Lac Buteux
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lac Buteux clear sky chart from 2005-11-05 to 2017-10-31.

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
28%
14758
12%
47334
6%
14726
36%
14726
15%
33609

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
16%
734
11%
2589
3%
730
25%
730
9%
1936
January16th to endNight
18%
768
13%
2688
3%
768
31%
768
11%
1925
February1st to 15thNight
19%
704
12%
2387
3%
701
30%
701
12%
1701
February16th to endNight
19%
631
12%
1898
3%
631
29%
631
12%
1433
March1st to 15thNight
22%
720
15%
2131
7%
720
31%
720
14%
1523
March16th to endNight
25%
768
19%
2064
6%
768
34%
768
19%
1433
April1st to 15thNight
23%
673
16%
1751
5%
673
29%
673
16%
1315
April16th to endNight
29%
540
16%
1620
8%
540
36%
540
19%
1117
May1st to 15thNight
33%
471
11%
1551
7%
471
39%
471
15%
1103
May16th to endNight
30%
375
10%
1350
7%
374
38%
374
13%
989
June1st to 15thNight
38%
360
6%
1260
5%
360
41%
360
16%
876
June16th to endNight
38%
360
5%
1260
4%
360
40%
360
15%
890
July1st to 15thNight
46%
340
8%
1195
8%
340
49%
340
19%
801
July16th to endNight
47%
376
8%
1418
10%
354
50%
354
16%
937
August1st to 15thNight
49%
431
10%
1502
9%
429
52%
429
18%
1019
August16th to endNight
45%
577
14%
1723
8%
577
49%
577
24%
1124
September1st to 15thNight
41%
720
11%
1873
5%
720
44%
720
25%
1315
September16th to endNight
39%
717
18%
1980
10%
717
45%
717
27%
1303
October1st to 15thNight
34%
720
18%
2091
8%
720
43%
720
22%
1395
October16th to endNight
26%
768
12%
2494
6%
768
34%
768
14%
1765
November1st to 15thNight
27%
705
16%
2304
9%
705
36%
705
14%
1640
November16th to endNight
24%
750
12%
2625
5%
750
33%
750
11%
1904
December1st to 15thNight
15%
750
9%
2700
2%
750
24%
750
9%
2017
December16th to endNight
16%
800
11%
2880
3%
800
26%
800
8%
2148

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%8%36%5%35%5%5%6%30%
48428
Night
17%9%46%5%3445%6%31%
47494
TransparencyDay
51%6%13%19%8%
48106
Night
52%5%12%20%8%
47334
SeeingDay
23%13%26%22%10%2
6493
Night
22%14%25%25%10%1
14758

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%12%5%7%7%46%45%5%26%
1346
16th to endDay
9%8%5%10%6%45%6%46%30%
1536
February1st to 15thDay
6%13%6%8%8%46%5%5%8%25%
1473
16th to endDay
13%14%49%6%45%45%5%26%
1572
March1st to 15thDay
16%11%5%7%43445%6%29%
1818
16th to endDay
13%12%5%7%6%34445%33%
2160
April1st to 15thDay
19%10%35%434446%31%
2197
16th to endDay
23%9%25%5%23345%35%
2340
May1st to 15thDay
21%7%36%435%445%34%
2409
16th to endDay
21%7%35%5%35%45%6%29%
2765
June1st to 15thDay
19%8%36%5%3446%8%28%
2700
16th to endDay
21%7%36%6%45%5%5%7%27%
2700
July1st to 15thDay
15%6%35%6%46%7%7%8%28%
2694
16th to endDay
16%5%26%6%35%5%6%7%33%
2654
August1st to 15thDay
17%5%26%6%36%7%8%8%28%
2436
16th to endDay
11%5%16%6%45%6%7%9%35%
2477
September1st to 15thDay
18%6%35%5%3445%7%36%
2086
16th to endDay
15%5%245%3445%7%40%
1980
October1st to 15thDay
19%7%27%5%345%5%6%32%
1867
16th to endDay
22%10%37%5%3445%5%25%
1728
November1st to 15thDay
17%9%48%6%46%446%27%
1554
16th to endDay
18%10%6%7%6%34345%27%
1332
December1st to 15thDay
20%15%46%5%35%435%26%
1260
16th to endDay
19%15%5%8%6%35%325%25%
1344
January1st to 15thNight
14%11%5%8%7%45%46%6%24%
2589
16th to endNight
10%12%5%10%6%35%6%5%7%26%
2688
February1st to 15thNight
8%10%5%9%7%36%46%7%28%
2386
16th to endNight
14%14%5%10%6%35%34427%
1898
March1st to 15thNight
15%11%47%42445%6%32%
2118
16th to endNight
12%10%46%5%34446%37%
2064
April1st to 15thNight
21%11%35%6%33336%31%
1751
16th to endNight
25%7%34323345%38%
1620
May1st to 15thNight
24%8%35%5%3445%430%
1551
16th to endNight
20%10%37%5%35%346%28%
1348
June1st to 15thNight
19%5%37%7%2446%5%32%
1260
16th to endNight
22%6%35%5%35%5%5%8%29%
1260
July1st to 15thNight
17%6%35%5%25%5%6%8%33%
1265
16th to endNight
14%5%25%6%37%5%5%7%36%
1514
August1st to 15thNight
15%5%26%6%36%5%7%8%32%
1512
16th to endNight
11%425%5%35%5%5%8%39%
1723
September1st to 15thNight
16%5%25%6%34446%39%
1873
16th to endNight
18%6%23422345%45%
1980
October1st to 15thNight
17%6%25%43435%7%38%
2091
16th to endNight
24%7%25%42445%6%31%
2494
November1st to 15thNight
21%8%35%5%35%45%6%31%
2304
16th to endNight
17%10%47%6%445%5%5%27%
2625
December1st to 15thNight
18%14%6%7%5%3434427%
2700
16th to endNight
17%12%5%8%6%245%5%6%24%
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
57%5%11%17%8%
1347
16th to endDay
52%6%13%17%10%
1536
February1st to 15thDay
55%6%13%15%7%1
1476
16th to endDay
58%47%18%10%
1572
March1st to 15thDay
54%49%16%13%2
1828
16th to endDay
53%49%19%11%1
2160
April1st to 15thDay
53%37%22%9%3
2197
16th to endDay
51%39%19%14%1
2340
May1st to 15thDay
50%412%20%11%
2409
16th to endDay
52%6%12%20%8%
2769
June1st to 15thDay
52%6%12%19%8%1
2700
16th to endDay
55%6%13%16%7%
2700
July1st to 15thDay
46%8%17%22%5%
2535
16th to endDay
47%8%17%19%7%
2487
August1st to 15thDay
46%9%21%17%4
2422
16th to endDay
40%8%21%25%4
2477
September1st to 15thDay
45%5%16%23%8%
2086
16th to endDay
40%6%17%26%8%
1980
October1st to 15thDay
50%5%14%19%9%
1867
16th to endDay
58%5%14%17%4
1728
November1st to 15thDay
55%7%10%20%4
1554
16th to endDay
58%5%12%18%4
1332
December1st to 15thDay
60%5%13%15%5%
1260
16th to endDay
63%48%14%8%
1344
January1st to 15thNight
59%5%12%15%6%
2589
16th to endNight
55%5%10%21%7%
2688
February1st to 15thNight
53%5%12%18%8%1
2387
16th to endNight
60%29%18%8%
1898
March1st to 15thNight
52%411%19%11%1
2131
16th to endNight
47%410%22%13%1
2064
April1st to 15thNight
54%46%17%14%2
1751
16th to endNight
49%39%20%14%2
1620
May1st to 15thNight
54%310%18%10%1
1551
16th to endNight
57%5%11%16%9%1
1350
June1st to 15thNight
52%5%12%19%10%
1260
16th to endNight
53%6%13%17%9%
1260
July1st to 15thNight
45%7%15%24%6%
1195
16th to endNight
47%7%15%20%8%
1418
August1st to 15thNight
45%9%17%21%4
1502
16th to endNight
40%7%21%23%6%
1723
September1st to 15thNight
46%5%16%23%8%
1873
16th to endNight
40%5%16%27%9%
1980
October1st to 15thNight
44%413%26%9%1
2091
16th to endNight
52%5%15%21%5%
2494
November1st to 15thNight
52%6%13%19%8%
2304
16th to endNight
56%5%12%17%6%
2625
December1st to 15thNight
59%5%13%17%5%
2700
16th to endNight
59%5%12%15%6%
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
20%31%36%10%1
60
16th to endDay
18%21%34%20%4
64
February1st to 15thDay
16%14%36%21%10%
134
16th to endDay
28%19%28%15%6%1
238
March1st to 15thDay
26%20%27%16%8%
270
16th to endDay
21%20%25%19%10%2
288
April1st to 15thDay
27%18%32%13%5%3
270
16th to endDay
28%16%27%17%7%1
270
May1st to 15thDay
29%11%27%22%7%1
288
16th to endDay
26%13%30%19%8%1
479
June1st to 15thDay
26%12%22%26%10%2
495
16th to endDay
23%7%26%26%13%2
495
July1st to 15thDay
20%9%25%26%13%3
469
16th to endDay
17%5%29%34%11%1
326
August1st to 15thDay
16%6%25%31%17%3
313
16th to endDay
18%12%25%24%15%4
332
September1st to 15thDay
23%7%26%26%10%6%
315
16th to endDay
15%12%27%24%13%5%
314
October1st to 15thDay
22%14%23%26%10%1
294
16th to endDay
31%19%24%13%9%2
288
November1st to 15thDay
24%17%23%22%9%1
235
16th to endDay
28%18%28%14%9%
132
December1st to 15thDay
31%18%30%13%5%1
60
16th to endDay
37%25%20%17%
64
January1st to 15thNight
20%19%32%23%4
734
16th to endNight
18%18%33%22%6%
768
February1st to 15thNight
15%20%33%23%8%
704
16th to endNight
23%18%28%20%7%
631
March1st to 15thNight
23%20%26%22%5%1
720
16th to endNight
18%22%26%23%8%
768
April1st to 15thNight
26%15%27%19%10%1
673
16th to endNight
30%12%21%25%8%1
540
May1st to 15thNight
28%8%20%28%12%1
471
16th to endNight
26%10%23%27%10%1
375
June1st to 15thNight
22%5%23%33%12%2
360
16th to endNight
25%320%33%15%1
360
July1st to 15thNight
19%5%18%37%17%2
340
16th to endNight
16%5%21%35%18%1
376
August1st to 15thNight
19%315%34%25%1
431
16th to endNight
14%6%23%35%17%2
577
September1st to 15thNight
19%5%24%33%14%2
720
16th to endNight
22%7%24%30%12%1
717
October1st to 15thNight
20%12%24%30%10%2
720
16th to endNight
29%14%22%22%10%
768
November1st to 15thNight
25%17%23%22%9%
705
16th to endNight
22%17%26%24%7%1
750
December1st to 15thNight
26%20%30%17%4
750
16th to endNight
25%20%26%19%7%1
800
Page generated at 2017-11-01 17:23:36. Version ac04

Copyright 2017 A. Danko


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