endDay
60%49%15%8%
2182
April1st to 15thDay
61%48%15%7%1
2182
16th to endDay
54%5%11%16%10%
2340
May1st to 15thDay
53%5%12%17%10%
2440
16th to endDay
56%8%9%17%7%
2750
June1st to 15thDay
56%7%10%15%8%
2700
16th to endDay
57%7%12%15%6%
2700
July1st to 15thDay
58%8%14%15%3
2514
16th to endDay
57%8%13%16%4
2487
August1st to 15thDay
59%11%13%12%2
2446
16th to endDay
54%9%16%17%2
2456
September1st to 15thDay
54%6%13%18%5%
2103
16th to endDay
51%8%15%17%6%
1980
October1st to 15thDay
62%6%10%13%6%
1766
16th to endDay
75%5%8%8%1
1584
November1st to 15thDay
67%6%11%10%3
1573
16th to endDay
71%8%9%8%1
1303
December1st to 15thDay
77%6%6%7%
1260
16th to endDay
77%6%5%6%3
1344
January1st to 15thNight
73%7%7%8%2
2571
16th to endNight
65%8%10%12%2
2688
February1st to 15thNight
63%7%12%11%4
2404
16th to endNight
69%49%12%4
1893
March1st to 15thNight
61%5%10%13%8%
2148
16th to endNight
57%49%19%8%1
2040
April1st to 15thNight
63%37%13%10%1
1766
16th to endNight
50%5%10%19%12%1
1620
May1st to 15thNight
56%6%10%15%10%
1521
16th to endNight
60%5%9%15%7%1
1369
June1st to 15thNight
56%6%11%17%7%
1260
16th to endNight
53%10%12%16%7%
1260
July1st to 15thNight
52%10%13%18%4
1215
16th to endNight
53%9%12%18%5%
1418
August1st to 15thNight
51%11%16%17%3
1478
16th to endNight
52%9%16%16%3
1744
September1st to 15thNight
52%7%14%18%7%
1857
16th to endNight
52%7%13%20%5%
1980
October1st to 15thNight
57%8%10%16%6%
1990
16th to endNight
73%5%7%9%3
2288
November1st to 15thNight
68%6%9%10%4
2283
16th to endNight
69%7%10%8%3
2655
December1st to 15thNight
79%6%7%5%
2700
16th to endNight
76%7%6%7%1
2880

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 15thDay
16%35%35%13%
60
16th to endDay
21%21%34%20%1
64
February1st to 15thDay
21%11%36%19%9%
111
16th to endDay
29%20%24%17%7%
239
March1st to 15thDay
31%17%27%16%7%
270
16th to endDay
27%19%22%18%12%
288
April1st to 15thDay
30%20%28%15%5%1
270
16th to endDay
25%18%28%19%6%1
270
May1st to 15thDay
29%12%33%15%7%1
288
16th to endDay
29%12%30%19%8%1
459
June1st to 15thDay
31%9%23%25%8%1
495
16th to endDay
22%15%25%23%11%1
495
July1st to 15thDay
29%10%22%25%10%1
448
16th to endDay
26%8%30%23%10%1
326
August1st to 15thDay
27%7%25%24%9%4
313
16th to endDay
29%11%21%22%10%4
332
September1st to 15thDay
30%14%23%16%10%4
315
16th to endDay
25%14%25%20%8%4
314
October1st to 15thDay
31%16%22%19%7%1
267
16th to endDay
43%16%23%12%4
240
November1st to 15thDay
36%20%18%16%6%1
235
16th to endDay
37%17%25%14%3
103
December1st to 15thDay
36%18%31%10%3
60
16th to endDay
45%21%25%43
64
January1st to 15thNight
24%22%30%17%4
731
16th to endNight
18%19%34%19%6%1
768
February1st to 15thNight
15%20%32%23%7%
704
16th to endNight
26%15%33%17%6%
631
March1st to 15thNight
24%18%30%21%4
720
16th to endNight
22%18%28%22%6%1
768
April1st to 15thNight
30%16%25%20%6%
688
16th to endNight
28%11%28%23%7%
540
May1st to 15thNight
26%7%31%26%8%
441
16th to endNight
28%11%23%26%9%
375
June1st to 15thNight
23%6%27%31%9%1
360
16th to endNight
17%6%27%35%12%
360
July1st to 15thNight
20%7%25%34%11%1
340
16th to endNight
21%6%23%36%10%1
376
August1st to 15thNight
19%6%19%34%18%1
407
16th to endNight
24%8%24%28%12%1
598
September1st to 15thNight
26%9%23%28%10%1
720
16th to endNight
25%10%27%23%10%1
717
October1st to 15thNight
29%12%26%21%7%1
684
16th to endNight
40%15%22%14%6%1
704
November1st to 15thNight
31%19%21%17%7%1
701
16th to endNight
29%19%26%18%6%
750
December1st to 15thNight
32%23%26%14%4
750
16th to endNight
28%18%27%18%6%1
800
Page generated at 2017-10-07 14:07:52. Version ac04

Copyright 2017 A. Danko


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