Club d'Astronomie Sirius du Saguenay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Club d'Astronomie Sirius du Saguenay clear sky chart from 2005-11-05 to 2017-09-19.

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%
14539
8%
46839
5%
14507
29%
14507
10%
37147

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
17%
729
6%
2562
4%
725
19%
725
5%
2217
January16th to endNight
22%
768
7%
2688
5%
768
25%
768
7%
2210
February1st to 15thNight
25%
704
9%
2413
6%
701
30%
701
10%
1881
February16th to endNight
22%
631
8%
1893
5%
631
26%
631
10%
1549
March1st to 15thNight
25%
720
12%
2160
9%
720
29%
720
13%
1660
March16th to endNight
28%
768
15%
2022
7%
768
33%
768
17%
1530
April1st to 15thNight
24%
697
12%
1775
5%
697
28%
697
15%
1398
April16th to endNight
27%
540
14%
1620
8%
540
33%
540
18%
1145
May1st to 15thNight
26%
416
11%
1496
10%
416
31%
416
13%
1093
May16th to endNight
28%
375
9%
1380
7%
374
35%
374
11%
1011
June1st to 15thNight
33%
360
4%
1260
2%
360
35%
360
13%
917
June16th to endNight
37%
360
4%
1260
3%
360
38%
360
14%
913
July1st to 15thNight
37%
340
5%
1226
5%
340
38%
340
12%
903
July16th to endNight
41%
376
6%
1418
9%
354
40%
354
11%
1043
August1st to 15thNight
41%
386
8%
1457
9%
384
44%
384
10%
1098
August16th to endNight
39%
613
9%
1759
5%
613
41%
613
15%
1343
September1st to 15thNight
38%
720
8%
1842
4%
720
39%
720
19%
1407
September16th to endNight
32%
673
12%
1858
8%
673
34%
673
18%
1384
October1st to 15thNight
27%
660
12%
1932
6%
660
33%
660
15%
1484
October16th to endNight
20%
704
6%
2288
5%
704
22%
704
7%
1945
November1st to 15thNight
22%
700
9%
2277
7%
700
25%
700
7%
1896
November16th to endNight
20%
749
5%
2673
4%
749
22%
749
6%
2215
December1st to 15thNight
14%
750
2%
2700
0%
750
15%
750
3%
2395
December16th to endNight
17%
800
5%
2880
3%
800
20%
800
4%
2510

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
20%10%47%6%35%5%5%6%23%
47988
Night
19%12%48%7%35%445%22%
47002
TransparencyDay
60%8%11%13%5%
47669
Night
62%7%10%13%5%
46839
SeeingDay
29%12%26%20%9%1
6192
Night
26%12%25%25%8%
14539

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
15%14%9%11%8%5%7%45%412%
1373
16th to endDay
12%14%7%10%7%47%8%6%5%13%
1536
February1st to 15thDay
7%12%7%11%10%6%10%5%6%6%16%
1446
16th to endDay
11%16%5%10%9%5%7%6%5%417%
1580
March1st to 15thDay
16%11%6%9%5%36%5%5%6%22%
1790
16th to endDay
14%12%5%9%5%35%435%28%
2201
April1st to 15thDay
20%12%5%6%5%25%445%26%
2172
16th to endDay
20%8%36%6%34446%31%
2340
May1st to 15thDay
23%9%35%5%24446%31%
2466
16th to endDay
22%7%46%5%35%447%28%
2735
June1st to 15thDay
20%7%36%6%345%5%6%28%
2700
16th to endDay
21%6%36%6%46%5%5%7%25%
2700
July1st to 15thDay
23%7%36%6%35%5%6%8%22%
2659
16th to endDay
19%7%36%6%36%5%5%7%27%
2654
August1st to 15thDay
21%9%38%6%45%5%6%6%21%
2481
16th to endDay
20%8%36%6%4445%8%26%
2441
September1st to 15thDay
25%7%26%5%24446%29%
2117
16th to endDay
24%8%35%5%24446%30%
1848
October1st to 15thDay
23%11%37%6%2444426%
1697
16th to endDay
31%17%47%6%2333315%
1584
November1st to 15thDay
23%14%49%6%2445%419%
1581
16th to endDay
24%20%6%8%6%3443314%
1283
December1st to 15thDay
23%19%5%10%8%5%5%33212%
1260
16th to endDay
19%20%6%9%6%46%44312%
1344
January1st to 15thNight
18%16%6%11%10%45%5%4412%
2562
16th to endNight
10%16%6%10%9%5%7%6%6%6%13%
2688
February1st to 15thNight
7%11%6%12%10%48%5%5%6%20%
2412
16th to endNight
11%18%7%11%9%35%35%420%
1893
March1st to 15thNight
17%12%5%8%5%35%445%26%
2147
16th to endNight
13%13%6%7%5%44336%31%
2022
April1st to 15thNight
24%12%37%6%24335%26%
1775
16th to endNight
21%8%34423447%34%
1620
May1st to 15thNight
24%9%47%5%23445%28%
1496
16th to endNight
22%9%37%6%25%445%28%
1378
June1st to 15thNight
21%8%35%5%35%45%6%29%
1260
16th to endNight
18%7%46%5%45%5%48%28%
1260
July1st to 15thNight
19%7%27%6%46%6%48%26%
1299
16th to endNight
16%7%47%6%36%5%6%7%28%
1514
August1st to 15thNight
19%8%36%7%35%5%5%8%25%
1467
16th to endNight
20%7%25%6%46%5%6%6%28%
1759
September1st to 15thNight
23%5%26%6%3435%6%32%
1842
16th to endNight
23%6%35%6%34335%34%
1858
October1st to 15thNight
24%8%36%5%34436%29%
1932
16th to endNight
32%15%36%434335%16%
2288
November1st to 15thNight
25%16%47%5%3443419%
2277
16th to endNight
22%17%5%8%5%3444418%
2673
December1st to 15thNight
22%19%6%10%7%35%5%3310%
2700
16th to endNight
16%19%7%10%9%46%5%4411%
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
74%7%8%7%2
1374
16th to endDay
66%7%8%13%4
1536
February1st to 15thDay
66%7%10%10%4
1449
16th to endDay
67%8%6%11%4
1580
March1st to 15thDay
61%7%9%12%8%
1800
16th to endDay
57%6%10%15%8%
2201
April1st to 15thDay
59%7%8%14%8%1
2172
16th to endDay
53%7%11%16%10%1
2340
May1st to 15thDay
53%7%11%16%10%
2466
16th to endDay
55%7%10%16%8%1
2739
June1st to 15thDay
54%8%10%15%10%1
2700
16th to endDay
56%9%11%15%6%
2700
July1st to 15thDay
56%9%15%14%2
2503
16th to endDay
56%11%12%15%3
2487
August1st to 15thDay
59%11%15%10%2
2467
16th to endDay
54%11%16%15%2
2441
September1st to 15thDay
55%8%13%17%5%
2117
16th to endDay
54%10%14%16%4
1848
October1st to 15thDay
60%8%10%14%41
1697
16th to endDay
74%6%9%7%2
1584
November1st to 15thDay
68%7%10%10%2
1581
16th to endDay
74%8%9%7%
1283
December1st to 15thDay
77%5%8%7%1
1260
16th to endDay
75%6%6%7%3
1344
January1st to 15thNight
74%6%7%8%2
2562
16th to endNight
68%6%9%12%2
2688
February1st to 15thNight
62%6%11%14%5%
2413
16th to endNight
66%6%9%13%4
1893
March1st to 15thNight
59%5%9%16%8%
2160
16th to endNight
55%5%9%19%8%1
2022
April1st to 15thNight
61%38%13%10%1
1775
16th to endNight
50%5%11%18%12%1
1620
May1st to 15thNight
57%5%8%16%11%
1496
16th to endNight
57%6%9%15%10%1
1380
June1st to 15thNight
54%7%12%15%8%
1260
16th to endNight
53%8%12%16%8%
1260
July1st to 15thNight
54%9%14%16%4
1226
16th to endNight
54%10%11%17%5%
1418
August1st to 15thNight
55%11%14%14%3
1457
16th to endNight
53%10%15%17%3
1759
September1st to 15thNight
52%8%14%17%6%
1842
16th to endNight
53%6%14%19%4
1858
October1st to 15thNight
56%7%12%15%6%1
1932
16th to endNight
72%6%8%10%2
2288
November1st to 15thNight
69%6%9%9%3
2277
16th to endNight
70%6%12%8%2
2673
December1st to 15thNight
77%7%8%5%1
2700
16th to endNight
75%7%7%7%2
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%26%41%11%3
60
16th to endDay
26%15%34%17%6%
64
February1st to 15thDay
17%17%34%21%7%2
93
16th to endDay
28%17%23%23%7%
239
March1st to 15thDay
30%13%26%19%9%
270
16th to endDay
22%15%26%21%12%1
288
April1st to 15thDay
30%13%27%19%7%1
270
16th to endDay
25%14%34%17%6%1
270
May1st to 15thDay
30%10%27%22%7%1
288
16th to endDay
28%13%29%19%8%
448
June1st to 15thDay
28%7%28%24%10%1
495
16th to endDay
25%9%28%23%10%2
495
July1st to 15thDay
27%9%25%22%13%1
437
16th to endDay
24%8%27%24%12%1
326
August1st to 15thDay
29%9%20%23%12%5%
313
16th to endDay
26%13%20%21%13%5%
332
September1st to 15thDay
29%10%25%17%11%4
315
16th to endDay
26%14%22%22%10%3
266
October1st to 15thDay
32%13%25%15%11%2
246
16th to endDay
47%10%21%13%42
240
November1st to 15thDay
36%15%24%15%7%1
235
16th to endDay
44%16%23%12%2
78
December1st to 15thDay
35%11%36%10%6%
60
16th to endDay
37%25%26%9%1
64
January1st to 15thNight
27%15%27%22%7%
729
16th to endNight
19%13%29%27%8%1
768
February1st to 15thNight
12%14%33%29%8%
704
16th to endNight
22%14%27%25%7%1
631
March1st to 15thNight
25%15%28%24%6%
720
16th to endNight
21%14%28%25%9%
768
April1st to 15thNight
31%11%27%23%5%
697
16th to endNight
24%11%32%23%8%
540
May1st to 15thNight
29%11%28%23%7%
416
16th to endNight
27%10%26%26%8%
375
June1st to 15thNight
26%5%28%30%8%
360
16th to endNight
20%8%25%34%10%
360
July1st to 15thNight
26%5%22%33%10%1
340
16th to endNight
18%7%21%37%14%
376
August1st to 15thNight
24%417%31%20%1
386
16th to endNight
24%7%21%31%13%1
613
September1st to 15thNight
28%7%19%31%11%1
720
16th to endNight
28%8%26%25%9%1
673
October1st to 15thNight
29%10%25%23%10%
660
16th to endNight
43%11%18%18%6%
704
November1st to 15thNight
33%15%21%19%8%1
700
16th to endNight
29%17%24%20%6%1
749
December1st to 15thNight
35%16%25%16%5%
750
16th to endNight
25%18%24%22%7%1
800
Page generated at 2017-09-20 04:49:48. Version ac04

Copyright 2017 A. Danko


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