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 2018-02-22.

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%
15241
13%
49043
8%
15209
38%
15209
17%
35183

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
21%
780
10%
2716
6%
776
28%
776
10%
2112
January16th to endNight
28%
832
11%
2912
7%
832
35%
832
12%
2194
February1st to 15thNight
24%
764
10%
2540
6%
761
31%
761
11%
1959
February16th to endNight
26%
659
13%
1976
8%
659
32%
659
14%
1508
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%
579
16%
1659
6%
579
38%
579
22%
1140
May1st to 15thNight
31%
420
15%
1500
12%
420
40%
420
16%
1031
May16th to endNight
30%
375
12%
1497
9%
374
42%
374
16%
1013
June1st to 15thNight
35%
360
7%
1440
6%
360
41%
360
14%
978
June16th to endNight
40%
360
8%
1440
10%
360
43%
360
17%
936
July1st to 15thNight
50%
340
10%
1360
15%
340
55%
340
22%
834
July16th to endNight
50%
376
11%
1418
14%
354
53%
354
20%
868
August1st to 15thNight
56%
384
12%
1455
13%
382
59%
382
20%
924
August16th to endNight
50%
699
18%
1845
10%
699
53%
699
31%
1199
September1st to 15thNight
47%
720
14%
1818
7%
720
48%
720
30%
1238
September16th to endNight
46%
717
21%
1980
14%
717
50%
717
31%
1277
October1st to 15thNight
34%
720
19%
2088
10%
720
44%
720
22%
1440
October16th to endNight
26%
768
11%
2496
8%
768
32%
768
15%
1838
November1st to 15thNight
29%
760
16%
2472
11%
760
36%
760
16%
1758
November16th to endNight
26%
780
13%
2694
9%
780
33%
780
12%
2025
December1st to 15thNight
21%
810
8%
2860
2%
810
27%
810
9%
2222
December16th to endNight
19%
832
11%
2912
5%
832
26%
832
9%
2286

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%
49205
Night
20%9%36%5%24445%31%
49213
TransparencyDay
52%412%20%9%1
48893
Night
54%310%19%9%1
49043
SeeingDay
24%5%24%26%14%4
6036
Night
25%6%26%30%10%
15241

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%6%6%3433423%
1552
16th to endDay
13%14%6%7%6%35%347%26%
1664
February1st to 15thDay
13%14%5%9%6%35%5%45%25%
1647
16th to endDay
18%12%48%6%36%35%426%
1644
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
22%7%25%423345%37%
2301
May1st to 15thDay
22%6%36%5%2445%6%33%
2462
16th to endDay
21%5%36%6%35%5%46%30%
2618
June1st to 15thDay
23%6%25%5%345%6%6%30%
2520
16th to endDay
18%7%36%5%46%5%5%7%30%
2520
July1st to 15thDay
14%5%25%5%36%6%7%8%34%
2520
16th to endDay
15%5%36%5%35%6%6%8%34%
2654
August1st to 15thDay
16%5%25%6%36%6%7%10%29%
2482
16th to endDay
11%4244345%6%8%43%
2356
September1st to 15thDay
18%5%345%24347%40%
2142
16th to endDay
17%5%23323346%47%
1980
October1st to 15thDay
24%6%36%424346%32%
1871
16th to endDay
25%9%37%6%24346%27%
1728
November1st to 15thDay
21%9%26%6%35%445%30%
1716
16th to endDay
24%11%45%5%2335%5%29%
1594
December1st to 15thDay
28%13%45%5%2343424%
1420
16th to endDay
26%12%5%8%5%2433424%
1661
January1st to 15thNight
21%15%5%8%6%2443422%
2716
16th to endNight
15%14%5%8%6%35%44426%
2912
February1st to 15thNight
12%13%6%11%9%35%44424%
2539
16th to endNight
18%13%5%8%6%35%34427%
1976
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%
1659
May1st to 15thNight
23%8%35%425%335%33%
1500
16th to endNight
23%7%25%424447%33%
1495
June1st to 15thNight
24%7%34425%447%30%
1440
16th to endNight
18%7%25%425%6%7%8%31%
1440
July1st to 15thNight
13%426%5%345%7%9%36%
1440
16th to endNight
14%5%26%435%46%7%39%
1514
August1st to 15thNight
14%425%5%346%7%8%36%
1465
16th to endNight
13%425%434448%43%
1845
September1st to 15thNight
20%5%24414446%41%
1818
16th to endNight
19%423422336%47%
1980
October1st to 15thNight
19%5%25%6%35%345%38%
2088
16th to endNight
29%7%25%43334431%
2496
November1st to 15thNight
22%8%36%5%34445%32%
2472
16th to endNight
25%12%47%42333428%
2694
December1st to 15thNight
24%12%48%6%2334424%
2860
16th to endNight
22%17%6%7%5%2433322%
2912

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%38%15%6%
1553
16th to endDay
59%310%19%6%
1664
February1st to 15thDay
60%311%16%6%
1650
16th to endDay
61%38%16%8%1
1644
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
2301
May1st to 15thDay
52%39%19%13%1
2462
16th to endDay
54%49%18%10%1
2622
June1st to 15thDay
52%412%19%9%1
2520
16th to endDay
53%5%10%20%9%
2520
July1st to 15thDay
42%7%15%25%9%
2371
16th to endDay
47%6%16%22%7%
2487
August1st to 15thDay
48%6%17%21%5%
2468
16th to endDay
36%5%17%29%10%
2356
September1st to 15thDay
43%315%25%11%
2142
16th to endDay
38%314%31%11%
1980
October1st to 15thDay
52%310%24%8%
1871
16th to endDay
57%412%20%4
1728
November1st to 15thDay
56%311%18%9%
1716
16th to endDay
57%311%19%7%
1594
December1st to 15thDay
64%311%15%4
1420
16th to endDay
65%38%13%8%
1661
January1st to 15thNight
65%38%15%5%
2716
16th to endNight
62%39%16%7%
2912
February1st to 15thNight
64%39%15%6%
2540
16th to endNight
61%28%14%11%
1976
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
47%39%18%16%4
1659
May1st to 15thNight
53%28%15%15%3
1500
16th to endNight
51%410%18%11%2
1497
June1st to 15thNight
53%311%18%10%1
1440
16th to endNight
47%5%11%20%13%1
1440
July1st to 15thNight
40%6%14%23%12%1
1360
16th to endNight
42%6%16%23%11%
1418
August1st to 15thNight
42%7%18%24%6%
1455
16th to endNight
39%415%29%10%
1845
September1st to 15thNight
43%313%26%11%
1818
16th to endNight
40%312%29%13%
1980
October1st to 15thNight
48%410%26%11%
2088
16th to endNight
57%311%19%6%
2496
November1st to 15thNight
55%312%18%8%1
2472
16th to endNight
61%39%18%7%
2694
December1st to 15thNight
65%311%14%4
2860
16th to endNight
67%28%12%7%
2912

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
32%8%18%32%7%
90
16th to endDay
23%5%35%26%6%3
96
February1st to 15thDay
26%435%26%42
142
16th to endDay
27%328%31%7%
265
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
24%8%29%24%11%2
270
May1st to 15thDay
30%7%25%20%12%4
288
16th to endDay
24%7%29%19%16%2
331
June1st to 15thDay
27%6%23%23%14%3
315
16th to endDay
21%226%30%15%4
315
July1st to 15thDay
17%224%31%18%5%
305
16th to endDay
18%315%34%22%5%
326
August1st to 15thDay
20%314%31%22%7%
313
16th to endDay
14%324%23%20%13%
332
September1st to 15thDay
21%218%27%20%10%
315
16th to endDay
15%424%23%21%10%
314
October1st to 15thDay
25%6%21%25%16%4
313
16th to endDay
32%6%22%24%13%
288
November1st to 15thDay
28%7%23%25%13%1
280
16th to endDay
34%9%23%19%10%2
124
December1st to 15thDay
37%5%24%25%24
90
16th to endDay
35%7%30%19%7%
96
January1st to 15thNight
30%6%29%26%6%
780
16th to endNight
23%6%28%32%9%
832
February1st to 15thNight
19%8%31%32%7%
764
16th to endNight
25%5%30%29%7%
659
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%28%27%8%
579
May1st to 15thNight
29%5%27%28%8%
420
16th to endNight
27%329%29%8%
375
June1st to 15thNight
28%322%33%11%
360
16th to endNight
20%126%39%11%
360
July1st to 15thNight
14%224%39%16%2
340
16th to endNight
14%220%45%15%1
376
August1st to 15thNight
16%314%43%20%1
384
16th to endNight
15%322%36%20%1
699
September1st to 15thNight
22%220%37%14%1
720
16th to endNight
21%423%29%19%1
717
October1st to 15thNight
22%5%30%29%11%
720
16th to endNight
31%8%26%25%8%
768
November1st to 15thNight
28%7%26%25%11%
760
16th to endNight
32%8%24%22%10%1
780
December1st to 15thNight
32%8%26%25%6%
810
16th to endNight
34%7%25%24%7%
832
Page generated at 2018-02-23 11:21:39. Version ac04

Copyright 2018 A. Danko


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