Observatoire du CEGEP de LÚvis-Lauzon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatoire du CEGEP de LÚvis-Lauzon clear sky chart from 2005-11-05 to 2018-02-13.

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%
15255
12%
48845
7%
15223
34%
15223
14%
36155

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
15%
780
9%
2716
3%
776
23%
776
8%
2138
January16th to endNight
20%
832
11%
2912
5%
832
29%
832
10%
2199
February1st to 15thNight
21%
753
9%
2525
4%
750
27%
750
10%
1944
February16th to endNight
18%
631
11%
1893
5%
631
27%
631
11%
1489
March1st to 15thNight
21%
720
14%
2157
8%
720
28%
720
15%
1613
March16th to endNight
32%
768
17%
2025
8%
768
38%
768
21%
1481
April1st to 15thNight
27%
715
14%
1793
6%
715
32%
715
18%
1377
April16th to endNight
28%
540
15%
1620
7%
540
34%
540
19%
1143
May1st to 15thNight
30%
459
12%
1539
10%
459
36%
459
15%
1113
May16th to endNight
31%
375
10%
1467
11%
374
39%
374
14%
1039
June1st to 15thNight
33%
360
6%
1260
4%
360
37%
360
13%
934
June16th to endNight
39%
360
7%
1260
8%
360
41%
360
16%
899
July1st to 15thNight
45%
340
7%
1324
10%
340
49%
340
19%
884
July16th to endNight
48%
376
9%
1418
12%
354
49%
354
18%
950
August1st to 15thNight
50%
419
11%
1490
10%
417
53%
417
18%
1023
August16th to endNight
45%
639
16%
1785
8%
639
48%
639
24%
1223
September1st to 15thNight
40%
720
11%
1850
6%
720
42%
720
24%
1317
September16th to endNight
42%
717
18%
1980
12%
717
47%
717
28%
1321
October1st to 15thNight
33%
720
15%
2082
8%
720
39%
720
20%
1489
October16th to endNight
22%
768
10%
2496
5%
768
29%
768
12%
1881
November1st to 15thNight
28%
760
15%
2472
11%
760
35%
760
14%
1791
November16th to endNight
25%
806
12%
2769
7%
806
33%
806
12%
2085
December1st to 15thNight
14%
825
5%
2925
2%
825
19%
825
7%
2386
December16th to endNight
14%
872
10%
3087
4%
872
22%
872
8%
2436

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
19%8%36%5%3445%6%30%
49195
Night
19%10%46%5%34445%30%
49015
TransparencyDay
52%7%12%17%8%
48883
Night
55%6%11%17%8%
48845
SeeingDay
25%10%26%23%11%2
6470
Night
25%9%28%26%8%
15255

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
19%13%5%8%6%45%445%23%
1552
16th to endDay
11%12%6%9%6%36%5%5%5%26%
1664
February1st to 15thDay
10%14%6%10%6%35%45%6%26%
1600
16th to endDay
14%13%5%7%7%345%5%5%25%
1580
March1st to 15thDay
17%11%47%5%33345%32%
1792
16th to endDay
15%9%36%5%35%5%5%5%35%
2196
April1st to 15thDay
23%8%35%5%3434433%
2155
16th to endDay
23%6%25%433335%37%
2340
May1st to 15thDay
24%6%25%5%25%446%31%
2421
16th to endDay
22%6%36%6%45%5%5%6%27%
2645
June1st to 15thDay
21%5%26%5%35%5%6%8%28%
2700
16th to endDay
21%6%36%5%45%5%6%7%26%
2700
July1st to 15thDay
15%5%26%5%46%6%7%9%31%
2553
16th to endDay
15%6%36%5%36%5%6%9%29%
2654
August1st to 15thDay
17%5%25%6%46%6%6%9%29%
2448
16th to endDay
14%415%5%3446%9%39%
2417
September1st to 15thDay
19%6%25%423447%39%
2109
16th to endDay
18%5%23323246%45%
1980
October1st to 15thDay
23%6%25%6%2345%7%31%
1878
16th to endDay
26%10%46%4345%45%24%
1728
November1st to 15thDay
21%8%47%6%34445%29%
1716
16th to endDay
25%13%35%423345%26%
1517
December1st to 15thDay
24%18%45%5%3334422%
1365
16th to endDay
21%16%5%8%5%23345%22%
1485
January1st to 15thNight
19%16%5%8%7%3434422%
2716
16th to endNight
12%15%6%8%6%45%5%5%5%24%
2912
February1st to 15thNight
10%12%5%10%10%45%445%25%
2524
16th to endNight
16%15%5%10%5%25%34425%
1893
March1st to 15thNight
19%10%45%6%25%44431%
2144
16th to endNight
15%10%35%5%34445%36%
2025
April1st to 15thNight
23%10%46%5%23445%28%
1793
16th to endNight
23%6%34413345%37%
1620
May1st to 15thNight
24%7%35%5%35%435%32%
1539
16th to endNight
26%6%35%5%3345%5%32%
1465
June1st to 15thNight
23%8%25%5%45%45%5%28%
1260
16th to endNight
21%6%36%5%25%5%5%6%31%
1260
July1st to 15thNight
17%7%23425%5%6%8%36%
1404
16th to endNight
15%6%25%5%35%46%7%36%
1514
August1st to 15thNight
15%6%35%435%5%6%8%35%
1500
16th to endNight
15%425%436%5%5%7%39%
1785
September1st to 15thNight
20%5%345%23347%38%
1850
16th to endNight
20%423322445%45%
1980
October1st to 15thNight
19%7%35%434446%35%
2082
16th to endNight
27%9%26%422445%29%
2496
November1st to 15thNight
20%7%36%5%34345%33%
2472
16th to endNight
23%12%45%5%2443429%
2769
December1st to 15thNight
23%15%5%8%6%3433320%
2925
16th to endNight
21%15%5%9%7%2333422%
3087

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
62%6%10%12%7%
1553
16th to endDay
56%6%10%18%7%
1664
February1st to 15thDay
58%5%12%13%7%1
1603
16th to endDay
58%6%8%15%8%1
1580
March1st to 15thDay
54%5%11%14%12%1
1802
16th to endDay
49%6%10%18%12%2
2196
April1st to 15thDay
53%49%18%9%4
2155
16th to endDay
50%5%10%18%13%2
2340
May1st to 15thDay
52%7%11%16%11%
2421
16th to endDay
56%9%9%16%7%
2649
June1st to 15thDay
52%8%13%15%7%1
2700
16th to endDay
55%9%10%16%8%
2700
July1st to 15thDay
45%11%15%20%6%
2404
16th to endDay
50%11%15%17%5%
2487
August1st to 15thDay
48%12%18%15%3
2434
16th to endDay
40%9%16%25%7%
2417
September1st to 15thDay
44%7%16%22%9%
2109
16th to endDay
40%5%16%29%8%
1980
October1st to 15thDay
51%6%13%20%7%
1878
16th to endDay
61%6%11%16%3
1728
November1st to 15thDay
56%7%12%17%6%
1716
16th to endDay
61%5%10%15%5%
1517
December1st to 15thDay
65%5%10%13%5%
1365
16th to endDay
65%47%13%7%
1485
January1st to 15thNight
65%5%9%13%5%
2716
16th to endNight
60%5%9%15%8%
2912
February1st to 15thNight
60%6%11%13%6%
2525
16th to endNight
62%5%8%13%9%
1893
March1st to 15thNight
56%5%9%15%11%2
2157
16th to endNight
49%6%10%18%12%3
2025
April1st to 15thNight
56%47%16%12%2
1793
16th to endNight
49%5%9%16%15%3
1620
May1st to 15thNight
54%5%9%15%13%1
1539
16th to endNight
54%6%11%16%10%
1467
June1st to 15thNight
57%7%12%15%6%1
1260
16th to endNight
52%7%10%18%10%
1260
July1st to 15thNight
44%9%16%20%8%
1324
16th to endNight
46%8%17%19%8%
1418
August1st to 15thNight
44%11%17%22%4
1490
16th to endNight
43%8%15%27%6%
1785
September1st to 15thNight
47%5%12%23%9%
1850
16th to endNight
40%6%15%26%11%
1980
October1st to 15thNight
49%6%12%23%8%
2082
16th to endNight
57%6%13%16%5%
2496
November1st to 15thNight
52%7%14%16%9%
2472
16th to endNight
59%5%10%17%7%
2769
December1st to 15thNight
68%5%10%10%4
2925
16th to endNight
65%5%9%11%7%
3087

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
31%14%34%20%
90
16th to endDay
18%25%39%13%3
96
February1st to 15thDay
22%18%34%18%5%
154
16th to endDay
24%9%33%25%5%1
239
March1st to 15thDay
27%15%28%21%6%
270
16th to endDay
21%11%24%24%14%3
288
April1st to 15thDay
33%10%22%22%9%1
270
16th to endDay
27%10%28%22%8%3
270
May1st to 15thDay
32%9%27%20%7%2
288
16th to endDay
24%15%29%20%8%1
358
June1st to 15thDay
26%8%24%29%11%
495
16th to endDay
26%7%27%27%10%1
495
July1st to 15thDay
23%8%24%27%13%2
338
16th to endDay
16%6%29%27%16%3
326
August1st to 15thDay
18%425%27%16%6%
313
16th to endDay
19%9%23%22%16%8%
332
September1st to 15thDay
21%10%22%23%17%4
315
16th to endDay
16%12%25%22%17%6%
314
October1st to 15thDay
26%7%29%20%11%3
304
16th to endDay
36%14%22%17%9%
288
November1st to 15thDay
27%13%25%22%9%1
280
16th to endDay
39%11%21%21%6%
161
December1st to 15thDay
33%15%26%18%23
90
16th to endDay
33%20%28%12%5%
96
January1st to 15thNight
26%14%32%22%3
780
16th to endNight
20%14%32%25%6%
832
February1st to 15thNight
17%11%35%27%7%
753
16th to endNight
26%11%33%23%4
631
March1st to 15thNight
26%10%33%24%4
720
16th to endNight
20%9%30%28%8%1
768
April1st to 15thNight
30%10%26%25%7%
715
16th to endNight
27%8%31%24%8%
540
May1st to 15thNight
27%8%28%28%7%
459
16th to endNight
32%6%24%30%6%
375
June1st to 15thNight
28%5%23%34%8%
360
16th to endNight
22%326%35%11%
360
July1st to 15thNight
20%324%34%15%1
340
16th to endNight
17%322%44%11%
376
August1st to 15thNight
19%318%38%19%1
419
16th to endNight
17%426%33%15%2
639
September1st to 15thNight
24%423%32%13%
720
16th to endNight
23%6%23%28%17%
717
October1st to 15thNight
23%9%27%30%8%
720
16th to endNight
33%11%28%20%6%
768
November1st to 15thNight
25%13%25%24%9%
760
16th to endNight
31%12%24%21%8%
806
December1st to 15thNight
32%12%30%18%5%
825
16th to endNight
31%15%28%19%41
872
Page generated at 2018-02-13 20:46:08. Version ac04

Copyright 2018 A. Danko


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