Notre-Dame-de-la-Merci
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Notre-Dame-de-la-Merci 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
26%
14448
13%
46481
7%
14416
34%
14416
15%
33195

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
2%
716
23%
716
8%
1943
January16th to endNight
19%
768
12%
2688
5%
768
28%
768
10%
1986
February1st to 15thNight
16%
704
11%
2315
3%
701
25%
701
11%
1755
February16th to endNight
18%
631
14%
1908
5%
631
30%
631
13%
1402
March1st to 15thNight
17%
720
13%
2160
6%
720
25%
720
13%
1635
March16th to endNight
27%
768
20%
1994
7%
768
36%
768
21%
1382
April1st to 15thNight
21%
718
16%
1796
4%
718
28%
718
19%
1329
April16th to endNight
25%
623
16%
1703
5%
623
33%
623
19%
1178
May1st to 15thNight
26%
366
15%
1446
11%
366
37%
366
14%
987
May16th to endNight
26%
375
13%
1497
10%
374
39%
374
16%
993
June1st to 15thNight
29%
360
7%
1440
5%
360
37%
360
13%
1008
June16th to endNight
41%
360
7%
1440
9%
360
46%
360
16%
964
July1st to 15thNight
47%
340
10%
1360
15%
340
52%
340
24%
782
July16th to endNight
47%
376
12%
1418
13%
354
52%
354
21%
870
August1st to 15thNight
54%
351
14%
1400
14%
349
59%
349
20%
874
August16th to endNight
46%
679
18%
1729
9%
679
50%
679
33%
1117
September1st to 15thNight
40%
660
13%
1650
6%
660
43%
660
28%
1150
September16th to endNight
39%
657
20%
1798
11%
657
45%
657
29%
1161
October1st to 15thNight
28%
660
18%
1958
9%
660
39%
660
18%
1371
October16th to endNight
21%
704
11%
2255
5%
704
30%
704
13%
1703
November1st to 15thNight
24%
700
17%
2292
9%
700
35%
700
14%
1655
November16th to endNight
20%
720
14%
2520
7%
720
28%
720
10%
1866
December1st to 15thNight
16%
720
9%
2520
3%
720
23%
720
9%
1966
December16th to endNight
10%
768
11%
2688
2%
768
20%
768
7%
2118

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%10%46%6%3445%6%29%
47503
Night
16%10%46%5%3445%7%31%
46650
Cloud CoverDay
18%10%46%6%3445%6%29%
47512
Night
16%9%46%5%3445%6%32%
46656
TransparencyDay
54%6%10%17%9%1
47190
Night
51%6%11%19%9%1
46481
SeeingDay
24%15%30%19%7%2
5388
Night
22%14%30%22%8%
14448

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
18%15%6%8%6%4445%421%
1432
16th to endDay
9%16%7%9%7%245%46%26%
1536
February1st to 15thDay
9%16%6%10%6%5%6%445%24%
1545
16th to endDay
13%17%6%8%6%3444426%
1564
March1st to 15thDay
13%12%5%9%8%45%33427%
1790
16th to endDay
14%10%37%5%23447%36%
2229
April1st to 15thDay
21%12%35%5%24445%31%
2152
16th to endDay
20%9%35%5%23446%33%
2260
May1st to 15thDay
22%10%36%6%33445%28%
2511
16th to endDay
23%7%36%6%34446%29%
2618
June1st to 15thDay
24%7%25%6%35%5%6%7%25%
2520
16th to endDay
22%7%35%7%35%5%6%6%26%
2520
July1st to 15thDay
17%6%36%6%36%5%6%8%31%
2520
16th to endDay
14%6%37%7%36%5%7%8%30%
2654
August1st to 15thDay
16%7%26%6%36%7%6%7%26%
2464
16th to endDay
11%5%35%6%35%46%8%38%
2107
September1st to 15thDay
18%5%37%6%35%45%6%33%
1980
16th to endDay
18%6%34423346%43%
1832
October1st to 15thDay
23%10%35%5%24346%29%
1671
16th to endDay
25%12%47%6%34335%21%
1617
November1st to 15thDay
16%12%46%445%45%6%28%
1565
16th to endDay
21%13%47%424335%27%
1440
December1st to 15thDay
21%18%5%7%5%23345%21%
1440
16th to endDay
19%16%6%8%6%34245%21%
1536
January1st to 15thNight
14%14%6%9%6%35%45%6%21%
2506
16th to endNight
9%13%5%10%7%45%447%26%
2688
February1st to 15thNight
8%14%6%9%8%46%5%46%25%
2313
16th to endNight
12%13%5%8%6%245%5%7%27%
1908
March1st to 15thNight
15%12%5%7%5%35%46%6%26%
2147
16th to endNight
12%9%46%5%3445%6%39%
1994
April1st to 15thNight
22%9%34434346%33%
1796
16th to endNight
19%7%25%3335%5%6%36%
1703
May1st to 15thNight
20%8%35%5%34336%34%
1446
16th to endNight
22%6%24424447%35%
1495
June1st to 15thNight
21%7%36%5%3345%7%30%
1440
16th to endNight
18%6%245%35%5%6%8%33%
1440
July1st to 15thNight
12%4224345%5%9%44%
1440
16th to endNight
10%5%15%435%37%8%42%
1514
August1st to 15thNight
12%4346%245%7%9%40%
1410
16th to endNight
12%41433445%8%47%
1729
September1st to 15thNight
14%6%245%3345%8%40%
1650
16th to endNight
17%5%23324246%47%
1798
October1st to 15thNight
18%7%36%5%25%345%37%
1958
16th to endNight
23%10%36%5%24447%27%
2255
November1st to 15thNight
17%9%36%6%35%447%30%
2292
16th to endNight
18%13%5%7%6%2435%6%26%
2520
December1st to 15thNight
18%14%6%8%5%35%45%6%21%
2520
16th to endNight
19%16%5%8%6%3435%5%20%
2688

Percentage Cloud Cover SE (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
18%14%5%9%6%45%44321%
1432
16th to endDay
10%16%6%9%7%33445%27%
1536
February1st to 15thDay
9%16%7%8%8%45%5%4425%
1545
16th to endDay
14%16%7%7%7%3433426%
1564
March1st to 15thDay
15%12%5%8%8%45%34427%
1800
16th to endDay
15%9%47%5%24346%36%
2228
April1st to 15thDay
21%12%35%5%24445%31%
2152
16th to endDay
20%10%35%5%23436%34%
2260
May1st to 15thDay
22%10%36%6%3345%5%28%
2511
16th to endDay
22%7%36%5%44446%30%
2618
June1st to 15thDay
24%6%26%5%35%5%7%6%25%
2520
16th to endDay
21%8%36%6%35%5%6%6%25%
2520
July1st to 15thDay
16%5%36%6%36%5%6%7%32%
2520
16th to endDay
13%6%37%6%47%5%6%8%30%
2654
August1st to 15thDay
16%8%26%6%46%6%6%7%27%
2464
16th to endDay
11%5%35%6%445%6%8%39%
2107
September1st to 15thDay
18%6%36%6%24447%34%
1980
16th to endDay
19%5%24423346%43%
1832
October1st to 15thDay
24%8%35%5%23446%30%
1671
16th to endDay
25%11%47%6%34445%23%
1617
November1st to 15thDay
17%9%46%5%35%5%47%30%
1565
16th to endDay
22%13%46%424345%28%
1440
December1st to 15thDay
22%16%6%7%5%23345%21%
1440
16th to endDay
20%15%7%7%6%4334422%
1536
January1st to 15thNight
15%14%6%9%7%35%45%6%22%
2506
16th to endNight
9%13%5%9%7%45%447%27%
2688
February1st to 15thNight
9%13%5%9%9%45%5%45%26%
2306
16th to endNight
13%13%5%7%6%245%47%28%
1908
March1st to 15thNight
15%12%5%7%5%35%46%5%27%
2160
16th to endNight
12%10%45%5%2445%5%40%
1994
April1st to 15thNight
22%8%35%5%24345%33%
1796
16th to endNight
19%8%25%3345%5%6%36%
1703
May1st to 15thNight
20%8%35%5%34346%34%
1446
16th to endNight
23%5%24434447%35%
1495
June1st to 15thNight
21%7%35%6%2435%7%30%
1440
16th to endNight
18%6%23435%5%7%7%34%
1440
July1st to 15thNight
12%4243345%5%9%44%
1440
16th to endNight
10%425%5%35%46%8%42%
1514
August1st to 15thNight
11%5%246%245%7%8%40%
1410
16th to endNight
11%41442445%7%48%
1729
September1st to 15thNight
14%6%245%3445%8%40%
1650
16th to endNight
17%413313346%47%
1798
October1st to 15thNight
18%6%36%434346%37%
1958
16th to endNight
23%9%36%434447%28%
2255
November1st to 15thNight
17%9%25%6%445%47%31%
2292
16th to endNight
19%12%5%8%5%24346%27%
2520
December1st to 15thNight
19%14%5%8%43445%6%23%
2520
16th to endNight
19%15%5%9%5%34345%22%
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
65%5%6%14%6%
1433
16th to endDay
57%6%8%16%9%1
1536
February1st to 15thDay
60%5%8%17%6%
1547
16th to endDay
61%47%15%9%2
1564
March1st to 15thDay
61%48%13%10%1
1800
16th to endDay
48%48%18%15%4
2229
April1st to 15thDay
54%48%17%11%3
2152
16th to endDay
51%5%7%18%12%3
2260
May1st to 15thDay
55%5%6%17%11%2
2511
16th to endDay
54%7%9%16%9%1
2622
June1st to 15thDay
55%8%11%15%8%1
2520
16th to endDay
56%7%9%18%7%
2520
July1st to 15thDay
47%7%14%21%9%
2371
16th to endDay
49%9%14%17%8%
2487
August1st to 15thDay
52%10%14%18%4
2450
16th to endDay
40%7%18%22%9%
2107
September1st to 15thDay
47%7%12%20%10%
1980
16th to endDay
42%5%11%29%10%
1832
October1st to 15thDay
53%6%9%19%9%
1671
16th to endDay
63%6%9%14%6%
1617
November1st to 15thDay
53%7%13%14%9%
1565
16th to endDay
58%6%10%16%7%
1440
December1st to 15thDay
64%6%10%14%4
1440
16th to endDay
66%5%6%10%10%
1536
January1st to 15thNight
61%6%9%14%6%
2506
16th to endNight
57%6%9%15%9%2
2688
February1st to 15thNight
59%6%9%17%7%
2315
16th to endNight
54%5%10%17%11%1
1908
March1st to 15thNight
56%6%8%17%9%1
2160
16th to endNight
45%5%10%18%18%2
1994
April1st to 15thNight
52%47%20%13%1
1796
16th to endNight
45%6%12%18%14%2
1703
May1st to 15thNight
52%49%17%13%3
1446
16th to endNight
47%6%11%20%11%1
1497
June1st to 15thNight
51%7%12%18%8%
1440
16th to endNight
46%8%11%20%12%
1440
July1st to 15thNight
34%7%19%24%11%
1360
16th to endNight
38%9%17%23%10%
1418
August1st to 15thNight
38%10%18%24%7%
1400
16th to endNight
34%7%17%29%10%
1729
September1st to 15thNight
41%7%14%25%11%
1650
16th to endNight
37%5%13%32%10%
1798
October1st to 15thNight
47%6%10%22%12%
1958
16th to endNight
54%8%10%18%7%
2255
November1st to 15thNight
51%8%11%18%7%2
2292
16th to endNight
58%5%9%19%6%
2520
December1st to 15thNight
61%8%10%15%4
2520
16th to endNight
64%6%9%12%6%1
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
31%11%38%16%1
60
16th to endDay
23%18%37%14%33
64
February1st to 15thDay
28%25%36%5%3
85
16th to endDay
26%21%33%15%4
223
March1st to 15thDay
24%22%31%17%3
270
16th to endDay
23%19%29%17%7%2
288
April1st to 15thDay
30%20%27%14%6%1
270
16th to endDay
26%17%30%17%7%1
270
May1st to 15thDay
33%17%25%15%43
288
16th to endDay
26%17%33%14%6%
331
June1st to 15thDay
28%15%30%18%5%
315
16th to endDay
22%14%34%19%6%1
315
July1st to 15thDay
20%9%36%25%6%2
305
16th to endDay
14%7%30%34%10%1
326
August1st to 15thDay
17%7%32%27%10%4
297
16th to endDay
13%7%32%23%14%8%
268
September1st to 15thDay
19%10%25%23%11%8%
255
16th to endDay
20%12%25%18%13%7%
254
October1st to 15thDay
26%14%25%19%10%3
255
16th to endDay
32%15%27%15%8%
246
November1st to 15thDay
20%20%28%24%5%1
219
16th to endDay
30%28%23%13%5%
60
December1st to 15thDay
30%23%33%10%3
60
16th to endDay
37%26%32%3
64
January1st to 15thNight
23%20%33%17%4
720
16th to endNight
16%18%35%22%5%
768
February1st to 15thNight
16%19%38%19%5%
704
16th to endNight
22%16%35%21%3
631
March1st to 15thNight
24%18%35%18%3
720
16th to endNight
18%17%31%23%6%2
768
April1st to 15thNight
27%16%29%21%4
718
16th to endNight
25%17%29%20%7%
623
May1st to 15thNight
24%10%32%22%7%1
366
16th to endNight
24%9%34%21%8%
375
June1st to 15thNight
25%8%30%28%6%
360
16th to endNight
21%5%27%31%13%1
360
July1st to 15thNight
12%9%27%33%15%1
340
16th to endNight
11%429%40%13%1
376
August1st to 15thNight
13%420%40%20%
351
16th to endNight
14%7%26%29%19%1
679
September1st to 15thNight
18%6%29%31%12%1
660
16th to endNight
20%9%27%24%15%2
657
October1st to 15thNight
23%14%27%22%11%
660
16th to endNight
30%14%29%17%6%
704
November1st to 15thNight
23%17%28%21%8%1
700
16th to endNight
25%22%26%17%7%1
720
December1st to 15thNight
27%19%29%18%4
720
16th to endNight
30%18%30%14%4
768
Page generated at 2017-08-13 14:16:34. Version ac04

Copyright 2017 A. Danko


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