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 2024-11-02.

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%
23345
11%
96002
7%
23158
32%
23158
11%
68899

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
13%
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%
755
14%
3705
7%
743
25%
743
8%
2625
March11th to 20thNight
18%
755
13%
3602
5%
740
27%
740
8%
2667
March21st to endNight
23%
834
12%
3418
6%
814
32%
814
12%
2319
April1st to 10thNight
21%
760
14%
1900
4%
760
26%
760
18%
1439
April11th to 20thNight
25%
751
15%
1875
5%
751
31%
751
21%
1357
April21st to endNight
23%
615
14%
1755
6%
615
29%
615
16%
1253
May1st to 10thNight
27%
380
13%
2510
11%
376
39%
376
9%
1695
May11th to 20thNight
30%
368
13%
2480
16%
364
44%
364
10%
1511
May21st to endNight
26%
407
8%
2731
7%
399
38%
399
10%
1736
June1st to 10thNight
29%
380
8%
1520
7%
380
38%
380
15%
1029
June11th to 20thNight
38%
380
9%
1520
10%
380
44%
380
17%
974
June21st to endNight
41%
380
9%
1520
11%
380
45%
380
16%
1035
July1st to 10thNight
45%
364
8%
2444
14%
360
52%
360
12%
1565
July11th to 20thNight
46%
363
8%
2355
16%
358
52%
358
13%
1444
July21st to endNight
47%
408
9%
2373
14%
383
51%
383
15%
1324
August1st to 10thNight
53%
372
12%
2299
14%
365
59%
365
12%
1479
August11th to 20thNight
48%
528
11%
2669
11%
520
53%
520
16%
1723
August21st to endNight
41%
824
12%
3255
7%
814
45%
814
18%
2163
September1st to 10thNight
40%
760
17%
1900
6%
760
44%
760
31%
1273
September11th to 20thNight
47%
760
18%
1954
11%
760
51%
760
33%
1265
September21st to endNight
38%
760
20%
2090
13%
760
44%
760
26%
1406
October1st to 10thNight
32%
760
18%
2256
11%
760
40%
760
18%
1591
October11th to 20thNight
23%
760
12%
2304
6%
760
31%
760
15%
1706
October21st to endNight
19%
836
11%
2717
5%
836
27%
836
12%
2062
November1st to 10thNight
22%
745
13%
2421
6%
745
31%
745
12%
1790
November11th to 20thNight
20%
760
13%
2603
9%
760
26%
760
10%
1969
November21st to endNight
15%
760
8%
2660
5%
760
20%
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
6%
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
17%12%49%5%5%445%6%29%
101561
Night
17%13%5%10%6%5%435%6%29%
97410
TransparencyDay
54%6%12%18%9%1
101322
Night
55%6%12%17%8%1
97269
SeeingDay
25%19%30%17%6%2
14482
Night
23%16%29%23%9%1
23436

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%17%8%17%7%6%434417%
2517
11th to 20thDay
12%16%6%18%12%6%223420%
2520
21st to endDay
10%15%9%16%5%5%5%5%5%5%19%
2772
February1st to 10thDay
9%20%6%12%9%6%3346%21%
1677
11th to 20thDay
11%17%7%14%7%45%245%24%
1720
21st to endDay
14%19%6%10%7%45%35%5%23%
1570
March1st to 10thDay
16%19%5%11%6%5%434424%
3116
11th to 20thDay
11%20%6%14%7%44235%23%
3338
21st to endDay
13%12%39%5%5%435%6%35%
4126
April1st to 10thDay
18%18%5%9%433346%27%
2280
11th to 20thDay
23%11%48%5%4334431%
2254
21st to endDay
21%12%48%5%44345%29%
2440
May1st to 10thDay
21%11%38%5%45%45%6%28%
4426
11th to 20thDay
19%8%37%5%5%5%47%8%29%
4398
21st to endDay
19%8%38%5%5%446%6%33%
4837
June1st to 10thDay
24%10%27%45%6%46%5%26%
2660
11th to 20thDay
18%7%37%6%5%5%5%5%7%31%
2660
21st to endDay
25%9%37%6%6%5%46%6%25%
2660
July1st to 10thDay
15%8%39%6%5%6%5%6%8%29%
4440
11th to 20thDay
16%7%37%6%5%5%47%8%33%
4440
21st to endDay
14%6%26%445%45%7%42%
4814
August1st to 10thDay
16%7%28%6%6%6%5%6%8%29%
4423
11th to 20thDay
18%7%37%445%5%6%7%33%
4047
21st to endDay
16%6%37%5%5%5%47%8%35%
4180
September1st to 10thDay
18%7%26%45%435%7%39%
2280
11th to 20thDay
16%7%26%44435%7%42%
2225
21st to endDay
21%9%26%344346%38%
2090
October1st to 10thDay
24%10%36%43445%5%31%
1920
11th to 20thDay
24%14%48%5%4435%424%
1875
21st to endDay
26%15%47%5%34345%23%
1881
November1st to 10thDay
17%16%47%5%4435%5%29%
1680
11th to 20thDay
20%16%6%11%6%3444421%
1577
21st to endDay
18%20%6%12%6%5%433419%
1520
December1st to 10thDay
20%21%6%13%5%43335%17%
1520
11th to 20thDay
19%19%6%12%6%4435%5%18%
1906
21st to endDay
20%19%7%12%5%43245%19%
2772
January1st to 10thNight
13%18%8%14%5%5%5%34419%
4429
11th to 20thNight
10%14%6%16%12%8%3345%18%
4440
21st to endNight
9%14%10%18%7%6%5%45%5%16%
4884
February1st to 10thNight
11%17%6%13%8%6%5%446%22%
2499
11th to 20thNight
10%16%7%13%6%6%5%35%424%
2346
21st to endNight
12%16%6%11%6%45%45%6%24%
1884
March1st to 10thNight
18%14%5%9%5%5%434427%
3724
11th to 20thNight
13%20%6%12%5%4424426%
3617
21st to endNight
13%12%410%6%5%4345%33%
3504
April1st to 10thNight
21%13%38%5%43345%29%
1900
11th to 20thNight
19%10%36%43445%6%35%
1875
21st to endNight
19%10%48%44435%5%33%
1755
May1st to 10thNight
19%11%47%5%5%5%45%6%30%
2514
11th to 20thNight
20%8%27%444347%37%
2495
21st to endNight
19%7%37%6%5%5%45%7%32%
2738
June1st to 10thNight
19%9%37%5%5%5%46%7%30%
1520
11th to 20thNight
19%8%26%44436%7%38%
1520
21st to endNight
21%7%36%45%436%6%35%
1520
July1st to 10thNight
16%6%38%6%5%5%46%7%33%
2520
11th to 20thNight
17%7%36%5%4446%7%38%
2520
21st to endNight
12%425%44446%8%46%
2739
August1st to 10thNight
14%7%38%5%4446%7%38%
2506
11th to 20thNight
19%9%27%44435%5%38%
2748
21st to endNight
19%6%26%45%435%6%39%
3476
September1st to 10thNight
15%7%26%44335%7%44%
1900
11th to 20thNight
17%5%25%33335%6%47%
1954
21st to endNight
18%8%25%5%2335%7%42%
2090
October1st to 10thNight
19%9%27%5%5%425%5%37%
2256
11th to 20thNight
23%13%38%5%44345%29%
2304
21st to endNight
24%14%49%44435%6%24%
2717
November1st to 10thNight
18%13%5%9%5%5%445%5%27%
2421
11th to 20thNight
16%15%5%12%6%5%445%6%22%
2603
21st to endNight
19%20%5%12%5%35%44420%
2660
December1st to 10thNight
18%19%8%15%7%5%3345%14%
2660
11th to 20thNight
20%18%5%12%7%5%4235%20%
3288
21st to endNight
20%21%6%12%6%4334417%
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
62%7%6%13%11%1
3119
11th to 20thDay
63%5%10%11%10%2
3338
21st to endDay
48%5%9%19%17%2
4126
April1st to 10thDay
58%410%16%11%3
2280
11th to 20thDay
54%6%8%20%11%2
2254
21st to endDay
56%6%8%15%12%3
2440
May1st to 10thDay
54%7%9%20%8%1
4440
11th to 20thDay
49%9%17%16%8%1
4402
21st to endDay
49%7%10%19%14%1
4837
June1st to 10thDay
56%6%11%16%10%1
2660
11th to 20thDay
49%7%12%19%10%3
2660
21st to endDay
58%7%10%16%8%
2660
July1st to 10thDay
48%8%15%21%7%
4370
11th to 20thDay
44%8%19%23%6%
4365
21st to endDay
40%7%15%29%9%
4661
August1st to 10thDay
50%8%16%20%5%
4409
11th to 20thDay
46%9%16%25%5%
4089
21st to endDay
44%7%16%20%12%1
4180
September1st to 10thDay
44%6%14%24%12%
2280
11th to 20thDay
41%7%13%28%10%1
2225
21st to endDay
47%7%11%25%10%
2090
October1st to 10thDay
53%6%11%22%9%1
1920
11th to 20thDay
62%6%10%17%5%1
1875
21st to endDay
63%412%13%7%1
1881
November1st to 10thDay
54%5%13%19%7%1
1680
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
57%6%11%12%11%3
3734
11th to 20thNight
60%6%9%12%12%1
3618
21st to endNight
52%49%19%13%4
3504
April1st to 10thNight
55%49%18%12%2
1900
11th to 20thNight
48%6%10%21%13%2
1875
21st to endNight
52%6%9%19%13%2
1755
May1st to 10thNight
51%9%13%17%8%2
2520
11th to 20thNight
45%9%17%16%12%2
2496
21st to endNight
49%7%11%19%13%2
2739
June1st to 10thNight
49%8%12%21%9%
1520
11th to 20thNight
45%7%13%21%12%2
1520
21st to endNight
49%8%12%19%12%1
1520
July1st to 10thNight
48%7%17%19%9%
2480
11th to 20thNight
42%8%20%24%5%
2472
21st to endNight
34%8%20%26%11%
2651
August1st to 10thNight
43%8%16%26%7%
2496
11th to 20thNight
45%7%20%22%6%
2772
21st to endNight
43%8%15%23%10%2
3476
September1st to 10thNight
39%6%15%26%13%1
1900
11th to 20thNight
37%6%16%31%9%1
1954
21st to endNight
41%7%13%28%11%
2090
October1st to 10thNight
49%6%10%23%12%1
2256
11th to 20thNight
56%5%13%19%7%
2304
21st to endNight
60%5%12%15%7%1
2717
November1st to 10thNight
56%7%13%18%6%1
2421
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
27%23%31%16%3
460
11th to 20thDay
27%25%32%13%31
460
21st to endDay
33%22%26%14%5%1
506
April1st to 10thDay
31%18%31%13%5%1
460
11th to 20thDay
34%21%22%14%8%1
452
21st to endDay
31%22%30%13%31
460
May1st to 10thDay
28%22%31%15%31
463
11th to 20thDay
24%19%30%19%6%1
487
21st to endDay
25%20%31%18%5%1
529
June1st to 10thDay
28%16%34%16%6%1
490
11th to 20thDay
20%21%30%19%8%2
490
21st to endDay
28%17%31%17%7%1
490
July1st to 10thDay
17%11%39%24%7%2
485
11th to 20thDay
16%13%38%26%6%1
484
21st to endDay
17%11%36%27%7%2
532
August1st to 10thDay
19%12%30%27%11%1
486
11th to 20thDay
18%9%30%26%11%6%
479
21st to endDay
17%19%28%19%10%6%
539
September1st to 10thDay
20%15%30%20%10%5%
490
11th to 20thDay
14%14%26%25%14%8%
490
21st to endDay
22%17%24%20%11%6%
490
October1st to 10thDay
29%17%25%18%9%3
490
11th to 20thDay
32%23%23%15%6%1
476
21st to endDay
35%15%29%17%4
429
November1st to 10thDay
34%19%27%16%41
368
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
25%19%33%20%4
760
11th to 20thNight
25%22%30%17%41
760
21st to endNight
24%17%31%22%6%1
836
April1st to 10thNight
29%17%27%22%5%
760
11th to 20thNight
25%19%28%22%6%1
751
21st to endNight
27%14%31%19%8%
615
May1st to 10thNight
23%13%31%23%8%2
380
11th to 20thNight
21%14%28%29%7%1
374
21st to endNight
19%13%37%23%7%
411
June1st to 10thNight
23%9%32%29%8%
380
11th to 20thNight
20%10%25%31%13%1
380
21st to endNight
23%6%23%33%14%1
380
July1st to 10thNight
16%6%27%36%15%
370
11th to 20thNight
13%6%27%36%17%1
368
21st to endNight
14%7%26%38%14%1
416
August1st to 10thNight
15%5%19%43%17%
378
11th to 20thNight
13%6%23%33%23%1
537
21st to endNight
17%9%26%28%17%3
836
September1st to 10thNight
16%10%29%31%14%1
760
11th to 20thNight
18%8%22%31%20%2
760
21st to endNight
21%12%25%24%17%2
760
October1st to 10thNight
23%14%25%23%14%1
760
11th to 20thNight
28%14%28%21%8%1
760
21st to endNight
29%18%27%21%5%
836
November1st to 10thNight
26%19%28%19%6%1
745
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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