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 2017-12-20.

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
29%
15007
12%
48089
7%
14976
35%
14976
14%
35233

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%
401
11%
1472
11%
399
57%
399
17%
991
August16th to endNight
45%
654
15%
1800
9%
654
48%
654
24%
1234
September1st to 15thNight
43%
720
11%
1838
6%
720
45%
720
26%
1298
September16th to endNight
43%
717
17%
1980
10%
717
47%
717
27%
1325
October1st to 15thNight
32%
720
16%
2086
8%
720
40%
720
21%
1470
October16th to endNight
24%
768
10%
2496
5%
768
30%
768
13%
1895
November1st to 15thNight
29%
760
15%
2472
10%
760
36%
760
14%
1788
November16th to endNight
25%
800
13%
2764
7%
800
33%
800
12%
2056
December1st to 15thNight
16%
825
6%
2925
2%
825
20%
825
7%
2367
December16th to endNight
14%
815
10%
2897
4%
815
22%
815
8%
2289

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%
48748
Night
20%10%36%5%34445%30%
48259
TransparencyDay
55%7%11%16%7%
48436
Night
55%5%12%17%8%
48089
SeeingDay
27%13%26%20%9%2
6266
Night
25%11%25%26%9%
15008

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%
2465
16th to endDay
16%5%25%5%345%5%8%35%
2399
September1st to 15thDay
22%6%24433446%36%
2121
16th to endDay
22%42443335%6%39%
1980
October1st to 15thDay
26%7%34435%445%30%
1871
16th to endDay
28%9%37%6%34435%23%
1728
November1st to 15thDay
22%9%47%7%3434428%
1716
16th to endDay
24%14%46%423425%24%
1524
December1st to 15thDay
27%15%47%5%2322424%
1365
16th to endDay
23%17%5%8%5%2443321%
1423
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%
1482
16th to endNight
15%6%25%5%35%447%38%
1800
September1st to 15thNight
21%6%2441335%6%40%
1838
16th to endNight
22%5%14323336%44%
1980
October1st to 15thNight
21%7%34424445%36%
2086
16th to endNight
28%10%25%42334428%
2496
November1st to 15thNight
20%10%36%5%34346%32%
2472
16th to endNight
25%12%45%424335%29%
2764
December1st to 15thNight
24%16%48%6%3333420%
2925
16th to endNight
21%17%6%9%6%2333421%
2897

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
2451
16th to endDay
44%10%15%22%6%
2399
September1st to 15thDay
48%7%14%20%8%
2121
16th to endDay
44%7%14%24%8%
1980
October1st to 15thDay
55%6%11%18%6%
1871
16th to endDay
64%6%10%15%3
1728
November1st to 15thDay
59%7%9%16%6%
1716
16th to endDay
62%5%9%15%5%
1524
December1st to 15thDay
66%5%9%13%5%
1365
16th to endDay
67%5%7%11%7%
1423
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
45%9%20%20%3
1472
16th to endNight
42%8%16%26%5%
1800
September1st to 15thNight
44%6%15%23%9%
1838
16th to endNight
42%5%16%26%9%
1980
October1st to 15thNight
48%5%12%23%9%
2086
16th to endNight
58%6%12%16%6%
2496
November1st to 15thNight
53%6%12%16%9%
2472
16th to endNight
59%411%17%7%
2764
December1st to 15thNight
68%411%10%4
2925
16th to endNight
66%49%12%7%
2897

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%5%26%24%15%3
313
16th to endDay
22%12%21%20%15%7%
332
September1st to 15thDay
24%10%21%23%15%4
315
16th to endDay
19%14%22%21%17%6%
314
October1st to 15thDay
28%12%27%18%11%1
306
16th to endDay
36%13%25%17%8%
288
November1st to 15thDay
30%17%19%21%10%1
280
16th to endDay
36%15%21%19%42
142
December1st to 15thDay
34%14%38%8%21
90
16th to endDay
40%20%27%6%4
72
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%25%
401
16th to endNight
17%5%22%35%17%1
654
September1st to 15thNight
24%5%20%33%14%2
720
16th to endNight
24%7%21%26%18%1
717
October1st to 15thNight
24%10%26%25%12%
720
16th to endNight
35%11%24%22%7%
768
November1st to 15thNight
26%13%22%26%9%1
760
16th to endNight
31%14%21%21%9%1
800
December1st to 15thNight
32%15%23%22%5%
825
16th to endNight
31%14%27%21%41
815
Page generated at 2017-12-21 07:04:49. Version ac04

Copyright 2017 A. Danko


Lac St-Joseph Clear Sky Chart |Charts Home