Rang St-Joachim
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rang St-Joachim clear sky chart from 2005-11-05 to 2017-09-17.

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%
14657
12%
46837
9%
14626
37%
14626
15%
34478

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
18%
720
7%
2506
4%
716
23%
716
7%
2065
January16th to endNight
22%
768
9%
2688
6%
768
27%
768
9%
2117
February1st to 15thNight
19%
704
7%
2302
4%
701
23%
701
8%
1902
February16th to endNight
24%
631
10%
1893
6%
631
30%
631
12%
1487
March1st to 15thNight
28%
720
13%
2160
10%
720
33%
720
14%
1652
March16th to endNight
31%
768
19%
2003
9%
768
38%
768
20%
1472
April1st to 15thNight
27%
718
15%
1796
5%
718
32%
718
17%
1395
April16th to endNight
29%
609
16%
1689
7%
609
36%
609
21%
1201
May1st to 15thNight
33%
423
17%
1503
14%
423
41%
423
18%
1008
May16th to endNight
36%
374
12%
1497
11%
374
46%
374
16%
993
June1st to 15thNight
33%
360
8%
1440
9%
360
40%
360
13%
1012
June16th to endNight
44%
360
9%
1440
12%
360
50%
360
19%
907
July1st to 15thNight
55%
340
11%
1360
18%
340
58%
340
22%
825
July16th to endNight
59%
376
12%
1418
17%
354
62%
354
22%
860
August1st to 15thNight
56%
385
14%
1456
16%
383
58%
383
21%
920
August16th to endNight
57%
744
20%
1890
12%
744
59%
744
34%
1223
September1st to 15thNight
52%
720
14%
1806
9%
720
53%
720
30%
1243
September16th to endNight
46%
665
20%
1836
14%
665
50%
665
30%
1199
October1st to 15thNight
34%
660
17%
1922
10%
660
42%
660
21%
1360
October16th to endNight
26%
704
10%
2269
7%
704
31%
704
13%
1734
November1st to 15thNight
28%
700
15%
2277
12%
700
35%
700
14%
1688
November16th to endNight
22%
720
12%
2478
9%
720
29%
720
11%
1884
December1st to 15thNight
17%
720
5%
2520
3%
720
20%
720
6%
2105
December16th to endNight
13%
768
7%
2688
3%
768
18%
768
7%
2226

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%9%36%5%3445%6%31%
47943
Night
20%10%47%5%34445%30%
47007
Cloud CoverDay
19%9%36%5%3445%6%31%
47953
Night
20%10%47%5%34345%29%
47012
TransparencyDay
52%5%12%19%8%
47631
Night
56%5%10%18%8%
46837
SeeingDay
24%7%24%24%13%4
5621
Night
25%7%25%28%11%
14658

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
23%16%5%8%6%3334418%
1432
16th to endDay
14%16%5%9%6%35%45%6%23%
1536
February1st to 15thDay
15%14%7%11%8%45%5%3420%
1556
16th to endDay
17%13%6%7%7%35%45%5%24%
1580
March1st to 15thDay
17%13%5%7%7%35%435%26%
1790
16th to endDay
20%7%37%5%24335%35%
2218
April1st to 15thDay
23%9%35%43444431%
2152
16th to endDay
20%7%345%34336%36%
2269
May1st to 15thDay
21%6%36%5%24447%33%
2457
16th to endDay
19%6%45%6%3445%7%32%
2618
June1st to 15thDay
25%6%35%425%45%7%30%
2520
16th to endDay
19%6%35%5%35%5%5%8%32%
2520
July1st to 15thDay
13%5%25%5%36%46%8%37%
2520
16th to endDay
13%6%25%5%25%6%7%8%36%
2654
August1st to 15thDay
13%7%26%6%45%6%6%8%33%
2481
16th to endDay
12%5%1442446%8%45%
2310
September1st to 15thDay
18%5%24422447%42%
2154
16th to endDay
15%5%2432435%7%45%
1830
October1st to 15thDay
22%8%25%43345%6%31%
1707
16th to endDay
26%10%26%6%23445%26%
1603
November1st to 15thDay
19%12%44434446%30%
1581
16th to endDay
22%12%5%6%5%3433426%
1479
December1st to 15thDay
25%14%5%9%5%3444418%
1440
16th to endDay
27%18%6%9%6%2422416%
1536
January1st to 15thNight
19%16%6%10%6%35%43417%
2506
16th to endNight
15%15%6%9%7%4443423%
2688
February1st to 15thNight
16%14%7%13%8%3443417%
2301
16th to endNight
18%13%5%8%6%45%33425%
1893
March1st to 15thNight
22%13%47%5%2424428%
2147
16th to endNight
19%11%46%32443336%
2003
April1st to 15thNight
25%9%36%5%3333429%
1796
16th to endNight
22%9%24423335%37%
1689
May1st to 15thNight
21%7%36%5%23336%35%
1503
16th to endNight
20%7%245%245%5%7%33%
1495
June1st to 15thNight
29%5%15%5%2445%7%28%
1440
16th to endNight
18%5%15%4345%6%9%35%
1440
July1st to 15thNight
12%435%5%26%5%6%10%38%
1440
16th to endNight
12%4246%35%5%6%7%40%
1514
August1st to 15thNight
13%5%25%6%3447%8%37%
1466
16th to endNight
13%5%1442345%7%46%
1890
September1st to 15thNight
16%5%24434446%41%
1806
16th to endNight
19%5%23313435%46%
1836
October1st to 15thNight
20%7%26%5%24445%35%
1922
16th to endNight
28%9%36%5%24245%26%
2269
November1st to 15thNight
20%10%36%425%5%5%5%28%
2277
16th to endNight
24%12%47%5%2433426%
2478
December1st to 15thNight
25%15%6%7%7%3434417%
2520
16th to endNight
23%19%6%8%6%2322419%
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
23%16%5%9%6%35%43318%
1432
16th to endDay
13%17%410%5%3446%6%22%
1536
February1st to 15thDay
14%15%7%11%7%45%44420%
1556
16th to endDay
18%13%5%7%6%35%346%23%
1580
March1st to 15thDay
18%12%5%8%6%35%435%26%
1800
16th to endDay
20%9%46%434335%35%
2218
April1st to 15thDay
23%10%35%42345%431%
2152
16th to endDay
21%7%245%24345%36%
2269
May1st to 15thDay
21%6%36%5%34437%33%
2457
16th to endDay
20%7%35%5%35%45%7%32%
2618
June1st to 15thDay
27%6%2443445%6%30%
2520
16th to endDay
20%5%25%435%5%5%7%32%
2520
July1st to 15thDay
14%5%25%435%46%8%36%
2520
16th to endDay
13%5%245%35%5%7%8%35%
2654
August1st to 15thDay
15%436%6%35%7%6%8%32%
2481
16th to endDay
12%41443446%8%44%
2310
September1st to 15thDay
18%6%25%424346%42%
2154
16th to endDay
15%5%2432445%6%45%
1830
October1st to 15thDay
24%8%245%3345%6%31%
1707
16th to endDay
27%10%36%5%23445%26%
1603
November1st to 15thDay
19%12%35%42445%6%30%
1581
16th to endDay
23%13%46%5%34445%25%
1479
December1st to 15thDay
25%14%5%7%6%4434418%
1440
16th to endDay
26%19%6%9%5%2234315%
1536
January1st to 15thNight
19%17%6%10%7%3443417%
2506
16th to endNight
15%15%6%10%7%3443423%
2688
February1st to 15thNight
17%14%7%13%8%4434417%
2294
16th to endNight
17%14%6%9%7%34325%25%
1893
March1st to 15thNight
24%12%46%6%2333427%
2160
16th to endNight
20%11%445%2433436%
2002
April1st to 15thNight
26%8%46%5%2334429%
1796
16th to endNight
23%8%14423345%37%
1689
May1st to 15thNight
22%6%36%5%23245%36%
1503
16th to endNight
21%6%245%3445%7%33%
1495
June1st to 15thNight
28%6%26%42445%7%28%
1440
16th to endNight
19%5%234245%5%9%35%
1440
July1st to 15thNight
12%325%5%26%47%10%37%
1440
16th to endNight
13%325%5%36%5%6%8%39%
1514
August1st to 15thNight
14%6%15%5%4446%9%37%
1466
16th to endNight
13%5%2443345%6%46%
1890
September1st to 15thNight
16%6%245%24346%42%
1806
16th to endNight
20%5%23323345%46%
1836
October1st to 15thNight
21%7%26%5%3335%5%35%
1922
16th to endNight
29%10%26%5%33335%26%
2269
November1st to 15thNight
21%10%35%5%35%446%27%
2277
16th to endNight
24%11%48%5%2343426%
2478
December1st to 15thNight
25%16%5%8%6%3433417%
2520
16th to endNight
24%21%6%8%5%2222418%
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
70%48%12%3
1433
16th to endDay
61%414%13%5%
1536
February1st to 15thDay
68%49%15%1
1559
16th to endDay
61%5%11%13%6%
1580
March1st to 15thDay
61%411%15%6%
1800
16th to endDay
51%49%20%11%1
2218
April1st to 15thDay
56%48%18%10%1
2152
16th to endDay
49%49%20%12%3
2269
May1st to 15thDay
51%411%18%13%
2457
16th to endDay
50%6%11%19%10%1
2622
June1st to 15thDay
52%6%12%19%8%
2520
16th to endDay
49%7%10%22%8%
2520
July1st to 15thDay
41%7%14%28%8%
2371
16th to endDay
42%7%17%24%7%
2487
August1st to 15thDay
46%8%17%20%6%
2467
16th to endDay
35%6%17%28%11%
2310
September1st to 15thDay
43%412%27%11%
2154
16th to endDay
38%5%13%31%10%
1830
October1st to 15thDay
53%413%19%7%
1707
16th to endDay
60%5%13%16%4
1603
November1st to 15thDay
53%6%11%18%8%
1581
16th to endDay
61%5%10%15%6%
1479
December1st to 15thDay
69%5%12%10%1
1440
16th to endDay
75%48%7%4
1536
January1st to 15thNight
70%48%12%3
2506
16th to endNight
64%5%9%13%6%
2688
February1st to 15thNight
71%38%13%3
2302
16th to endNight
64%39%13%8%
1893
March1st to 15thNight
60%48%18%7%1
2160
16th to endNight
54%27%17%14%3
2003
April1st to 15thNight
59%35%17%13%1
1796
16th to endNight
50%48%18%15%3
1689
May1st to 15thNight
50%36%19%16%4
1503
16th to endNight
48%6%10%21%11%2
1497
June1st to 15thNight
55%5%11%19%7%1
1440
16th to endNight
42%7%14%21%12%1
1440
July1st to 15thNight
38%8%14%26%11%
1360
16th to endNight
39%6%15%25%11%
1418
August1st to 15thNight
41%7%17%22%10%
1456
16th to endNight
36%5%14%29%13%
1890
September1st to 15thNight
41%5%12%27%12%
1806
16th to endNight
40%5%10%30%12%
1836
October1st to 15thNight
50%5%11%21%10%
1922
16th to endNight
61%411%16%6%
2269
November1st to 15thNight
56%5%11%16%7%2
2277
16th to endNight
62%410%16%6%
2478
December1st to 15thNight
72%49%11%1
2520
16th to endNight
72%39%9%4
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
25%18%16%25%13%1
60
16th to endDay
40%434%12%43
64
February1st to 15thDay
30%20%30%13%5%
105
16th to endDay
29%10%29%23%6%
239
March1st to 15thDay
30%8%30%24%6%
270
16th to endDay
28%10%23%21%11%4
288
April1st to 15thDay
31%11%25%20%9%1
270
16th to endDay
24%10%28%17%14%5%
270
May1st to 15thDay
31%6%24%20%12%4
288
16th to endDay
20%7%31%22%15%2
331
June1st to 15thDay
32%5%20%28%10%2
315
16th to endDay
23%329%30%9%2
315
July1st to 15thDay
16%227%31%15%6%
305
16th to endDay
16%315%40%20%3
326
August1st to 15thDay
17%320%29%21%7%
313
16th to endDay
15%5%17%26%23%11%
332
September1st to 15thDay
16%5%19%23%22%12%
315
16th to endDay
13%6%25%20%22%11%
259
October1st to 15thDay
24%7%26%20%17%3
255
16th to endDay
39%9%20%24%6%
243
November1st to 15thDay
28%8%28%22%10%2
235
16th to endDay
35%16%19%15%13%1
99
December1st to 15thDay
28%11%23%31%31
60
16th to endDay
46%12%23%15%1
64
January1st to 15thNight
25%12%31%24%5%
720
16th to endNight
23%11%28%27%8%
768
February1st to 15thNight
23%7%33%28%6%
704
16th to endNight
26%9%30%26%6%
631
March1st to 15thNight
30%9%24%29%5%
720
16th to endNight
26%9%26%26%8%1
768
April1st to 15thNight
30%8%26%28%5%
718
16th to endNight
27%10%26%23%11%
609
May1st to 15thNight
24%5%28%28%12%
423
16th to endNight
22%5%28%33%8%1
375
June1st to 15thNight
32%420%28%12%
360
16th to endNight
21%323%36%14%
360
July1st to 15thNight
10%225%42%18%1
340
16th to endNight
13%216%49%17%
376
August1st to 15thNight
18%115%39%24%1
385
16th to endNight
16%315%37%25%2
744
September1st to 15thNight
20%416%39%17%2
720
16th to endNight
22%421%27%20%3
665
October1st to 15thNight
25%5%25%28%13%1
660
16th to endNight
35%6%25%23%8%
704
November1st to 15thNight
26%8%29%24%9%1
700
16th to endNight
30%12%26%18%11%
720
December1st to 15thNight
33%12%28%19%5%
720
16th to endNight
34%10%29%19%5%1
768
Page generated at 2017-09-18 08:38:26. Version ac04

Copyright 2017 A. Danko


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