Vernon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Vernon clear sky chart from 2005-11-05 to 2018-10-08.

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
45%
16167
9%
50748
8%
16139
47%
16139
16%
37249

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
28%
813
4%
2810
4%
810
29%
810
6%
2438
January16th to endNight
29%
832
3%
2912
3%
832
31%
832
6%
2479
February1st to 15thNight
35%
759
6%
2603
6%
758
37%
758
9%
2103
February16th to endNight
44%
684
10%
2125
10%
684
46%
684
16%
1568
March1st to 15thNight
35%
780
6%
2340
5%
780
36%
780
12%
1863
March16th to endNight
38%
832
9%
2171
4%
832
40%
832
17%
1665
April1st to 15thNight
44%
779
8%
1949
4%
779
45%
779
18%
1509
April16th to endNight
42%
527
11%
1685
10%
527
44%
527
17%
1223
May1st to 15thNight
54%
389
12%
1560
19%
389
55%
389
18%
995
May16th to endNight
56%
406
7%
1566
9%
406
57%
406
18%
1033
June1st to 15thNight
46%
390
2%
1271
0%
390
46%
390
18%
891
June16th to endNight
54%
390
4%
1170
0%
390
54%
390
22%
794
July1st to 15thNight
67%
370
8%
1242
3%
370
69%
370
36%
653
July16th to endNight
74%
408
13%
1544
18%
386
78%
386
39%
703
August1st to 15thNight
79%
384
22%
1528
32%
382
82%
382
41%
685
August16th to endNight
71%
666
24%
1908
21%
666
73%
666
42%
1043
September1st to 15thNight
67%
780
21%
1950
12%
780
69%
780
41%
1197
September16th to endNight
60%
776
19%
2101
13%
776
62%
776
29%
1379
October1st to 15thNight
53%
752
12%
2256
12%
752
55%
752
23%
1535
October16th to endNight
43%
768
10%
2483
8%
768
47%
768
17%
1778
November1st to 15thNight
35%
760
8%
2594
7%
760
37%
760
9%
2092
November16th to endNight
30%
884
5%
2834
3%
884
33%
884
7%
2402
December1st to 15thNight
35%
975
5%
2925
3%
975
37%
975
10%
2434
December16th to endNight
28%
1063
4%
3221
3%
1063
29%
1063
8%
2787

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
9%7%37%7%46%5%6%7%34%
52396
Night
9%9%47%6%35%5%5%7%33%
50905
Cloud CoverDay
11%8%37%6%35%5%6%7%33%
52396
Night
11%10%47%6%35%5%5%6%32%
50908
TransparencyDay
48%11%15%16%7%1
52057
Night
50%10%15%16%7%
50748
SeeingDay
14%12%26%26%15%3
7547
Night
15%7%22%31%20%3
16175

By Month

Percentage Cloud Cover NW (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
14%13%6%9%6%6%8%7%6%6%14%
1465
16th to endDay
9%13%410%9%5%7%7%6%6%19%
1664
February1st to 15thDay
9%12%5%10%9%46%5%5%5%23%
1591
16th to endDay
8%10%5%8%9%47%6%7%8%24%
1635
March1st to 15thDay
9%10%48%9%5%6%5%7%8%24%
1950
16th to endDay
9%10%5%8%7%5%6%7%7%8%23%
2402
April1st to 15thDay
9%10%5%8%8%46%6%6%7%24%
2329
16th to endDay
10%9%47%7%36%5%7%7%29%
2548
May1st to 15thDay
9%7%36%6%45%5%5%7%37%
2721
16th to endDay
12%7%37%6%35%5%6%7%33%
2895
June1st to 15thDay
15%6%37%7%35%6%6%6%29%
3016
16th to endDay
12%5%36%6%35%6%5%7%35%
3120
July1st to 15thDay
42145%35%5%6%8%51%
2970
16th to endDay
4213425%35%8%58%
2881
August1st to 15thDay
32135%345%5%8%55%
2676
16th to endDay
6%2144345%6%7%53%
2644
September1st to 15thDay
5%415%5%3446%7%50%
2340
16th to endDay
10%6%35%6%35%5%6%8%38%
2187
October1st to 15thDay
10%7%36%7%46%5%5%6%34%
1873
16th to endDay
16%8%39%6%345%5%7%29%
1740
November1st to 15thDay
14%11%49%6%46%6%5%6%23%
1592
16th to endDay
9%11%6%9%9%5%9%7%6%6%17%
1443
December1st to 15thDay
6%12%6%12%12%5%7%6%46%18%
1365
16th to endDay
12%12%410%8%47%6%6%8%17%
1349
January1st to 15thNight
13%17%6%10%9%5%7%5%5%6%12%
2810
16th to endNight
9%15%6%14%10%47%45%6%14%
2912
February1st to 15thNight
13%15%5%9%7%35%6%5%6%21%
2591
16th to endNight
7%12%49%7%35%5%5%7%32%
2125
March1st to 15thNight
9%11%6%8%7%46%5%5%7%27%
2340
16th to endNight
8%8%48%6%46%5%6%8%31%
2167
April1st to 15thNight
9%7%46%7%5%6%6%6%8%33%
1949
16th to endNight
10%8%47%6%46%446%35%
1685
May1st to 15thNight
6%7%36%7%35%5%6%6%41%
1559
16th to endNight
11%7%26%5%35%5%6%8%37%
1566
June1st to 15thNight
13%5%35%6%35%6%7%9%34%
1271
16th to endNight
8%427%6%26%7%6%8%40%
1170
July1st to 15thNight
3313425%45%8%58%
1312
16th to endNight
4212314347%63%
1640
August1st to 15thNight
411232345%8%62%
1536
16th to endNight
311433445%7%59%
1908
September1st to 15thNight
5%22342445%6%58%
1950
16th to endNight
8%425%4245%48%47%
2101
October1st to 15thNight
8%6%25%6%35%45%7%42%
2256
16th to endNight
12%7%26%7%35%45%8%34%
2483
November1st to 15thNight
16%11%48%6%45%5%5%7%23%
2594
16th to endNight
12%13%7%11%9%46%5%5%5%18%
2834
December1st to 15thNight
9%14%6%12%8%46%6%6%6%19%
2925
16th to endNight
12%16%6%10%9%5%6%6%5%5%15%
3221

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 15thDay
16%16%6%9%8%45%6%7%5%14%
1465
16th to endDay
12%13%48%7%5%8%6%5%7%18%
1664
February1st to 15thDay
12%14%5%10%9%35%5%6%422%
1591
16th to endDay
9%12%5%9%7%46%6%7%8%23%
1635
March1st to 15thDay
11%12%5%9%8%46%6%5%6%22%
1950
16th to endDay
12%10%5%8%9%46%6%6%7%22%
2402
April1st to 15thDay
12%12%5%8%8%47%47%7%22%
2329
16th to endDay
12%10%49%7%46%5%5%7%27%
2548
May1st to 15thDay
11%8%36%5%35%45%7%35%
2721
16th to endDay
14%7%36%7%36%6%5%6%31%
2895
June1st to 15thDay
16%8%47%7%45%5%5%7%28%
3016
16th to endDay
14%6%26%6%35%5%6%7%34%
3120
July1st to 15thDay
6%324335%5%6%8%51%
2970
16th to endDay
421332445%7%59%
2881
August1st to 15thDay
43135%345%5%8%55%
2676
16th to endDay
6%4144345%6%7%51%
2644
September1st to 15thDay
6%5%244245%6%8%50%
2340
16th to endDay
12%6%25%5%35%6%5%8%37%
2187
October1st to 15thDay
11%9%27%6%46%46%7%32%
1873
16th to endDay
18%9%37%6%245%5%6%29%
1740
November1st to 15thDay
17%13%5%8%6%45%5%6%5%21%
1592
16th to endDay
11%14%6%8%8%5%8%7%6%7%15%
1443
December1st to 15thDay
9%14%6%11%11%47%5%5%6%17%
1365
16th to endDay
14%14%5%9%7%45%5%8%6%18%
1349
January1st to 15thNight
18%17%6%9%7%46%45%5%14%
2809
16th to endNight
11%15%6%10%10%5%6%5%5%6%15%
2912
February1st to 15thNight
16%15%5%7%6%45%5%5%5%22%
2591
16th to endNight
8%14%49%5%35%45%7%30%
2125
March1st to 15thNight
12%13%5%9%6%45%5%5%7%25%
2340
16th to endNight
9%10%5%7%6%35%5%6%7%30%
2171
April1st to 15thNight
10%10%36%7%46%6%6%8%29%
1949
16th to endNight
11%9%38%7%36%446%34%
1685
May1st to 15thNight
6%9%27%5%35%5%5%6%39%
1559
16th to endNight
12%7%37%435%5%5%8%37%
1566
June1st to 15thNight
13%7%46%6%235%6%8%33%
1271
16th to endNight
9%5%35%5%36%6%6%8%39%
1170
July1st to 15thNight
431333445%8%56%
1312
16th to endNight
42122346%7%63%
1640
August1st to 15thNight
411332345%8%61%
1536
16th to endNight
431332345%7%59%
1908
September1st to 15thNight
6%31342345%7%56%
1950
16th to endNight
9%5%25%4345%48%45%
2101
October1st to 15thNight
10%7%26%5%36%45%6%41%
2256
16th to endNight
15%7%36%6%35%45%6%34%
2483
November1st to 15thNight
19%14%46%5%445%5%5%23%
2594
16th to endNight
15%15%6%8%7%46%6%5%5%18%
2834
December1st to 15thNight
11%15%6%10%7%47%5%5%6%21%
2925
16th to endNight
12%17%7%10%8%46%5%5%5%16%
3221

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
66%16%11%4
1465
16th to endDay
61%14%15%6%11
1664
February1st to 15thDay
61%13%13%9%2
1591
16th to endDay
55%13%16%11%3
1635
March1st to 15thDay
58%12%14%11%2
1950
16th to endDay
58%11%16%9%2
2402
April1st to 15thDay
58%11%14%13%1
2329
16th to endDay
53%10%14%14%5%
2548
May1st to 15thDay
45%10%14%19%9%
2721
16th to endDay
50%10%16%18%4
2899
June1st to 15thDay
54%10%13%14%6%1
3016
16th to endDay
46%10%13%17%10%1
3120
July1st to 15thDay
30%10%13%22%17%5%
2811
16th to endDay
23%7%16%26%22%2
2714
August1st to 15thDay
25%9%18%28%15%2
2659
16th to endDay
29%9%16%28%14%1
2644
September1st to 15thDay
30%9%14%29%14%
2340
16th to endDay
42%11%18%19%6%1
2187
October1st to 15thDay
47%10%20%17%4
1873
16th to endDay
53%11%18%13%2
1740
November1st to 15thDay
62%12%13%9%2
1592
16th to endDay
64%13%12%7%1
1443
December1st to 15thDay
64%12%13%9%
1365
16th to endDay
62%15%14%6%1
1349
January1st to 15thNight
69%11%11%6%1
2810
16th to endNight
67%11%12%6%2
2912
February1st to 15thNight
61%10%12%11%3
2603
16th to endNight
52%9%18%14%5%
2125
March1st to 15thNight
57%11%15%12%2
2340
16th to endNight
51%10%17%16%3
2171
April1st to 15thNight
48%13%18%14%4
1949
16th to endNight
50%9%13%19%6%
1685
May1st to 15thNight
42%9%14%20%12%
1560
16th to endNight
44%8%17%21%7%
1566
June1st to 15thNight
46%9%14%19%8%1
1271
16th to endNight
40%11%16%19%11%
1170
July1st to 15thNight
26%6%16%24%18%7%
1242
16th to endNight
19%8%14%27%26%4
1544
August1st to 15thNight
20%5%16%31%20%4
1528
16th to endNight
22%8%17%29%19%2
1908
September1st to 15thNight
26%9%14%26%19%2
1950
16th to endNight
35%10%17%25%9%2
2101
October1st to 15thNight
41%10%17%21%8%
2256
16th to endNight
49%9%19%19%2
2483
November1st to 15thNight
60%11%12%10%4
2594
16th to endNight
66%11%11%8%2
2834
December1st to 15thNight
62%11%14%9%1
2925
16th to endNight
68%11%12%6%1
3221

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
13%314%26%21%21%
90
16th to endDay
28%5%25%25%13%3
96
February1st to 15thDay
16%18%30%24%7%2
161
16th to endDay
11%12%30%31%12%2
273
March1st to 15thDay
20%23%27%19%6%1
330
16th to endDay
19%23%29%20%7%
352
April1st to 15thDay
23%20%30%16%8%1
329
16th to endDay
17%20%28%20%9%4
318
May1st to 15thDay
14%15%31%24%10%3
348
16th to endDay
16%11%20%24%21%6%
450
June1st to 15thDay
17%11%25%26%17%2
661
16th to endDay
13%10%28%26%16%3
765
July1st to 15thDay
8%9%24%33%22%1
595
16th to endDay
49%28%33%18%5%
391
August1st to 15thDay
47%23%32%23%8%
359
16th to endDay
8%8%27%35%14%7%
396
September1st to 15thDay
10%11%28%26%18%3
375
16th to endDay
17%10%30%22%15%3
375
October1st to 15thDay
18%15%26%23%12%2
345
16th to endDay
21%6%25%26%17%2
156
November1st to 15thDay
27%11%27%17%14%1
106
16th to endDay
15%14%31%20%10%8%
90
December1st to 15thDay
15%7%16%23%25%11%
90
16th to endDay
15%6%29%35%10%3
96
January1st to 15thNight
24%10%23%24%14%2
814
16th to endNight
17%6%28%29%15%3
832
February1st to 15thNight
23%9%19%31%14%2
764
16th to endNight
14%6%25%30%19%3
684
March1st to 15thNight
17%11%26%28%13%2
780
16th to endNight
14%10%28%30%14%2
832
April1st to 15thNight
13%11%23%30%19%2
779
16th to endNight
15%6%26%34%15%2
527
May1st to 15thNight
11%7%17%39%23%1
390
16th to endNight
15%417%29%28%3
407
June1st to 15thNight
16%325%29%22%2
390
16th to endNight
10%422%38%20%3
390
July1st to 15thNight
6%316%33%37%2
370
16th to endNight
6%115%32%39%3
408
August1st to 15thNight
5%19%29%43%10%
384
16th to endNight
5%314%37%34%4
666
September1st to 15thNight
7%316%29%33%9%
780
16th to endNight
14%5%15%32%27%5%
776
October1st to 15thNight
13%5%19%35%23%3
752
16th to endNight
17%8%21%32%17%2
768
November1st to 15thNight
24%11%22%30%9%1
760
16th to endNight
20%11%24%26%12%3
884
December1st to 15thNight
16%8%27%30%15%2
975
16th to endNight
20%7%30%30%9%
1063
Page generated at 2018-10-09 07:39:16. Version ac04

Copyright 2018 A. Danko


Vernon Clear Sky Chart |Charts Home