Saint-Casimir
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saint-Casimir clear sky chart from 2005-11-05 to 2017-09-23.

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
30%
14630
13%
46969
7%
14598
36%
14598
16%
34066

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
15%
720
10%
2506
5%
716
23%
716
9%
1997
January16th to endNight
25%
768
11%
2688
7%
768
32%
768
11%
2058
February1st to 15thNight
21%
704
11%
2352
5%
701
29%
701
12%
1795
February16th to endNight
22%
631
12%
1893
6%
631
29%
631
13%
1472
March1st to 15thNight
23%
720
14%
2160
8%
720
31%
720
15%
1603
March16th to endNight
31%
768
18%
2013
7%
768
40%
768
22%
1419
April1st to 15thNight
26%
718
16%
1796
6%
718
31%
718
19%
1370
April16th to endNight
27%
564
16%
1644
5%
564
37%
564
21%
1125
May1st to 15thNight
29%
426
15%
1506
12%
426
37%
426
16%
1023
May16th to endNight
31%
375
11%
1497
10%
374
41%
374
14%
1029
June1st to 15thNight
36%
360
7%
1332
6%
360
42%
360
15%
939
June16th to endNight
43%
360
8%
1329
9%
360
46%
360
17%
915
July1st to 15thNight
43%
340
8%
1360
11%
340
48%
340
20%
854
July16th to endNight
51%
376
10%
1418
14%
354
54%
354
19%
895
August1st to 15thNight
52%
392
12%
1463
12%
390
55%
390
18%
951
August16th to endNight
48%
678
16%
1824
10%
678
51%
678
27%
1224
September1st to 15thNight
44%
720
13%
1827
7%
720
47%
720
29%
1252
September16th to endNight
42%
689
20%
1902
12%
689
48%
689
30%
1225
October1st to 15thNight
32%
660
18%
1913
9%
660
41%
660
20%
1352
October16th to endNight
24%
704
10%
2288
5%
704
30%
704
14%
1706
November1st to 15thNight
28%
700
16%
2277
10%
700
37%
700
15%
1631
November16th to endNight
25%
725
13%
2509
8%
725
32%
725
11%
1879
December1st to 15thNight
18%
750
6%
2700
2%
750
23%
750
9%
2120
December16th to endNight
17%
782
10%
2772
4%
782
25%
782
7%
2232

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%8%36%5%3445%6%30%
47931
Night
20%9%46%5%34445%30%
47139
TransparencyDay
54%412%19%8%1
47619
Night
55%411%18%9%
46969
SeeingDay
26%8%25%23%12%3
5846
Night
26%7%26%27%9%
14630

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%14%5%9%6%3423422%
1432
16th to endDay
13%14%6%9%7%45%5%45%22%
1536
February1st to 15thDay
11%15%6%11%6%45%445%24%
1506
16th to endDay
17%13%5%9%6%3435%5%23%
1580
March1st to 15thDay
19%11%46%5%34345%30%
1790
16th to endDay
15%10%37%5%3445%6%34%
2207
April1st to 15thDay
25%9%345%2333433%
2152
16th to endDay
22%7%26%433345%35%
2316
May1st to 15thDay
23%6%35%5%3445%6%31%
2454
16th to endDay
22%7%36%6%35%446%28%
2618
June1st to 15thDay
22%6%35%6%345%5%7%28%
2625
16th to endDay
20%6%46%6%36%5%6%6%26%
2625
July1st to 15thDay
14%5%37%6%46%6%6%8%31%
2520
16th to endDay
16%6%35%6%35%5%7%7%30%
2654
August1st to 15thDay
17%6%25%5%46%5%6%10%27%
2475
16th to endDay
13%5%25%5%35%5%5%8%40%
2377
September1st to 15thDay
19%6%25%434346%39%
2133
16th to endDay
20%5%2332335%7%42%
1895
October1st to 15thDay
26%6%26%5%25%336%30%
1716
16th to endDay
27%9%26%7%3344424%
1584
November1st to 15thDay
21%8%48%5%34335%30%
1581
16th to endDay
24%13%46%42333428%
1446
December1st to 15thDay
29%12%46%5%2334324%
1260
16th to endDay
26%14%5%6%6%3333423%
1449
January1st to 15thNight
22%16%6%7%7%23335%20%
2506
16th to endNight
15%13%5%9%7%46%345%24%
2688
February1st to 15thNight
10%12%6%12%9%35%445%24%
2351
16th to endNight
17%13%5%8%7%35%43425%
1893
March1st to 15thNight
19%10%47%6%3443430%
2147
16th to endNight
15%9%46%424445%37%
2013
April1st to 15thNight
26%10%45%324345%29%
1796
16th to endNight
22%6%34423346%37%
1644
May1st to 15thNight
23%7%25%5%2434434%
1506
16th to endNight
25%7%3443345%6%31%
1495
June1st to 15thNight
23%7%36%4345%5%6%30%
1332
16th to endNight
20%7%36%435%5%5%7%30%
1329
July1st to 15thNight
15%6%45%5%25%5%6%7%35%
1440
16th to endNight
14%5%25%5%446%5%7%36%
1514
August1st to 15thNight
14%5%26%7%446%6%9%31%
1473
16th to endNight
14%426%5%3445%9%39%
1824
September1st to 15thNight
19%6%25%323347%40%
1827
16th to endNight
21%423323245%46%
1902
October1st to 15thNight
20%6%26%5%2445%6%35%
1913
16th to endNight
28%9%26%5%22335%28%
2288
November1st to 15thNight
21%9%36%5%2445%6%31%
2277
16th to endNight
27%11%46%43333428%
2509
December1st to 15thNight
26%13%47%6%3333422%
2700
16th to endNight
24%17%47%5%3443419%
2772

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%48%14%6%
1433
16th to endDay
62%47%17%6%
1536
February1st to 15thDay
61%213%14%6%
1509
16th to endDay
61%38%16%7%1
1580
March1st to 15thDay
56%211%16%11%1
1800
16th to endDay
50%48%19%12%3
2207
April1st to 15thDay
55%28%18%10%4
2152
16th to endDay
51%39%18%14%2
2316
May1st to 15thDay
52%310%18%12%1
2454
16th to endDay
55%411%16%11%
2622
June1st to 15thDay
53%413%16%9%2
2625
16th to endDay
55%411%18%8%
2625
July1st to 15thDay
46%417%22%7%
2371
16th to endDay
51%6%16%19%6%
2487
August1st to 15thDay
50%6%19%17%4
2461
16th to endDay
40%418%27%8%
2377
September1st to 15thDay
45%314%23%11%
2133
16th to endDay
41%316%29%9%
1895
October1st to 15thDay
55%311%20%7%
1716
16th to endDay
62%410%18%3
1584
November1st to 15thDay
56%410%19%8%
1581
16th to endDay
59%312%18%5%
1446
December1st to 15thDay
64%211%15%4
1260
16th to endDay
66%38%13%7%
1449
January1st to 15thNight
67%48%15%5%
2506
16th to endNight
63%48%16%7%
2688
February1st to 15thNight
62%39%16%7%
2352
16th to endNight
63%38%14%10%
1893
March1st to 15thNight
58%38%16%11%2
2160
16th to endNight
48%39%19%15%2
2013
April1st to 15thNight
57%26%18%12%2
1796
16th to endNight
47%310%18%15%3
1644
May1st to 15thNight
52%210%16%15%2
1506
16th to endNight
53%410%18%11%2
1497
June1st to 15thNight
54%412%18%8%1
1332
16th to endNight
51%410%19%12%
1329
July1st to 15thNight
44%5%17%21%10%
1360
16th to endNight
43%7%16%21%10%
1418
August1st to 15thNight
46%6%18%22%5%
1463
16th to endNight
42%5%15%27%8%
1824
September1st to 15thNight
44%314%25%11%
1827
16th to endNight
41%315%28%11%
1902
October1st to 15thNight
50%411%22%11%
1913
16th to endNight
59%311%19%5%
2288
November1st to 15thNight
53%5%12%17%9%
2277
16th to endNight
61%29%19%6%
2509
December1st to 15thNight
67%312%13%4
2700
16th to endNight
69%38%11%6%
2772

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
35%8%25%25%6%
60
16th to endDay
31%7%40%12%6%1
64
February1st to 15thDay
24%17%32%20%31
105
16th to endDay
27%9%30%24%7%
239
March1st to 15thDay
29%14%27%20%7%
270
16th to endDay
21%11%31%19%11%4
288
April1st to 15thDay
33%11%21%21%8%2
270
16th to endDay
29%10%26%20%11%2
270
May1st to 15thDay
32%7%26%22%7%2
288
16th to endDay
27%12%23%24%9%1
331
June1st to 15thDay
28%6%29%23%10%1
420
16th to endDay
22%6%26%30%11%2
420
July1st to 15thDay
20%5%25%27%15%3
305
16th to endDay
20%420%34%17%2
326
August1st to 15thDay
19%321%28%22%5%
313
16th to endDay
19%325%22%19%9%
332
September1st to 15thDay
23%7%20%23%17%7%
315
16th to endDay
20%8%21%22%16%9%
283
October1st to 15thDay
30%228%23%13%1
252
16th to endDay
35%7%24%22%9%
240
November1st to 15thDay
28%9%24%24%9%2
235
16th to endDay
33%13%23%16%12%
96
December1st to 15thDay
38%330%25%3
60
16th to endDay
48%12%31%43
64
January1st to 15thNight
29%9%32%23%4
720
16th to endNight
24%9%27%29%8%
768
February1st to 15thNight
17%11%35%27%9%
704
16th to endNight
25%9%31%26%6%
631
March1st to 15thNight
27%9%30%28%4
720
16th to endNight
20%9%30%27%9%1
768
April1st to 15thNight
33%7%25%26%6%
718
16th to endNight
26%12%29%23%8%
564
May1st to 15thNight
27%7%27%27%7%
426
16th to endNight
29%6%25%29%8%
375
June1st to 15thNight
30%5%22%33%8%
360
16th to endNight
24%220%35%15%
360
July1st to 15thNight
17%324%33%18%1
340
16th to endNight
17%219%44%15%
376
August1st to 15thNight
17%315%38%23%1
392
16th to endNight
17%321%36%17%1
678
September1st to 15thNight
24%421%33%13%2
720
16th to endNight
24%425%25%19%1
689
October1st to 15thNight
25%7%28%27%10%
660
16th to endNight
34%7%27%23%5%
704
November1st to 15thNight
27%9%27%25%9%1
700
16th to endNight
34%10%22%21%9%
725
December1st to 15thNight
35%10%25%23%5%
750
16th to endNight
35%11%25%20%5%
782
Page generated at 2017-09-24 09:15:51. Version ac04

Copyright 2017 A. Danko


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