Parc de la Frayère
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Parc de la Frayère clear sky chart from 2005-11-06 to 2025-04-26.

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
30%
24038
11%
114811
9%
23666
37%
23666
11%
81409

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
19%
791
7%
6286
6%
757
26%
757
3%
4855
January11th to 20thNight
19%
786
7%
6251
6%
760
25%
760
4%
4830
January21st to endNight
24%
864
11%
6776
8%
836
33%
836
6%
4909
February1st to 10thNight
18%
800
11%
2660
5%
800
26%
800
11%
2055
February11th to 20thNight
20%
782
12%
2420
5%
780
30%
780
13%
1829
February21st to endNight
25%
660
15%
1980
8%
660
36%
660
16%
1465
March1st to 10thNight
25%
792
14%
5020
9%
763
33%
763
7%
3654
March11th to 20thNight
25%
788
11%
4909
7%
760
33%
760
7%
3345
March21st to endNight
27%
875
12%
4639
8%
836
36%
836
10%
3325
April1st to 10thNight
26%
800
15%
2000
5%
800
31%
800
19%
1514
April11th to 20thNight
26%
791
14%
1975
4%
791
32%
791
21%
1463
April21st to endNight
26%
609
16%
1783
7%
609
34%
609
19%
1253
May1st to 10thNight
29%
446
14%
2614
11%
443
38%
443
10%
1770
May11th to 20thNight
32%
369
12%
2466
17%
364
43%
364
9%
1580
May21st to endNight
31%
407
9%
2721
10%
399
43%
399
12%
1586
June1st to 10thNight
36%
380
10%
1520
10%
380
44%
380
16%
1012
June11th to 20thNight
42%
380
10%
1520
12%
380
48%
380
19%
956
June21st to endNight
40%
380
9%
1520
12%
380
45%
380
16%
1033
July1st to 10thNight
47%
366
9%
2423
15%
360
55%
360
13%
1486
July11th to 20thNight
53%
362
10%
2291
18%
358
57%
358
14%
1350
July21st to endNight
51%
409
9%
2427
15%
383
55%
383
14%
1388
August1st to 10thNight
55%
372
14%
2310
18%
365
59%
365
12%
1551
August11th to 20thNight
52%
543
12%
2678
11%
536
56%
536
16%
1766
August21st to endNight
50%
823
14%
3281
10%
814
52%
814
19%
2215
September1st to 10thNight
48%
760
16%
1900
8%
760
50%
760
31%
1290
September11th to 20thNight
51%
760
19%
1990
11%
760
54%
760
34%
1258
September21st to endNight
43%
760
22%
2090
15%
760
48%
760
27%
1398
October1st to 10thNight
38%
760
14%
3148
13%
740
47%
740
15%
2200
October11th to 20thNight
32%
760
11%
3074
9%
740
39%
740
13%
2264
October21st to endNight
25%
836
8%
3713
7%
814
33%
814
10%
2656
November1st to 10thNight
24%
780
16%
2537
9%
780
33%
780
16%
1784
November11th to 20thNight
25%
800
17%
2665
10%
800
34%
800
16%
1885
November21st to endNight
20%
800
12%
2800
6%
800
29%
800
11%
2118
December1st to 10thNight
18%
792
6%
4533
4%
780
24%
780
5%
3625
December11th to 20thNight
16%
796
8%
5091
5%
779
26%
779
5%
3685
December21st to endNight
16%
859
9%
6800
3%
839
24%
839
4%
5056

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
16%10%38%5%5%5%46%7%32%
113575
Night
17%12%49%5%5%435%6%30%
115037
TransparencyDay
50%7%13%21%10%1
117081
Night
54%6%11%18%10%1
119695
SeeingDay
21%11%28%25%12%3
15087
Night
23%9%29%29%10%1
24190

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
16%20%7%12%5%5%433322%
3597
11th to 20thDay
13%15%7%12%6%6%4346%24%
3570
21st to endDay
12%14%5%10%5%6%5%46%6%27%
3960
February1st to 10thDay
15%16%410%5%5%5%346%27%
1736
11th to 20thDay
13%12%5%11%7%45%46%5%27%
1867
21st to endDay
17%16%48%6%4435%6%27%
1650
March1st to 10thDay
18%13%411%7%5%5%345%26%
4476
11th to 20thDay
12%13%49%5%5%436%7%32%
4688
21st to endDay
17%11%410%5%4435%5%33%
5970
April1st to 10thDay
21%11%38%445%346%31%
2400
11th to 20thDay
20%9%37%443345%37%
2374
21st to endDay
21%9%38%5%4445%5%32%
2512
May1st to 10thDay
19%9%38%5%45%46%7%30%
4348
11th to 20thDay
17%8%38%5%5%5%46%8%31%
4398
21st to endDay
14%7%26%5%45%47%9%36%
4837
June1st to 10thDay
20%8%37%5%5%5%36%8%30%
2660
11th to 20thDay
14%6%36%5%4446%9%38%
2660
21st to endDay
19%8%38%6%5%5%45%7%31%
2660
July1st to 10thDay
11%6%27%6%5%6%47%9%37%
4440
11th to 20thDay
12%5%26%5%5%6%5%7%9%37%
4440
21st to endDay
11%6%25%44447%8%45%
4814
August1st to 10thDay
13%6%28%6%5%6%5%7%10%32%
4423
11th to 20thDay
13%6%38%5%4446%9%38%
4018
21st to endDay
15%6%26%44446%8%40%
4180
September1st to 10thDay
11%5%27%5%45%5%6%8%42%
2280
11th to 20thDay
14%5%25%33436%7%49%
2190
21st to endDay
15%6%27%445%45%7%41%
2090
October1st to 10thDay
18%6%37%6%5%435%8%35%
1976
11th to 20thDay
17%9%38%5%7%5%5%6%7%29%
1843
21st to endDay
24%9%37%44435%5%31%
1881
November1st to 10thDay
17%10%37%5%45%47%6%32%
1761
11th to 20thDay
17%10%39%5%5%5%5%6%5%31%
1730
21st to endDay
22%12%39%5%46%446%25%
1600
December1st to 10thDay
20%19%5%12%5%44345%18%
2600
11th to 20thDay
19%13%410%44445%6%26%
2986
21st to endDay
23%13%310%6%5%6%5%6%5%19%
3960
January1st to 10thNight
14%20%7%15%5%4433420%
6349
11th to 20thNight
10%15%7%16%8%6%5%35%6%19%
6315
21st to endNight
13%15%5%12%7%5%5%346%24%
6996
February1st to 10thNight
14%15%6%12%7%5%435%5%23%
2660
11th to 20thNight
14%13%5%10%5%6%435%5%29%
2418
21st to endNight
15%15%39%5%5%4346%31%
1980
March1st to 10thNight
22%12%48%5%44345%30%
5364
11th to 20thNight
14%14%38%5%5%5%45%7%30%
5269
21st to endNight
15%12%49%6%5%4345%32%
4962
April1st to 10thNight
23%10%37%5%44346%31%
2000
11th to 20thNight
22%9%37%5%44446%34%
1975
21st to endNight
22%10%36%44435%5%35%
1783
May1st to 10thNight
21%9%37%5%5%5%45%6%31%
2620
11th to 20thNight
22%8%37%44436%7%33%
2495
21st to endNight
14%8%37%5%5%446%8%36%
2738
June1st to 10thNight
22%7%28%445%46%7%32%
1520
11th to 20thNight
15%6%37%445%38%7%38%
1520
21st to endNight
18%7%27%5%6%5%45%8%32%
1520
July1st to 10thNight
13%7%38%5%5%6%47%9%34%
2520
11th to 20thNight
14%6%26%445%47%8%40%
2520
21st to endNight
10%6%26%5%5%447%8%43%
2739
August1st to 10thNight
14%9%48%5%5%5%36%6%36%
2506
11th to 20thNight
15%7%38%5%5%5%36%7%37%
2775
21st to endNight
16%6%37%5%5%446%7%38%
3476
September1st to 10thNight
12%5%27%5%4446%7%44%
1900
11th to 20thNight
15%6%25%32335%7%49%
1990
21st to endNight
16%7%25%5%4335%7%43%
2090
October1st to 10thNight
17%7%27%445%35%7%39%
2199
11th to 20thNight
21%9%37%5%44346%34%
2335
21st to endNight
23%9%39%5%44345%31%
2717
November1st to 10thNight
19%9%38%5%5%435%5%33%
2537
11th to 20thNight
19%11%38%5%5%435%6%33%
2665
21st to endNight
22%13%38%6%44346%26%
2800
December1st to 10thNight
18%17%6%13%6%5%5%345%18%
4580
11th to 20thNight
23%13%49%5%4436%5%24%
5208
21st to endNight
24%15%5%9%43446%5%21%
6996

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
65%7%9%16%3
3598
11th to 20thDay
61%6%10%15%7%1
3600
21st to endDay
57%6%11%15%11%1
3960
February1st to 10thDay
60%5%9%18%7%2
1736
11th to 20thDay
58%7%11%14%9%1
1876
21st to endDay
58%410%16%9%2
1650
March1st to 10thDay
59%5%8%14%10%3
4479
11th to 20thDay
50%7%16%14%11%2
4688
21st to endDay
53%5%8%16%16%2
5970
April1st to 10thDay
55%5%8%19%12%2
2400
11th to 20thDay
49%49%22%14%2
2374
21st to endDay
54%5%9%18%11%3
2512
May1st to 10thDay
49%8%11%22%9%1
4362
11th to 20thDay
47%10%16%17%9%1
4402
21st to endDay
42%8%13%23%13%1
4837
June1st to 10thDay
50%7%11%19%11%2
2660
11th to 20thDay
41%7%13%24%12%3
2660
21st to endDay
52%7%13%19%10%1
2660
July1st to 10thDay
42%7%15%27%9%1
4370
11th to 20thDay
40%8%17%28%7%
4365
21st to endDay
36%7%15%33%9%
4661
August1st to 10thDay
46%7%18%22%7%
4409
11th to 20thDay
42%7%20%25%6%
4060
21st to endDay
42%7%15%21%14%
4180
September1st to 10thDay
37%8%15%29%11%1
2280
11th to 20thDay
35%6%14%32%13%1
2190
21st to endDay
42%8%14%25%11%
2090
October1st to 10thDay
44%6%15%27%7%
3288
11th to 20thDay
44%6%18%25%7%
3046
21st to endDay
43%6%19%23%9%1
3081
November1st to 10thDay
49%7%13%22%9%1
1761
11th to 20thDay
51%7%11%19%12%
1730
21st to endDay
58%8%14%14%6%
1600
December1st to 10thDay
69%48%16%3
2600
11th to 20thDay
59%5%9%17%11%
2986
21st to endDay
65%6%11%11%6%
3960
January1st to 10thNight
67%6%11%12%4
6349
11th to 20thNight
64%8%10%13%4
6360
21st to endNight
60%5%10%11%13%
6996
February1st to 10thNight
62%5%9%15%8%1
2660
11th to 20thNight
59%5%9%17%10%
2420
21st to endNight
55%6%8%17%12%2
1980
March1st to 10thNight
58%48%14%11%5%
5374
11th to 20thNight
52%6%13%15%13%1
5270
21st to endNight
55%5%6%21%11%2
4962
April1st to 10thNight
55%47%18%14%2
2000
11th to 20thNight
52%47%20%14%2
1975
21st to endNight
51%48%20%14%3
1783
May1st to 10thNight
51%9%10%19%8%3
2626
11th to 20thNight
48%9%12%19%10%2
2496
21st to endNight
45%6%11%20%17%2
2739
June1st to 10thNight
49%7%10%21%12%1
1520
11th to 20thNight
44%7%11%21%14%3
1520
21st to endNight
49%7%10%18%14%1
1520
July1st to 10thNight
45%7%15%20%12%1
2480
11th to 20thNight
40%7%18%26%9%
2472
21st to endNight
38%7%19%24%12%
2651
August1st to 10thNight
48%7%12%25%9%
2496
11th to 20thNight
46%7%17%22%7%
2799
21st to endNight
45%6%13%21%14%1
3476
September1st to 10thNight
38%8%12%26%15%1
1900
11th to 20thNight
36%5%14%31%13%1
1990
21st to endNight
40%8%10%27%15%
2090
October1st to 10thNight
44%6%13%26%10%
3667
11th to 20thNight
45%5%11%30%8%
3871
21st to endNight
48%415%18%12%2
4467
November1st to 10thNight
53%5%12%21%8%1
2537
11th to 20thNight
52%6%11%19%11%2
2665
21st to endNight
60%5%11%17%7%
2800
December1st to 10thNight
69%5%11%11%4
4580
11th to 20thNight
61%5%8%14%11%
5208
21st to endNight
64%49%14%9%
6996

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
28%14%31%17%11%
200
11th to 20thDay
25%15%35%20%6%1
200
21st to endDay
19%11%37%22%10%1
220
February1st to 10thDay
28%16%35%18%3
268
11th to 20thDay
22%16%33%25%4
415
21st to endDay
26%13%33%24%4
414
March1st to 10thDay
23%13%30%25%9%
500
11th to 20thDay
21%15%36%22%6%1
500
21st to endDay
27%12%32%21%7%1
550
April1st to 10thDay
28%15%27%20%8%1
500
11th to 20thDay
28%18%24%20%7%3
492
21st to endDay
28%13%31%18%9%1
480
May1st to 10thDay
23%11%33%20%11%2
463
11th to 20thDay
17%11%28%26%14%4
487
21st to endDay
19%13%30%26%10%2
529
June1st to 10thDay
22%11%25%29%10%2
490
11th to 20thDay
16%10%26%32%14%2
490
21st to endDay
23%11%23%26%14%3
490
July1st to 10thDay
13%8%24%31%19%5%
485
11th to 20thDay
14%8%26%33%16%4
484
21st to endDay
14%7%24%33%18%3
532
August1st to 10thDay
15%5%23%30%21%6%
486
11th to 20thDay
12%6%20%30%22%9%
479
21st to endDay
16%8%22%26%18%10%
539
September1st to 10thDay
12%9%27%29%16%7%
490
11th to 20thDay
14%8%20%27%19%13%
490
21st to endDay
18%8%26%24%18%6%
490
October1st to 10thDay
20%13%26%23%14%4
490
11th to 20thDay
23%12%29%23%11%2
460
21st to endDay
30%11%27%24%8%
429
November1st to 10thDay
26%13%30%21%9%
395
11th to 20thDay
23%15%31%21%8%2
330
21st to endDay
33%13%30%16%9%1
200
December1st to 10thDay
30%10%25%21%12%3
200
11th to 20thDay
26%22%32%16%41
200
21st to endDay
33%16%26%18%42
220
January1st to 10thNight
28%10%31%26%5%
800
11th to 20thNight
25%11%33%25%7%
800
21st to endNight
19%9%34%31%6%1
880
February1st to 10thNight
22%10%36%27%5%1
800
11th to 20thNight
20%11%38%24%41
783
21st to endNight
22%11%33%30%4
660
March1st to 10thNight
26%9%31%29%6%
800
11th to 20thNight
25%11%31%26%7%1
800
21st to endNight
23%9%31%28%8%
880
April1st to 10thNight
28%12%26%28%6%
800
11th to 20thNight
25%13%30%26%6%1
791
21st to endNight
28%11%30%24%7%
609
May1st to 10thNight
26%7%32%27%8%1
447
11th to 20thNight
23%9%28%30%9%1
374
21st to endNight
18%9%36%29%9%
411
June1st to 10thNight
23%6%26%35%9%1
380
11th to 20thNight
19%329%36%13%
380
21st to endNight
18%7%27%33%14%1
380
July1st to 10thNight
12%5%29%38%15%1
370
11th to 20thNight
12%224%46%14%1
368
21st to endNight
13%421%45%16%
416
August1st to 10thNight
14%5%17%44%19%2
378
11th to 20thNight
14%320%38%24%2
551
21st to endNight
16%421%36%20%2
836
September1st to 10thNight
15%5%23%41%15%1
760
11th to 20thNight
17%5%21%34%21%2
760
21st to endNight
18%6%26%31%15%3
760
October1st to 10thNight
21%7%27%31%13%1
760
11th to 20thNight
26%8%27%29%9%1
760
21st to endNight
27%10%31%25%7%
836
November1st to 10thNight
24%12%31%25%8%
780
11th to 20thNight
25%10%33%23%9%1
800
21st to endNight
30%12%30%21%7%
800
December1st to 10thNight
29%11%29%25%7%
800
11th to 20thNight
28%12%31%21%6%1
800
21st to endNight
31%11%30%21%7%
880
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