Louiseville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Louiseville 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
34%
22477
14%
74731
9%
22436
40%
22436
17%
53096

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
23%
759
9%
2649
5%
757
29%
757
10%
2089
January11th to 20thNight
24%
744
10%
2602
8%
744
29%
744
11%
2017
January21st to endNight
31%
792
13%
2772
8%
792
38%
792
15%
1988
February1st to 10thNight
25%
720
11%
2435
6%
720
33%
720
13%
1838
February11th to 20thNight
25%
703
12%
2163
7%
700
32%
700
15%
1635
February21st to endNight
30%
592
16%
1776
10%
592
39%
592
18%
1297
March1st to 10thNight
29%
720
15%
2160
11%
720
36%
720
16%
1606
March11th to 20thNight
28%
720
15%
2111
8%
720
36%
720
17%
1558
March21st to endNight
31%
792
20%
1980
7%
792
38%
792
22%
1439
April1st to 10thNight
29%
720
13%
1800
5%
720
33%
720
19%
1359
April11th to 20thNight
30%
698
17%
1762
5%
698
37%
698
25%
1254
April21st to endNight
28%
540
17%
1620
7%
540
36%
540
19%
1148
May1st to 10thNight
28%
431
15%
1511
9%
431
38%
431
17%
1050
May11th to 20thNight
36%
354
17%
1416
18%
354
46%
354
16%
943
May21st to endNight
31%
389
13%
1551
9%
388
45%
388
18%
986
June1st to 10thNight
37%
360
9%
1440
9%
360
46%
360
18%
933
June11th to 20thNight
43%
360
9%
1440
11%
360
48%
360
18%
917
June21st to endNight
45%
360
9%
1440
12%
360
48%
360
15%
973
July1st to 10thNight
51%
350
10%
1400
15%
350
57%
350
21%
855
July11th to 20thNight
51%
348
12%
1392
18%
348
55%
348
20%
854
July21st to endNight
53%
394
13%
1486
17%
372
57%
372
22%
914
August1st to 10thNight
58%
358
15%
1422
18%
356
62%
356
21%
862
August11th to 20thNight
57%
482
16%
1546
13%
482
59%
482
25%
1007
August21st to endNight
50%
792
18%
1980
10%
792
53%
792
31%
1351
September1st to 10thNight
52%
720
15%
1800
6%
720
55%
720
32%
1207
September11th to 20thNight
51%
720
20%
1901
12%
720
55%
720
33%
1214
September21st to endNight
45%
720
22%
1980
15%
720
50%
720
28%
1321
October1st to 10thNight
37%
720
21%
2061
13%
720
46%
720
23%
1421
October11th to 20thNight
34%
720
14%
2240
9%
720
41%
720
18%
1598
October21st to endNight
27%
792
12%
2574
7%
792
34%
792
16%
1861
November1st to 10thNight
27%
740
15%
2407
10%
740
35%
740
17%
1692
November11th to 20thNight
29%
760
17%
2531
12%
760
37%
760
16%
1813
November21st to endNight
26%
760
11%
2660
7%
760
33%
760
12%
1994
December1st to 10thNight
22%
760
9%
2660
5%
760
28%
760
10%
2063
December11th to 20thNight
22%
760
11%
3229
5%
759
29%
759
10%
2417
December21st to endNight
22%
827
8%
4834
6%
817
29%
817
6%
3622

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
17%9%36%6%35%5%5%7%33%
74794
Night
19%10%47%6%3445%6%33%
75012
TransparencyDay
49%8%13%19%10%1
74499
Night
52%6%11%19%10%1
74841
SeeingDay
21%9%28%26%13%3
13454
Night
23%6%28%32%10%1
22487

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
19%15%5%9%7%4444426%
1517
11th to 20thDay
18%16%47%6%46%445%25%
1480
21st to endDay
10%14%5%8%7%35%45%8%30%
1584
February1st to 10thDay
14%17%5%8%7%45%446%26%
1521
11th to 20thDay
15%14%5%8%6%45%5%5%5%28%
1684
21st to endDay
16%13%6%8%7%35%35%5%28%
1480
March1st to 10thDay
15%11%47%7%36%5%5%7%30%
1797
11th to 20thDay
15%13%48%6%345%46%33%
1848
21st to endDay
18%9%37%6%35%5%5%5%35%
2376
April1st to 10thDay
21%9%47%5%3446%6%31%
2160
11th to 20thDay
20%6%25%5%345%45%40%
2146
21st to endDay
22%10%45%6%3445%6%32%
2340
May1st to 10thDay
20%8%36%5%3445%6%36%
2465
11th to 20thDay
16%7%36%5%45%5%6%7%37%
2478
21st to endDay
18%7%36%6%36%45%8%34%
2725
June1st to 10thDay
20%7%46%5%45%5%6%8%30%
2520
11th to 20thDay
15%6%35%6%45%5%6%9%37%
2520
21st to endDay
19%6%37%7%46%5%5%8%29%
2520
July1st to 10thDay
12%5%25%6%46%6%7%10%37%
2520
11th to 20thDay
12%6%26%6%46%6%7%9%36%
2520
21st to endDay
11%5%27%5%46%8%8%9%35%
2744
August1st to 10thDay
13%6%35%6%36%7%8%10%32%
2506
11th to 20thDay
11%5%35%6%36%5%7%10%39%
2334
21st to endDay
12%425%5%35%5%7%9%42%
2376
September1st to 10thDay
13%5%25%6%35%5%6%9%41%
2160
11th to 20thDay
15%6%2443445%7%47%
2058
21st to endDay
19%6%35%5%345%47%41%
1980
October1st to 10thDay
20%6%36%6%3445%7%36%
1895
11th to 20thDay
21%7%37%7%46%5%6%6%28%
1720
21st to endDay
25%10%38%5%34446%29%
1782
November1st to 10thDay
16%9%37%6%45%5%5%7%34%
1671
11th to 20thDay
21%9%46%6%35%5%5%6%29%
1649
21st to endDay
21%13%46%6%445%5%5%28%
1520
December1st to 10thDay
26%13%47%5%4444424%
1520
11th to 20thDay
22%13%5%8%6%3434428%
1906
21st to endDay
25%17%5%9%5%22345%23%
2772
January1st to 10thNight
18%17%6%10%6%35%445%22%
2649
11th to 20thNight
18%16%6%9%6%44445%25%
2602
21st to endNight
12%13%5%8%8%45%5%5%6%31%
2772
February1st to 10thNight
13%14%6%9%7%45%5%5%5%26%
2435
11th to 20thNight
15%11%5%9%7%45%5%5%429%
2161
21st to endNight
17%11%5%8%6%35%445%32%
1776
March1st to 10thNight
17%12%5%8%8%3445%5%30%
2150
11th to 20thNight
18%13%5%7%6%3345%6%31%
2111
21st to endNight
17%10%46%5%35%445%37%
1980
April1st to 10thNight
24%10%47%5%345%46%30%
1800
11th to 20thNight
20%8%35%43445%7%37%
1762
21st to endNight
23%9%35%5%23447%34%
1620
May1st to 10thNight
22%8%46%5%3445%5%34%
1511
11th to 20thNight
19%7%37%5%35%5%5%7%35%
1415
21st to endNight
18%6%35%5%35%446%40%
1550
June1st to 10thNight
20%7%245%345%6%9%34%
1440
11th to 20thNight
17%7%45%435%5%6%9%36%
1440
21st to endNight
20%7%26%5%35%6%5%8%33%
1440
July1st to 10thNight
12%435%6%37%5%7%11%38%
1440
11th to 20thNight
12%6%26%6%36%5%6%6%41%
1440
21st to endNight
13%6%345%345%7%9%40%
1574
August1st to 10thNight
12%5%36%6%35%5%6%9%40%
1432
11th to 20thNight
13%5%25%6%36%5%6%7%41%
1546
21st to endNight
15%5%25%5%3446%7%44%
1980
September1st to 10thNight
12%425%6%45%5%5%7%45%
1800
11th to 20thNight
16%5%2442345%7%49%
1901
21st to endNight
18%5%25%434447%44%
1980
October1st to 10thNight
17%7%36%6%45%44441%
2061
11th to 20thNight
21%8%37%5%3445%6%34%
2240
21st to endNight
26%7%36%5%34446%31%
2574
November1st to 10thNight
19%9%47%5%34446%34%
2407
11th to 20thNight
20%8%46%6%345%5%6%32%
2531
21st to endNight
23%12%47%6%35%335%28%
2660
December1st to 10thNight
22%12%5%8%7%45%45%5%23%
2660
11th to 20thNight
24%13%5%8%6%3344428%
3288
21st to endNight
27%17%5%8%42333425%
4884

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
63%6%11%14%6%
1518
11th to 20thDay
62%412%12%9%1
1480
21st to endDay
52%6%9%20%10%1
1584
February1st to 10thDay
60%6%9%17%7%2
1521
11th to 20thDay
57%6%13%12%10%1
1693
21st to endDay
58%5%9%16%9%2
1480
March1st to 10thDay
52%9%11%16%11%2
1800
11th to 20thDay
51%6%12%14%15%3
1848
21st to endDay
50%6%11%18%12%3
2376
April1st to 10thDay
53%6%11%16%12%2
2160
11th to 20thDay
46%6%11%22%13%3
2146
21st to endDay
54%6%10%16%13%3
2340
May1st to 10thDay
48%5%10%20%14%2
2465
11th to 20thDay
45%7%11%19%15%3
2482
21st to endDay
48%8%10%18%14%2
2725
June1st to 10thDay
50%8%12%19%9%2
2520
11th to 20thDay
43%8%13%23%12%2
2520
21st to endDay
52%10%10%18%10%1
2520
July1st to 10thDay
38%12%16%24%10%1
2450
11th to 20thDay
40%10%16%24%9%
2445
21st to endDay
41%13%17%22%8%
2591
August1st to 10thDay
43%12%17%22%6%
2492
11th to 20thDay
38%11%17%25%9%
2334
21st to endDay
36%10%16%25%13%
2376
September1st to 10thDay
38%8%17%24%12%1
2160
11th to 20thDay
36%7%15%29%12%1
2058
21st to endDay
42%8%14%26%10%
1980
October1st to 10thDay
48%6%12%24%10%1
1895
11th to 20thDay
54%8%14%19%5%
1720
21st to endDay
57%6%12%16%8%1
1782
November1st to 10thDay
49%8%13%19%9%1
1671
11th to 20thDay
55%5%13%16%10%
1649
21st to endDay
59%6%14%15%5%1
1520
December1st to 10thDay
64%5%10%15%6%
1520
11th to 20thDay
61%49%19%7%
1906
21st to endDay
65%5%11%11%7%
2772
January1st to 10thNight
66%5%10%13%6%
2649
11th to 20thNight
63%5%10%13%7%1
2602
21st to endNight
55%5%11%16%11%1
2772
February1st to 10thNight
60%5%10%16%8%1
2435
11th to 20thNight
57%6%10%15%11%1
2163
21st to endNight
55%5%8%17%14%2
1776
March1st to 10thNight
56%6%10%16%11%2
2160
11th to 20thNight
55%5%9%15%13%4
2112
21st to endNight
50%5%8%20%13%4
1980
April1st to 10thNight
55%5%10%15%14%2
1800
11th to 20thNight
46%6%10%20%15%3
1762
21st to endNight
52%48%18%15%3
1620
May1st to 10thNight
52%5%9%15%15%4
1511
11th to 20thNight
50%6%9%16%16%4
1416
21st to endNight
45%6%11%19%16%3
1551
June1st to 10thNight
45%7%14%20%12%1
1440
11th to 20thNight
44%8%11%20%13%4
1440
21st to endNight
47%10%12%18%13%1
1440
July1st to 10thNight
38%10%16%22%13%1
1400
11th to 20thNight
40%9%14%26%11%1
1392
21st to endNight
39%9%18%23%11%
1486
August1st to 10thNight
38%9%18%26%8%
1422
11th to 20thNight
40%9%16%24%11%
1546
21st to endNight
38%8%14%27%12%
1980
September1st to 10thNight
38%7%15%26%13%1
1800
11th to 20thNight
36%6%15%31%11%1
1901
21st to endNight
40%7%10%28%14%
1980
October1st to 10thNight
46%6%9%25%14%
2061
11th to 20thNight
50%7%13%22%7%
2240
21st to endNight
55%5%13%17%10%
2574
November1st to 10thNight
52%6%14%20%8%1
2407
11th to 20thNight
54%6%13%17%10%1
2531
21st to endNight
60%5%13%15%7%
2660
December1st to 10thNight
64%5%13%13%5%
2660
11th to 20thNight
61%410%17%7%1
3288
21st to endNight
65%48%16%6%1
4884

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
26%12%31%24%7%
180
11th to 20thDay
26%10%29%26%6%2
170
21st to endDay
19%7%34%28%9%3
176
February1st to 10thDay
27%11%42%18%2
196
11th to 20thDay
24%8%35%25%7%
352
21st to endDay
26%9%31%27%6%1
346
March1st to 10thDay
25%7%30%29%9%
420
11th to 20thDay
20%15%28%25%11%1
420
21st to endDay
27%10%25%25%10%3
462
April1st to 10thDay
25%11%26%26%11%1
420
11th to 20thDay
26%13%26%23%11%2
412
21st to endDay
28%11%30%20%8%3
420
May1st to 10thDay
23%10%36%17%11%2
423
11th to 20thDay
18%8%33%24%14%4
447
21st to endDay
19%12%33%20%14%2
485
June1st to 10thDay
21%11%30%25%12%2
450
11th to 20thDay
18%8%26%27%18%3
450
21st to endDay
19%7%25%27%17%4
450
July1st to 10thDay
13%6%22%32%20%6%
445
11th to 20thDay
15%7%25%31%18%4
444
21st to endDay
14%422%33%20%6%
488
August1st to 10thDay
15%6%21%31%22%6%
446
11th to 20thDay
13%419%34%19%11%
439
21st to endDay
13%7%26%22%21%11%
495
September1st to 10thDay
14%7%27%28%16%8%
450
11th to 20thDay
15%8%22%28%19%8%
450
21st to endDay
19%6%26%28%15%6%
450
October1st to 10thDay
22%9%25%25%17%2
450
11th to 20thDay
24%8%30%24%11%2
410
21st to endDay
31%9%27%21%12%
396
November1st to 10thDay
25%12%29%24%9%1
365
11th to 20thDay
26%8%31%24%11%
309
21st to endDay
28%12%32%19%8%1
180
December1st to 10thDay
31%9%25%23%7%4
180
11th to 20thDay
28%11%31%24%32
180
21st to endDay
32%11%28%20%9%1
198
January1st to 10thNight
28%9%28%29%6%
760
11th to 20thNight
27%7%30%28%7%
744
21st to endNight
18%5%29%38%8%1
792
February1st to 10thNight
21%7%34%30%8%1
720
11th to 20thNight
21%8%35%29%6%1
703
21st to endNight
22%5%32%34%7%
592
March1st to 10thNight
23%8%28%35%6%
720
11th to 20thNight
23%9%31%29%6%1
720
21st to endNight
22%7%32%30%9%
792
April1st to 10thNight
27%8%28%30%7%
720
11th to 20thNight
25%9%32%28%7%
698
21st to endNight
28%8%30%26%8%
540
May1st to 10thNight
26%7%31%29%7%
431
11th to 20thNight
24%5%28%35%7%1
354
21st to endNight
21%438%27%10%
389
June1st to 10thNight
22%428%34%11%1
360
11th to 20thNight
20%424%38%14%1
360
21st to endNight
22%421%38%14%
360
July1st to 10thNight
13%5%23%41%16%2
350
11th to 20thNight
11%225%44%18%1
348
21st to endNight
15%220%45%16%1
394
August1st to 10thNight
15%315%44%23%1
358
11th to 20thNight
16%217%43%21%2
482
21st to endNight
17%421%36%21%2
792
September1st to 10thNight
15%322%42%17%1
720
11th to 20thNight
18%5%21%34%21%1
720
21st to endNight
19%6%25%31%17%2
720
October1st to 10thNight
21%6%27%34%11%1
720
11th to 20thNight
25%7%26%31%10%1
720
21st to endNight
30%7%30%27%6%
792
November1st to 10thNight
24%9%30%28%9%1
740
11th to 20thNight
23%8%32%25%11%1
760
21st to endNight
31%8%28%26%7%1
760
December1st to 10thNight
30%7%29%27%6%1
760
11th to 20thNight
25%9%31%26%8%1
760
21st to endNight
34%8%25%26%7%
836
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