Val-d'Or
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Val-d'Or 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
24%
14839
9%
46702
6%
14806
28%
14806
12%
36772

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%
900
4%
2685
2%
895
15%
895
5%
2400
January16th to endNight
22%
771
6%
2646
4%
771
26%
771
6%
2251
February1st to 15thNight
21%
704
8%
2287
4%
701
26%
701
9%
1892
February16th to endNight
16%
631
6%
2028
3%
631
21%
631
8%
1685
March1st to 15thNight
22%
720
10%
2049
6%
720
26%
720
12%
1643
March16th to endNight
29%
768
17%
2074
9%
768
34%
768
18%
1531
April1st to 15thNight
23%
718
13%
1796
5%
718
27%
718
17%
1384
April16th to endNight
26%
540
15%
1620
8%
540
33%
540
19%
1147
May1st to 15thNight
30%
360
13%
1440
13%
360
36%
360
15%
986
May16th to endNight
31%
375
8%
1497
8%
374
37%
374
13%
1049
June1st to 15thNight
30%
360
6%
1293
5%
360
33%
360
13%
947
June16th to endNight
39%
360
7%
1260
5%
360
41%
360
19%
830
July1st to 15thNight
39%
340
8%
1190
7%
340
41%
340
19%
791
July16th to endNight
46%
376
9%
1380
12%
354
47%
354
17%
923
August1st to 15thNight
41%
449
9%
1520
8%
447
45%
447
16%
1105
August16th to endNight
41%
626
14%
1772
10%
626
43%
626
23%
1226
September1st to 15thNight
33%
720
11%
1800
4%
720
35%
720
23%
1320
September16th to endNight
33%
669
14%
1848
8%
669
37%
669
21%
1320
October1st to 15thNight
22%
660
11%
1980
7%
660
27%
660
13%
1543
October16th to endNight
18%
704
7%
2183
5%
704
21%
704
8%
1839
November1st to 15thNight
15%
700
8%
2446
5%
700
20%
700
8%
1995
November16th to endNight
12%
720
6%
2520
4%
720
15%
720
5%
2169
December1st to 15thNight
11%
720
4%
2520
1%
720
15%
720
4%
2218
December16th to endNight
14%
948
5%
2868
3%
948
15%
948
4%
2578

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
21%12%47%6%34445%24%
48104
Night
20%13%5%8%6%35%445%23%
46861
TransparencyDay
60%6%10%15%6%
47781
Night
62%5%10%14%6%
46702
SeeingDay
27%12%30%19%8%2
5817
Night
27%11%29%22%8%
14839

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
21%17%8%12%7%26%5%5%39%
1253
16th to endDay
13%17%7%12%8%5%6%7%5%411%
1574
February1st to 15thDay
9%14%7%12%11%6%7%46%6%13%
1575
16th to endDay
14%18%6%11%8%445%3318%
1443
March1st to 15thDay
16%13%5%9%7%45%43425%
1899
16th to endDay
13%14%46%5%35%445%32%
2149
April1st to 15thDay
24%14%45%5%2333426%
2152
16th to endDay
20%11%36%5%33345%31%
2349
May1st to 15thDay
21%10%35%5%25%5%5%5%28%
2511
16th to endDay
25%9%35%423345%32%
2618
June1st to 15thDay
21%8%36%5%35%6%5%7%26%
2664
16th to endDay
19%7%36%6%35%5%5%6%29%
2700
July1st to 15thDay
19%6%36%5%35%6%6%8%27%
2700
16th to endDay
19%7%36%5%35%5%5%8%28%
2692
August1st to 15thDay
23%8%36%6%35%45%7%24%
2430
16th to endDay
20%8%36%6%35%5%47%27%
2417
September1st to 15thDay
23%7%35%6%2445%6%31%
2160
16th to endDay
25%7%35%5%2345%7%30%
1835
October1st to 15thDay
23%16%36%43335%5%23%
1650
16th to endDay
34%20%45%6%2322312%
1689
November1st to 15thDay
25%20%6%7%42433319%
1411
16th to endDay
26%18%8%11%6%4323310%
1440
December1st to 15thDay
22%21%8%11%7%35%3339%
1440
16th to endDay
19%20%8%11%9%35%3439%
1353
January1st to 15thNight
20%18%8%12%8%36%43210%
2685
16th to endNight
12%16%7%13%8%5%8%6%5%311%
2646
February1st to 15thNight
11%14%6%11%10%47%5%5%5%15%
2285
16th to endNight
16%14%6%12%9%46%5%45%15%
2028
March1st to 15thNight
17%15%5%6%7%36%5%5%5%20%
2037
16th to endNight
15%12%47%5%36%435%33%
2074
April1st to 15thNight
22%11%5%7%5%2334429%
1796
16th to endNight
19%9%37%433346%35%
1620
May1st to 15thNight
18%10%45%5%34346%33%
1440
16th to endNight
23%8%35%5%2445%7%29%
1495
June1st to 15thNight
22%7%27%6%25%5%46%27%
1293
16th to endNight
14%7%26%445%6%5%7%36%
1260
July1st to 15thNight
17%5%36%5%35%5%7%8%33%
1260
16th to endNight
15%6%26%5%35%45%7%36%
1475
August1st to 15thNight
20%6%36%6%246%6%7%30%
1530
16th to endNight
14%7%36%5%2445%7%38%
1772
September1st to 15thNight
19%9%36%423445%36%
1800
16th to endNight
23%5%25%5%13345%37%
1848
October1st to 15thNight
24%10%46%6%34335%27%
1980
16th to endNight
33%18%35%42334416%
2183
November1st to 15thNight
23%16%6%9%6%23335%19%
2446
16th to endNight
28%19%6%8%5%3323315%
2520
December1st to 15thNight
21%23%8%11%6%2332212%
2520
16th to endNight
20%21%8%12%8%35%42210%
2868

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
77%48%7%
1254
16th to endDay
73%45%11%4
1574
February1st to 15thDay
70%5%7%11%5%
1577
16th to endDay
68%46%15%4
1443
March1st to 15thDay
62%5%6%15%9%
1910
16th to endDay
53%5%9%19%9%2
2149
April1st to 15thDay
61%48%14%10%1
2152
16th to endDay
54%410%16%12%1
2349
May1st to 15thDay
54%6%9%16%11%1
2511
16th to endDay
55%5%8%19%10%
2622
June1st to 15thDay
54%7%10%18%9%
2664
16th to endDay
51%8%11%19%8%
2700
July1st to 15thDay
50%8%15%18%7%
2541
16th to endDay
54%8%12%18%5%
2524
August1st to 15thDay
57%9%13%17%3
2416
16th to endDay
54%8%14%16%6%
2417
September1st to 15thDay
53%6%15%17%5%1
2160
16th to endDay
53%7%13%20%4
1835
October1st to 15thDay
61%6%12%11%6%
1650
16th to endDay
78%47%6%3
1689
November1st to 15thDay
70%5%10%9%3
1411
16th to endDay
80%35%6%2
1440
December1st to 15thDay
79%5%6%8%
1440
16th to endDay
79%46%7%2
1353
January1st to 15thNight
80%36%7%1
2685
16th to endNight
73%46%9%4
2646
February1st to 15thNight
69%5%8%11%6%
2287
16th to endNight
70%47%12%4
2028
March1st to 15thNight
64%5%9%12%8%
2049
16th to endNight
53%48%18%12%1
2074
April1st to 15thNight
57%38%16%10%1
1796
16th to endNight
51%48%19%14%1
1620
May1st to 15thNight
51%5%10%16%14%2
1440
16th to endNight
53%6%11%17%10%
1497
June1st to 15thNight
56%6%9%16%10%1
1293
16th to endNight
44%7%13%21%11%1
1260
July1st to 15thNight
43%9%14%23%7%
1190
16th to endNight
47%7%17%21%6%
1380
August1st to 15thNight
51%9%14%20%3
1520
16th to endNight
44%7%19%23%5%
1772
September1st to 15thNight
48%6%17%18%8%
1800
16th to endNight
48%6%15%23%5%
1848
October1st to 15thNight
60%6%11%13%6%1
1980
16th to endNight
70%5%9%10%3
2183
November1st to 15thNight
68%5%11%11%3
2446
16th to endNight
75%5%8%8%2
2520
December1st to 15thNight
78%47%8%1
2520
16th to endNight
80%45%6%2
2868

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
26%23%30%16%3
60
16th to endDay
33%15%29%16%21
71
February1st to 15thDay
20%11%52%14%2
90
16th to endDay
30%15%36%15%1
102
March1st to 15thDay
22%18%34%17%6%1
270
16th to endDay
22%13%36%17%7%1
288
April1st to 15thDay
32%14%27%16%5%2
270
16th to endDay
27%15%30%15%8%3
270
May1st to 15thDay
30%13%28%17%8%1
288
16th to endDay
32%12%26%21%5%1
331
June1st to 15thDay
28%11%31%19%7%
459
16th to endDay
20%11%32%23%9%1
495
July1st to 15thDay
20%11%33%23%9%1
475
16th to endDay
24%6%31%23%11%2
363
August1st to 15thDay
28%428%21%12%4
313
16th to endDay
27%7%28%21%10%4
332
September1st to 15thDay
22%9%29%24%10%3
315
16th to endDay
25%10%31%23%6%2
262
October1st to 15thDay
32%15%26%16%7%1
255
16th to endDay
40%15%20%14%7%1
259
November1st to 15thDay
33%20%32%10%3
65
16th to endDay
45%13%30%5%6%
60
December1st to 15thDay
30%11%41%11%5%
60
16th to endDay
37%14%37%9%1
64
January1st to 15thNight
32%12%31%18%5%
900
16th to endNight
20%11%31%24%10%1
771
February1st to 15thNight
17%12%35%26%6%
704
16th to endNight
23%12%34%23%5%
631
March1st to 15thNight
27%19%25%22%5%
720
16th to endNight
22%14%31%22%8%1
768
April1st to 15thNight
29%13%27%22%5%
718
16th to endNight
25%11%32%21%6%1
540
May1st to 15thNight
25%6%33%23%10%
360
16th to endNight
26%8%29%28%6%
375
June1st to 15thNight
24%7%30%28%8%
360
16th to endNight
18%5%28%35%12%
360
July1st to 15thNight
17%432%32%11%1
340
16th to endNight
16%325%37%14%1
376
August1st to 15thNight
21%325%27%18%2
449
16th to endNight
18%5%28%29%15%2
626
September1st to 15thNight
23%7%31%21%14%1
720
16th to endNight
27%7%27%24%11%1
669
October1st to 15thNight
31%12%28%19%7%1
660
16th to endNight
44%9%22%16%5%
704
November1st to 15thNight
32%14%29%14%7%
700
16th to endNight
38%14%28%14%4
720
December1st to 15thNight
32%15%28%16%5%
720
16th to endNight
31%14%25%20%5%1
948
Page generated at 2017-09-19 07:32:28. Version ac04

Copyright 2017 A. Danko


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