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

2017-09-12
.

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%
14610
12%
46780
8%
14579
37%
14579
16%
34064

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%
720
7%
2506
4%
716
23%
716
8%
2016
January16th to endNight
22%
768
9%
2688
6%
768
28%
768
10%
2070
February1st to 15thNight
20%
704
7%
2313
5%
701
24%
701
10%
1855
February16th to endNight
26%
631
11%
1893
7%
631
32%
631
13%
1462
March1st to 15thNight
28%
720
13%
2160
10%
720
33%
720
14%
1653
March16th to endNight
34%
768
18%
2002
9%
768
40%
768
23%
1450
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%
707
13%
1771
7%
707
51%
707
28%
1237
September16th to endNight
46%
657
19%
1815
13%
657
50%
657
30%
1173
October1st to 15thNight
32%
660
19%
1925
11%
660
41%
660
21%
1354
October16th to endNight
26%
704
10%
2271
7%
704
32%
704
14%
1704
November1st to 15thNight
28%
700
16%
2277
12%
700
35%
700
15%
1643
November16th to endNight
23%
720
12%
2488
8%
720
29%
720
11%
1891
December1st to 15thNight
20%
720
6%
2520
3%
720
23%
720
8%
2021
December16th to endNight
14%
768
9%
2688
3%
768
21%
768
8%
2174

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%
47886
Night
19%9%46%5%34445%31%
46949
Cloud CoverDay
18%8%36%5%3445%6%31%
47896
Night
19%10%47%5%24445%30%
46954
TransparencyDay
51%6%12%19%8%
47573
Night
54%6%11%18%9%1
46780
SeeingDay
22%7%26%25%13%4
5585
Night
24%7%28%28%10%
14611

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%35%32321%
1432
16th to endDay
14%14%5%8%6%25%5%45%25%
1536
February1st to 15thDay
14%15%5%9%7%45%435%22%
1545
16th to endDay
18%13%5%8%7%33345%26%
1580
March1st to 15thDay
18%12%5%7%7%35%445%27%
1790
16th to endDay
18%9%35%5%2345%5%35%
2220
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%41%
2109
16th to endDay
15%5%235%24446%46%
1815
October1st to 15thDay
21%7%35%6%24447%32%
1702
16th to endDay
25%9%35%5%44445%27%
1601
November1st to 15thDay
18%9%36%6%245%46%31%
1581
16th to endDay
23%11%36%5%23446%28%
1470
December1st to 15thDay
26%12%5%8%7%34445%19%
1440
16th to endDay
27%16%47%5%3432419%
1536
January1st to 15thNight
19%15%5%10%6%3444421%
2506
16th to endNight
13%15%6%8%7%45%44424%
2688
February1st to 15thNight
15%14%8%10%9%35%34420%
2311
16th to endNight
18%11%5%9%6%35%445%26%
1893
March1st to 15thNight
21%12%5%7%5%3343428%
2147
16th to endNight
18%10%36%5%2433436%
2002
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
18%5%25%4225%5%6%40%
1771
16th to endNight
18%423423247%46%
1815
October1st to 15thNight
19%6%36%6%24445%37%
1925
16th to endNight
27%8%37%5%32335%29%
2271
November1st to 15thNight
20%9%36%6%3445%5%31%
2277
16th to endNight
25%11%37%5%2434327%
2488
December1st to 15thNight
25%14%5%7%6%23335%21%
2520
16th to endNight
24%16%6%7%5%3423421%
2688

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%5%9%7%3433321%
1432
16th to endDay
14%14%49%6%36%446%24%
1536
February1st to 15thDay
14%15%5%9%8%44345%20%
1545
16th to endDay
18%13%5%9%6%33345%25%
1580
March1st to 15thDay
18%11%5%7%6%35%345%26%
1800
16th to endDay
18%10%35%5%24446%34%
2220
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
17%5%25%43435%7%41%
2109
16th to endDay
15%5%24424446%45%
1815
October1st to 15thDay
21%7%36%5%34446%32%
1702
16th to endDay
25%10%25%5%34445%27%
1601
November1st to 15thDay
18%10%35%6%34446%31%
1581
16th to endDay
23%11%46%5%23445%28%
1470
December1st to 15thDay
26%12%5%8%7%34445%17%
1440
16th to endDay
27%16%5%7%5%3342418%
1536
January1st to 15thNight
19%15%6%10%7%3344420%
2506
16th to endNight
14%15%6%9%7%4444424%
2688
February1st to 15thNight
15%14%7%11%8%35%34420%
2304
16th to endNight
18%12%5%9%6%35%44426%
1893
March1st to 15thNight
21%12%5%7%5%2343428%
2160
16th to endNight
18%10%46%42434436%
2001
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%
1771
16th to endNight
19%5%13322336%46%
1815
October1st to 15thNight
18%7%27%5%24445%37%
1925
16th to endNight
27%8%37%6%23325%29%
2271
November1st to 15thNight
19%10%37%5%3445%5%30%
2277
16th to endNight
25%11%47%5%2434327%
2488
December1st to 15thNight
25%14%5%8%6%2333420%
2520
16th to endNight
24%16%7%8%43423421%
2688

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
1433
16th to endDay
59%7%12%15%5%
1536
February1st to 15thDay
64%410%16%2
1547
16th to endDay
61%411%13%8%
1580
March1st to 15thDay
60%411%15%6%1
1800
16th to endDay
49%410%20%11%2
2220
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
41%5%15%25%11%
2109
16th to endDay
38%5%13%30%11%
1815
October1st to 15thDay
51%6%12%21%7%
1702
16th to endDay
59%5%13%16%5%
1601
November1st to 15thDay
52%6%12%18%9%
1581
16th to endDay
57%6%12%15%7%
1470
December1st to 15thDay
67%6%11%12%1
1440
16th to endDay
69%5%11%7%5%
1536
January1st to 15thNight
66%6%10%12%3
2506
16th to endNight
62%5%10%14%6%
2688
February1st to 15thNight
66%410%14%3
2313
16th to endNight
60%5%10%13%9%
1893
March1st to 15thNight
59%5%8%17%8%1
2160
16th to endNight
50%49%16%15%3
2002
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%7%12%24%12%
1771
16th to endNight
38%6%11%29%13%
1815
October1st to 15thNight
48%6%10%24%9%
1925
16th to endNight
58%411%17%6%
2271
November1st to 15thNight
53%6%12%18%7%1
2277
16th to endNight
60%5%10%16%6%
2488
December1st to 15thNight
66%5%12%13%1
2520
16th to endNight
68%5%10%10%5%
2688

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
25%13%21%28%11%
60
16th to endDay
32%12%26%20%6%1
64
February1st to 15thDay
32%11%34%18%4
99
16th to endDay
26%8%28%30%5%
239
March1st to 15thDay
25%10%32%25%6%
270
16th to endDay
24%5%30%25%12%2
288
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
18%321%28%15%12%
299
16th to endDay
16%6%29%21%15%10%
254
October1st to 15thDay
21%8%29%20%17%2
255
16th to endDay
32%7%26%21%10%
243
November1st to 15thDay
27%8%28%22%11%2
235
16th to endDay
28%12%27%24%6%
90
December1st to 15thDay
35%8%21%28%33
60
16th to endDay
37%17%32%12%
64
January1st to 15thNight
26%11%31%24%6%
720
16th to endNight
22%10%33%24%7%
768
February1st to 15thNight
22%7%36%26%6%
704
16th to endNight
24%8%32%27%6%
631
March1st to 15thNight
27%10%28%27%6%
720
16th to endNight
23%6%30%29%8%1
768
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
707
16th to endNight
20%424%30%17%2
657
October1st to 15thNight
23%5%30%27%11%
660
16th to endNight
32%8%27%25%6%
704
November1st to 15thNight
25%9%30%24%9%
700
16th to endNight
29%12%28%18%10%
720
December1st to 15thNight
31%10%28%23%5%
720
16th to endNight
33%10%30%19%41
768
Page generated at 2017-09-13 07:39:17. Version ac04

Copyright 2017 A. Danko


Beloeil Clear Sky Chart | Charts Home