Lac Georges
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lac Georges clear sky chart from 2005-11-05 to 2017-10-06.

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%
14696
14%
47068
8%
14664
35%
14664
16%
33320

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
13%
720
7%
2506
2%
716
20%
716
6%
2046
January16th to endNight
19%
768
11%
2639
5%
768
27%
768
11%
1978
February1st to 15thNight
16%
704
11%
2287
3%
701
25%
701
11%
1737
February16th to endNight
18%
631
14%
1964
5%
631
30%
631
12%
1473
March1st to 15thNight
18%
720
14%
2087
6%
720
27%
720
14%
1567
March16th to endNight
26%
768
21%
2043
8%
768
36%
768
21%
1396
April1st to 15thNight
20%
718
16%
1796
5%
718
27%
718
20%
1322
April16th to endNight
25%
624
18%
1704
8%
624
32%
624
21%
1197
May1st to 15thNight
32%
360
18%
1440
17%
360
41%
360
16%
948
May16th to endNight
31%
375
14%
1497
8%
374
46%
374
18%
933
June1st to 15thNight
31%
360
9%
1440
7%
360
41%
360
15%
942
June16th to endNight
41%
360
9%
1440
13%
360
46%
360
19%
908
July1st to 15thNight
49%
340
13%
1360
17%
340
55%
340
26%
747
July16th to endNight
54%
376
14%
1418
17%
354
59%
354
29%
770
August1st to 15thNight
50%
446
15%
1517
12%
444
55%
444
25%
919
August16th to endNight
50%
693
21%
1839
11%
693
55%
693
37%
1127
September1st to 15thNight
41%
720
16%
1800
7%
720
45%
720
29%
1233
September16th to endNight
44%
717
22%
1963
14%
717
50%
717
33%
1241
October1st to 15thNight
29%
684
18%
2051
10%
684
39%
684
20%
1408
October16th to endNight
23%
704
11%
2194
6%
704
30%
704
14%
1649
November1st to 15thNight
25%
700
17%
2355
11%
700
35%
700
15%
1660
November16th to endNight
18%
720
10%
2520
6%
720
24%
720
9%
1947
December1st to 15thNight
16%
720
8%
2520
3%
720
22%
720
8%
2020
December16th to endNight
12%
768
10%
2688
3%
768
22%
768
8%
2152

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%9%37%6%34446%31%
48134
Night
17%10%47%5%34446%32%
47238
TransparencyDay
53%311%20%9%1
47821
Night
53%311%21%9%
47069
SeeingDay
23%12%29%21%9%3
5517
Night
23%12%29%23%9%
14696

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
22%15%5%9%7%3433320%
1432
16th to endDay
13%17%5%10%7%2444424%
1584
February1st to 15thDay
12%15%6%13%7%4445%422%
1575
16th to endDay
15%15%6%9%5%3434426%
1508
March1st to 15thDay
16%13%6%7%7%35%435%27%
1859
16th to endDay
14%8%47%5%24336%39%
2181
April1st to 15thDay
22%12%36%5%22235%32%
2152
16th to endDay
22%9%26%5%3343435%
2263
May1st to 15thDay
22%8%37%5%24336%32%
2511
16th to endDay
19%7%26%6%35%445%33%
2618
June1st to 15thDay
22%7%35%6%345%5%7%29%
2520
16th to endDay
18%6%25%5%46%5%5%7%32%
2520
July1st to 15thDay
15%5%26%5%35%5%6%8%35%
2520
16th to endDay
13%5%25%6%45%5%6%8%34%
2654
August1st to 15thDay
14%5%26%7%36%5%5%6%35%
2431
16th to endDay
13%6%25%5%35%45%9%39%
2351
September1st to 15thDay
17%6%26%5%23346%40%
2160
16th to endDay
17%6%2432335%6%43%
1993
October1st to 15thDay
22%9%245%245%45%33%
1707
16th to endDay
29%10%37%6%2333424%
1676
November1st to 15thDay
16%10%46%5%3445%6%32%
1503
16th to endDay
23%15%5%8%6%2333422%
1440
December1st to 15thDay
20%18%7%9%7%35%345%14%
1440
16th to endDay
20%19%7%9%5%2342419%
1536
January1st to 15thNight
17%16%7%11%7%4444416%
2506
16th to endNight
12%15%6%8%8%35%445%26%
2639
February1st to 15thNight
11%14%6%11%8%35%5%4422%
2285
16th to endNight
15%13%5%7%8%45%445%26%
1964
March1st to 15thNight
18%12%5%8%5%34435%28%
2075
16th to endNight
13%9%37%5%2324441%
2043
April1st to 15thNight
22%9%35%424446%32%
1796
16th to endNight
18%10%26%433335%37%
1704
May1st to 15thNight
22%7%36%5%13345%35%
1440
16th to endNight
16%7%25%6%25%35%8%36%
1495
June1st to 15thNight
19%5%26%6%25%45%7%33%
1440
16th to endNight
16%5%245%25%7%5%7%37%
1440
July1st to 15thNight
12%324425%5%5%8%45%
1440
16th to endNight
10%32433446%10%45%
1514
August1st to 15thNight
10%5%25%435%47%7%41%
1527
16th to endNight
9%425%433447%50%
1839
September1st to 15thNight
16%6%35%5%3345%5%40%
1800
16th to endNight
15%5%24423236%48%
1963
October1st to 15thNight
20%7%35%5%23346%36%
2051
16th to endNight
24%10%37%5%34435%26%
2194
November1st to 15thNight
18%9%47%5%34446%31%
2355
16th to endNight
22%13%5%9%6%34335%23%
2520
December1st to 15thNight
20%18%6%8%5%2434419%
2520
16th to endNight
22%17%6%8%6%34325%19%
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%28%13%5%
1433
16th to endDay
63%38%15%7%
1584
February1st to 15thDay
64%310%16%4
1577
16th to endDay
61%210%13%10%1
1508
March1st to 15thDay
60%210%16%8%
1869
16th to endDay
47%29%20%14%5%
2181
April1st to 15thDay
56%26%18%13%2
2152
16th to endDay
53%25%21%14%3
2263
May1st to 15thDay
54%26%19%14%1
2511
16th to endDay
51%410%19%12%1
2622
June1st to 15thDay
54%311%21%8%
2520
16th to endDay
49%5%13%21%10%1
2520
July1st to 15thDay
42%413%26%11%
2371
16th to endDay
46%416%23%8%
2487
August1st to 15thDay
46%5%17%22%8%
2417
16th to endDay
41%415%28%9%
2351
September1st to 15thDay
44%312%26%11%
2160
16th to endDay
40%413%31%9%
1993
October1st to 15thDay
52%312%21%9%
1707
16th to endDay
65%211%15%5%
1676
November1st to 15thDay
51%414%20%8%
1503
16th to endDay
66%311%12%6%1
1440
December1st to 15thDay
72%310%11%2
1440
16th to endDay
70%210%10%5%
1536
January1st to 15thNight
70%38%11%3
2506
16th to endNight
61%39%17%7%
2639
February1st to 15thNight
63%29%18%5%
2287
16th to endNight
60%29%18%8%
1964
March1st to 15thNight
59%29%20%7%1
2088
16th to endNight
47%28%21%16%3
2043
April1st to 15thNight
52%37%20%15%1
1796
16th to endNight
50%36%21%15%3
1704
May1st to 15thNight
50%25%20%16%3
1440
16th to endNight
46%311%23%12%2
1497
June1st to 15thNight
48%413%25%6%1
1440
16th to endNight
44%5%12%23%13%
1440
July1st to 15thNight
34%5%14%29%16%
1360
16th to endNight
33%418%30%13%
1418
August1st to 15thNight
38%5%18%25%10%
1517
16th to endNight
33%318%34%10%
1839
September1st to 15thNight
44%312%27%12%
1800
16th to endNight
38%212%36%8%
1963
October1st to 15thNight
49%310%25%11%
2051
16th to endNight
59%313%18%5%
2194
November1st to 15thNight
54%312%18%10%
2355
16th to endNight
65%310%16%3
2520
December1st to 15thNight
68%310%13%3
2520
16th to endNight
69%29%12%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
30%20%28%18%3
60
16th to endDay
36%11%34%12%5%
72
February1st to 15thDay
30%24%34%10%1
90
16th to endDay
30%21%26%16%21
167
March1st to 15thDay
26%18%34%14%5%
270
16th to endDay
22%19%30%16%9%2
288
April1st to 15thDay
32%21%22%16%6%
270
16th to endDay
27%18%25%16%9%1
270
May1st to 15thDay
33%11%27%17%5%3
288
16th to endDay
25%13%32%17%7%2
331
June1st to 15thDay
29%11%31%20%5%1
315
16th to endDay
15%11%34%26%9%2
315
July1st to 15thDay
14%6%36%29%8%4
305
16th to endDay
12%6%33%28%15%3
326
August1st to 15thDay
16%426%32%13%7%
313
16th to endDay
16%7%24%30%11%9%
332
September1st to 15thDay
19%7%28%21%13%9%
315
16th to endDay
20%8%25%19%18%8%
314
October1st to 15thDay
25%13%25%21%10%2
278
16th to endDay
34%16%27%15%6%
257
November1st to 15thDay
22%12%31%23%7%1
157
16th to endDay
36%15%26%16%5%
60
December1st to 15thDay
28%15%43%11%1
60
16th to endDay
35%29%31%3
64
January1st to 15thNight
28%14%33%18%5%
720
16th to endNight
22%13%34%22%6%
768
February1st to 15thNight
18%16%37%20%5%
704
16th to endNight
24%18%32%19%4
631
March1st to 15thNight
27%14%33%20%3
720
16th to endNight
20%16%31%20%9%
768
April1st to 15thNight
28%15%29%21%5%
718
16th to endNight
25%14%30%23%5%
624
May1st to 15thNight
26%9%25%27%10%
360
16th to endNight
20%9%34%25%10%
375
June1st to 15thNight
22%9%30%28%9%
360
16th to endNight
16%6%28%35%11%
360
July1st to 15thNight
10%428%37%18%
340
16th to endNight
10%325%43%14%1
376
August1st to 15thNight
13%323%36%21%2
446
16th to endNight
11%5%26%34%20%2
693
September1st to 15thNight
20%427%29%16%2
720
16th to endNight
17%7%25%27%19%2
717
October1st to 15thNight
25%11%28%21%11%1
684
16th to endNight
31%12%27%21%6%
704
November1st to 15thNight
25%14%30%19%10%1
700
16th to endNight
32%18%23%18%6%
720
December1st to 15thNight
30%18%28%18%3
720
16th to endNight
34%14%30%15%41
768
Page generated at 2017-10-07 14:07:56. Version ac04

Copyright 2017 A. Danko


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