Observatoire de Saint-Camille
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatoire de Saint-Camille clear sky chart from 2005-11-05 to 2017-09-18.

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%
14665
11%
47025
7%
14633
33%
14633
13%
35525

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
7%
2506
3%
716
18%
716
6%
2107
January16th to endNight
19%
768
7%
2688
4%
768
23%
768
7%
2224
February1st to 15thNight
16%
704
7%
2318
4%
701
21%
701
7%
1937
February16th to endNight
18%
631
10%
1893
5%
631
24%
631
10%
1524
March1st to 15thNight
19%
720
13%
2160
8%
720
26%
720
12%
1667
March16th to endNight
28%
768
17%
2020
7%
768
35%
768
17%
1507
April1st to 15thNight
25%
718
15%
1796
6%
718
31%
718
17%
1391
April16th to endNight
26%
564
17%
1644
6%
564
34%
564
18%
1152
May1st to 15thNight
27%
468
15%
1548
10%
468
35%
468
16%
1084
May16th to endNight
33%
375
11%
1497
12%
374
41%
374
13%
1045
June1st to 15thNight
33%
360
8%
1440
7%
360
39%
360
12%
1019
June16th to endNight
42%
360
8%
1440
11%
360
46%
360
17%
951
July1st to 15thNight
47%
340
10%
1360
15%
340
50%
340
18%
880
July16th to endNight
51%
376
11%
1418
15%
354
52%
354
17%
916
August1st to 15thNight
46%
422
12%
1493
11%
420
48%
420
18%
984
August16th to endNight
49%
678
17%
1824
11%
678
52%
678
30%
1204
September1st to 15thNight
44%
720
11%
1840
7%
720
45%
720
24%
1318
September16th to endNight
45%
669
20%
1847
14%
669
48%
669
29%
1191
October1st to 15thNight
33%
660
16%
1895
10%
660
40%
660
19%
1368
October16th to endNight
24%
704
9%
2288
6%
704
29%
704
11%
1796
November1st to 15thNight
23%
700
14%
2277
10%
700
30%
700
12%
1737
November16th to endNight
24%
720
12%
2439
10%
720
28%
720
10%
1893
December1st to 15thNight
14%
747
5%
2679
1%
747
18%
747
5%
2290
December16th to endNight
12%
773
7%
2715
3%
773
17%
773
4%
2340

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
22%11%47%5%34445%25%
47766
Night
20%12%5%7%5%34445%27%
47195
TransparencyDay
59%410%17%7%
47454
Night
60%49%17%7%
47025
SeeingDay
29%13%24%19%9%2
5688
Night
27%12%24%25%9%
14665

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%17%8%13%8%35%43312%
1432
16th to endDay
13%17%7%11%10%36%5%4316%
1536
February1st to 15thDay
13%20%8%13%9%45%5%3214%
1538
16th to endDay
15%19%6%11%9%4443317%
1580
March1st to 15thDay
19%14%6%9%6%3343424%
1790
16th to endDay
18%13%48%44443329%
2203
April1st to 15thDay
23%13%37%5%2333427%
2152
16th to endDay
23%11%35%42333433%
2316
May1st to 15thDay
25%8%36%5%35%345%28%
2412
16th to endDay
24%8%26%6%345%5%6%26%
2618
June1st to 15thDay
31%6%35%42445%6%25%
2520
16th to endDay
23%7%26%5%45%45%8%25%
2520
July1st to 15thDay
19%6%26%6%35%5%6%8%30%
2520
16th to endDay
21%6%25%6%46%6%6%8%25%
2654
August1st to 15thDay
23%5%36%6%35%5%6%7%25%
2444
16th to endDay
18%6%25%5%335%5%7%37%
2377
September1st to 15thDay
23%6%24423346%36%
2119
16th to endDay
21%6%2431345%8%38%
1838
October1st to 15thDay
26%10%35%42444428%
1732
16th to endDay
28%17%36%5%3443318%
1584
November1st to 15thDay
22%16%46%424435%25%
1581
16th to endDay
21%18%7%6%42324424%
1521
December1st to 15thDay
24%20%7%10%6%2334214%
1275
16th to endDay
24%18%9%11%6%2422313%
1504
January1st to 15thNight
18%16%8%12%7%4443316%
2506
16th to endNight
12%17%7%10%9%37%5%3417%
2688
February1st to 15thNight
12%15%8%13%10%5%5%33417%
2317
16th to endNight
17%15%7%10%6%35%33322%
1893
March1st to 15thNight
20%14%6%7%6%2433426%
2147
16th to endNight
17%10%46%5%35%44432%
2020
April1st to 15thNight
24%12%36%5%3334427%
1796
16th to endNight
21%9%25%423446%35%
1644
May1st to 15thNight
24%9%35%424347%31%
1548
16th to endNight
21%8%45%5%25%5%47%29%
1495
June1st to 15thNight
29%7%36%32346%7%25%
1440
16th to endNight
20%6%26%5%25%46%9%31%
1440
July1st to 15thNight
17%436%6%35%5%5%9%33%
1440
16th to endNight
15%5%25%5%446%5%8%35%
1514
August1st to 15thNight
16%7%26%5%2437%8%34%
1503
16th to endNight
15%6%25%4235%47%41%
1824
September1st to 15thNight
22%6%25%423445%37%
1840
16th to endNight
21%423223335%46%
1847
October1st to 15thNight
22%10%25%424345%32%
1895
16th to endNight
29%12%36%5%2343423%
2288
November1st to 15thNight
21%13%5%7%5%2435%5%25%
2277
16th to endNight
22%15%6%8%42333325%
2439
December1st to 15thNight
24%19%7%11%5%2422315%
2679
16th to endNight
23%20%7%10%7%3432213%
2715

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
77%46%8%3
1433
16th to endDay
71%36%13%3
1536
February1st to 15thDay
76%35%10%3
1541
16th to endDay
72%35%11%6%1
1580
March1st to 15thDay
65%38%14%7%1
1800
16th to endDay
59%47%16%11%1
2203
April1st to 15thDay
60%37%16%9%2
2152
16th to endDay
54%29%17%12%2
2316
May1st to 15thDay
57%39%18%10%
2412
16th to endDay
57%5%11%16%8%
2622
June1st to 15thDay
58%5%11%17%6%
2520
16th to endDay
55%5%10%21%6%
2520
July1st to 15thDay
49%6%15%22%6%
2371
16th to endDay
55%6%14%19%5%
2487
August1st to 15thDay
53%7%17%18%2
2430
16th to endDay
44%5%15%24%9%
2377
September1st to 15thDay
48%5%12%23%9%
2119
16th to endDay
45%411%27%10%
1838
October1st to 15thDay
57%411%19%6%
1732
16th to endDay
69%39%13%3
1584
November1st to 15thDay
62%310%15%6%1
1581
16th to endDay
64%310%15%5%
1521
December1st to 15thDay
75%47%10%1
1275
16th to endDay
79%346%5%
1504
January1st to 15thNight
73%47%11%3
2506
16th to endNight
71%47%12%4
2688
February1st to 15thNight
72%36%12%4
2318
16th to endNight
67%37%11%8%
1893
March1st to 15thNight
63%27%15%8%1
2160
16th to endNight
55%38%16%12%3
2020
April1st to 15thNight
59%2418%12%1
1796
16th to endNight
50%48%21%11%3
1644
May1st to 15thNight
54%37%19%13%1
1548
16th to endNight
54%5%10%19%9%
1497
June1st to 15thNight
56%411%19%7%
1440
16th to endNight
48%5%12%22%10%
1440
July1st to 15thNight
45%6%15%22%9%
1360
16th to endNight
45%7%15%21%9%
1418
August1st to 15thNight
47%5%17%23%5%
1493
16th to endNight
40%5%17%27%9%
1824
September1st to 15thNight
48%412%25%8%
1840
16th to endNight
40%412%30%11%
1847
October1st to 15thNight
53%410%22%8%
1895
16th to endNight
64%49%16%5%
2288
November1st to 15thNight
61%410%15%5%1
2277
16th to endNight
65%28%16%6%
2439
December1st to 15thNight
76%37%10%2
2679
16th to endNight
77%36%8%4
2715

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%35%15%6%
60
16th to endDay
34%25%28%9%11
64
February1st to 15thDay
31%22%24%17%3
134
16th to endDay
27%20%26%19%5%
239
March1st to 15thDay
30%22%19%22%4
270
16th to endDay
27%15%23%17%11%4
288
April1st to 15thDay
35%16%21%17%7%1
270
16th to endDay
29%17%26%13%8%4
270
May1st to 15thDay
35%12%27%12%9%1
288
16th to endDay
27%19%26%19%6%
331
June1st to 15thDay
34%12%24%19%8%
315
16th to endDay
25%15%33%19%6%
315
July1st to 15thDay
22%7%35%21%10%2
305
16th to endDay
24%429%32%7%2
326
August1st to 15thDay
27%8%23%21%16%1
313
16th to endDay
22%10%21%19%17%8%
332
September1st to 15thDay
21%6%26%20%17%8%
315
16th to endDay
22%10%19%22%16%8%
262
October1st to 15thDay
29%11%21%15%17%3
251
16th to endDay
42%12%17%17%10%
240
November1st to 15thDay
33%13%23%21%7%
235
16th to endDay
36%16%14%22%7%3
141
December1st to 15thDay
46%13%26%11%1
60
16th to endDay
45%23%23%6%1
64
January1st to 15thNight
27%20%28%19%4
720
16th to endNight
24%17%28%22%5%
768
February1st to 15thNight
20%18%30%24%5%
704
16th to endNight
26%15%29%22%5%
631
March1st to 15thNight
31%14%28%21%4
720
16th to endNight
24%15%25%24%9%1
768
April1st to 15thNight
31%13%23%25%5%
718
16th to endNight
28%15%26%20%9%
564
May1st to 15thNight
29%9%28%22%9%1
468
16th to endNight
26%7%26%30%8%
375
June1st to 15thNight
31%6%20%31%9%
360
16th to endNight
22%5%23%36%12%
360
July1st to 15thNight
15%5%24%36%15%2
340
16th to endNight
16%319%41%17%
376
August1st to 15thNight
20%5%16%36%20%
422
16th to endNight
19%319%33%21%2
678
September1st to 15thNight
23%6%18%34%15%2
720
16th to endNight
24%5%21%27%18%2
669
October1st to 15thNight
28%10%21%24%13%1
660
16th to endNight
36%11%22%22%5%
704
November1st to 15thNight
28%14%24%21%10%
700
16th to endNight
32%16%20%20%9%1
720
December1st to 15thNight
35%17%25%16%4
747
16th to endNight
36%16%21%19%4
773
Page generated at 2017-09-19 07:32:31. Version ac04

Copyright 2017 A. Danko


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