Saint-Calixte
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saint-Calixte 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
28%
14603
14%
46837
7%
14571
36%
14571
18%
32598

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
16%
720
10%
2506
3%
716
25%
716
10%
1888
January16th to endNight
22%
768
12%
2688
5%
768
31%
768
13%
1922
February1st to 15thNight
18%
704
11%
2317
3%
701
27%
701
12%
1736
February16th to endNight
20%
631
15%
1899
6%
631
31%
631
14%
1388
March1st to 15thNight
20%
720
15%
2160
8%
720
28%
720
15%
1610
March16th to endNight
29%
768
20%
1996
8%
768
37%
768
23%
1381
April1st to 15thNight
23%
718
17%
1796
5%
718
30%
718
20%
1335
April16th to endNight
26%
621
16%
1701
5%
621
35%
621
21%
1180
May1st to 15thNight
28%
378
15%
1458
11%
378
38%
378
16%
989
May16th to endNight
28%
375
13%
1497
11%
374
40%
374
17%
969
June1st to 15thNight
30%
360
8%
1440
6%
360
38%
360
15%
1001
June16th to endNight
38%
360
8%
1440
9%
360
43%
360
17%
947
July1st to 15thNight
43%
340
12%
1360
15%
340
50%
340
24%
759
July16th to endNight
50%
376
12%
1418
15%
354
55%
354
23%
838
August1st to 15thNight
53%
359
14%
1430
15%
357
59%
357
20%
873
August16th to endNight
48%
748
20%
1894
10%
748
53%
748
37%
1191
September1st to 15thNight
45%
720
14%
1800
6%
720
47%
720
32%
1203
September16th to endNight
43%
665
21%
1821
13%
665
48%
665
32%
1141
October1st to 15thNight
29%
660
20%
1950
9%
660
41%
660
22%
1310
October16th to endNight
24%
704
12%
2258
6%
704
34%
704
17%
1610
November1st to 15thNight
26%
700
18%
2280
9%
700
37%
700
17%
1595
November16th to endNight
21%
720
14%
2520
8%
720
30%
720
12%
1808
December1st to 15thNight
20%
720
11%
2520
4%
720
29%
720
12%
1867
December16th to endNight
14%
768
12%
2688
3%
768
24%
768
9%
2057

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%8%36%5%34446%32%
47948
Night
17%8%36%5%34446%34%
47006
Cloud CoverDay
17%8%36%5%35%45%6%32%
47957
Night
17%8%36%5%34446%34%
47012
TransparencyDay
51%6%11%19%10%1
47635
Night
50%5%11%20%10%1
46837
SeeingDay
20%12%30%23%9%3
5554
Night
21%10%32%25%8%
14603

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
20%14%48%6%445%4423%
1432
16th to endDay
12%14%6%8%7%35%34429%
1536
February1st to 15thDay
12%14%5%9%7%36%34425%
1545
16th to endDay
15%14%5%10%6%3444427%
1573
March1st to 15thDay
17%11%6%9%7%4434427%
1790
16th to endDay
16%9%35%5%24445%38%
2226
April1st to 15thDay
22%9%35%43334433%
2152
16th to endDay
21%8%25%5%34345%36%
2259
May1st to 15thDay
23%8%36%6%34346%30%
2502
16th to endDay
22%6%26%5%35%446%31%
2618
June1st to 15thDay
23%6%35%6%245%5%7%28%
2520
16th to endDay
20%7%36%6%36%6%5%6%27%
2520
July1st to 15thDay
14%5%35%6%46%5%5%7%35%
2520
16th to endDay
14%5%25%6%46%6%7%8%33%
2654
August1st to 15thDay
14%5%36%7%46%6%5%7%31%
2514
16th to endDay
11%425%5%3445%8%43%
2297
September1st to 15thDay
18%6%25%424446%40%
2160
16th to endDay
16%423323346%47%
1844
October1st to 15thDay
22%7%35%434346%33%
1678
16th to endDay
23%11%37%5%43336%26%
1614
November1st to 15thDay
16%9%36%5%35%45%6%33%
1578
16th to endDay
22%11%36%5%23436%30%
1440
December1st to 15thDay
22%15%5%5%5%24445%23%
1440
16th to endDay
23%14%5%9%5%2432424%
1536
January1st to 15thNight
16%13%5%8%6%35%45%5%25%
2506
16th to endNight
11%12%5%8%6%45%5%5%5%28%
2688
February1st to 15thNight
11%11%5%10%9%36%5%5%5%26%
2315
16th to endNight
15%10%5%7%6%35%44431%
1899
March1st to 15thNight
17%10%5%6%6%345%45%29%
2147
16th to endNight
14%9%36%5%2434442%
1996
April1st to 15thNight
23%8%35%5%2344434%
1796
16th to endNight
22%6%24315%446%38%
1701
May1st to 15thNight
21%6%35%5%34445%35%
1458
16th to endNight
23%424425%347%36%
1495
June1st to 15thNight
23%8%35%5%2445%6%31%
1440
16th to endNight
18%6%345%345%5%8%35%
1440
July1st to 15thNight
11%42442447%9%44%
1440
16th to endNight
11%425%335%5%5%7%44%
1514
August1st to 15thNight
12%5%25%5%25%5%6%9%39%
1440
16th to endNight
12%41342345%7%50%
1894
September1st to 15thNight
14%5%2443446%8%42%
1800
16th to endNight
17%41322345%6%48%
1821
October1st to 15thNight
18%7%25%424345%40%
1950
16th to endNight
24%7%34424346%32%
2258
November1st to 15thNight
19%8%35%5%34446%34%
2280
16th to endNight
20%11%47%5%23435%30%
2520
December1st to 15thNight
20%13%47%5%24346%26%
2520
16th to endNight
21%15%5%7%5%3343425%
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
19%13%48%6%3444424%
1432
16th to endDay
12%14%6%7%7%34445%29%
1536
February1st to 15thDay
12%15%5%8%8%45%445%26%
1545
16th to endDay
15%13%6%10%7%3433427%
1573
March1st to 15thDay
17%10%5%9%6%45%34428%
1800
16th to endDay
15%9%36%424446%38%
2225
April1st to 15thDay
22%9%35%434345%33%
2152
16th to endDay
20%7%25%5%44345%37%
2259
May1st to 15thDay
21%8%36%6%34446%31%
2502
16th to endDay
21%6%26%5%35%5%5%7%31%
2618
June1st to 15thDay
21%6%35%435%5%6%8%29%
2520
16th to endDay
18%7%26%7%36%5%6%8%27%
2520
July1st to 15thDay
13%5%25%6%46%6%6%7%35%
2520
16th to endDay
12%5%25%6%36%7%6%9%34%
2654
August1st to 15thDay
13%6%17%6%46%7%7%7%31%
2514
16th to endDay
9%425%5%3445%9%44%
2297
September1st to 15thDay
17%425%3245%5%6%40%
2160
16th to endDay
15%5%24322447%47%
1844
October1st to 15thDay
20%9%25%5%34436%34%
1678
16th to endDay
21%11%37%5%35%445%27%
1614
November1st to 15thDay
15%9%35%435%46%6%33%
1578
16th to endDay
21%10%35%434436%31%
1440
December1st to 15thDay
23%12%5%6%5%24445%24%
1440
16th to endDay
24%12%5%8%5%2433425%
1536
January1st to 15thNight
16%13%5%9%5%3445%6%24%
2506
16th to endNight
11%12%5%8%7%46%5%5%5%28%
2688
February1st to 15thNight
11%12%5%10%8%45%46%426%
2308
16th to endNight
16%10%48%6%35%435%30%
1899
March1st to 15thNight
18%10%47%5%35%45%430%
2160
16th to endNight
13%9%35%5%34435%41%
1996
April1st to 15thNight
23%8%45%42344434%
1796
16th to endNight
21%7%23424446%37%
1701
May1st to 15thNight
20%7%26%435%45%5%34%
1458
16th to endNight
22%5%25%42445%7%36%
1495
June1st to 15thNight
23%6%36%415%346%32%
1440
16th to endNight
17%5%35%43445%8%35%
1440
July1st to 15thNight
11%4244245%7%8%43%
1440
16th to endNight
11%424435%5%6%9%42%
1514
August1st to 15thNight
11%426%5%36%5%6%8%39%
1440
16th to endNight
12%42442445%7%48%
1894
September1st to 15thNight
13%5%245%335%47%43%
1800
16th to endNight
17%42231345%6%48%
1821
October1st to 15thNight
17%7%25%4245%45%40%
1950
16th to endNight
23%8%35%5%23345%33%
2258
November1st to 15thNight
19%8%35%5%34446%34%
2280
16th to endNight
20%11%47%5%24335%31%
2520
December1st to 15thNight
21%11%47%5%24445%27%
2520
16th to endNight
21%15%5%7%5%2334425%
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
62%5%9%15%7%
1433
16th to endDay
56%5%8%18%9%1
1536
February1st to 15thDay
59%49%17%6%
1547
16th to endDay
61%47%15%9%2
1573
March1st to 15thDay
59%39%15%10%1
1800
16th to endDay
46%5%10%18%14%4
2226
April1st to 15thDay
53%38%19%11%3
2152
16th to endDay
49%5%7%20%13%4
2259
May1st to 15thDay
54%48%18%12%2
2502
16th to endDay
51%7%10%18%11%1
2622
June1st to 15thDay
51%6%11%17%10%1
2520
16th to endDay
52%8%10%19%8%
2520
July1st to 15thDay
43%8%13%23%11%
2371
16th to endDay
43%9%16%21%8%
2487
August1st to 15thDay
47%9%16%20%6%
2500
16th to endDay
36%8%18%26%10%
2297
September1st to 15thDay
41%7%12%25%12%
2160
16th to endDay
37%413%31%11%
1844
October1st to 15thDay
51%5%9%22%10%
1678
16th to endDay
58%5%12%16%7%
1614
November1st to 15thDay
48%7%13%18%10%
1578
16th to endDay
54%5%11%19%7%
1440
December1st to 15thDay
61%412%15%4
1440
16th to endDay
63%49%12%9%
1536
January1st to 15thNight
59%5%11%17%5%
2506
16th to endNight
55%412%17%8%1
2688
February1st to 15thNight
59%5%9%18%6%
2317
16th to endNight
55%49%18%11%1
1899
March1st to 15thNight
56%5%8%17%10%1
2160
16th to endNight
46%410%18%17%3
1996
April1st to 15thNight
52%46%20%14%1
1796
16th to endNight
48%49%19%15%3
1701
May1st to 15thNight
50%5%8%17%13%4
1458
16th to endNight
47%5%10%22%12%2
1497
June1st to 15thNight
53%5%11%18%10%
1440
16th to endNight
47%6%11%20%13%
1440
July1st to 15thNight
34%7%16%27%13%
1360
16th to endNight
36%8%17%24%12%
1418
August1st to 15thNight
40%7%17%24%9%
1430
16th to endNight
33%417%31%11%
1894
September1st to 15thNight
39%5%15%25%12%
1800
16th to endNight
35%5%13%33%12%
1821
October1st to 15thNight
45%5%11%24%13%1
1950
16th to endNight
52%5%13%20%8%
2258
November1st to 15thNight
50%5%13%19%8%2
2280
16th to endNight
56%410%20%7%
2520
December1st to 15thNight
58%413%19%3
2520
16th to endNight
63%39%14%7%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
21%20%26%28%3
60
16th to endDay
28%15%39%10%6%
64
February1st to 15thDay
24%23%36%14%1
85
16th to endDay
25%13%32%22%5%
232
March1st to 15thDay
21%20%32%22%3
270
16th to endDay
21%13%35%18%7%3
288
April1st to 15thDay
26%18%29%16%6%2
270
16th to endDay
22%17%31%18%8%1
270
May1st to 15thDay
28%14%30%18%7%1
288
16th to endDay
20%16%32%20%7%1
331
June1st to 15thDay
24%13%32%20%8%
315
16th to endDay
20%8%36%25%8%1
315
July1st to 15thDay
15%6%34%26%11%4
305
16th to endDay
13%424%39%15%2
326
August1st to 15thDay
15%7%23%31%17%4
313
16th to endDay
9%7%27%29%15%11%
332
September1st to 15thDay
18%6%25%26%14%8%
315
16th to endDay
17%9%27%20%14%9%
259
October1st to 15thDay
22%12%30%18%12%2
255
16th to endDay
26%15%23%26%7%
245
November1st to 15thDay
20%14%34%20%9%
232
16th to endDay
33%13%28%21%3
60
December1st to 15thDay
23%11%41%18%5%
60
16th to endDay
35%25%31%7%
64
January1st to 15thNight
20%16%36%21%4
720
16th to endNight
16%12%38%23%7%
768
February1st to 15thNight
16%13%40%23%6%
704
16th to endNight
20%12%37%23%4
631
March1st to 15thNight
23%15%36%21%3
720
16th to endNight
18%12%33%26%7%
768
April1st to 15thNight
27%13%30%24%3
718
16th to endNight
26%13%31%21%6%
621
May1st to 15thNight
22%7%35%25%7%1
378
16th to endNight
24%7%35%24%7%
375
June1st to 15thNight
28%7%28%26%9%
360
16th to endNight
21%330%28%14%
360
July1st to 15thNight
11%7%32%30%16%2
340
16th to endNight
10%330%42%12%
376
August1st to 15thNight
15%319%40%19%1
359
16th to endNight
14%425%32%19%2
748
September1st to 15thNight
16%5%27%35%12%1
720
16th to endNight
19%6%28%27%15%3
665
October1st to 15thNight
20%9%33%24%10%1
660
16th to endNight
29%8%32%22%7%
704
November1st to 15thNight
23%10%31%23%9%1
700
16th to endNight
24%14%30%19%8%1
720
December1st to 15thNight
28%13%30%22%5%
720
16th to endNight
30%13%31%19%31
768
Page generated at 2017-09-18 08:38:28. Version ac04

Copyright 2017 A. Danko


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