Val Marie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Val Marie clear sky chart from 2005-11-06 to 2024-02-05.

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
40%
24218
16%
80150
10%
24147
46%
24147
24%
49874

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
32%
931
14%
4670
6%
926
39%
926
13%
2879
January11th to 20thNight
29%
943
18%
4655
7%
930
38%
930
12%
3026
January21st to endNight
27%
1025
9%
4640
5%
1013
35%
1013
13%
2751
February1st to 10thNight
39%
738
15%
2398
11%
738
46%
738
20%
1619
February11th to 20thNight
32%
702
12%
2273
9%
700
37%
700
18%
1581
February21st to endNight
39%
592
16%
1902
10%
592
48%
592
20%
1308
March1st to 10thNight
34%
720
14%
2111
8%
720
39%
720
21%
1485
March11th to 20thNight
38%
720
16%
1980
9%
720
44%
720
26%
1341
March21st to endNight
37%
730
13%
2116
7%
730
43%
730
20%
1511
April1st to 10thNight
39%
540
17%
1800
12%
540
46%
540
22%
1156
April11th to 20thNight
34%
533
14%
1700
9%
533
40%
533
19%
1173
April21st to endNight
38%
540
15%
1558
11%
540
42%
540
22%
1072
May1st to 10thNight
46%
540
14%
1440
10%
540
49%
540
29%
953
May11th to 20thNight
49%
531
16%
1418
9%
531
53%
531
32%
913
May21st to endNight
42%
547
8%
1515
5%
545
45%
545
24%
1039
June1st to 10thNight
49%
360
9%
1260
8%
360
52%
360
23%
771
June11th to 20thNight
43%
360
8%
1260
6%
360
47%
360
27%
744
June21st to endNight
58%
360
10%
1260
10%
360
61%
360
35%
652
July1st to 10thNight
63%
350
11%
1225
10%
350
67%
350
40%
606
July11th to 20thNight
59%
348
16%
1218
13%
348
65%
348
41%
584
July21st to endNight
63%
551
21%
1451
15%
521
68%
521
55%
728
August1st to 10thNight
60%
537
22%
1425
15%
534
65%
534
49%
768
August11th to 20thNight
65%
534
25%
1602
20%
534
70%
534
46%
841
August21st to endNight
58%
594
26%
1845
21%
594
65%
594
40%
985
September1st to 10thNight
55%
540
23%
1800
22%
540
62%
540
37%
960
September11th to 20thNight
52%
540
26%
1800
23%
540
61%
540
33%
1006
September21st to endNight
49%
706
26%
2060
17%
706
58%
706
38%
1157
October1st to 10thNight
44%
720
21%
2160
13%
720
51%
720
27%
1343
October11th to 20thNight
41%
720
23%
2160
11%
720
50%
720
29%
1305
October21st to endNight
32%
913
18%
2518
7%
913
41%
913
24%
1706
November1st to 10thNight
30%
925
16%
2590
7%
925
37%
925
21%
1811
November11th to 20thNight
32%
950
19%
2660
9%
950
41%
950
25%
1765
November21st to endNight
29%
950
14%
2660
5%
950
36%
950
24%
1819
December1st to 10thNight
31%
950
11%
2660
5%
950
37%
950
19%
1944
December11th to 20thNight
29%
948
14%
3433
7%
948
37%
948
18%
2262
December21st to endNight
31%
1030
11%
4927
7%
1026
39%
1026
17%
2310

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
8%7%37%6%45%5%6%8%41%
77849
Night
6%7%47%6%45%5%6%8%42%
81038
TransparencyDay
40%7%16%24%12%2
77538
Night
39%7%16%24%13%2
80871
SeeingDay
11%10%30%30%16%4
14652
Night
10%8%34%35%12%1
24273

By Month

Percentage Cloud Cover SW (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
5%11%410%8%5%7%6%6%9%29%
2219
11th to 20thDay
27%5%10%11%5%8%7%7%9%29%
2220
21st to endDay
410%47%7%46%6%5%8%40%
2835
February1st to 10thDay
8%10%6%10%10%5%6%46%6%27%
1656
11th to 20thDay
6%11%6%13%10%6%6%6%7%8%23%
1575
21st to endDay
5%11%5%10%10%6%7%8%6%8%26%
1354
March1st to 10thDay
5%10%411%9%46%6%7%9%29%
1844
11th to 20thDay
6%9%5%8%8%5%6%6%6%9%33%
1980
21st to endDay
7%11%5%11%7%46%5%6%9%28%
2240
April1st to 10thDay
8%8%48%8%46%6%6%8%35%
2160
11th to 20thDay
12%13%48%6%46%5%6%7%30%
2206
21st to endDay
13%10%36%6%35%5%5%8%36%
2402
May1st to 10thDay
13%11%36%6%35%5%6%7%35%
2520
11th to 20thDay
9%6%37%6%45%5%5%8%42%
2478
21st to endDay
20%7%36%6%345%6%8%32%
2758
June1st to 10thDay
14%5%36%5%45%6%6%9%37%
2700
11th to 20thDay
14%5%35%6%37%5%6%9%37%
2700
21st to endDay
6%4245%35%5%7%9%49%
2700
July1st to 10thDay
43145%35%6%7%9%53%
2700
11th to 20thDay
43134345%6%9%57%
2700
21st to endDay
422332335%7%65%
2779
August1st to 10thDay
6%42443446%8%55%
2503
11th to 20thDay
6%42442345%9%56%
2299
21st to endDay
8%3134335%5%8%58%
2510
September1st to 10thDay
9%6%245%345%5%6%50%
2160
11th to 20thDay
11%6%25%42445%7%50%
2160
21st to endDay
12%6%2442345%7%50%
1899
October1st to 10thDay
12%9%36%43335%7%45%
1800
11th to 20thDay
7%6%47%6%36%5%5%8%43%
1800
21st to endDay
6%10%36%5%45%6%7%8%41%
1817
November1st to 10thDay
10%13%47%6%35%45%8%36%
1488
11th to 20thDay
47%48%7%46%6%6%8%40%
1520
21st to endDay
6%10%48%6%45%6%5%9%36%
1520
December1st to 10thDay
7%8%5%10%11%5%5%6%6%6%29%
1520
11th to 20thDay
49%7%11%8%5%5%6%6%7%34%
1685
21st to endDay
5%8%37%6%345%7%8%44%
2442
January1st to 10thNight
36%49%8%6%6%8%9%9%32%
4726
11th to 20thNight
36%5%11%10%5%6%8%9%7%29%
4738
21st to endNight
38%5%9%7%46%5%6%8%40%
4863
February1st to 10thNight
5%8%5%9%8%5%6%6%6%8%35%
2398
11th to 20thNight
410%5%10%9%46%6%6%9%31%
2272
21st to endNight
5%8%6%10%9%46%6%6%8%34%
1902
March1st to 10thNight
6%9%5%10%7%45%6%6%9%33%
2111
11th to 20thNight
7%7%48%6%45%6%7%10%38%
1980
21st to endNight
7%9%5%9%7%46%7%7%9%30%
2116
April1st to 10thNight
7%7%36%7%47%6%6%7%40%
1800
11th to 20thNight
12%11%46%6%45%6%6%8%33%
1700
21st to endNight
10%8%47%7%46%6%5%7%36%
1558
May1st to 10thNight
11%8%36%6%35%5%5%7%42%
1440
11th to 20thNight
9%6%245%46%5%6%9%45%
1417
21st to endNight
15%6%36%5%346%7%8%36%
1515
June1st to 10thNight
13%5%25%5%35%46%9%43%
1260
11th to 20thNight
14%324435%6%7%8%43%
1260
21st to endNight
5%3245%25%5%49%56%
1260
July1st to 10thNight
5%313425%6%5%8%58%
1260
11th to 20thNight
34233245%6%8%59%
1260
21st to endNight
421342346%9%62%
1536
August1st to 10thNight
5%31442436%7%60%
1433
11th to 20thNight
6%31342346%9%59%
1602
21st to endNight
8%42432435%7%58%
1845
September1st to 10thNight
9%42342345%7%56%
1800
11th to 20thNight
9%6%25%4245%5%7%52%
1800
21st to endNight
9%5%2432446%10%52%
2060
October1st to 10thNight
11%7%35%43346%7%47%
2160
11th to 20thNight
7%7%46%5%345%5%8%47%
2160
21st to endNight
9%8%38%5%346%6%8%40%
2518
November1st to 10thNight
11%10%5%7%7%36%45%7%37%
2590
11th to 20thNight
5%7%5%7%8%45%6%6%8%40%
2660
21st to endNight
6%8%5%9%7%45%5%6%8%39%
2660
December1st to 10thNight
5%8%410%10%5%8%6%6%8%29%
2660
11th to 20thNight
49%5%10%7%46%6%7%8%35%
3504
21st to endNight
46%35%5%3445%7%53%
5214

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
50%10%18%17%5%
2219
11th to 20thDay
50%7%16%14%11%1
2220
21st to endDay
42%8%21%23%6%
2835
February1st to 10thDay
55%6%13%16%9%
1656
11th to 20thDay
56%6%16%13%8%1
1584
21st to endDay
55%7%16%12%9%1
1354
March1st to 10thDay
51%9%17%17%6%
1844
11th to 20thDay
48%7%18%21%5%1
1980
21st to endDay
51%9%18%16%6%
2240
April1st to 10thDay
46%8%15%21%9%
2160
11th to 20thDay
53%6%14%19%7%1
2209
21st to endDay
46%6%15%26%8%1
2402
May1st to 10thDay
47%6%12%22%12%1
2520
11th to 20thDay
40%7%15%27%11%
2482
21st to endDay
49%8%14%20%9%
2758
June1st to 10thDay
42%9%17%21%10%1
2700
11th to 20thDay
42%8%15%22%12%1
2700
21st to endDay
29%7%16%33%13%1
2700
July1st to 10thDay
25%8%16%31%15%5%
2626
11th to 20thDay
23%7%16%25%24%6%
2619
21st to endDay
19%5%11%33%27%6%
2624
August1st to 10thDay
27%7%13%31%19%5%
2487
11th to 20thDay
25%6%17%30%18%4
2299
21st to endDay
24%5%12%30%24%5%
2510
September1st to 10thDay
33%5%11%29%17%5%
2160
11th to 20thDay
33%6%15%29%14%3
2160
21st to endDay
34%413%31%16%2
1899
October1st to 10thDay
40%6%17%27%11%
1800
11th to 20thDay
39%6%15%28%11%1
1800
21st to endDay
39%7%19%26%9%
1817
November1st to 10thDay
47%6%16%22%8%1
1488
11th to 20thDay
42%8%18%24%8%1
1520
21st to endDay
44%8%20%21%7%1
1520
December1st to 10thDay
53%8%14%19%5%1
1520
11th to 20thDay
47%7%22%20%4
1684
21st to endDay
36%6%15%22%14%7%
2442
January1st to 10thNight
41%11%21%20%7%1
4726
11th to 20thNight
48%6%15%17%13%1
4738
21st to endNight
41%6%21%26%5%
4863
February1st to 10thNight
47%6%16%20%10%1
2398
11th to 20thNight
48%8%17%17%9%1
2273
21st to endNight
47%7%12%21%12%1
1902
March1st to 10thNight
47%8%17%18%10%
2111
11th to 20thNight
41%7%18%24%7%1
1980
21st to endNight
48%8%17%19%8%
2116
April1st to 10thNight
42%7%15%25%11%1
1800
11th to 20thNight
47%7%11%21%10%3
1700
21st to endNight
46%6%13%24%10%1
1558
May1st to 10thNight
39%7%11%28%14%1
1440
11th to 20thNight
35%8%13%27%17%1
1418
21st to endNight
43%8%16%24%8%1
1515
June1st to 10thNight
38%8%17%25%12%1
1260
11th to 20thNight
36%7%15%26%15%1
1260
21st to endNight
26%7%18%31%17%1
1260
July1st to 10thNight
23%6%13%32%20%6%
1225
11th to 20thNight
22%6%17%24%23%8%
1218
21st to endNight
18%413%30%29%6%
1451
August1st to 10thNight
22%414%31%21%7%
1425
11th to 20thNight
22%6%13%33%22%4
1602
21st to endNight
26%5%10%24%28%7%
1845
September1st to 10thNight
29%410%29%19%8%
1800
11th to 20thNight
32%5%11%28%19%5%
1800
21st to endNight
29%5%12%32%20%3
2060
October1st to 10thNight
37%7%13%25%17%1
2160
11th to 20thNight
35%6%14%29%15%1
2160
21st to endNight
41%8%15%24%11%1
2518
November1st to 10thNight
47%6%15%20%10%2
2590
11th to 20thNight
41%7%19%24%9%1
2660
21st to endNight
44%7%22%20%8%
2660
December1st to 10thNight
51%7%17%16%8%1
2660
11th to 20thNight
44%8%21%22%41
3505
21st to endNight
31%5%13%28%17%6%
5214

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
8%12%32%25%17%6%
180
11th to 20thDay
6%12%34%27%19%2
180
21st to endDay
9%14%32%30%14%1
297
February1st to 10thDay
14%10%40%29%6%1
252
11th to 20thDay
8%11%41%28%11%1
240
21st to endDay
9%7%33%38%8%5%
198
March1st to 10thDay
11%10%35%32%12%
284
11th to 20thDay
8%10%40%27%13%3
420
21st to endDay
11%11%33%26%17%3
462
April1st to 10thDay
11%13%38%30%7%
420
11th to 20thDay
14%17%34%27%7%1
412
21st to endDay
20%12%29%29%10%1
482
May1st to 10thDay
15%10%25%28%19%4
603
11th to 20thDay
13%7%26%29%19%6%
625
21st to endDay
17%10%24%24%18%6%
679
June1st to 10thDay
13%11%26%27%20%3
630
11th to 20thDay
15%12%35%24%12%2
630
21st to endDay
9%7%26%31%22%5%
630
July1st to 10thDay
5%426%40%20%5%
621
11th to 20thDay
46%29%38%18%4
618
21st to endDay
45%25%38%23%5%
684
August1st to 10thDay
7%5%23%38%20%6%
622
11th to 20thDay
8%8%21%33%21%9%
437
21st to endDay
6%8%23%36%20%6%
495
September1st to 10thDay
12%9%32%31%13%3
450
11th to 20thDay
12%8%26%32%20%3
450
21st to endDay
15%11%27%27%16%4
356
October1st to 10thDay
24%10%20%22%20%4
270
11th to 20thDay
8%8%40%27%15%3
270
21st to endDay
12%14%39%22%10%2
297
November1st to 10thDay
18%15%33%26%8%
270
11th to 20thDay
10%16%37%27%8%1
270
21st to endDay
9%11%39%26%11%3
270
December1st to 10thDay
10%8%41%29%10%2
270
11th to 20thDay
7%16%38%31%7%2
180
21st to endDay
10%7%36%27%19%3
198
January1st to 10thNight
7%10%39%32%11%1
950
11th to 20thNight
9%13%37%32%7%2
950
21st to endNight
8%13%39%30%10%1
1035
February1st to 10thNight
7%9%33%36%13%1
738
11th to 20thNight
9%7%40%36%7%1
704
21st to endNight
7%6%32%35%18%3
592
March1st to 10thNight
10%9%38%33%11%1
720
11th to 20thNight
10%8%36%33%10%2
720
21st to endNight
10%8%34%34%12%2
730
April1st to 10thNight
10%7%36%37%10%1
540
11th to 20thNight
19%8%34%30%9%
533
21st to endNight
13%9%32%37%9%
540
May1st to 10thNight
13%8%26%38%14%1
540
11th to 20thNight
12%430%37%15%1
531
21st to endNight
18%7%25%30%18%2
547
June1st to 10thNight
14%9%24%34%18%1
360
11th to 20thNight
14%6%32%38%9%
360
21st to endNight
6%5%24%44%19%1
360
July1st to 10thNight
7%323%47%19%
350
11th to 20thNight
6%328%50%11%1
348
21st to endNight
3426%48%18%1
551
August1st to 10thNight
7%226%46%18%2
537
11th to 20thNight
7%420%45%23%1
534
21st to endNight
9%5%23%42%20%1
594
September1st to 10thNight
12%326%40%17%1
540
11th to 20thNight
11%6%27%38%18%1
540
21st to endNight
10%6%32%36%14%1
706
October1st to 10thNight
14%7%30%33%15%1
720
11th to 20thNight
10%10%32%33%14%1
720
21st to endNight
13%10%38%32%6%1
913
November1st to 10thNight
16%11%36%29%8%
925
11th to 20thNight
8%13%40%30%9%1
950
21st to endNight
9%10%42%31%8%
950
December1st to 10thNight
9%9%37%32%12%1
950
11th to 20thNight
9%9%40%31%10%
950
21st to endNight
12%7%36%34%10%2
1045
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