Ferme Alarie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ferme Alarie clear sky chart from 2005-11-05 to 2017-09-24.

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%
14625
12%
46918
7%
14593
34%
14593
14%
34354

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
13%
720
6%
2506
2%
716
19%
716
7%
2067
January16th to endNight
18%
768
9%
2688
4%
768
25%
768
9%
2052
February1st to 15thNight
16%
704
10%
2293
3%
701
24%
701
10%
1781
February16th to endNight
20%
631
11%
1925
5%
631
28%
631
11%
1482
March1st to 15thNight
18%
720
13%
2142
6%
720
25%
720
12%
1650
March16th to endNight
29%
768
19%
2004
8%
768
37%
768
20%
1406
April1st to 15thNight
22%
718
15%
1796
5%
718
28%
718
19%
1339
April16th to endNight
26%
628
16%
1708
6%
628
34%
628
20%
1215
May1st to 15thNight
30%
360
15%
1440
11%
360
41%
360
14%
989
May16th to endNight
31%
375
12%
1497
10%
374
42%
374
15%
1005
June1st to 15thNight
31%
360
7%
1440
5%
360
39%
360
12%
1023
June16th to endNight
44%
360
7%
1440
10%
360
47%
360
16%
945
July1st to 15thNight
51%
340
11%
1360
14%
340
56%
340
24%
780
July16th to endNight
53%
376
12%
1418
15%
354
56%
354
22%
860
August1st to 15thNight
52%
380
13%
1451
13%
378
56%
378
20%
947
August16th to endNight
49%
732
18%
1878
10%
732
52%
732
32%
1219
September1st to 15thNight
45%
720
13%
1800
6%
720
47%
720
27%
1259
September16th to endNight
47%
693
20%
1880
13%
693
51%
693
30%
1220
October1st to 15thNight
30%
660
16%
1977
9%
660
38%
660
17%
1411
October16th to endNight
23%
704
10%
2238
5%
704
29%
704
12%
1730
November1st to 15thNight
25%
700
16%
2309
10%
700
34%
700
14%
1692
November16th to endNight
18%
720
10%
2520
6%
720
23%
720
8%
2000
December1st to 15thNight
14%
720
7%
2520
2%
720
19%
720
6%
2074
December16th to endNight
10%
768
9%
2688
3%
768
18%
768
6%
2208

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
20%10%47%5%34446%28%
48021
Night
18%11%47%5%34445%30%
47087
Cloud CoverDay
19%10%46%5%34446%28%
48030
Night
18%11%47%5%24446%30%
47093
TransparencyDay
55%6%11%17%8%1
47708
Night
54%6%11%18%8%
46918
SeeingDay
26%13%27%19%9%2
5535
Night
24%13%27%23%9%
14625

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
22%17%6%11%7%3423317%
1432
16th to endDay
13%16%7%9%7%345%5%6%20%
1536
February1st to 15thDay
12%16%5%12%9%34345%20%
1569
16th to endDay
14%18%6%9%7%4423423%
1548
March1st to 15thDay
17%13%5%9%6%23445%26%
1805
16th to endDay
16%9%46%5%3335%6%34%
2220
April1st to 15thDay
23%13%36%423335%31%
2152
16th to endDay
21%9%35%5%2444434%
2262
May1st to 15thDay
23%8%26%5%24346%29%
2511
16th to endDay
22%8%36%5%34446%30%
2618
June1st to 15thDay
23%7%36%5%36%45%6%26%
2520
16th to endDay
21%6%35%6%36%5%5%8%27%
2520
July1st to 15thDay
16%6%26%5%35%5%5%9%32%
2520
16th to endDay
15%6%36%5%36%5%6%9%30%
2654
August1st to 15thDay
16%7%36%7%46%6%6%7%28%
2496
16th to endDay
13%6%25%5%345%5%8%37%
2311
September1st to 15thDay
21%5%35%434347%36%
2160
16th to endDay
20%6%23313446%43%
1939
October1st to 15thDay
24%10%25%335%346%30%
1650
16th to endDay
29%14%47%43333421%
1634
November1st to 15thDay
18%11%46%4345%5%7%28%
1548
16th to endDay
26%14%5%7%5%2333424%
1440
December1st to 15thDay
25%18%6%8%5%25%335%16%
1440
16th to endDay
23%18%6%9%6%2433417%
1536
January1st to 15thNight
19%17%7%10%8%3434415%
2506
16th to endNight
12%17%6%8%7%35%45%6%21%
2688
February1st to 15thNight
11%15%7%11%8%3345%423%
2291
16th to endNight
17%12%6%10%6%3435%6%23%
1925
March1st to 15thNight
20%12%48%6%34335%26%
2129
16th to endNight
14%10%26%5%34345%39%
2004
April1st to 15thNight
25%9%35%413345%33%
1796
16th to endNight
19%9%245%33345%37%
1708
May1st to 15thNight
21%7%36%5%34345%35%
1440
16th to endNight
18%7%35%5%24446%37%
1495
June1st to 15thNight
19%8%37%5%345%5%7%30%
1440
16th to endNight
18%6%15%5%346%5%7%35%
1440
July1st to 15thNight
11%5%25%33445%8%44%
1440
16th to endNight
11%5%244245%8%8%41%
1514
August1st to 15thNight
12%5%35%6%3447%8%38%
1461
16th to endNight
11%415%43345%7%47%
1878
September1st to 15thNight
17%7%25%33445%6%40%
1800
16th to endNight
17%5%23323346%47%
1880
October1st to 15thNight
20%9%36%5%23445%33%
1977
16th to endNight
28%11%36%423435%25%
2238
November1st to 15thNight
21%10%45%5%4445%6%29%
2309
16th to endNight
23%15%6%8%6%2343421%
2520
December1st to 15thNight
23%17%6%8%7%3343417%
2520
16th to endNight
23%19%6%7%6%3343417%
2688

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 15thDay
22%18%6%10%7%3332416%
1432
16th to endDay
12%16%8%9%7%35%45%6%20%
1536
February1st to 15thDay
12%15%6%12%9%35%345%21%
1569
16th to endDay
14%18%5%8%7%3434423%
1548
March1st to 15thDay
18%14%5%9%6%24435%26%
1815
16th to endDay
16%9%46%5%24447%34%
2219
April1st to 15thDay
22%12%36%423335%31%
2152
16th to endDay
21%10%26%5%2444334%
2262
May1st to 15thDay
22%9%37%5%24346%28%
2511
16th to endDay
21%8%46%5%34446%29%
2618
June1st to 15thDay
22%8%36%5%36%5%5%6%25%
2520
16th to endDay
21%7%36%6%35%6%5%7%26%
2520
July1st to 15thDay
17%5%36%5%36%5%5%9%32%
2520
16th to endDay
15%6%36%6%36%5%7%8%29%
2654
August1st to 15thDay
16%7%36%6%36%5%5%8%28%
2496
16th to endDay
13%5%25%6%35%5%5%8%37%
2311
September1st to 15thDay
20%6%25%424347%36%
2160
16th to endDay
20%6%23323337%42%
1939
October1st to 15thDay
24%10%34424446%30%
1650
16th to endDay
28%14%39%43433420%
1634
November1st to 15thDay
17%11%46%6%25%45%7%28%
1548
16th to endDay
26%14%5%6%5%2424424%
1440
December1st to 15thDay
25%19%5%7%6%34345%16%
1440
16th to endDay
22%18%7%9%6%2433317%
1536
January1st to 15thNight
19%18%7%10%8%24345%15%
2506
16th to endNight
12%16%6%9%7%345%5%6%21%
2688
February1st to 15thNight
11%15%7%10%8%4444423%
2284
16th to endNight
16%13%5%11%6%2435%6%23%
1925
March1st to 15thNight
20%11%5%8%6%34235%26%
2142
16th to endNight
14%9%36%5%33345%39%
2004
April1st to 15thNight
25%10%35%423345%32%
1796
16th to endNight
20%9%34423346%36%
1708
May1st to 15thNight
20%9%36%5%23445%34%
1440
16th to endNight
18%6%36%425%5%45%36%
1495
June1st to 15thNight
19%8%36%5%3445%7%28%
1440
16th to endNight
18%6%25%435%6%5%7%35%
1440
July1st to 15thNight
10%5%3442446%8%43%
1440
16th to endNight
11%5%24425%5%7%9%41%
1514
August1st to 15thNight
11%5%25%6%35%47%7%38%
1461
16th to endNight
11%4235%2345%8%47%
1878
September1st to 15thNight
17%6%35%425%446%40%
1800
16th to endNight
17%5%14223346%47%
1880
October1st to 15thNight
19%8%36%5%24346%33%
1977
16th to endNight
27%12%36%423446%24%
2238
November1st to 15thNight
21%9%46%5%3445%6%29%
2309
16th to endNight
22%16%6%8%5%2443422%
2520
December1st to 15thNight
22%18%6%8%7%2434417%
2520
16th to endNight
22%18%7%8%6%2443417%
2688

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
72%46%11%4
1433
16th to endDay
61%6%9%13%7%
1536
February1st to 15thDay
64%310%15%5%
1571
16th to endDay
64%27%14%8%1
1548
March1st to 15thDay
60%410%14%8%1
1815
16th to endDay
48%5%9%17%14%3
2220
April1st to 15thDay
55%38%17%11%2
2152
16th to endDay
53%5%7%17%12%3
2262
May1st to 15thDay
55%5%8%16%12%1
2511
16th to endDay
54%6%10%17%10%1
2622
June1st to 15thDay
56%7%11%14%9%
2520
16th to endDay
54%7%11%17%7%1
2520
July1st to 15thDay
44%8%15%22%8%
2371
16th to endDay
50%7%16%16%8%
2487
August1st to 15thDay
52%8%15%18%5%
2482
16th to endDay
42%7%17%23%9%
2311
September1st to 15thDay
46%6%12%23%10%
2160
16th to endDay
41%5%12%29%9%
1939
October1st to 15thDay
53%5%12%19%9%
1650
16th to endDay
67%5%9%12%4
1634
November1st to 15thDay
53%8%14%14%8%
1548
16th to endDay
63%5%10%14%5%
1440
December1st to 15thDay
71%5%10%11%2
1440
16th to endDay
71%47%9%6%
1536
January1st to 15thNight
70%5%9%10%3
2506
16th to endNight
61%5%10%13%7%1
2688
February1st to 15thNight
63%410%15%5%
2293
16th to endNight
60%5%9%14%9%
1925
March1st to 15thNight
60%48%16%8%1
2142
16th to endNight
47%410%17%16%2
2004
April1st to 15thNight
53%46%20%12%1
1796
16th to endNight
48%5%10%17%15%2
1708
May1st to 15thNight
51%6%8%17%13%3
1440
16th to endNight
47%8%9%20%12%1
1497
June1st to 15thNight
52%8%10%19%7%
1440
16th to endNight
45%8%12%19%12%
1440
July1st to 15thNight
35%7%18%25%12%
1360
16th to endNight
37%9%17%24%11%
1418
August1st to 15thNight
39%12%16%24%7%
1451
16th to endNight
34%7%17%30%9%
1878
September1st to 15thNight
43%7%13%25%10%
1800
16th to endNight
38%5%13%33%9%
1880
October1st to 15thNight
51%5%11%20%10%
1977
16th to endNight
60%5%12%15%5%
2238
November1st to 15thNight
54%6%12%16%8%1
2309
16th to endNight
65%5%9%13%5%
2520
December1st to 15thNight
70%49%12%2
2520
16th to endNight
69%5%8%10%5%
2688

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
33%18%26%16%5%
60
16th to endDay
31%20%28%12%43
64
February1st to 15thDay
34%23%33%5%2
89
16th to endDay
30%22%28%15%3
207
March1st to 15thDay
27%21%30%17%2
270
16th to endDay
25%15%29%18%8%2
288
April1st to 15thDay
32%18%24%16%7%1
270
16th to endDay
28%17%24%19%7%2
270
May1st to 15thDay
34%14%27%15%6%1
288
16th to endDay
29%13%30%17%7%1
331
June1st to 15thDay
29%12%33%17%6%
315
16th to endDay
22%13%34%20%8%1
315
July1st to 15thDay
19%9%34%23%9%2
305
16th to endDay
19%5%31%30%10%2
326
August1st to 15thDay
16%7%27%30%13%3
313
16th to endDay
18%7%27%22%15%8%
332
September1st to 15thDay
23%8%22%20%16%9%
315
16th to endDay
21%9%21%19%17%9%
287
October1st to 15thDay
28%18%18%20%11%2
255
16th to endDay
37%14%22%15%9%
249
November1st to 15thDay
24%15%24%24%9%1
202
16th to endDay
41%18%26%11%1
60
December1st to 15thDay
41%18%23%16%
60
16th to endDay
45%26%26%1
64
January1st to 15thNight
29%17%32%16%4
720
16th to endNight
22%17%33%19%6%1
768
February1st to 15thNight
19%20%33%20%4
704
16th to endNight
23%19%30%21%4
631
March1st to 15thNight
27%17%30%20%3
720
16th to endNight
22%14%29%24%7%1
768
April1st to 15thNight
29%14%28%23%3
718
16th to endNight
26%17%26%20%9%
628
May1st to 15thNight
25%10%29%26%7%1
360
16th to endNight
21%9%34%24%9%
375
June1st to 15thNight
23%9%30%29%7%
360
16th to endNight
20%5%22%35%15%
360
July1st to 15thNight
10%5%27%38%16%1
340
16th to endNight
11%5%26%38%17%1
376
August1st to 15thNight
14%318%39%21%1
380
16th to endNight
14%5%24%32%21%1
732
September1st to 15thNight
19%5%24%32%16%1
720
16th to endNight
19%7%22%27%21%1
693
October1st to 15thNight
24%12%26%24%10%
660
16th to endNight
33%13%24%21%6%
704
November1st to 15thNight
27%13%28%20%9%1
700
16th to endNight
31%19%25%15%7%1
720
December1st to 15thNight
33%18%27%17%3
720
16th to endNight
35%15%28%15%3
768
Page generated at 2017-09-25 09:02:22. Version ac04

Copyright 2017 A. Danko


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