Lac Georges
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lac Georges 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
27%
22536
14%
74789
8%
22493
35%
22493
16%
53142

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
11%
760
8%
2649
2%
757
20%
757
7%
2170
January11th to 20thNight
16%
744
9%
2602
4%
744
22%
744
8%
2048
January21st to endNight
20%
792
14%
2698
7%
792
29%
792
13%
1974
February1st to 10thNight
14%
720
10%
2340
3%
720
23%
720
10%
1801
February11th to 20thNight
14%
703
14%
2275
4%
700
28%
700
12%
1687
February21st to endNight
20%
592
15%
1794
6%
592
31%
592
13%
1323
March1st to 10thNight
18%
720
15%
2142
8%
720
27%
720
13%
1602
March11th to 20thNight
19%
720
17%
1979
6%
720
31%
720
17%
1441
March21st to endNight
22%
792
21%
2075
7%
792
32%
792
20%
1451
April1st to 10thNight
20%
720
16%
1800
5%
720
26%
720
18%
1352
April11th to 20thNight
24%
711
19%
1775
6%
711
31%
711
22%
1264
April21st to endNight
24%
582
16%
1662
7%
582
31%
582
17%
1214
May1st to 10thNight
31%
360
19%
1440
15%
360
42%
360
18%
918
May11th to 20thNight
31%
354
21%
1416
17%
354
47%
354
17%
889
May21st to endNight
32%
389
14%
1551
10%
388
48%
388
22%
909
June1st to 10thNight
34%
360
10%
1440
10%
360
44%
360
18%
908
June11th to 20thNight
40%
360
13%
1440
15%
360
48%
360
21%
852
June21st to endNight
41%
360
11%
1440
14%
360
47%
360
19%
924
July1st to 10thNight
49%
350
14%
1400
18%
350
57%
350
27%
769
July11th to 20thNight
49%
348
15%
1392
21%
348
54%
348
25%
793
July21st to endNight
52%
394
16%
1486
17%
372
57%
372
26%
818
August1st to 10thNight
51%
397
16%
1461
13%
395
57%
395
24%
866
August11th to 20thNight
53%
534
18%
1598
13%
534
58%
534
32%
987
August21st to endNight
44%
774
19%
1962
8%
774
49%
774
33%
1278
September1st to 10thNight
43%
720
19%
1800
7%
720
48%
720
33%
1188
September11th to 20thNight
46%
720
22%
1800
12%
720
51%
720
36%
1147
September21st to endNight
39%
720
20%
2043
14%
720
45%
720
26%
1343
October1st to 10thNight
32%
720
19%
2160
11%
720
41%
720
21%
1452
October11th to 20thNight
23%
720
14%
2160
8%
720
33%
720
16%
1584
October21st to endNight
22%
792
13%
2511
6%
792
31%
792
13%
1885
November1st to 10thNight
25%
740
16%
2435
10%
740
34%
740
16%
1682
November11th to 20thNight
21%
760
14%
2660
9%
760
30%
760
11%
1961
November21st to endNight
17%
760
9%
2660
4%
760
24%
760
8%
2075
December1st to 10thNight
15%
760
9%
2660
4%
760
21%
760
7%
2165
December11th to 20thNight
17%
760
12%
3241
5%
759
26%
759
8%
2467
December21st to endNight
12%
828
6%
4842
2%
817
20%
817
4%
3955

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%10%48%6%35%45%6%32%
74761
Night
17%11%48%6%35%446%31%
75050
TransparencyDay
54%311%21%10%1
74466
Night
55%310%21%10%1
74879
SeeingDay
24%16%31%19%8%2
13313
Night
23%13%30%24%9%1
22544

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
16%17%7%14%9%4434320%
1517
11th to 20thDay
17%17%6%9%7%45%44422%
1486
21st to endDay
12%16%6%10%8%36%46%5%24%
1656
February1st to 10thDay
13%16%6%13%8%45%5%5%5%21%
1620
11th to 20thDay
12%16%7%11%5%45%45%5%27%
1573
21st to endDay
17%14%6%10%7%45%445%25%
1461
March1st to 10thDay
14%13%7%9%7%45%446%28%
1811
11th to 20thDay
14%13%6%8%9%44446%29%
1980
21st to endDay
18%10%47%5%34445%37%
2281
April1st to 10thDay
21%13%47%6%33346%29%
2160
11th to 20thDay
22%9%36%6%2435%5%36%
2134
21st to endDay
22%11%47%5%34445%31%
2313
May1st to 10thDay
21%8%37%5%35%446%34%
2520
11th to 20thDay
17%8%47%6%34346%38%
2478
21st to endDay
17%6%27%6%35%5%5%6%37%
2725
June1st to 10thDay
21%8%36%7%346%5%7%29%
2520
11th to 20thDay
16%5%35%5%35%5%6%8%39%
2520
21st to endDay
18%7%36%6%46%5%5%7%32%
2520
July1st to 10thDay
13%5%26%6%36%6%6%8%38%
2520
11th to 20thDay
13%6%36%6%36%6%6%9%36%
2520
21st to endDay
12%6%36%6%45%6%6%9%38%
2744
August1st to 10thDay
13%6%37%6%36%6%6%8%37%
2465
11th to 20thDay
13%6%36%6%36%5%6%7%39%
2303
21st to endDay
15%7%25%5%35%46%10%38%
2376
September1st to 10thDay
15%6%25%5%245%5%7%43%
2160
11th to 20thDay
14%6%36%6%3445%7%42%
2160
21st to endDay
19%7%25%5%3446%8%37%
1914
October1st to 10thDay
20%10%35%5%346%46%34%
1800
11th to 20thDay
24%11%37%7%345%46%25%
1800
21st to endDay
28%10%36%7%34445%26%
1844
November1st to 10thDay
15%11%45%6%35%5%6%7%33%
1642
11th to 20thDay
19%13%6%9%7%3445%5%24%
1520
21st to endDay
20%17%6%10%7%35%445%19%
1520
December1st to 10thDay
21%19%7%10%7%35%345%15%
1520
11th to 20thDay
18%14%6%11%7%3445%5%23%
1906
21st to endDay
24%21%7%12%6%2332319%
2772
January1st to 10thNight
16%17%7%13%8%45%445%17%
2649
11th to 20thNight
16%16%7%10%8%45%5%45%21%
2602
21st to endNight
11%13%6%9%8%46%5%4429%
2698
February1st to 10thNight
12%14%6%12%9%46%6%46%21%
2340
11th to 20thNight
12%14%6%9%8%46%5%45%27%
2273
21st to endNight
13%14%5%9%7%45%45%6%28%
1794
March1st to 10thNight
16%14%5%9%7%45%435%28%
2132
11th to 20thNight
15%12%5%8%6%3445%6%32%
1979
21st to endNight
15%11%48%5%3434440%
2075
April1st to 10thNight
21%11%47%6%25%447%30%
1800
11th to 20thNight
18%10%35%5%3445%6%37%
1775
21st to endNight
20%11%48%5%33445%33%
1662
May1st to 10thNight
20%7%35%6%2445%6%37%
1440
11th to 20thNight
19%7%36%5%2445%6%39%
1415
21st to endNight
13%6%36%6%35%45%8%42%
1550
June1st to 10thNight
19%5%25%5%35%5%6%9%34%
1440
11th to 20thNight
14%6%36%5%35%5%6%6%43%
1440
21st to endNight
17%6%346%36%6%5%9%36%
1440
July1st to 10thNight
11%4345%35%6%5%9%46%
1440
11th to 20thNight
13%5%344345%7%8%43%
1440
21st to endNight
8%5%35%6%445%6%11%44%
1574
August1st to 10thNight
9%6%26%6%35%5%6%8%42%
1471
11th to 20thNight
10%5%36%5%3446%9%44%
1598
21st to endNight
12%6%26%5%4446%7%44%
1962
September1st to 10thNight
12%6%35%5%445%5%6%46%
1800
11th to 20thNight
15%5%2442435%8%47%
1800
21st to endNight
17%7%35%5%33346%43%
2043
October1st to 10thNight
20%8%35%5%3445%6%38%
2160
11th to 20thNight
21%9%48%6%4445%7%29%
2160
21st to endNight
23%11%38%6%45%445%27%
2511
November1st to 10thNight
17%11%47%5%45%5%5%6%32%
2435
11th to 20thNight
18%12%49%7%45%5%45%27%
2660
21st to endNight
20%14%5%11%7%35%446%21%
2660
December1st to 10thNight
19%18%7%10%7%35%445%17%
2660
11th to 20thNight
21%15%5%10%6%3433425%
3288
21st to endNight
26%20%6%10%7%2433417%
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
71%27%14%5%
1518
11th to 20thDay
66%39%11%11%1
1486
21st to endDay
62%37%16%10%1
1656
February1st to 10thDay
65%38%17%5%1
1620
11th to 20thDay
60%212%14%10%1
1582
21st to endDay
63%29%14%10%1
1461
March1st to 10thDay
60%28%18%11%1
1814
11th to 20thDay
59%210%15%11%3
1980
21st to endDay
52%27%20%13%5%
2281
April1st to 10thDay
59%26%18%12%3
2160
11th to 20thDay
53%26%22%15%2
2134
21st to endDay
58%27%16%13%4
2313
May1st to 10thDay
53%36%21%14%3
2520
11th to 20thDay
50%27%22%17%2
2482
21st to endDay
48%5%11%20%14%2
2725
June1st to 10thDay
55%310%20%11%1
2520
11th to 20thDay
44%411%26%12%3
2520
21st to endDay
51%413%21%10%1
2520
July1st to 10thDay
42%412%28%13%1
2450
11th to 20thDay
43%414%27%11%
2445
21st to endDay
43%416%27%9%
2591
August1st to 10thDay
44%5%17%25%9%
2451
11th to 20thDay
44%416%27%8%1
2303
21st to endDay
43%414%27%11%1
2376
September1st to 10thDay
41%413%30%12%
2160
11th to 20thDay
43%312%31%11%1
2160
21st to endDay
46%415%27%8%
1914
October1st to 10thDay
50%411%24%10%1
1800
11th to 20thDay
61%313%17%5%1
1800
21st to endDay
62%312%16%7%1
1844
November1st to 10thDay
50%314%24%7%1
1642
11th to 20thDay
62%313%14%8%1
1520
21st to endDay
69%411%10%6%1
1520
December1st to 10thDay
72%410%11%4
1520
11th to 20thDay
65%311%14%7%
1906
21st to endDay
75%16%14%4
2772
January1st to 10thNight
72%39%12%4
2649
11th to 20thNight
67%310%12%7%1
2602
21st to endNight
58%47%18%12%1
2698
February1st to 10thNight
65%38%17%7%1
2340
11th to 20thNight
60%39%20%7%1
2275
21st to endNight
58%39%20%10%1
1794
March1st to 10thNight
60%28%19%9%2
2142
11th to 20thNight
55%310%18%12%2
1980
21st to endNight
50%27%21%15%5%
2075
April1st to 10thNight
55%37%19%14%2
1800
11th to 20thNight
49%37%24%16%2
1775
21st to endNight
56%36%17%15%3
1662
May1st to 10thNight
48%36%22%18%4
1440
11th to 20thNight
47%36%23%17%4
1416
21st to endNight
41%313%23%17%3
1551
June1st to 10thNight
46%414%27%8%1
1440
11th to 20thNight
42%410%28%14%2
1440
21st to endNight
45%6%13%23%12%1
1440
July1st to 10thNight
36%414%28%17%1
1400
11th to 20thNight
38%413%31%14%
1392
21st to endNight
35%5%18%30%12%
1486
August1st to 10thNight
39%5%18%25%12%
1461
11th to 20thNight
38%418%28%11%
1598
21st to endNight
39%316%31%10%
1962
September1st to 10thNight
39%412%31%14%1
1800
11th to 20thNight
37%314%35%10%1
1800
21st to endNight
44%312%32%9%
2043
October1st to 10thNight
47%311%25%14%
2160
11th to 20thNight
56%312%21%7%1
2160
21st to endNight
60%312%17%7%
2511
November1st to 10thNight
53%314%21%9%
2435
11th to 20thNight
60%311%17%8%1
2660
21st to endNight
66%311%16%4
2660
December1st to 10thNight
70%48%14%4
2660
11th to 20thNight
65%28%17%8%1
3288
21st to endNight
75%26%13%4
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
23%24%32%18%31
180
11th to 20thDay
25%16%37%17%5%1
172
21st to endDay
23%21%33%18%6%
208
February1st to 10thDay
33%25%30%12%
240
11th to 20thDay
28%29%35%8%
240
21st to endDay
31%24%29%14%11
327
March1st to 10thDay
25%20%37%13%5%
420
11th to 20thDay
28%21%31%16%41
420
21st to endDay
31%20%28%15%5%1
462
April1st to 10thDay
33%19%26%16%5%1
420
11th to 20thDay
34%20%21%15%9%2
412
21st to endDay
31%19%31%14%5%
420
May1st to 10thDay
30%15%32%15%6%3
423
11th to 20thDay
23%17%32%21%5%3
447
21st to endDay
22%17%33%19%8%1
485
June1st to 10thDay
27%12%35%19%6%2
450
11th to 20thDay
20%13%31%24%10%3
450
21st to endDay
19%12%34%24%10%2
450
July1st to 10thDay
12%7%34%34%11%2
445
11th to 20thDay
14%9%37%25%12%3
444
21st to endDay
13%9%35%30%11%3
488
August1st to 10thDay
16%7%31%27%14%4
446
11th to 20thDay
15%6%25%33%12%8%
439
21st to endDay
18%12%29%23%12%6%
495
September1st to 10thDay
16%11%31%21%14%6%
450
11th to 20thDay
16%12%25%23%17%7%
450
21st to endDay
22%13%29%18%12%6%
450
October1st to 10thDay
25%17%22%22%10%3
450
11th to 20thDay
29%22%29%14%6%1
450
21st to endDay
32%16%30%16%5%
426
November1st to 10thDay
28%17%30%20%41
336
11th to 20thDay
30%22%30%11%6%1
180
21st to endDay
29%24%29%12%41
180
December1st to 10thDay
32%12%41%12%3
180
11th to 20thDay
29%29%31%9%11
180
21st to endDay
31%20%36%10%31
198
January1st to 10thNight
28%14%37%17%4
760
11th to 20thNight
30%16%29%20%5%
744
21st to endNight
18%13%38%23%6%1
792
February1st to 10thNight
20%19%38%19%4
720
11th to 20thNight
23%18%39%16%3
703
21st to endNight
23%21%29%23%4
592
March1st to 10thNight
25%17%34%21%4
720
11th to 20thNight
24%17%35%18%6%1
720
21st to endNight
23%16%33%20%8%
792
April1st to 10thNight
27%16%29%23%5%
720
11th to 20thNight
26%15%30%20%8%1
711
21st to endNight
27%14%30%23%6%1
582
May1st to 10thNight
25%11%28%26%10%1
360
11th to 20thNight
24%10%28%30%8%
354
21st to endNight
16%9%37%28%11%
389
June1st to 10thNight
21%8%32%31%8%
360
11th to 20thNight
17%9%28%31%14%1
360
21st to endNight
17%6%30%34%13%1
360
July1st to 10thNight
11%5%30%39%16%1
350
11th to 20thNight
14%5%27%37%17%1
348
21st to endNight
10%5%27%43%13%2
394
August1st to 10thNight
12%5%22%38%22%1
397
11th to 20thNight
11%322%39%22%3
534
21st to endNight
15%7%27%32%17%2
774
September1st to 10thNight
16%6%29%32%17%1
720
11th to 20thNight
17%7%25%32%17%3
720
21st to endNight
21%10%26%25%17%2
720
October1st to 10thNight
25%13%26%23%13%1
720
11th to 20thNight
26%12%33%21%7%1
720
21st to endNight
29%14%29%22%5%
792
November1st to 10thNight
25%16%29%22%7%1
740
11th to 20thNight
27%18%30%16%9%
760
21st to endNight
31%18%26%20%5%1
760
December1st to 10thNight
31%18%30%18%3
760
11th to 20thNight
27%19%28%20%5%1
760
21st to endNight
35%16%29%16%3
836
Page generated at 2024-01-13 19:28:29. Version ac07

Copyright 2024 Attilla Danko


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