Beloeil
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beloeil clear sky chart from 2005-11-05 to 2018-03-21.

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
32%
15371
12%
49229
9%
15340
37%
15340
16%
35819

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
20%
780
8%
2716
5%
776
24%
776
9%
2173
January16th to endNight
22%
832
9%
2912
5%
832
28%
832
10%
2241
February1st to 15thNight
20%
764
8%
2509
5%
761
25%
761
10%
2011
February16th to endNight
26%
683
11%
2049
7%
683
32%
683
13%
1568
March1st to 15thNight
27%
780
13%
2340
9%
780
32%
780
13%
1818
March16th to endNight
34%
792
20%
2069
10%
792
41%
792
23%
1481
April1st to 15thNight
28%
718
15%
1796
5%
718
33%
718
18%
1387
April16th to endNight
31%
606
16%
1686
6%
606
37%
606
20%
1197
May1st to 15thNight
31%
414
16%
1494
14%
414
39%
414
18%
1014
May16th to endNight
33%
374
12%
1497
11%
374
41%
374
16%
1002
June1st to 15thNight
33%
360
8%
1440
8%
360
41%
360
12%
1013
June16th to endNight
46%
360
8%
1440
11%
360
50%
360
18%
925
July1st to 15thNight
50%
340
12%
1360
17%
340
55%
340
23%
815
July16th to endNight
54%
376
12%
1418
16%
354
57%
354
22%
860
August1st to 15thNight
55%
377
14%
1448
15%
375
57%
375
20%
919
August16th to endNight
55%
738
18%
1884
12%
738
56%
738
34%
1229
September1st to 15thNight
50%
720
13%
1803
7%
720
51%
720
28%
1258
September16th to endNight
49%
717
21%
1980
15%
717
53%
717
31%
1257
October1st to 15thNight
34%
720
18%
2100
11%
720
43%
720
22%
1461
October16th to endNight
26%
768
11%
2478
7%
768
32%
768
14%
1841
November1st to 15thNight
28%
760
16%
2472
12%
760
35%
760
15%
1776
November16th to endNight
22%
780
12%
2696
8%
780
28%
780
11%
2051
December1st to 15thNight
19%
780
7%
2730
3%
780
24%
780
8%
2182
December16th to endNight
14%
832
9%
2912
3%
832
22%
832
8%
2340

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%8%36%5%3445%6%32%
49626
Night
19%10%46%5%34445%31%
49398
Cloud CoverDay
18%8%36%5%3445%6%31%
49636
Night
19%10%47%5%34445%31%
49403
TransparencyDay
51%6%12%19%8%
49313
Night
54%5%11%18%9%1
49229
SeeingDay
23%7%26%24%13%4
6149
Night
24%7%28%28%10%
15372

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
23%14%5%9%6%3432321%
1552
16th to endDay
14%14%49%6%35%5%45%26%
1664
February1st to 15thDay
15%15%5%9%7%45%435%22%
1678
16th to endDay
19%13%5%8%7%33345%26%
1710
March1st to 15thDay
19%13%5%7%6%35%435%26%
1940
16th to endDay
18%9%35%5%2345%5%36%
2281
April1st to 15thDay
23%9%46%5%2443431%
2152
16th to endDay
21%7%24434445%37%
2273
May1st to 15thDay
21%6%26%5%24446%33%
2468
16th to endDay
20%6%25%5%25%5%5%7%32%
2618
June1st to 15thDay
24%6%25%435%448%31%
2520
16th to endDay
19%5%36%5%35%5%6%8%30%
2520
July1st to 15thDay
13%426%5%345%6%9%37%
2520
16th to endDay
12%5%25%5%35%5%6%9%35%
2654
August1st to 15thDay
13%5%36%6%46%5%6%8%33%
2489
16th to endDay
10%4245%2446%8%45%
2315
September1st to 15thDay
16%425%42345%7%42%
2157
16th to endDay
14%5%13423446%48%
1980
October1st to 15thDay
20%7%35%6%33447%33%
1857
16th to endDay
24%9%35%5%44446%28%
1746
November1st to 15thDay
18%9%36%5%345%46%31%
1716
16th to endDay
23%10%36%5%335%46%27%
1592
December1st to 15thDay
25%13%5%8%7%34345%20%
1560
16th to endDay
26%16%47%5%3432420%
1664
January1st to 15thNight
19%16%5%9%6%3444421%
2716
16th to endNight
14%15%6%8%7%4444424%
2912
February1st to 15thNight
15%14%8%10%8%35%34421%
2507
16th to endNight
18%11%5%8%6%35%445%27%
2049
March1st to 15thNight
21%13%5%7%5%3343426%
2327
16th to endNight
17%10%46%42433438%
2069
April1st to 15thNight
26%9%36%42243430%
1796
16th to endNight
22%7%24334436%36%
1686
May1st to 15thNight
20%8%35%5%13446%35%
1494
16th to endNight
21%7%35%42445%8%33%
1495
June1st to 15thNight
26%7%25%42445%6%29%
1440
16th to endNight
16%5%26%5%236%5%8%35%
1440
July1st to 15thNight
13%4246%35%5%6%10%37%
1440
16th to endNight
12%315%6%35%5%7%8%39%
1514
August1st to 15thNight
13%5%25%5%346%7%9%36%
1458
16th to endNight
12%42443445%8%44%
1884
September1st to 15thNight
17%5%25%4225%5%6%41%
1803
16th to endNight
17%423423247%47%
1980
October1st to 15thNight
18%6%36%6%24345%38%
2100
16th to endNight
27%8%27%5%33335%29%
2478
November1st to 15thNight
21%9%26%6%3445%5%31%
2472
16th to endNight
24%11%37%5%2434327%
2696
December1st to 15thNight
24%14%6%8%6%23335%21%
2730
16th to endNight
23%15%6%7%5%3423422%
2912

Percentage Cloud Cover SE (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
23%14%6%9%6%3433320%
1552
16th to endDay
14%14%49%6%36%445%25%
1664
February1st to 15thDay
15%15%5%9%8%44345%20%
1678
16th to endDay
18%13%5%8%6%33345%25%
1710
March1st to 15thDay
19%14%5%7%6%35%345%25%
1950
16th to endDay
17%9%35%5%24446%35%
2281
April1st to 15thDay
23%9%36%5%24435%30%
2152
16th to endDay
21%7%25%424446%36%
2273
May1st to 15thDay
21%6%36%5%24447%32%
2468
16th to endDay
20%6%26%5%345%5%7%32%
2618
June1st to 15thDay
23%6%35%425%45%8%30%
2520
16th to endDay
19%6%35%5%35%6%6%8%30%
2520
July1st to 15thDay
12%5%26%6%35%6%6%9%36%
2520
16th to endDay
13%5%26%5%35%5%6%9%35%
2654
August1st to 15thDay
13%6%37%6%45%6%6%8%33%
2489
16th to endDay
10%5%25%4245%6%8%45%
2315
September1st to 15thDay
16%5%25%43435%7%42%
2157
16th to endDay
13%5%23324446%48%
1980
October1st to 15thDay
20%7%36%5%34446%33%
1857
16th to endDay
25%9%25%5%34445%28%
1746
November1st to 15thDay
18%10%35%6%34446%31%
1716
16th to endDay
23%10%46%5%335%45%27%
1592
December1st to 15thDay
25%12%5%8%7%34345%18%
1560
16th to endDay
26%16%47%5%3342419%
1664
January1st to 15thNight
19%15%6%9%6%3334421%
2716
16th to endNight
15%15%6%9%7%4444424%
2912
February1st to 15thNight
15%14%7%11%8%35%34420%
2500
16th to endNight
18%11%5%9%5%35%44427%
2049
March1st to 15thNight
21%13%5%7%5%2333426%
2340
16th to endNight
17%10%45%42433438%
2068
April1st to 15thNight
26%9%36%43334429%
1796
16th to endNight
21%8%25%323446%36%
1686
May1st to 15thNight
20%9%35%5%13346%35%
1494
16th to endNight
21%7%245%2445%7%33%
1495
June1st to 15thNight
27%7%35%42445%6%28%
1440
16th to endNight
16%5%35%5%145%5%10%35%
1440
July1st to 15thNight
12%5%245%35%6%6%9%37%
1440
16th to endNight
11%425%5%45%5%7%8%39%
1514
August1st to 15thNight
13%435%5%345%7%9%36%
1458
16th to endNight
13%4243245%5%8%44%
1884
September1st to 15thNight
17%6%25%42345%6%41%
1803
16th to endNight
17%423422347%47%
1980
October1st to 15thNight
18%7%27%5%24445%38%
2100
16th to endNight
27%8%36%6%23335%29%
2478
November1st to 15thNight
20%10%36%5%3445%5%31%
2472
16th to endNight
25%11%47%42434327%
2696
December1st to 15thNight
24%14%5%8%6%2333420%
2730
16th to endNight
23%16%7%8%43433421%
2912

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
69%5%8%12%4
1553
16th to endDay
58%7%13%15%4
1664
February1st to 15thDay
64%410%16%2
1680
16th to endDay
60%411%14%8%
1710
March1st to 15thDay
62%410%15%6%1
1950
16th to endDay
49%410%20%12%2
2281
April1st to 15thDay
56%48%18%10%1
2152
16th to endDay
48%5%9%20%12%3
2273
May1st to 15thDay
51%411%18%12%1
2468
16th to endDay
49%7%11%18%10%1
2622
June1st to 15thDay
51%7%12%18%9%
2520
16th to endDay
48%7%13%21%8%
2520
July1st to 15thDay
40%8%15%25%9%
2371
16th to endDay
42%7%18%23%7%
2487
August1st to 15thDay
46%8%16%22%6%
2475
16th to endDay
34%7%18%28%11%
2315
September1st to 15thDay
40%5%15%26%11%
2157
16th to endDay
36%5%14%32%11%
1980
October1st to 15thDay
50%6%12%22%7%
1857
16th to endDay
58%5%13%17%5%
1746
November1st to 15thDay
52%7%12%18%8%
1716
16th to endDay
58%7%12%14%7%
1592
December1st to 15thDay
67%6%11%12%2
1560
16th to endDay
69%5%11%8%6%
1664
January1st to 15thNight
65%6%10%12%4
2716
16th to endNight
62%5%10%14%6%
2912
February1st to 15thNight
66%410%14%3
2509
16th to endNight
59%5%10%14%10%
2049
March1st to 15thNight
61%47%16%8%1
2340
16th to endNight
49%48%16%16%3
2069
April1st to 15thNight
57%45%17%12%1
1796
16th to endNight
49%5%7%19%14%3
1686
May1st to 15thNight
50%47%17%14%4
1494
16th to endNight
48%7%10%20%11%2
1497
June1st to 15thNight
54%6%9%19%8%1
1440
16th to endNight
43%9%13%18%14%1
1440
July1st to 15thNight
38%7%14%26%13%
1360
16th to endNight
38%8%16%23%11%
1418
August1st to 15thNight
40%9%16%23%10%
1448
16th to endNight
36%6%16%27%11%
1884
September1st to 15thNight
42%6%12%24%12%
1803
16th to endNight
37%6%11%30%14%
1980
October1st to 15thNight
46%6%10%25%9%
2100
16th to endNight
57%412%18%6%
2478
November1st to 15thNight
53%6%12%18%7%1
2472
16th to endNight
60%5%10%16%6%
2696
December1st to 15thNight
66%5%12%13%2
2730
16th to endNight
67%5%10%11%5%
2912

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
27%11%25%25%10%
90
16th to endDay
28%16%31%18%41
96
February1st to 15thDay
33%11%33%18%2
142
16th to endDay
27%9%29%28%4
291
March1st to 15thDay
29%9%30%23%6%
330
16th to endDay
22%6%31%25%11%1
311
April1st to 15thDay
28%10%31%18%8%2
270
16th to endDay
22%11%27%19%14%4
270
May1st to 15thDay
27%9%28%16%13%4
288
16th to endDay
21%9%31%19%15%2
331
June1st to 15thDay
29%7%20%30%9%2
315
16th to endDay
20%6%27%29%13%2
315
July1st to 15thDay
16%428%28%16%5%
305
16th to endDay
16%219%36%20%3
326
August1st to 15thDay
16%320%31%20%7%
313
16th to endDay
12%5%20%27%20%13%
332
September1st to 15thDay
17%321%28%16%13%
315
16th to endDay
13%5%26%22%20%10%
314
October1st to 15thDay
20%8%29%20%17%2
315
16th to endDay
30%9%27%21%10%
292
November1st to 15thDay
28%7%26%22%12%2
280
16th to endDay
26%13%32%21%5%
122
December1st to 15thDay
31%8%22%30%43
90
16th to endDay
33%17%33%12%3
96
January1st to 15thNight
26%11%30%24%6%
780
16th to endNight
23%10%33%24%7%
832
February1st to 15thNight
22%8%36%25%6%
764
16th to endNight
25%8%32%27%5%
683
March1st to 15thNight
28%9%28%27%5%
780
16th to endNight
22%6%31%29%8%1
792
April1st to 15thNight
28%10%25%28%5%
718
16th to endNight
25%11%27%25%9%
606
May1st to 15thNight
25%431%27%9%1
414
16th to endNight
22%6%31%30%8%
375
June1st to 15thNight
30%5%23%30%10%
360
16th to endNight
18%227%38%12%
360
July1st to 15thNight
10%229%36%19%
340
16th to endNight
13%122%44%17%
376
August1st to 15thNight
13%317%41%22%1
377
16th to endNight
14%220%36%23%2
738
September1st to 15thNight
21%220%37%16%1
720
16th to endNight
19%423%31%18%3
717
October1st to 15thNight
22%5%30%28%13%
720
16th to endNight
31%8%28%24%6%
768
November1st to 15thNight
26%9%29%24%9%
760
16th to endNight
29%12%28%18%9%
780
December1st to 15thNight
31%11%28%23%5%
780
16th to endNight
31%10%31%19%5%1
832
Page generated at 2018-03-22 11:34:22. Version ac04

Copyright 2018 A. Danko


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