Rue de Renard Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rue de Renard Observatory clear sky chart from 2005-11-06 to 2024-03-08.

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
43%
24312
21%
80262
15%
24204
50%
24204
24%
51581

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 10thNight
23%
945
16%
4348
8%
926
32%
926
12%
2823
January11th to 20thNight
17%
950
17%
4318
6%
930
25%
930
9%
3085
January21st to endNight
20%
910
12%
4339
7%
893
32%
893
11%
3038
February1st to 10thNight
21%
760
17%
2280
7%
760
30%
760
16%
1677
February11th to 20thNight
19%
743
18%
2219
8%
740
27%
740
19%
1551
February21st to endNight
16%
628
16%
1884
5%
628
26%
628
17%
1352
March1st to 10thNight
28%
751
20%
2251
11%
751
35%
751
22%
1480
March11th to 20thNight
26%
720
16%
2089
9%
720
32%
720
21%
1458
March21st to endNight
32%
648
15%
2034
9%
648
38%
648
18%
1423
April1st to 10thNight
38%
540
24%
1800
14%
540
51%
540
28%
1042
April11th to 20thNight
38%
533
24%
1775
17%
533
50%
533
25%
1086
April21st to endNight
39%
540
19%
1760
14%
540
47%
540
23%
1131
May1st to 10thNight
40%
540
19%
1620
12%
540
47%
540
26%
1055
May11th to 20thNight
50%
531
18%
1593
13%
531
54%
531
25%
1046
May21st to endNight
63%
582
18%
1744
14%
582
66%
582
31%
1066
June1st to 10thNight
62%
540
21%
1467
16%
540
64%
540
36%
902
June11th to 20thNight
73%
540
26%
1440
19%
540
76%
540
45%
805
June21st to endNight
72%
540
24%
1440
18%
540
75%
540
43%
835
July1st to 10thNight
70%
525
20%
1400
16%
525
71%
525
37%
870
July11th to 20thNight
73%
522
21%
1392
17%
522
75%
522
38%
851
July21st to endNight
68%
591
22%
1606
20%
558
71%
558
33%
990
August1st to 10thNight
74%
537
23%
1693
24%
534
74%
534
35%
977
August11th to 20thNight
72%
534
21%
1776
23%
534
73%
534
31%
1018
August21st to endNight
75%
594
26%
1980
29%
594
76%
594
36%
1087
September1st to 10thNight
66%
540
25%
1800
27%
540
68%
540
32%
1031
September11th to 20thNight
66%
702
29%
1962
24%
702
69%
702
36%
1175
September21st to endNight
59%
720
31%
1980
22%
720
64%
720
40%
1146
October1st to 10thNight
60%
720
33%
1980
25%
720
66%
720
42%
1119
October11th to 20thNight
44%
720
27%
2066
17%
720
54%
720
31%
1276
October21st to endNight
38%
792
25%
2556
18%
792
48%
792
25%
1598
November1st to 10thNight
46%
740
28%
2406
25%
740
55%
740
32%
1364
November11th to 20thNight
35%
760
28%
2470
18%
760
48%
760
30%
1428
November21st to endNight
37%
760
25%
2470
19%
760
47%
760
25%
1507
December1st to 10thNight
29%
760
17%
2470
11%
760
38%
760
18%
1715
December11th to 20thNight
30%
816
20%
3050
12%
815
39%
815
17%
2027
December21st to endNight
22%
1038
11%
4804
7%
1026
31%
1026
10%
3547

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
14%7%36%6%35%5%5%7%40%
78702
Night
15%8%35%5%3445%7%42%
80876
TransparencyDay
43%6%11%22%15%3
78412
Night
42%5%10%22%17%3
80687
SeeingDay
17%10%23%24%17%8%
14376
Night
18%9%24%29%18%2
24332

By Month

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 10thDay
13%12%8%8%7%445%4431%
2527
11th to 20thDay
19%9%48%8%36%435%31%
2530
21st to endDay
26%13%7%4424345%27%
3246
February1st to 10thDay
17%11%47%5%3435%6%35%
1900
11th to 20thDay
19%9%5%6%7%33445%36%
1848
21st to endDay
17%11%47%6%2445%6%34%
1570
March1st to 10thDay
18%9%35%4345%45%40%
1870
11th to 20thDay
20%10%37%6%33446%34%
1869
21st to endDay
18%9%48%7%35%5%46%32%
2335
April1st to 10thDay
13%5%36%5%3445%8%44%
2160
11th to 20thDay
14%8%35%6%3445%5%41%
2134
21st to endDay
17%7%35%5%45%447%41%
2198
May1st to 10thDay
17%6%26%7%3445%7%38%
2340
11th to 20thDay
16%7%37%5%3445%8%38%
2301
21st to endDay
8%5%35%7%46%7%8%9%38%
2531
June1st to 10thDay
9%5%25%5%35%5%7%8%47%
2488
11th to 20thDay
5%3245%45%7%7%10%48%
2520
21st to endDay
6%4245%47%6%8%11%43%
2520
July1st to 10thDay
10%6%26%6%47%7%7%11%34%
2520
11th to 20thDay
7%5%25%7%35%7%7%9%43%
2520
21st to endDay
9%425%6%46%6%8%10%39%
2613
August1st to 10thDay
8%5%35%6%36%5%7%11%40%
2230
11th to 20thDay
10%5%26%6%36%5%6%9%40%
2125
21st to endDay
8%4246%35%6%6%10%45%
2376
September1st to 10thDay
11%6%26%5%346%5%9%42%
2160
11th to 20thDay
12%435%5%45%5%5%7%46%
1980
21st to endDay
10%6%25%43345%6%52%
1980
October1st to 10thDay
11%5%2442445%6%55%
1980
11th to 20thDay
13%424434436%51%
1890
21st to endDay
21%7%24423445%45%
1800
November1st to 10thDay
11%5%25%423335%56%
1672
11th to 20thDay
16%6%34424346%47%
1710
21st to endDay
17%8%35%42445%5%44%
1710
December1st to 10thDay
19%11%35%43445%6%36%
1710
11th to 20thDay
16%12%5%6%5%44445%34%
2056
21st to endDay
17%14%46%6%35%45%7%28%
2783
January1st to 10thNight
18%11%47%5%24446%35%
4428
11th to 20thNight
17%13%5%8%7%35%33432%
4440
21st to endNight
24%13%45%423347%30%
4393
February1st to 10thNight
23%10%47%5%3434433%
2280
11th to 20thNight
20%8%47%5%33436%37%
2218
21st to endNight
21%10%47%5%24345%34%
1884
March1st to 10thNight
17%9%3442445%5%42%
2251
11th to 20thNight
18%10%37%5%2445%6%37%
2089
21st to endNight
19%9%35%5%3445%7%35%
2034
April1st to 10thNight
12%425%4245%6%7%48%
1800
11th to 20thNight
16%6%25%43345%7%45%
1775
21st to endNight
14%6%36%5%345%6%8%39%
1760
May1st to 10thNight
16%6%36%43345%8%42%
1620
11th to 20thNight
12%6%35%6%446%6%8%40%
1592
21st to endNight
6%4246%37%6%7%11%45%
1744
June1st to 10thNight
10%5%33435%5%5%9%47%
1467
11th to 20thNight
5%2234345%7%10%54%
1440
21st to endNight
3324335%5%7%15%51%
1440
July1st to 10thNight
8%4245%346%6%12%46%
1440
11th to 20thNight
8%4244346%8%10%49%
1440
21st to endNight
8%4246%36%5%7%10%46%
1701
August1st to 10thNight
8%5%245%25%45%8%52%
1704
11th to 20thNight
6%425%5%35%6%8%9%47%
1776
21st to endNight
7%424435%45%9%54%
1980
September1st to 10thNight
12%4345%3446%6%51%
1800
11th to 20thNight
10%435%435%5%5%6%51%
1962
21st to endNight
10%42442445%7%56%
1980
October1st to 10thNight
9%423323446%60%
1980
11th to 20thNight
17%5%24423445%51%
2066
21st to endNight
18%7%25%434336%45%
2556
November1st to 10thNight
13%5%24424335%54%
2406
11th to 20thNight
14%5%24434346%50%
2470
21st to endNight
18%6%25%423346%46%
2470
December1st to 10thNight
21%11%46%42445%5%35%
2470
11th to 20thNight
18%10%46%434445%38%
3136
21st to endNight
17%14%5%8%6%45%5%45%26%
4884

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 10thDay
56%5%8%21%9%1
2528
11th to 20thDay
58%38%20%10%1
2530
21st to endDay
60%47%20%8%1
3246
February1st to 10thDay
51%39%22%13%2
1900
11th to 20thDay
52%47%21%13%4
1858
21st to endDay
51%5%9%15%15%5%
1570
March1st to 10thDay
47%47%22%17%3
1870
11th to 20thDay
53%49%21%10%2
1869
21st to endDay
53%6%10%19%10%2
2335
April1st to 10thDay
39%5%11%24%19%2
2160
11th to 20thDay
44%49%21%19%3
2134
21st to endDay
43%5%11%25%13%2
2198
May1st to 10thDay
45%7%11%25%11%1
2340
11th to 20thDay
45%8%11%21%14%1
2305
21st to endDay
38%11%16%21%11%2
2531
June1st to 10thDay
34%7%12%24%20%2
2488
11th to 20thDay
29%9%15%26%19%2
2520
21st to endDay
31%9%15%24%16%5%
2520
July1st to 10thDay
39%10%13%21%13%4
2451
11th to 20thDay
35%10%15%22%15%3
2445
21st to endDay
35%10%16%25%12%2
2468
August1st to 10thDay
35%10%16%25%14%
2217
11th to 20thDay
39%9%11%23%16%2
2125
21st to endDay
34%9%13%24%17%5%
2376
September1st to 10thDay
38%7%11%22%18%3
2160
11th to 20thDay
37%7%10%22%22%2
1980
21st to endDay
32%5%8%26%23%5%
1980
October1st to 10thDay
31%5%9%23%27%5%
1980
11th to 20thDay
36%5%7%22%24%6%
1890
21st to endDay
42%47%24%19%4
1800
November1st to 10thDay
32%48%26%25%5%
1672
11th to 20thDay
39%38%24%21%5%
1710
21st to endDay
43%37%26%17%4
1710
December1st to 10thDay
49%410%23%12%2
1710
11th to 20thDay
53%49%20%12%1
2053
21st to endDay
54%6%12%17%10%
2783
January1st to 10thNight
51%49%24%12%1
4428
11th to 20thNight
58%36%19%11%2
4440
21st to endNight
57%38%20%11%1
4393
February1st to 10thNight
57%38%19%12%1
2280
11th to 20thNight
51%47%20%15%3
2219
21st to endNight
54%48%15%15%4
1884
March1st to 10thNight
44%5%8%17%21%5%
2251
11th to 20thNight
49%410%22%12%2
2089
21st to endNight
50%6%10%21%12%2
2034
April1st to 10thNight
34%5%12%26%19%3
1800
11th to 20thNight
39%5%10%18%22%6%
1775
21st to endNight
42%7%9%23%17%2
1760
May1st to 10thNight
42%5%10%25%16%2
1620
11th to 20thNight
40%8%13%23%15%1
1593
21st to endNight
30%12%16%23%16%3
1745
June1st to 10thNight
33%6%13%24%21%3
1467
11th to 20thNight
23%8%17%25%23%4
1440
21st to endNight
23%10%18%26%18%6%
1440
July1st to 10thNight
30%9%15%27%16%4
1400
11th to 20thNight
28%9%16%24%17%5%
1392
21st to endNight
31%10%15%28%15%2
1606
August1st to 10thNight
30%7%14%28%20%1
1693
11th to 20thNight
29%10%15%26%18%2
1776
21st to endNight
27%7%13%28%20%5%
1980
September1st to 10thNight
32%7%10%25%22%5%
1800
11th to 20thNight
32%5%9%24%24%5%
1962
21st to endNight
29%5%8%23%28%7%
1980
October1st to 10thNight
27%5%8%23%31%6%
1980
11th to 20thNight
37%48%20%24%7%
2066
21st to endNight
42%46%22%21%5%
2556
November1st to 10thNight
34%47%24%25%6%
2406
11th to 20thNight
35%48%23%22%8%
2470
21st to endNight
41%38%25%20%3
2470
December1st to 10thNight
51%5%10%21%12%2
2470
11th to 20thNight
49%48%20%17%2
3138
21st to endNight
59%5%10%15%9%2
4884

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 10thDay
24%22%31%18%4
270
11th to 20thDay
28%27%29%12%3
270
21st to endDay
25%23%38%10%3
297
February1st to 10thDay
25%24%31%16%21
270
11th to 20thDay
31%26%33%8%3
270
21st to endDay
33%24%28%11%3
225
March1st to 10thDay
29%19%37%13%3
261
11th to 20thDay
30%20%30%13%6%1
309
21st to endDay
28%19%29%15%8%
462
April1st to 10thDay
18%20%27%25%10%
420
11th to 20thDay
22%13%29%23%12%2
412
21st to endDay
24%13%33%18%10%2
420
May1st to 10thDay
22%13%28%24%9%3
423
11th to 20thDay
19%10%24%29%11%7%
447
21st to endDay
11%5%20%32%19%13%
485
June1st to 10thDay
11%5%21%26%26%12%
598
11th to 20thDay
45%19%33%28%11%
630
21st to endDay
7%323%31%23%13%
630
July1st to 10thDay
12%214%29%24%19%
621
11th to 20thDay
8%415%30%28%16%
618
21st to endDay
10%213%30%28%17%
554
August1st to 10thDay
13%212%31%27%15%
446
11th to 20thDay
14%216%31%27%10%
439
21st to endDay
11%211%25%35%17%
495
September1st to 10thDay
12%215%24%35%12%
450
11th to 20thDay
12%212%27%32%15%
450
21st to endDay
15%8%19%23%24%11%
450
October1st to 10thDay
12%422%31%23%8%
450
11th to 20thDay
15%14%32%25%11%4
360
21st to endDay
30%12%27%22%7%2
297
November1st to 10thDay
15%11%36%22%12%3
270
11th to 20thDay
19%19%30%24%7%1
270
21st to endDay
26%13%31%21%8%2
270
December1st to 10thDay
25%20%28%19%6%1
270
11th to 20thDay
24%17%32%21%6%
270
21st to endDay
28%21%33%16%3
297
January1st to 10thNight
25%17%29%24%4
950
11th to 20thNight
29%16%32%18%4
950
21st to endNight
24%16%36%22%2
915
February1st to 10thNight
28%14%32%23%3
760
11th to 20thNight
27%16%35%20%2
743
21st to endNight
27%18%36%17%2
628
March1st to 10thNight
24%15%30%28%4
751
11th to 20thNight
24%13%32%24%6%
720
21st to endNight
23%11%29%29%7%
648
April1st to 10thNight
16%12%31%33%8%1
540
11th to 20thNight
20%8%31%28%12%1
533
21st to endNight
17%8%31%33%11%1
540
May1st to 10thNight
20%7%28%28%15%1
540
11th to 20thNight
14%6%23%34%19%4
531
21st to endNight
7%318%36%32%4
584
June1st to 10thNight
11%317%35%30%4
540
11th to 20thNight
6%214%42%34%3
540
21st to endNight
4216%40%34%5%
540
July1st to 10thNight
9%110%30%40%10%
525
11th to 20thNight
8%29%26%47%7%
522
21st to endNight
9%212%34%37%7%
591
August1st to 10thNight
8%18%32%44%8%
537
11th to 20thNight
7%12%37%39%5%
534
21st to endNight
8%18%30%45%7%
594
September1st to 10thNight
13%211%32%37%6%
540
11th to 20thNight
10%310%31%39%7%
702
21st to endNight
11%320%30%30%5%
720
October1st to 10thNight
13%417%32%28%5%
720
11th to 20thNight
19%7%25%31%17%1
720
21st to endNight
22%8%29%27%14%1
792
November1st to 10thNight
15%9%26%33%16%1
740
11th to 20thNight
16%12%32%28%11%
760
21st to endNight
22%13%24%28%13%1
760
December1st to 10thNight
28%10%27%28%6%
760
11th to 20thNight
24%12%29%26%8%1
817
21st to endNight
28%15%30%23%4
1045
Page generated at 2024-03-05 06:24:04. Version ac07

Copyright © 2024 Attilla Danko.


Rue de Renard Observatory Clear Sky Chart |Charts Home