St-Pierre de la rivière du sud, portail étoilé de la côte du sud
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the St-Pierre de la rivière du sud, portail étoilé de la côte du sud 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
24%
15042
11%
48063
6%
15011
31%
15011
14%
35758

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
12%
721
9%
2512
3%
717
18%
717
6%
2030
January16th to endNight
16%
768
12%
2688
3%
768
27%
768
9%
2022
February1st to 15thNight
16%
703
9%
2359
3%
701
24%
701
10%
1812
February16th to endNight
15%
631
12%
1893
4%
631
25%
631
10%
1495
March1st to 15thNight
18%
720
14%
2143
8%
720
26%
720
13%
1615
March16th to endNight
28%
768
16%
2046
7%
768
34%
768
20%
1495
April1st to 15thNight
24%
699
15%
1777
6%
699
30%
699
18%
1375
April16th to endNight
24%
540
15%
1620
7%
540
31%
540
17%
1152
May1st to 15thNight
30%
481
12%
1561
9%
481
36%
481
15%
1130
May16th to endNight
29%
375
9%
1428
8%
374
37%
374
13%
1030
June1st to 15thNight
31%
360
6%
1260
5%
360
35%
360
12%
954
June16th to endNight
35%
360
7%
1260
6%
360
37%
360
15%
889
July1st to 15thNight
36%
340
7%
1281
8%
340
40%
340
19%
863
July16th to endNight
39%
376
8%
1418
11%
354
41%
354
16%
936
August1st to 15thNight
43%
436
11%
1507
10%
434
46%
434
19%
1031
August16th to endNight
39%
615
15%
1761
8%
615
45%
615
24%
1187
September1st to 15thNight
33%
720
11%
1863
5%
720
36%
720
24%
1327
September16th to endNight
36%
717
18%
1980
10%
717
42%
717
26%
1315
October1st to 15thNight
26%
720
15%
2076
6%
720
36%
720
21%
1480
October16th to endNight
20%
768
9%
2496
5%
768
26%
768
11%
1915
November1st to 15thNight
23%
760
14%
2472
9%
760
31%
760
12%
1826
November16th to endNight
19%
815
12%
2786
5%
815
27%
815
11%
2122
December1st to 15thNight
11%
825
5%
2925
1%
825
15%
825
6%
2406
December16th to endNight
12%
824
10%
2951
3%
824
21%
824
7%
2351

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
20%10%46%5%34446%29%
48778
Night
20%11%47%5%34445%28%
48231
TransparencyDay
56%5%13%17%7%
48464
Night
57%5%11%17%7%
48063
SeeingDay
27%11%27%21%8%1
6474
Night
26%13%29%22%7%
15043

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%5%9%7%34335%21%
1424
16th to endDay
10%14%7%10%7%4445%6%25%
1536
February1st to 15thDay
11%16%7%9%8%35%345%24%
1500
16th to endDay
15%16%6%9%6%35%34424%
1580
March1st to 15thDay
18%13%5%7%6%33335%29%
1806
16th to endDay
16%10%5%7%5%35%445%31%
2175
April1st to 15thDay
24%10%345%23336%30%
2170
16th to endDay
23%10%35%42233435%
2340
May1st to 15thDay
24%8%35%5%34337%31%
2400
16th to endDay
23%9%37%6%3435%7%26%
2686
June1st to 15thDay
23%7%35%5%35%5%6%7%26%
2700
16th to endDay
23%7%46%6%35%5%5%6%24%
2700
July1st to 15thDay
17%6%26%5%35%6%6%8%30%
2598
16th to endDay
20%8%25%5%45%5%6%7%28%
2654
August1st to 15thDay
19%6%36%6%45%5%6%9%26%
2430
16th to endDay
15%6%25%5%3445%8%38%
2440
September1st to 15thDay
24%6%25%422336%39%
2096
16th to endDay
20%5%24322345%43%
1980
October1st to 15thDay
23%10%35%423345%32%
1881
16th to endDay
29%13%25%5%33335%22%
1728
November1st to 15thDay
21%11%48%6%3434427%
1716
16th to endDay
23%16%5%8%42233425%
1501
December1st to 15thDay
24%18%48%5%2433419%
1365
16th to endDay
24%16%6%8%5%3323321%
1372
January1st to 15thNight
18%16%7%8%9%35%33320%
2512
16th to endNight
11%14%6%9%6%46%5%5%423%
2688
February1st to 15thNight
10%13%6%11%10%45%445%23%
2358
16th to endNight
16%17%6%9%6%3433423%
1893
March1st to 15thNight
18%13%46%5%25%345%29%
2130
16th to endNight
15%11%48%5%34346%33%
2046
April1st to 15thNight
24%13%46%42344428%
1777
16th to endNight
24%9%25%41344434%
1620
May1st to 15thNight
25%8%35%5%3335%430%
1561
16th to endNight
24%5%45%6%245%4431%
1426
June1st to 15thNight
25%8%35%7%35%5%5%427%
1260
16th to endNight
18%9%25%5%45%45%7%31%
1260
July1st to 15thNight
18%6%46%42445%8%33%
1359
16th to endNight
17%7%25%5%35%46%8%34%
1514
August1st to 15thNight
16%7%25%5%345%6%8%33%
1517
16th to endNight
16%5%25%435%5%6%8%36%
1761
September1st to 15thNight
21%7%25%5%23445%36%
1863
16th to endNight
22%5%24323345%44%
1980
October1st to 15thNight
21%9%35%42335%5%35%
2076
16th to endNight
28%13%35%433335%25%
2496
November1st to 15thNight
20%11%37%5%34446%28%
2472
16th to endNight
22%14%5%8%42343427%
2786
December1st to 15thNight
22%18%6%10%6%2333318%
2925
16th to endNight
22%17%5%8%6%3333321%
2951

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
66%49%13%6%
1425
16th to endDay
59%310%18%6%
1536
February1st to 15thDay
61%314%13%6%
1503
16th to endDay
62%38%16%7%1
1580
March1st to 15thDay
58%48%15%11%
1816
16th to endDay
54%5%10%17%10%1
2175
April1st to 15thDay
56%210%17%9%2
2170
16th to endDay
52%310%17%13%2
2340
May1st to 15thDay
54%312%17%10%
2400
16th to endDay
58%6%11%16%6%
2690
June1st to 15thDay
54%8%14%15%6%1
2700
16th to endDay
58%6%12%15%6%
2700
July1st to 15thDay
48%7%17%20%6%
2447
16th to endDay
54%7%16%16%5%
2487
August1st to 15thDay
53%7%19%15%3
2416
16th to endDay
43%5%20%23%6%
2440
September1st to 15thDay
48%315%21%10%
2096
16th to endDay
42%315%26%10%
1980
October1st to 15thDay
54%314%21%6%
1881
16th to endDay
65%411%15%3
1728
November1st to 15thDay
59%5%12%16%5%
1716
16th to endDay
63%411%15%4
1501
December1st to 15thDay
68%311%12%3
1365
16th to endDay
68%38%12%6%
1372
January1st to 15thNight
69%37%12%5%
2512
16th to endNight
60%5%9%16%7%
2688
February1st to 15thNight
62%411%14%6%
2359
16th to endNight
64%47%14%9%
1893
March1st to 15thNight
57%5%8%16%10%1
2143
16th to endNight
52%411%19%10%2
2046
April1st to 15thNight
58%36%16%12%2
1777
16th to endNight
52%48%18%13%2
1620
May1st to 15thNight
55%410%16%11%1
1561
16th to endNight
55%5%12%15%10%
1428
June1st to 15thNight
58%7%9%16%5%1
1260
16th to endNight
52%6%14%17%8%
1260
July1st to 15thNight
47%7%17%19%7%
1281
16th to endNight
48%6%16%20%7%
1418
August1st to 15thNight
46%8%19%22%3
1507
16th to endNight
42%8%17%25%5%
1761
September1st to 15thNight
48%5%13%21%9%1
1863
16th to endNight
42%5%15%26%9%
1980
October1st to 15thNight
50%412%23%8%
2076
16th to endNight
61%413%15%4
2496
November1st to 15thNight
56%6%13%16%7%
2472
16th to endNight
61%410%17%4
2786
December1st to 15thNight
71%410%10%3
2925
16th to endNight
67%38%12%6%
2951

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
25%18%45%10%1
60
16th to endDay
23%25%37%9%31
64
February1st to 15thDay
24%18%28%22%5%
142
16th to endDay
25%14%35%19%4
239
March1st to 15thDay
26%18%25%23%5%
270
16th to endDay
21%15%25%23%12%2
288
April1st to 15thDay
33%14%25%18%6%1
270
16th to endDay
27%15%25%20%7%3
270
May1st to 15thDay
33%10%26%19%7%2
288
16th to endDay
26%13%33%19%7%
399
June1st to 15thDay
29%8%26%27%8%
495
16th to endDay
27%7%29%25%9%
495
July1st to 15thDay
24%8%29%25%11%1
381
16th to endDay
23%6%30%28%10%
326
August1st to 15thDay
22%7%26%26%13%2
313
16th to endDay
23%9%23%21%17%4
332
September1st to 15thDay
27%6%27%22%12%2
315
16th to endDay
20%11%30%21%11%4
314
October1st to 15thDay
29%11%30%17%9%2
299
16th to endDay
39%13%25%15%6%
288
November1st to 15thDay
30%16%26%20%5%1
280
16th to endDay
35%12%27%18%5%
184
December1st to 15thDay
38%20%20%16%22
90
16th to endDay
45%23%18%9%2
72
January1st to 15thNight
28%20%32%16%2
721
16th to endNight
18%20%36%19%5%
768
February1st to 15thNight
15%19%38%20%5%
704
16th to endNight
27%15%32%18%5%
631
March1st to 15thNight
24%14%37%19%3
720
16th to endNight
20%12%30%26%8%1
768
April1st to 15thNight
31%12%25%22%6%
699
16th to endNight
30%11%27%22%7%
540
May1st to 15thNight
27%8%26%26%9%
481
16th to endNight
29%8%27%27%7%
375
June1st to 15thNight
29%423%34%7%
360
16th to endNight
21%8%28%32%9%
360
July1st to 15thNight
21%233%27%12%1
340
16th to endNight
20%429%33%11%
376
August1st to 15thNight
20%423%32%17%1
436
16th to endNight
20%6%27%32%10%2
615
September1st to 15thNight
26%5%28%28%10%1
720
16th to endNight
22%10%27%26%12%
717
October1st to 15thNight
25%10%31%23%6%1
720
16th to endNight
36%11%26%17%7%
768
November1st to 15thNight
28%17%25%22%6%
760
16th to endNight
29%16%29%17%6%
815
December1st to 15thNight
31%20%28%14%4
825
16th to endNight
33%18%26%15%5%
824
Page generated at 2017-12-21 07:04:55. Version ac04

Copyright 2017 A. Danko


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