Ferme Véronneau
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ferme Véronneau clear sky chart from 2005-11-05 to 2017-09-18.

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%
14673
10%
46844
7%
14642
30%
14642
12%
36191

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
12%
720
6%
2506
4%
716
15%
716
5%
2150
January16th to endNight
13%
768
6%
2688
3%
768
18%
768
5%
2285
February1st to 15thNight
13%
704
5%
2300
2%
701
17%
701
5%
1997
February16th to endNight
15%
631
8%
1893
4%
631
21%
631
8%
1567
March1st to 15thNight
18%
720
11%
2160
7%
720
24%
720
10%
1719
March16th to endNight
23%
768
16%
2019
6%
768
30%
768
15%
1555
April1st to 15thNight
21%
718
12%
1796
4%
718
26%
718
14%
1449
April16th to endNight
23%
575
15%
1655
5%
575
31%
575
17%
1183
May1st to 15thNight
25%
477
14%
1557
9%
477
33%
477
15%
1103
May16th to endNight
31%
374
10%
1497
10%
374
39%
374
12%
1062
June1st to 15thNight
32%
360
8%
1440
8%
360
39%
360
11%
1064
June16th to endNight
41%
360
7%
1440
10%
360
45%
360
15%
978
July1st to 15thNight
46%
340
10%
1360
16%
340
50%
340
18%
890
July16th to endNight
50%
376
11%
1418
14%
354
51%
354
18%
914
August1st to 15thNight
48%
428
11%
1499
11%
426
50%
426
19%
1015
August16th to endNight
49%
693
18%
1839
10%
693
52%
693
31%
1197
September1st to 15thNight
41%
720
11%
1839
5%
720
43%
720
25%
1308
September16th to endNight
43%
669
19%
1847
13%
669
46%
669
29%
1195
October1st to 15thNight
28%
660
15%
1889
8%
660
34%
660
16%
1414
October16th to endNight
20%
704
8%
2288
4%
704
25%
704
9%
1838
November1st to 15thNight
20%
700
13%
2277
9%
700
26%
700
10%
1778
November16th to endNight
20%
720
11%
2429
9%
720
24%
720
8%
1930
December1st to 15thNight
12%
720
3%
2520
0%
720
15%
720
4%
2210
December16th to endNight
8%
768
5%
2688
2%
768
12%
768
3%
2390

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%11%47%6%34446%25%
47958
Night
19%12%5%8%6%34445%26%
47014
TransparencyDay
59%6%10%15%6%
47646
Night
60%5%9%15%7%
46844
SeeingDay
29%15%26%17%9%2
5706
Night
26%15%26%21%8%
14674

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
17%15%8%13%9%46%5%3412%
1432
16th to endDay
10%17%7%12%9%45%445%16%
1536
February1st to 15thDay
13%17%9%15%10%47%42312%
1558
16th to endDay
11%18%9%12%10%45%33317%
1580
March1st to 15thDay
15%15%7%10%6%35%33422%
1790
16th to endDay
19%14%6%9%5%3222429%
2203
April1st to 15thDay
22%16%47%42333428%
2152
16th to endDay
22%11%24434345%32%
2304
May1st to 15thDay
25%8%36%5%34345%28%
2404
16th to endDay
22%7%36%5%45%46%8%25%
2618
June1st to 15thDay
30%8%25%434446%24%
2520
16th to endDay
22%7%36%5%25%5%5%7%28%
2520
July1st to 15thDay
18%7%35%5%35%5%6%9%28%
2520
16th to endDay
19%6%36%6%36%5%7%8%25%
2654
August1st to 15thDay
20%6%25%6%45%6%6%8%25%
2439
16th to endDay
17%6%25%5%345%5%8%35%
2360
September1st to 15thDay
21%6%25%424445%38%
2121
16th to endDay
19%6%23424438%39%
1838
October1st to 15thDay
24%11%36%42335%6%28%
1738
16th to endDay
25%20%35%43333421%
1584
November1st to 15thDay
22%14%46%433345%25%
1581
16th to endDay
19%15%7%8%5%34445%23%
1530
December1st to 15thDay
19%22%7%9%7%3343314%
1440
16th to endDay
23%19%9%11%8%3332311%
1536
January1st to 15thNight
15%18%7%13%8%46%43414%
2506
16th to endNight
11%17%8%12%9%5%6%43315%
2688
February1st to 15thNight
11%15%8%15%12%5%6%33314%
2299
16th to endNight
14%18%8%11%9%3432321%
1893
March1st to 15thNight
18%16%6%8%6%2443425%
2147
16th to endNight
17%15%6%8%5%3322431%
2019
April1st to 15thNight
22%14%46%5%2435%326%
1796
16th to endNight
22%10%35%423336%34%
1655
May1st to 15thNight
22%8%36%5%23446%31%
1557
16th to endNight
21%6%26%6%45%447%30%
1495
June1st to 15thNight
30%6%45%2245%5%6%26%
1440
16th to endNight
19%6%25%426%5%5%8%34%
1440
July1st to 15thNight
15%5%35%6%25%5%6%8%34%
1440
16th to endNight
13%6%25%5%35%46%9%37%
1514
August1st to 15thNight
18%5%25%6%345%6%8%33%
1509
16th to endNight
14%5%25%424447%46%
1839
September1st to 15thNight
19%7%25%5%33345%39%
1839
16th to endNight
21%413223347%46%
1847
October1st to 15thNight
23%10%36%5%13335%32%
1889
16th to endNight
28%14%26%5%3344421%
2288
November1st to 15thNight
20%14%48%6%33345%23%
2277
16th to endNight
19%15%6%10%5%2333324%
2429
December1st to 15thNight
21%20%7%11%6%3433313%
2520
16th to endNight
21%21%8%12%7%35%32311%
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
76%5%7%7%2
1433
16th to endDay
69%49%11%3
1536
February1st to 15thDay
77%45%9%2
1561
16th to endDay
73%36%8%6%1
1580
March1st to 15thDay
66%49%12%6%1
1800
16th to endDay
62%38%15%9%1
2203
April1st to 15thDay
60%38%15%9%1
2152
16th to endDay
54%5%9%17%10%3
2304
May1st to 15thDay
57%5%8%17%9%
2404
16th to endDay
55%8%11%15%8%
2622
June1st to 15thDay
61%6%11%14%5%
2520
16th to endDay
54%8%11%19%6%
2520
July1st to 15thDay
49%8%14%21%6%
2371
16th to endDay
54%8%13%18%4
2487
August1st to 15thDay
54%9%16%15%3
2425
16th to endDay
45%7%15%21%9%
2360
September1st to 15thDay
47%5%12%24%9%
2121
16th to endDay
44%6%11%25%12%
1838
October1st to 15thDay
56%5%12%17%7%
1738
16th to endDay
67%411%12%4
1584
November1st to 15thDay
61%5%10%13%7%1
1581
16th to endDay
64%5%11%12%6%
1530
December1st to 15thDay
74%6%7%9%2
1440
16th to endDay
80%5%45%4
1536
January1st to 15thNight
74%5%8%8%2
2506
16th to endNight
73%5%6%10%3
2688
February1st to 15thNight
75%45%10%3
2300
16th to endNight
70%36%10%8%
1893
March1st to 15thNight
64%47%15%6%1
2160
16th to endNight
59%37%15%11%2
2019
April1st to 15thNight
61%5%6%14%11%
1796
16th to endNight
52%49%18%12%2
1655
May1st to 15thNight
53%5%8%17%13%1
1557
16th to endNight
53%7%11%18%7%1
1497
June1st to 15thNight
58%7%8%19%5%
1440
16th to endNight
47%8%13%21%7%
1440
July1st to 15thNight
43%10%14%24%7%
1360
16th to endNight
43%9%16%22%9%
1418
August1st to 15thNight
46%8%18%21%6%
1499
16th to endNight
38%5%17%26%10%
1839
September1st to 15thNight
47%5%13%24%8%
1839
16th to endNight
39%5%13%28%12%
1847
October1st to 15thNight
55%49%19%9%
1889
16th to endNight
65%6%9%13%5%
2288
November1st to 15thNight
63%49%13%6%2
2277
16th to endNight
65%48%14%5%
2429
December1st to 15thNight
77%46%8%2
2520
16th to endNight
80%446%4
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
21%26%35%15%1
60
16th to endDay
32%25%29%9%11
64
February1st to 15thDay
31%23%27%14%3
142
16th to endDay
25%26%26%17%21
239
March1st to 15thDay
31%22%24%17%2
270
16th to endDay
29%19%23%15%9%2
288
April1st to 15thDay
34%17%27%12%6%
270
16th to endDay
31%21%23%12%8%3
270
May1st to 15thDay
40%12%23%12%7%3
288
16th to endDay
25%18%29%18%6%1
331
June1st to 15thDay
38%12%25%15%9%
315
16th to endDay
25%15%33%16%7%1
315
July1st to 15thDay
23%10%33%20%9%2
305
16th to endDay
19%8%34%27%7%2
326
August1st to 15thDay
24%7%30%21%12%3
313
16th to endDay
23%9%21%18%19%6%
332
September1st to 15thDay
25%10%19%21%16%6%
315
16th to endDay
19%12%20%21%14%11%
262
October1st to 15thDay
30%16%20%16%11%3
252
16th to endDay
38%17%21%13%7%
240
November1st to 15thDay
31%16%28%14%6%1
235
16th to endDay
36%18%18%16%8%2
150
December1st to 15thDay
38%23%26%8%3
60
16th to endDay
48%21%26%3
64
January1st to 15thNight
25%24%30%16%3
720
16th to endNight
22%25%29%17%4
768
February1st to 15thNight
21%24%32%19%3
704
16th to endNight
26%18%31%18%3
631
March1st to 15thNight
31%19%27%18%3
720
16th to endNight
27%19%24%19%8%
768
April1st to 15thNight
33%19%23%19%4
718
16th to endNight
29%16%27%17%8%
575
May1st to 15thNight
27%12%31%20%6%1
477
16th to endNight
24%10%26%29%7%1
375
June1st to 15thNight
34%6%20%28%9%
360
16th to endNight
17%6%29%35%10%
360
July1st to 15thNight
16%5%24%35%17%1
340
16th to endNight
14%424%36%18%
376
August1st to 15thNight
22%417%34%20%
428
16th to endNight
17%423%31%20%2
693
September1st to 15thNight
23%6%22%31%15%1
720
16th to endNight
22%8%24%24%17%2
669
October1st to 15thNight
30%11%24%19%12%1
660
16th to endNight
38%16%21%17%4
704
November1st to 15thNight
29%16%29%15%7%1
700
16th to endNight
28%21%24%15%8%1
720
December1st to 15thNight
34%25%24%12%3
720
16th to endNight
33%21%26%14%2
768
Page generated at 2017-09-19 07:32:30. Version ac04

Copyright 2017 A. Danko


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