Lac St-Joseph
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lac St-Joseph clear sky chart from 2005-11-05 to 2017-08-12.

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%
14471
12%
46501
7%
14440
35%
14440
14%
34098

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
14%
720
10%
2506
3%
716
22%
716
9%
1962
January16th to endNight
22%
768
11%
2688
5%
768
30%
768
10%
2026
February1st to 15thNight
20%
703
10%
2360
3%
701
30%
701
11%
1776
February16th to endNight
20%
631
11%
1893
5%
631
28%
631
11%
1484
March1st to 15thNight
22%
720
14%
2160
7%
720
30%
720
14%
1602
March16th to endNight
29%
768
19%
2019
7%
768
37%
768
19%
1447
April1st to 15thNight
25%
718
15%
1796
5%
718
31%
718
17%
1380
April16th to endNight
25%
549
15%
1629
6%
549
32%
549
18%
1132
May1st to 15thNight
26%
439
13%
1519
10%
439
34%
439
15%
1052
May16th to endNight
29%
375
10%
1497
8%
374
38%
374
14%
1052
June1st to 15thNight
34%
360
6%
1260
5%
360
38%
360
14%
907
June16th to endNight
42%
360
7%
1260
8%
360
44%
360
16%
885
July1st to 15thNight
50%
340
6%
1354
9%
340
52%
340
18%
885
July16th to endNight
50%
376
9%
1418
12%
354
52%
354
17%
930
August1st to 15thNight
54%
390
11%
1439
12%
388
57%
388
17%
963
August16th to endNight
45%
599
13%
1649
8%
599
48%
599
23%
1134
September1st to 15thNight
43%
660
10%
1685
6%
660
44%
660
26%
1199
September16th to endNight
40%
657
18%
1815
11%
657
45%
657
26%
1220
October1st to 15thNight
30%
660
17%
1912
9%
660
39%
660
19%
1369
October16th to endNight
23%
704
9%
2288
5%
704
29%
704
13%
1739
November1st to 15thNight
29%
700
15%
2277
10%
700
37%
700
14%
1647
November16th to endNight
26%
733
12%
2551
7%
733
34%
733
12%
1899
December1st to 15thNight
16%
750
6%
2700
2%
750
21%
750
7%
2169
December16th to endNight
14%
791
10%
2826
4%
791
22%
791
7%
2239

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
21%9%36%5%34446%28%
47468
Night
20%10%36%5%34445%30%
46671
TransparencyDay
56%7%11%16%7%
47156
Night
55%5%12%17%8%
46501
SeeingDay
27%13%26%20%9%2
5844
Night
25%11%26%26%9%
14472

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%16%5%7%7%35%34421%
1432
16th to endDay
12%13%8%9%6%26%5%45%24%
1536
February1st to 15thDay
10%15%7%11%7%45%43425%
1497
16th to endDay
14%14%5%10%7%445%46%22%
1580
March1st to 15thDay
18%11%5%7%6%2434430%
1790
16th to endDay
14%10%36%6%36%445%33%
2204
April1st to 15thDay
25%9%36%5%2333431%
2152
16th to endDay
24%8%35%423335%34%
2331
May1st to 15thDay
26%6%45%424445%30%
2442
16th to endDay
24%6%37%6%44445%26%
2618
June1st to 15thDay
22%6%36%5%35%45%7%26%
2697
16th to endDay
24%8%36%6%35%5%5%6%24%
2700
July1st to 15thDay
17%6%26%5%46%6%6%7%29%
2523
16th to endDay
20%5%25%6%46%5%6%8%26%
2654
August1st to 15thDay
21%6%36%6%36%6%6%7%24%
2413
16th to endDay
16%6%25%6%345%5%8%35%
2198
September1st to 15thDay
23%6%24434346%36%
1944
16th to endDay
24%42432335%6%39%
1815
October1st to 15thDay
26%7%35%5%35%445%29%
1715
16th to endDay
28%9%37%6%3443422%
1584
November1st to 15thDay
22%9%47%7%3434428%
1581
16th to endDay
24%14%46%423425%25%
1407
December1st to 15thDay
28%15%36%5%1332324%
1260
16th to endDay
23%17%5%8%5%2443321%
1395
January1st to 15thNight
20%16%5%7%7%34225%22%
2506
16th to endNight
12%15%5%8%7%45%46%5%23%
2688
February1st to 15thNight
10%12%5%10%10%44445%26%
2359
16th to endNight
16%13%6%10%6%34435%25%
1893
March1st to 15thNight
19%10%36%6%45%446%30%
2147
16th to endNight
14%9%36%6%2435%6%36%
2019
April1st to 15thNight
25%10%45%42435%5%29%
1796
16th to endNight
21%8%34323437%36%
1629
May1st to 15thNight
25%6%35%43444433%
1519
16th to endNight
26%5%35%424446%31%
1495
June1st to 15thNight
23%7%27%435%5%46%28%
1260
16th to endNight
22%5%35%5%245%5%6%31%
1260
July1st to 15thNight
19%5%24425%45%9%34%
1434
16th to endNight
16%6%25%5%25%47%6%36%
1514
August1st to 15thNight
17%6%26%435%6%6%8%33%
1449
16th to endNight
16%6%245%35%448%38%
1649
September1st to 15thNight
21%6%2441335%6%39%
1685
16th to endNight
24%5%13323335%43%
1815
October1st to 15thNight
22%7%34424445%35%
1912
16th to endNight
28%10%25%42334428%
2288
November1st to 15thNight
20%10%35%5%34346%31%
2277
16th to endNight
25%12%45%424335%28%
2551
December1st to 15thNight
24%16%47%6%3333421%
2700
16th to endNight
21%17%6%9%6%2333421%
2826

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
65%5%9%12%7%
1433
16th to endDay
59%5%9%16%8%
1536
February1st to 15thDay
61%5%11%13%6%1
1500
16th to endDay
61%6%7%13%8%2
1580
March1st to 15thDay
57%6%9%13%11%1
1800
16th to endDay
51%6%8%17%12%3
2204
April1st to 15thDay
56%5%8%14%9%5%
2152
16th to endDay
52%49%17%13%2
2331
May1st to 15thDay
54%5%10%16%11%1
2442
16th to endDay
57%8%9%15%8%
2622
June1st to 15thDay
54%7%12%14%8%1
2697
16th to endDay
58%7%11%14%7%
2700
July1st to 15thDay
50%11%15%16%5%
2374
16th to endDay
54%11%12%16%4
2487
August1st to 15thDay
53%12%16%13%3
2399
16th to endDay
44%11%16%22%5%
2198
September1st to 15thDay
48%7%15%20%9%
1944
16th to endDay
45%7%14%24%8%
1815
October1st to 15thDay
56%6%11%17%7%
1715
16th to endDay
65%6%9%15%3
1584
November1st to 15thDay
59%6%9%16%7%
1581
16th to endDay
62%5%10%16%5%
1407
December1st to 15thDay
66%5%9%13%4
1260
16th to endDay
67%6%7%11%7%
1395
January1st to 15thNight
66%310%14%4
2506
16th to endNight
60%5%9%16%8%
2688
February1st to 15thNight
59%410%16%7%1
2360
16th to endNight
62%5%8%13%9%1
1893
March1st to 15thNight
55%5%10%14%11%2
2160
16th to endNight
48%5%9%19%13%3
2019
April1st to 15thNight
56%47%17%11%2
1796
16th to endNight
48%5%10%17%14%2
1629
May1st to 15thNight
53%411%17%11%2
1519
16th to endNight
53%6%11%17%10%
1497
June1st to 15thNight
54%6%14%16%6%1
1260
16th to endNight
50%7%12%18%10%
1260
July1st to 15thNight
44%8%20%18%7%
1354
16th to endNight
45%8%17%20%8%
1418
August1st to 15thNight
44%9%19%21%3
1439
16th to endNight
43%8%17%24%6%
1649
September1st to 15thNight
45%6%15%22%9%
1685
16th to endNight
43%414%27%9%
1815
October1st to 15thNight
50%5%12%21%9%
1912
16th to endNight
58%6%12%16%6%
2288
November1st to 15thNight
52%7%13%16%9%
2277
16th to endNight
59%411%17%7%
2551
December1st to 15thNight
68%411%10%5%
2700
16th to endNight
66%49%11%7%
2826

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%16%35%18%
60
16th to endDay
26%21%34%10%6%
64
February1st to 15thDay
20%20%38%15%4
113
16th to endDay
24%15%30%23%41
239
March1st to 15thDay
24%20%28%19%6%
270
16th to endDay
21%17%22%25%11%2
288
April1st to 15thDay
34%16%21%20%6%1
270
16th to endDay
31%14%27%16%6%3
270
May1st to 15thDay
36%11%27%14%7%1
288
16th to endDay
27%17%28%19%6%
331
June1st to 15thDay
26%9%27%25%10%
492
16th to endDay
27%10%27%23%10%1
495
July1st to 15thDay
23%10%31%21%12%1
308
16th to endDay
23%11%23%28%10%2
326
August1st to 15thDay
24%6%26%23%15%3
297
16th to endDay
23%10%21%22%15%7%
268
September1st to 15thDay
24%8%22%23%16%5%
255
16th to endDay
22%14%21%18%15%6%
254
October1st to 15thDay
28%12%27%16%12%2
249
16th to endDay
37%10%25%17%8%
240
November1st to 15thDay
28%17%19%20%11%1
235
16th to endDay
34%13%21%21%6%2
108
December1st to 15thDay
40%8%38%11%1
60
16th to endDay
42%21%29%41
64
January1st to 15thNight
26%13%31%22%5%
720
16th to endNight
19%15%29%27%7%
768
February1st to 15thNight
16%14%35%26%7%
704
16th to endNight
24%15%29%24%5%
631
March1st to 15thNight
25%14%33%22%4
720
16th to endNight
19%14%29%25%8%2
768
April1st to 15thNight
30%12%26%25%5%
718
16th to endNight
26%15%28%21%8%
549
May1st to 15thNight
25%10%31%22%8%
439
16th to endNight
31%6%26%26%8%
375
June1st to 15thNight
28%422%35%8%
360
16th to endNight
23%5%20%37%13%
360
July1st to 15thNight
20%5%15%40%16%1
340
16th to endNight
19%318%40%17%
376
August1st to 15thNight
21%215%33%26%
390
16th to endNight
18%5%22%36%17%
599
September1st to 15thNight
24%5%21%32%13%2
660
16th to endNight
26%7%22%26%15%1
657
October1st to 15thNight
25%11%27%23%11%
660
16th to endNight
34%11%25%21%6%
704
November1st to 15thNight
26%13%23%26%9%1
700
16th to endNight
31%14%20%22%9%1
733
December1st to 15thNight
33%14%23%23%5%
750
16th to endNight
31%15%27%20%41
791
Page generated at 2017-08-13 14:16:40. Version ac04

Copyright 2017 A. Danko


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