Observatoire Saint-Raymond
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatoire Saint-Raymond 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
28%
15008
13%
48104
7%
14977
36%
14977
16%
34517

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
11%
2506
4%
716
22%
716
9%
1954
January16th to endNight
22%
768
12%
2688
6%
768
31%
768
11%
2022
February1st to 15thNight
20%
703
12%
2360
5%
701
30%
701
12%
1754
February16th to endNight
22%
631
12%
1893
5%
631
31%
631
13%
1441
March1st to 15thNight
22%
720
15%
2160
7%
720
31%
720
15%
1576
March16th to endNight
28%
768
20%
2019
7%
768
37%
768
20%
1430
April1st to 15thNight
24%
718
16%
1796
5%
718
31%
718
19%
1353
April16th to endNight
25%
554
17%
1634
6%
554
35%
554
20%
1119
May1st to 15thNight
26%
435
15%
1515
9%
435
36%
435
17%
1037
May16th to endNight
28%
375
11%
1497
9%
374
39%
374
15%
1007
June1st to 15thNight
33%
360
8%
1278
6%
360
39%
360
15%
897
June16th to endNight
45%
360
7%
1272
9%
360
46%
360
18%
865
July1st to 15thNight
48%
340
8%
1360
11%
340
51%
340
20%
843
July16th to endNight
49%
376
10%
1418
13%
354
52%
354
18%
884
August1st to 15thNight
53%
398
12%
1469
12%
396
57%
396
19%
962
August16th to endNight
45%
662
17%
1808
10%
662
49%
662
27%
1193
September1st to 15thNight
41%
720
13%
1833
7%
720
44%
720
29%
1259
September16th to endNight
41%
717
19%
1980
11%
717
47%
717
29%
1280
October1st to 15thNight
32%
720
18%
2088
8%
720
42%
720
22%
1429
October16th to endNight
24%
768
11%
2496
6%
768
31%
768
14%
1833
November1st to 15thNight
27%
760
16%
2472
9%
760
36%
760
15%
1758
November16th to endNight
25%
797
14%
2753
8%
797
34%
797
12%
2014
December1st to 15thNight
17%
825
7%
2925
3%
825
23%
825
8%
2304
December16th to endNight
14%
813
11%
2884
4%
813
23%
813
7%
2303

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
21%9%36%5%34446%29%
48734
Night
20%10%46%5%34345%30%
48274
TransparencyDay
56%312%18%8%1
48422
Night
55%211%19%9%
48104
SeeingDay
29%11%25%21%10%2
6220
Night
27%9%25%26%10%
15009

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%16%5%8%7%2444420%
1432
16th to endDay
13%14%7%9%6%25%6%5%5%23%
1536
February1st to 15thDay
10%14%7%11%7%35%43425%
1498
16th to endDay
15%14%6%10%6%34445%23%
1580
March1st to 15thDay
19%11%5%6%6%3434431%
1790
16th to endDay
14%9%46%6%35%445%35%
2205
April1st to 15thDay
25%9%35%43433432%
2152
16th to endDay
23%8%25%5%23335%35%
2325
May1st to 15thDay
25%7%35%434445%31%
2447
16th to endDay
24%7%27%6%445%45%27%
2618
June1st to 15thDay
23%7%25%5%35%45%7%27%
2679
16th to endDay
24%7%46%5%35%5%5%6%24%
2685
July1st to 15thDay
17%6%35%6%46%5%6%8%29%
2520
16th to endDay
20%6%26%6%45%6%6%8%27%
2654
August1st to 15thDay
21%6%26%5%46%5%6%8%26%
2469
16th to endDay
15%6%25%4345%6%8%36%
2393
September1st to 15thDay
22%5%24424346%38%
2127
16th to endDay
22%5%14322447%40%
1980
October1st to 15thDay
27%7%24435%445%30%
1869
16th to endDay
28%9%27%6%34345%23%
1728
November1st to 15thDay
22%9%37%7%3444428%
1716
16th to endDay
25%14%36%5%3343425%
1530
December1st to 15thDay
28%15%35%6%1333424%
1365
16th to endDay
24%16%5%8%5%1433321%
1436
January1st to 15thNight
21%16%5%8%6%23335%21%
2506
16th to endNight
13%14%6%9%7%45%5%45%24%
2688
February1st to 15thNight
10%12%5%11%9%5%5%345%26%
2359
16th to endNight
17%12%5%9%5%45%34426%
1893
March1st to 15thNight
19%10%46%5%25%435%30%
2147
16th to endNight
14%10%46%5%24445%37%
2019
April1st to 15thNight
26%9%35%42345%5%29%
1796
16th to endNight
21%7%23423447%36%
1634
May1st to 15thNight
25%6%34425%345%34%
1515
16th to endNight
26%6%35%5%23245%33%
1495
June1st to 15thNight
23%7%25%5%35%45%6%29%
1278
16th to endNight
22%5%346%35%5%47%31%
1272
July1st to 15thNight
18%6%25%4246%6%8%34%
1440
16th to endNight
17%5%34435%5%6%7%37%
1514
August1st to 15thNight
17%6%35%425%5%6%9%33%
1479
16th to endNight
16%425%5%4435%7%40%
1808
September1st to 15thNight
21%5%25%322346%40%
1833
16th to endNight
22%413313336%44%
1980
October1st to 15thNight
21%7%25%424446%37%
2088
16th to endNight
30%8%25%422336%28%
2496
November1st to 15thNight
21%9%35%6%34345%32%
2472
16th to endNight
25%11%45%42333429%
2753
December1st to 15thNight
25%15%5%7%6%3433421%
2925
16th to endNight
22%17%5%9%6%2433420%
2884

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%38%13%7%
1433
16th to endDay
61%38%17%8%
1536
February1st to 15thDay
63%111%14%7%
1501
16th to endDay
63%27%16%8%2
1580
March1st to 15thDay
57%210%15%12%1
1800
16th to endDay
52%37%18%14%3
2205
April1st to 15thDay
57%18%16%10%4
2152
16th to endDay
53%28%18%14%2
2325
May1st to 15thDay
54%29%19%12%1
2447
16th to endDay
57%39%17%10%
2622
June1st to 15thDay
54%313%17%8%1
2679
16th to endDay
58%311%17%8%
2685
July1st to 15thDay
50%416%21%6%
2371
16th to endDay
54%416%18%6%
2487
August1st to 15thDay
54%419%17%4
2455
16th to endDay
44%318%26%7%
2393
September1st to 15thDay
47%215%23%9%
2127
16th to endDay
43%216%28%8%
1980
October1st to 15thDay
56%211%21%8%
1869
16th to endDay
62%311%19%3
1728
November1st to 15thDay
59%210%18%7%
1716
16th to endDay
63%29%17%6%
1530
December1st to 15thDay
65%111%16%5%
1365
16th to endDay
67%36%13%8%
1436
January1st to 15thNight
66%38%16%5%
2506
16th to endNight
61%38%17%8%
2688
February1st to 15thNight
60%29%18%8%1
2360
16th to endNight
61%28%15%10%
1893
March1st to 15thNight
56%29%15%12%2
2160
16th to endNight
48%38%19%15%3
2019
April1st to 15thNight
56%15%18%14%2
1796
16th to endNight
48%39%19%15%3
1634
May1st to 15thNight
53%29%18%14%2
1515
16th to endNight
54%210%19%11%1
1497
June1st to 15thNight
54%411%20%8%1
1278
16th to endNight
51%311%20%12%
1272
July1st to 15thNight
44%419%22%8%
1360
16th to endNight
45%418%20%10%
1418
August1st to 15thNight
47%5%19%23%4
1469
16th to endNight
44%216%28%7%
1808
September1st to 15thNight
45%214%26%10%
1833
16th to endNight
42%215%28%10%
1980
October1st to 15thNight
48%211%25%10%
2088
16th to endNight
58%212%19%6%
2496
November1st to 15thNight
54%312%18%10%
2472
16th to endNight
59%28%20%8%
2753
December1st to 15thNight
68%211%13%4
2925
16th to endNight
69%26%12%7%
2884

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
40%11%26%20%1
60
16th to endDay
29%21%28%12%7%
64
February1st to 15thDay
26%18%28%22%4
109
16th to endDay
25%14%30%21%6%1
239
March1st to 15thDay
30%20%22%18%7%1
270
16th to endDay
22%16%22%25%10%2
288
April1st to 15thDay
34%14%24%18%5%1
270
16th to endDay
32%12%27%14%8%3
270
May1st to 15thDay
38%10%23%17%9%1
288
16th to endDay
27%16%28%20%6%
331
June1st to 15thDay
29%8%28%22%9%1
474
16th to endDay
25%9%26%24%11%1
480
July1st to 15thDay
24%7%31%18%13%2
305
16th to endDay
26%6%22%29%12%2
326
August1st to 15thDay
23%423%30%13%4
313
16th to endDay
22%8%25%19%17%7%
332
September1st to 15thDay
26%6%20%24%14%5%
315
16th to endDay
21%12%21%20%17%6%
314
October1st to 15thDay
31%8%26%20%12%1
307
16th to endDay
38%10%20%20%9%
288
November1st to 15thDay
33%11%22%20%12%
280
16th to endDay
38%13%24%17%5%
135
December1st to 15thDay
42%6%38%10%2
90
16th to endDay
45%15%25%9%4
72
January1st to 15thNight
30%12%29%21%5%
720
16th to endNight
21%14%27%26%8%
768
February1st to 15thNight
16%13%34%26%8%
704
16th to endNight
26%13%28%24%6%
631
March1st to 15thNight
28%11%31%22%5%
720
16th to endNight
23%13%27%24%9%1
768
April1st to 15thNight
33%10%24%24%7%
718
16th to endNight
28%12%27%23%7%
554
May1st to 15thNight
30%7%31%20%8%
435
16th to endNight
29%8%26%27%8%
375
June1st to 15thNight
29%5%22%33%8%
360
16th to endNight
25%317%36%15%
360
July1st to 15thNight
21%219%36%17%1
340
16th to endNight
19%317%41%17%1
376
August1st to 15thNight
20%214%36%25%
398
16th to endNight
19%422%34%18%1
662
September1st to 15thNight
25%321%32%15%1
720
16th to endNight
25%5%21%28%17%1
717
October1st to 15thNight
26%8%25%27%10%
720
16th to endNight
36%10%24%22%7%
768
November1st to 15thNight
28%10%25%24%9%1
760
16th to endNight
34%12%20%21%9%1
797
December1st to 15thNight
35%13%23%21%6%
825
16th to endNight
35%12%25%20%5%1
813
Page generated at 2017-12-21 07:04:53. Version ac04

Copyright 2017 A. Danko


Observatoire Saint-Raymond Clear Sky Chart |Charts Home