Observatoire d'Astronomie Berrada
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatoire d'Astronomie Berrada 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
25%
22683
12%
80895
7%
22593
32%
22593
13%
59195

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
10%
756
8%
4391
2%
737
18%
737
4%
3370
January11th to 20thNight
14%
757
8%
4419
3%
740
22%
740
4%
3435
January21st to endNight
18%
830
7%
4876
6%
814
26%
814
6%
3903
February1st to 10thNight
14%
760
11%
2499
4%
760
22%
760
10%
1904
February11th to 20thNight
13%
743
11%
2348
3%
740
23%
740
9%
1775
February21st to endNight
17%
628
12%
1884
5%
628
27%
628
12%
1408
March1st to 10thNight
17%
751
13%
2251
7%
751
26%
751
13%
1691
March11th to 20thNight
18%
720
14%
2062
5%
720
27%
720
13%
1546
March21st to endNight
24%
792
19%
2004
6%
792
32%
792
19%
1447
April1st to 10thNight
21%
720
14%
1800
4%
720
26%
720
17%
1366
April11th to 20thNight
26%
711
16%
1775
5%
711
33%
711
22%
1265
April21st to endNight
23%
584
15%
1664
6%
584
29%
584
16%
1191
May1st to 10thNight
28%
360
15%
1440
11%
360
40%
360
16%
962
May11th to 20thNight
30%
354
19%
1416
16%
354
44%
354
16%
919
May21st to endNight
27%
389
11%
1551
7%
388
39%
388
17%
989
June1st to 10thNight
28%
360
8%
1440
7%
360
38%
360
15%
975
June11th to 20thNight
38%
360
9%
1440
11%
360
44%
360
17%
931
June21st to endNight
43%
360
9%
1440
12%
360
47%
360
17%
970
July1st to 10thNight
46%
350
11%
1400
14%
350
53%
350
23%
826
July11th to 20thNight
47%
348
12%
1392
16%
348
53%
348
21%
855
July21st to endNight
47%
394
12%
1486
14%
372
51%
372
21%
904
August1st to 10thNight
54%
358
13%
1422
14%
356
59%
356
21%
875
August11th to 20thNight
50%
508
15%
1572
11%
508
54%
508
26%
1017
August21st to endNight
42%
792
15%
1980
7%
792
45%
792
28%
1357
September1st to 10thNight
40%
720
15%
1800
6%
720
44%
720
30%
1213
September11th to 20thNight
45%
720
19%
1851
11%
720
49%
720
31%
1213
September21st to endNight
38%
720
20%
1980
13%
720
44%
720
26%
1332
October1st to 10thNight
31%
720
18%
2137
11%
720
40%
720
18%
1509
October11th to 20thNight
23%
720
13%
2182
7%
720
31%
720
14%
1627
October21st to endNight
19%
792
10%
2574
5%
792
26%
792
11%
1971
November1st to 10thNight
22%
740
13%
2407
6%
740
31%
740
12%
1776
November11th to 20thNight
20%
760
13%
2603
9%
760
26%
760
10%
1969
November21st to endNight
16%
760
9%
2660
5%
760
21%
760
8%
2098
December1st to 10thNight
13%
760
7%
2660
2%
760
19%
760
6%
2219
December11th to 20thNight
12%
760
10%
3246
4%
759
19%
759
5%
2544
December21st to endNight
11%
826
7%
4843
3%
817
18%
817
3%
3843

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%11%5%8%7%3445%6%28%
78341
Night
16%12%5%9%7%45%45%6%28%
81216
TransparencyDay
56%6%11%17%9%1
78046
Night
56%6%11%18%8%1
81045
SeeingDay
25%19%30%17%6%2
13540
Night
23%16%29%22%9%1
22706

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 10thDay
14%16%9%15%9%45%44417%
2517
11th to 20thDay
12%15%7%16%14%6%222420%
2520
21st to endDay
10%14%9%15%7%46%6%5%5%19%
2772
February1st to 10thDay
9%19%7%11%10%4445%6%22%
1677
11th to 20thDay
11%16%8%13%8%34345%24%
1720
21st to endDay
14%18%7%9%7%45%445%23%
1570
March1st to 10thDay
13%13%7%10%8%5%5%446%26%
1867
11th to 20thDay
14%15%5%9%7%45%336%27%
1894
21st to endDay
19%11%47%6%35%445%32%
2350
April1st to 10thDay
19%16%5%8%5%34446%27%
2160
11th to 20thDay
22%10%47%6%3444432%
2134
21st to endDay
21%11%48%6%35%445%29%
2310
May1st to 10thDay
21%10%47%5%25%45%6%30%
2520
11th to 20thDay
20%9%37%7%4445%5%32%
2478
21st to endDay
21%8%46%5%345%5%6%32%
2725
June1st to 10thDay
25%9%36%5%36%5%5%6%27%
2520
11th to 20thDay
18%7%37%7%45%6%5%7%32%
2520
21st to endDay
24%8%36%7%45%5%6%6%26%
2520
July1st to 10thDay
16%6%36%5%36%6%5%8%35%
2520
11th to 20thDay
16%6%36%7%46%6%7%9%32%
2520
21st to endDay
14%8%37%6%45%6%6%9%31%
2744
August1st to 10thDay
16%9%37%6%5%5%6%6%7%29%
2506
11th to 20thDay
17%6%36%6%46%6%6%8%33%
2309
21st to endDay
15%7%37%5%445%6%9%35%
2376
September1st to 10thDay
18%6%35%5%4446%7%38%
2160
11th to 20thDay
17%6%36%435%46%6%40%
2108
21st to endDay
21%8%345%34446%38%
1980
October1st to 10thDay
25%10%35%5%345%46%31%
1819
11th to 20thDay
26%13%5%7%6%3344423%
1777
21st to endDay
27%14%5%7%6%23445%22%
1782
November1st to 10thDay
17%15%5%6%6%3445%5%30%
1671
11th to 20thDay
20%15%7%10%7%345%4421%
1577
21st to endDay
19%19%7%10%7%45%43419%
1520
December1st to 10thDay
21%19%8%11%6%33345%17%
1520
11th to 20thDay
19%17%7%11%8%35%35%5%18%
1906
21st to endDay
20%19%8%10%7%33345%19%
2772
January1st to 10thNight
14%17%9%13%7%36%44419%
4429
11th to 20thNight
10%13%7%14%15%7%4345%18%
4440
21st to endNight
9%14%10%16%9%46%5%45%16%
4884
February1st to 10thNight
11%16%6%11%8%5%5%5%46%23%
2499
11th to 20thNight
11%15%7%12%8%5%6%445%24%
2346
21st to endNight
12%15%6%10%7%45%5%5%7%24%
1884
March1st to 10thNight
14%12%5%9%8%5%6%45%5%27%
2241
11th to 20thNight
16%14%5%8%7%44445%28%
2061
21st to endNight
16%10%36%6%35%45%6%35%
2004
April1st to 10thNight
22%12%47%6%33445%29%
1800
11th to 20thNight
18%9%36%5%245%5%6%36%
1775
21st to endNight
19%10%5%8%5%35%45%6%32%
1664
May1st to 10thNight
20%10%45%5%35%35%6%35%
1440
11th to 20thNight
20%7%35%5%3445%7%37%
1415
21st to endNight
17%7%36%6%345%5%7%38%
1550
June1st to 10thNight
19%8%36%5%45%6%6%8%30%
1440
11th to 20thNight
20%7%35%43445%8%37%
1440
21st to endNight
20%7%35%5%35%45%7%36%
1440
July1st to 10thNight
14%5%26%5%345%5%8%43%
1440
11th to 20thNight
13%6%26%5%35%47%8%41%
1440
21st to endNight
13%5%246%346%7%9%41%
1574
August1st to 10thNight
12%7%36%4346%7%9%39%
1432
11th to 20thNight
12%7%26%5%45%6%5%6%42%
1572
21st to endNight
17%6%35%435%45%8%40%
1980
September1st to 10thNight
16%7%25%42445%7%43%
1800
11th to 20thNight
18%5%2442345%6%45%
1851
21st to endNight
19%7%345%2345%7%42%
1980
October1st to 10thNight
19%9%36%6%35%35%5%37%
2137
11th to 20thNight
24%13%37%5%33445%29%
2182
21st to endNight
25%14%48%5%34346%24%
2574
November1st to 10thNight
18%12%5%8%6%345%5%5%28%
2407
11th to 20thNight
17%13%6%11%7%45%5%5%6%22%
2603
21st to endNight
19%19%5%10%6%35%5%4420%
2660
December1st to 10thNight
18%17%9%14%8%34345%14%
2660
11th to 20thNight
20%16%6%10%8%34335%20%
3288
21st to endNight
20%21%6%10%8%3434417%
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
69%6%10%12%4
2518
11th to 20thDay
70%4414%7%1
2520
21st to endDay
64%8%9%12%6%1
2772
February1st to 10thDay
64%47%16%7%2
1677
11th to 20thDay
62%49%13%10%1
1729
21st to endDay
64%48%13%9%2
1570
March1st to 10thDay
59%5%8%16%10%2
1870
11th to 20thDay
58%410%13%11%2
1894
21st to endDay
53%5%8%17%13%4
2350
April1st to 10thDay
58%410%16%11%3
2160
11th to 20thDay
54%5%8%20%11%2
2134
21st to endDay
57%6%8%15%12%3
2310
May1st to 10thDay
54%5%8%19%12%2
2520
11th to 20thDay
53%5%9%18%14%2
2482
21st to endDay
52%6%10%18%12%1
2725
June1st to 10thDay
56%6%11%16%10%1
2520
11th to 20thDay
50%7%11%19%10%3
2520
21st to endDay
58%7%10%16%9%
2520
July1st to 10thDay
44%8%15%24%9%
2450
11th to 20thDay
45%8%15%23%9%
2445
21st to endDay
47%8%15%21%8%
2591
August1st to 10thDay
51%8%16%21%4
2492
11th to 20thDay
45%10%16%21%7%
2309
21st to endDay
45%6%14%23%11%1
2376
September1st to 10thDay
45%5%14%23%13%
2160
11th to 20thDay
43%7%12%27%10%1
2108
21st to endDay
47%7%12%25%10%
1980
October1st to 10thDay
53%6%11%21%9%1
1819
11th to 20thDay
63%6%10%16%41
1777
21st to endDay
64%411%13%6%1
1782
November1st to 10thDay
54%5%13%19%7%1
1671
11th to 20thDay
64%5%11%12%7%1
1577
21st to endDay
67%6%10%12%41
1520
December1st to 10thDay
70%410%10%5%
1520
11th to 20thDay
67%5%9%13%6%
1906
21st to endDay
68%5%7%13%7%
2772
January1st to 10thNight
65%8%12%12%3
4429
11th to 20thNight
64%8%9%12%5%1
4440
21st to endNight
67%7%9%9%7%1
4884
February1st to 10thNight
61%5%10%17%6%1
2499
11th to 20thNight
60%5%10%16%8%1
2348
21st to endNight
57%5%10%16%10%2
1884
March1st to 10thNight
58%5%10%16%9%2
2251
11th to 20thNight
57%410%14%13%1
2062
21st to endNight
50%49%20%14%4
2004
April1st to 10thNight
55%49%18%12%2
1800
11th to 20thNight
47%6%11%21%14%2
1775
21st to endNight
52%5%9%19%12%2
1664
May1st to 10thNight
50%5%10%18%14%4
1440
11th to 20thNight
46%7%10%18%16%3
1416
21st to endNight
45%7%13%21%12%2
1551
June1st to 10thNight
49%8%13%22%9%
1440
11th to 20thNight
46%7%12%22%12%2
1440
21st to endNight
47%8%13%20%11%
1440
July1st to 10thNight
37%8%17%26%12%1
1400
11th to 20thNight
40%8%16%27%9%1
1392
21st to endNight
38%9%19%25%9%
1486
August1st to 10thNight
37%10%20%26%7%
1422
11th to 20thNight
39%8%18%25%10%
1572
21st to endNight
39%8%16%26%9%
1980
September1st to 10thNight
39%6%15%26%13%1
1800
11th to 20thNight
38%6%15%31%9%1
1851
21st to endNight
41%7%13%28%10%
1980
October1st to 10thNight
49%6%9%23%12%1
2137
11th to 20thNight
57%5%13%19%7%
2182
21st to endNight
61%5%12%15%7%1
2574
November1st to 10thNight
55%7%13%18%6%1
2407
11th to 20thNight
59%6%11%15%6%2
2603
21st to endNight
65%6%11%13%5%
2660
December1st to 10thNight
72%5%9%10%4
2660
11th to 20thNight
67%48%14%6%1
3288
21st to endNight
69%5%7%12%6%
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
20%23%38%17%2
180
11th to 20thDay
28%22%33%12%5%1
180
21st to endDay
23%20%39%15%31
198
February1st to 10thDay
29%33%30%5%3
255
11th to 20thDay
27%28%38%7%
327
21st to endDay
29%26%31%13%2
382
March1st to 10thDay
26%24%31%16%3
448
11th to 20thDay
28%24%31%13%31
420
21st to endDay
33%20%25%15%5%2
462
April1st to 10thDay
31%17%31%13%6%1
420
11th to 20thDay
33%20%22%15%9%1
412
21st to endDay
30%21%30%14%31
420
May1st to 10thDay
28%22%31%15%31
423
11th to 20thDay
26%20%30%17%6%2
447
21st to endDay
25%20%32%18%5%1
485
June1st to 10thDay
28%16%35%14%6%
450
11th to 20thDay
21%21%29%19%8%2
450
21st to endDay
26%16%32%18%7%1
450
July1st to 10thDay
17%11%38%25%7%3
445
11th to 20thDay
16%13%37%27%6%1
444
21st to endDay
17%11%35%28%7%2
488
August1st to 10thDay
18%12%30%27%12%2
446
11th to 20thDay
17%8%31%26%11%6%
439
21st to endDay
17%20%27%18%11%7%
495
September1st to 10thDay
19%14%30%20%11%5%
450
11th to 20thDay
15%15%27%24%12%6%
450
21st to endDay
22%18%24%20%10%6%
450
October1st to 10thDay
29%16%25%18%9%3
450
11th to 20thDay
32%23%23%15%6%1
438
21st to endDay
36%14%29%16%4
396
November1st to 10thDay
33%19%27%16%41
365
11th to 20thDay
28%23%31%12%6%
237
21st to endDay
30%31%27%11%2
180
December1st to 10thDay
33%18%29%15%31
180
11th to 20thDay
27%32%30%8%21
180
21st to endDay
33%26%25%11%41
198
January1st to 10thNight
24%22%34%15%4
760
11th to 20thNight
26%21%29%18%5%
760
21st to endNight
16%18%38%21%6%1
836
February1st to 10thNight
19%24%34%19%4
760
11th to 20thNight
21%23%38%15%3
743
21st to endNight
23%20%34%21%3
628
March1st to 10thNight
24%19%33%19%4
751
11th to 20thNight
26%21%30%17%5%1
720
21st to endNight
25%17%30%22%6%1
792
April1st to 10thNight
29%17%26%22%5%
720
11th to 20thNight
24%18%28%23%6%1
711
21st to endNight
26%15%31%19%8%1
584
May1st to 10thNight
24%13%30%23%9%2
360
11th to 20thNight
21%14%29%28%7%1
354
21st to endNight
20%12%38%23%8%
389
June1st to 10thNight
23%9%33%28%7%
360
11th to 20thNight
20%10%26%31%13%1
360
21st to endNight
21%6%23%34%15%1
360
July1st to 10thNight
15%6%27%35%16%
350
11th to 20thNight
14%6%27%36%18%1
348
21st to endNight
13%7%27%37%14%1
394
August1st to 10thNight
15%5%19%42%18%
358
11th to 20thNight
12%6%24%34%23%1
508
21st to endNight
17%9%27%27%17%3
792
September1st to 10thNight
16%10%28%30%14%1
720
11th to 20thNight
19%8%23%31%18%1
720
21st to endNight
21%12%25%24%16%2
720
October1st to 10thNight
23%14%25%23%13%1
720
11th to 20thNight
29%14%27%21%8%1
720
21st to endNight
29%18%27%21%5%
792
November1st to 10thNight
26%19%28%19%6%1
740
11th to 20thNight
24%21%29%16%8%1
760
21st to endNight
30%23%26%16%41
760
December1st to 10thNight
29%20%27%17%6%1
760
11th to 20thNight
29%23%26%15%5%1
760
21st to endNight
33%21%27%15%4
836
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