Trois-Rivières
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Trois-Rivières clear sky chart from 2005-11-05 to 2017-04-30.

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
32%
14253
13%
45772
8%
14221
38%
14221
16%
32945

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
20%
720
10%
2506
5%
716
27%
716
9%
1959
January16th to endNight
29%
768
11%
2688
8%
768
36%
768
12%
2037
February1st to 15thNight
24%
704
10%
2341
6%
701
31%
701
12%
1801
February16th to endNight
26%
631
12%
1893
8%
631
32%
631
13%
1447
March1st to 15thNight
26%
720
14%
2160
9%
720
33%
720
16%
1603
March16th to endNight
33%
768
20%
2009
9%
768
40%
768
24%
1426
April1st to 15thNight
29%
718
16%
1796
6%
718
34%
718
19%
1374
April16th to endNight
30%
577
16%
1652
6%
577
37%
577
22%
1138
May1st to 15thNight
32%
385
16%
1375
13%
385
42%
385
17%
930
May16th to endNight
30%
343
12%
1369
9%
342
41%
342
16%
931
June1st to 15thNight
34%
330
7%
1320
7%
330
40%
330
13%
911
June16th to endNight
42%
330
8%
1320
10%
330
44%
330
18%
843
July1st to 15thNight
50%
310
11%
1240
16%
310
56%
310
22%
755
July16th to endNight
48%
348
9%
1306
11%
326
52%
326
20%
809
August1st to 15thNight
56%
352
13%
1333
14%
350
59%
350
20%
846
August16th to endNight
50%
640
17%
1690
10%
640
52%
640
30%
1100
September1st to 15thNight
46%
660
14%
1666
7%
660
47%
660
30%
1147
September16th to endNight
42%
657
20%
1815
13%
657
47%
657
29%
1188
October1st to 15thNight
32%
660
20%
1913
10%
660
43%
660
22%
1338
October16th to endNight
26%
704
10%
2288
7%
704
32%
704
14%
1696
November1st to 15thNight
30%
700
17%
2277
12%
700
37%
700
16%
1619
November16th to endNight
26%
720
13%
2487
8%
720
33%
720
12%
1871
December1st to 15thNight
21%
740
7%
2640
2%
740
27%
740
9%
2052
December16th to endNight
18%
768
10%
2688
5%
768
25%
768
9%
2124

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%32%
45954
Night
20%9%36%5%24445%31%
45942
TransparencyDay
52%412%20%9%1
45642
Night
55%310%19%9%1
45772
SeeingDay
24%5%24%26%14%4
5054
Night
25%6%26%30%10%
14253

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%6%6%7%3333424%
1432
16th to endDay
13%14%6%7%6%36%347%25%
1536
February1st to 15thDay
12%14%5%9%6%35%5%45%26%
1517
16th to endDay
17%12%5%8%6%36%35%426%
1580
March1st to 15thDay
18%10%37%5%33446%31%
1790
16th to endDay
16%9%35%5%25%45%5%35%
2211
April1st to 15thDay
24%7%25%423445%34%
2152
16th to endDay
21%7%25%423345%37%
2288
May1st to 15thDay
21%6%25%5%2435%6%35%
2256
16th to endDay
21%5%36%6%35%446%31%
2394
June1st to 15thDay
24%6%244345%6%6%29%
2310
16th to endDay
18%7%35%5%46%5%5%7%30%
2310
July1st to 15thDay
13%5%35%5%36%6%7%9%35%
2310
16th to endDay
15%5%36%5%35%6%6%8%33%
2458
August1st to 15thDay
17%5%25%6%36%6%7%10%28%
2275
16th to endDay
11%4245%345%7%8%43%
2159
September1st to 15thDay
18%5%34423447%40%
1964
16th to endDay
18%5%23323345%46%
1815
October1st to 15thDay
24%6%36%424346%31%
1716
16th to endDay
25%9%37%6%23346%26%
1584
November1st to 15thDay
20%9%26%6%34345%31%
1581
16th to endDay
23%11%45%423345%30%
1472
December1st to 15thDay
29%13%45%5%2343324%
1311
16th to endDay
27%12%47%5%2432324%
1533
January1st to 15thNight
21%16%48%6%2443422%
2506
16th to endNight
15%14%5%8%6%35%44425%
2688
February1st to 15thNight
11%13%6%11%9%45%44424%
2340
16th to endNight
17%13%5%8%6%35%44427%
1893
March1st to 15thNight
21%11%37%5%25%345%29%
2147
16th to endNight
16%10%35%424336%38%
2009
April1st to 15thNight
25%9%45%423346%29%
1796
16th to endNight
23%7%24323447%36%
1652
May1st to 15thNight
21%8%35%425%435%35%
1375
16th to endNight
23%7%25%5%24347%33%
1367
June1st to 15thNight
25%6%34435%447%28%
1320
16th to endNight
18%6%24425%5%7%8%33%
1320
July1st to 15thNight
13%426%5%345%7%9%36%
1320
16th to endNight
14%5%26%5%35%46%7%38%
1402
August1st to 15thNight
15%5%25%5%345%6%9%36%
1343
16th to endNight
14%425%435%448%42%
1690
September1st to 15thNight
20%5%24414446%40%
1666
16th to endNight
21%423322335%45%
1815
October1st to 15thNight
20%6%25%6%35%346%37%
1913
16th to endNight
29%7%25%43334431%
2288
November1st to 15thNight
22%8%36%5%34445%32%
2277
16th to endNight
25%12%46%42333428%
2487
December1st to 15thNight
25%12%47%6%2334424%
2640
16th to endNight
24%17%6%7%5%2433322%
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
64%39%15%6%
1433
16th to endDay
59%39%19%6%
1536
February1st to 15thDay
60%311%16%6%
1520
16th to endDay
61%38%16%8%1
1580
March1st to 15thDay
55%312%15%11%1
1800
16th to endDay
49%39%20%13%3
2211
April1st to 15thDay
52%38%20%11%3
2152
16th to endDay
50%39%18%15%3
2288
May1st to 15thDay
49%310%20%14%1
2256
16th to endDay
53%49%19%11%1
2398
June1st to 15thDay
53%412%18%9%1
2310
16th to endDay
52%5%10%21%9%
2310
July1st to 15thDay
42%7%15%24%9%
2161
16th to endDay
48%6%16%21%6%
2291
August1st to 15thDay
49%6%17%21%5%
2261
16th to endDay
36%5%18%29%10%
2159
September1st to 15thDay
44%315%25%11%
1964
16th to endDay
40%314%31%10%
1815
October1st to 15thDay
53%310%22%9%
1716
16th to endDay
59%411%19%5%
1584
November1st to 15thDay
56%311%18%9%
1581
16th to endDay
56%311%20%7%
1472
December1st to 15thDay
65%311%15%3
1311
16th to endDay
66%39%12%7%
1533
January1st to 15thNight
66%38%15%5%
2506
16th to endNight
62%39%16%7%
2688
February1st to 15thNight
63%39%15%6%
2341
16th to endNight
62%28%14%11%
1893
March1st to 15thNight
58%310%16%10%1
2160
16th to endNight
49%38%18%16%3
2009
April1st to 15thNight
57%25%18%13%2
1796
16th to endNight
48%39%18%16%4
1652
May1st to 15thNight
51%38%16%16%3
1375
16th to endNight
52%49%18%11%2
1369
June1st to 15thNight
55%311%17%9%1
1320
16th to endNight
45%5%11%21%13%1
1320
July1st to 15thNight
40%6%14%25%11%1
1240
16th to endNight
43%5%16%22%10%
1306
August1st to 15thNight
43%7%18%24%6%
1333
16th to endNight
40%415%28%10%
1690
September1st to 15thNight
44%313%26%11%
1666
16th to endNight
41%311%30%12%
1815
October1st to 15thNight
49%49%24%11%
1913
16th to endNight
58%411%18%7%
2288
November1st to 15thNight
54%312%18%8%1
2277
16th to endNight
61%39%18%7%
2487
December1st to 15thNight
65%311%14%3
2640
16th to endNight
68%29%12%6%
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
28%11%15%36%8%
60
16th to endDay
28%431%23%7%4
64
February1st to 15thDay
25%430%29%6%2
102
16th to endDay
26%327%33%8%
239
March1st to 15thDay
27%9%25%27%10%
270
16th to endDay
22%5%28%23%15%4
288
April1st to 15thDay
30%8%22%27%8%2
270
16th to endDay
23%9%29%24%11%2
266
May1st to 15thDay
27%7%25%22%12%4
228
16th to endDay
24%7%27%20%17%2
267
June1st to 15thDay
30%6%23%20%14%4
255
16th to endDay
21%223%30%17%5%
255
July1st to 15thDay
15%226%30%18%6%
245
16th to endDay
19%415%34%20%5%
270
August1st to 15thDay
21%415%29%21%7%
253
16th to endDay
14%225%23%21%12%
268
September1st to 15thDay
22%216%28%19%10%
255
16th to endDay
19%427%22%15%9%
254
October1st to 15thDay
25%5%23%24%16%4
254
16th to endDay
32%6%20%26%14%
240
November1st to 15thDay
27%6%25%25%13%1
235
16th to endDay
34%7%25%15%14%3
92
December1st to 15thDay
38%126%26%15%
60
16th to endDay
42%7%35%12%1
64
January1st to 15thNight
29%7%29%25%6%
720
16th to endNight
22%6%27%33%9%
768
February1st to 15thNight
18%8%31%32%8%
704
16th to endNight
25%6%30%29%7%
631
March1st to 15thNight
27%6%30%30%4
720
16th to endNight
22%6%30%29%9%1
768
April1st to 15thNight
29%7%25%29%7%
718
16th to endNight
27%8%27%27%8%
577
May1st to 15thNight
27%5%28%29%8%1
385
16th to endNight
27%329%30%8%
343
June1st to 15thNight
29%322%32%10%
330
16th to endNight
19%125%40%12%
330
July1st to 15thNight
14%225%38%17%2
310
16th to endNight
14%321%45%14%1
348
August1st to 15thNight
17%315%41%20%1
352
16th to endNight
16%322%36%20%1
640
September1st to 15thNight
23%320%37%13%1
660
16th to endNight
22%5%24%29%16%1
657
October1st to 15thNight
23%5%30%28%11%
660
16th to endNight
31%7%26%25%7%
704
November1st to 15thNight
27%7%26%26%11%
700
16th to endNight
33%9%23%22%10%1
720
December1st to 15thNight
32%8%26%25%6%
740
16th to endNight
35%8%25%22%6%
768
Page generated at 2017-04-30 20:40:12. Version ac04

Copyright 2017 A. Danko


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