Vernon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Vernon clear sky chart from 2005-11-06 to 2024-01-15.

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
50%
24139
31%
74317
20%
24082
61%
24082
43%
38407

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
45%
950
33%
2458
13%
946
58%
946
46%
1383
January11th to 20thNight
45%
921
34%
2393
15%
921
57%
921
48%
1300
January21st to endNight
45%
940
38%
2524
17%
940
58%
940
47%
1371
February1st to 10thNight
35%
720
32%
2160
12%
720
52%
720
38%
1181
February11th to 20thNight
34%
704
29%
2098
12%
700
48%
700
39%
1138
February21st to endNight
29%
592
34%
1776
10%
592
49%
592
35%
976
March1st to 10thNight
34%
666
30%
2106
14%
666
48%
666
35%
1156
March11th to 20thNight
33%
540
29%
1980
17%
540
49%
540
33%
1009
March21st to endNight
33%
594
29%
2178
15%
594
53%
594
36%
1070
April1st to 10thNight
27%
540
30%
1940
13%
540
52%
540
38%
933
April11th to 20thNight
27%
533
28%
1777
12%
533
48%
533
37%
921
April21st to endNight
34%
540
32%
1652
16%
540
56%
540
40%
880
May1st to 10thNight
32%
540
30%
1620
15%
540
53%
540
39%
879
May11th to 20thNight
41%
531
21%
1594
16%
531
52%
531
38%
896
May21st to endNight
48%
582
27%
1745
20%
582
62%
582
43%
909
June1st to 10thNight
62%
540
25%
1620
19%
540
73%
540
52%
791
June11th to 20thNight
54%
540
27%
1620
21%
540
65%
540
50%
805
June21st to endNight
63%
540
30%
1620
29%
540
69%
540
53%
782
July1st to 10thNight
74%
525
22%
1575
23%
525
76%
525
42%
846
July11th to 20thNight
81%
522
32%
1566
34%
522
85%
522
59%
723
July21st to endNight
85%
591
35%
1673
39%
558
87%
558
55%
788
August1st to 10thNight
83%
537
37%
1601
40%
534
87%
534
58%
738
August11th to 20thNight
74%
534
29%
1730
34%
534
76%
534
40%
906
August21st to endNight
81%
594
32%
1980
36%
594
84%
594
52%
895
September1st to 10thNight
71%
540
28%
1952
33%
540
74%
540
40%
944
September11th to 20thNight
63%
540
28%
1980
28%
540
69%
540
33%
1056
September21st to endNight
67%
540
36%
1980
33%
540
74%
540
41%
940
October1st to 10thNight
58%
540
36%
1980
31%
540
67%
540
42%
936
October11th to 20thNight
52%
623
39%
2063
23%
623
66%
623
47%
979
October21st to endNight
49%
792
37%
2376
19%
792
61%
792
46%
1202
November1st to 10thNight
51%
911
35%
2391
14%
911
62%
911
54%
1233
November11th to 20thNight
51%
950
36%
2470
16%
950
61%
950
55%
1262
November21st to endNight
44%
950
35%
2470
15%
950
55%
950
45%
1382
December1st to 10thNight
47%
950
37%
2470
18%
950
58%
950
48%
1348
December11th to 20thNight
39%
948
35%
2864
15%
948
51%
948
36%
1614
December21st to endNight
39%
1039
22%
4335
14%
1026
52%
1026
28%
2235

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%42442445%7%58%
74908
Night
7%32332345%7%60%
74893
TransparencyDay
27%38%24%27%10%
74633
Night
25%38%23%28%14%
74688
SeeingDay
10%422%32%24%7%
14105
Night
9%5%31%39%15%1
24149

By Month

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 10thDay
6%5%23323446%63%
1707
11th to 20thDay
10%5%23323345%60%
1656
21st to endDay
7%424424345%61%
1847
February1st to 10thDay
9%6%24323336%58%
1800
11th to 20thDay
10%5%25%333347%55%
1749
21st to endDay
13%7%2432233457%
1480
March1st to 10thDay
12%5%23433447%52%
1851
11th to 20thDay
12%5%24323445%56%
1980
21st to endDay
9%5%25%42345%6%55%
2178
April1st to 10thDay
8%313334347%62%
2016
11th to 20thDay
14%424324446%54%
2134
21st to endDay
10%41442435%6%58%
2308
May1st to 10thDay
11%32443335%6%56%
2340
11th to 20thDay
11%424324448%54%
2302
21st to endDay
9%325%5%35%6%6%8%48%
2531
June1st to 10thDay
6%3144345%6%7%57%
2340
11th to 20thDay
5%214335%45%9%59%
2340
21st to endDay
5%21332345%9%63%
2340
July1st to 10thDay
7%3135%45%5%6%10%51%
2340
11th to 20thDay
421332445%7%64%
2340
21st to endDay
3213325%5%6%10%60%
2546
August1st to 10thDay
321342446%9%61%
2328
11th to 20thDay
6%4245%245%7%10%52%
2167
21st to endDay
5%31343445%8%59%
2376
September1st to 10thDay
10%313423446%60%
2005
11th to 20thDay
11%5%35%4345%5%6%50%
1980
21st to endDay
10%313323346%61%
1980
October1st to 10thDay
7%3134235%47%61%
1980
11th to 20thDay
11%212222335%67%
1877
21st to endDay
10%41232233464%
1980
November1st to 10thDay
8%422323346%64%
1684
11th to 20thDay
6%312213346%70%
1710
21st to endDay
11%5%23322336%61%
1710
December1st to 10thDay
8%5%2443335%5%58%
1710
11th to 20thDay
9%5%2442345%6%56%
2161
21st to endDay
10%6%25%434445%53%
3135
January1st to 10thNight
7%32343445%6%60%
2458
11th to 20thNight
8%323323335%65%
2393
21st to endNight
7%424223446%62%
2524
February1st to 10thNight
11%5%24323335%59%
2160
11th to 20thNight
10%5%24323447%57%
2098
21st to endNight
9%5%34423346%57%
1776
March1st to 10thNight
8%5%3443445%7%54%
2106
11th to 20thNight
13%413323335%59%
1980
21st to endNight
7%41432335%7%59%
2178
April1st to 10thNight
7%413323347%61%
1940
11th to 20thNight
11%313334448%57%
1777
21st to endNight
9%323424447%59%
1652
May1st to 10thNight
8%32442445%6%57%
1620
11th to 20thNight
9%4145%2345%9%53%
1593
21st to endNight
6%313425%46%9%57%
1745
June1st to 10thNight
421332347%12%58%
1620
11th to 20thNight
322432447%11%58%
1620
21st to endNight
3224422347%67%
1620
July1st to 10thNight
4324425%5%7%11%52%
1620
11th to 20thNight
321232336%8%66%
1620
21st to endNight
21133146%7%12%60%
1772
August1st to 10thNight
1212425%5%6%11%62%
1611
11th to 20thNight
5%324425%7%7%10%50%
1730
21st to endNight
32123245%6%10%62%
1980
September1st to 10thNight
8%32333345%7%59%
1952
11th to 20thNight
9%426%43435%8%51%
1980
21st to endNight
8%31443335%6%61%
1980
October1st to 10thNight
7%323323446%62%
1980
11th to 20thNight
8%32332223469%
2063
21st to endNight
9%314322235%67%
2376
November1st to 10thNight
7%41222224469%
2391
11th to 20thNight
5%213323346%68%
2470
21st to endNight
10%423323346%61%
2470
December1st to 10thNight
10%412323345%64%
2470
11th to 20thNight
8%5%245%33446%57%
3036
21st to endNight
10%5%24433445%56%
4532

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
24%27%26%31%10%
1708
11th to 20thDay
29%2321%36%9%
1656
21st to endDay
28%36%23%30%11%
1847
February1st to 10thDay
30%36%22%32%8%
1800
11th to 20thDay
32%35%25%23%12%
1759
21st to endDay
34%2317%27%17%
1480
March1st to 10thDay
34%26%19%25%15%
1851
11th to 20thDay
32%38%23%24%11%
1980
21st to endDay
30%38%24%25%10%
2178
April1st to 10thDay
25%38%24%26%14%
2016
11th to 20thDay
32%37%20%23%15%
2134
21st to endDay
28%39%24%28%8%
2308
May1st to 10thDay
31%39%21%24%12%
2340
11th to 20thDay
30%312%26%22%6%
2306
21st to endDay
33%6%12%24%21%5%
2531
June1st to 10thDay
26%5%14%29%18%8%
2340
11th to 20thDay
22%410%28%27%9%
2340
21st to endDay
20%412%24%30%10%
2340
July1st to 10thDay
28%5%13%29%20%4
2276
11th to 20thDay
19%38%30%32%9%
2271
21st to endDay
18%413%34%28%3
2405
August1st to 10thDay
19%310%33%25%10%
2314
11th to 20thDay
25%5%13%29%21%7%
2167
21st to endDay
23%411%27%26%9%
2376
September1st to 10thDay
27%37%24%26%13%
2005
11th to 20thDay
35%48%19%25%9%
1980
21st to endDay
25%36%22%32%11%
1980
October1st to 10thDay
23%310%23%27%12%
1980
11th to 20thDay
23%25%18%32%20%
1877
21st to endDay
26%26%24%28%15%
1980
November1st to 10thDay
24%25%24%30%15%
1684
11th to 20thDay
19%26%26%35%13%
1710
21st to endDay
28%25%21%30%15%
1710
December1st to 10thDay
29%36%27%26%8%
1710
11th to 20thDay
32%210%17%30%10%
2159
21st to endDay
34%36%23%27%8%
3135
January1st to 10thNight
26%26%23%31%12%
2458
11th to 20thNight
24%25%20%34%15%
2393
21st to endNight
25%25%20%32%16%
2524
February1st to 10thNight
30%27%21%28%12%
2160
11th to 20thNight
29%26%22%24%16%
2098
21st to endNight
31%2318%25%20%
1776
March1st to 10thNight
31%36%16%25%19%
2106
11th to 20thNight
30%26%23%24%14%
1980
21st to endNight
27%310%25%25%11%
2178
April1st to 10thNight
25%29%21%25%18%
1940
11th to 20thNight
28%310%20%22%16%
1777
21st to endNight
27%48%24%27%10%
1652
May1st to 10thNight
28%49%21%24%15%
1620
11th to 20thNight
29%5%15%22%20%10%
1594
21st to endNight
25%415%25%23%7%
1746
June1st to 10thNight
19%418%32%19%8%
1620
11th to 20thNight
21%314%27%26%8%
1620
21st to endNight
20%29%25%30%14%
1620
July1st to 10thNight
26%5%14%29%22%5%
1575
11th to 20thNight
16%38%27%34%13%
1566
21st to endNight
17%310%35%30%5%
1673
August1st to 10thNight
16%39%29%30%13%
1601
11th to 20thNight
27%412%26%25%6%
1730
21st to endNight
17%412%29%28%11%
1980
September1st to 10thNight
25%49%21%27%14%
1952
11th to 20thNight
33%310%18%24%12%
1980
21st to endNight
24%45%22%29%16%
1980
October1st to 10thNight
24%38%22%27%16%
1980
11th to 20thNight
23%1417%30%25%
2063
21st to endNight
24%2422%30%18%
2376
November1st to 10thNight
21%16%24%30%18%
2391
11th to 20thNight
19%3424%34%16%
2470
21st to endNight
26%2420%31%16%
2470
December1st to 10thNight
25%26%25%29%13%
2470
11th to 20thNight
31%25%19%32%12%
3037
21st to endNight
31%35%21%28%11%
4532

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
11%6%40%31%11%2
270
11th to 20thDay
14%11%31%30%13%1
252
21st to endDay
8%8%41%30%11%2
264
February1st to 10thDay
16%8%33%34%9%1
240
11th to 20thDay
11%9%45%28%7%
240
21st to endDay
23%6%38%28%5%1
198
March1st to 10thDay
12%10%38%29%10%1
240
11th to 20thDay
17%11%35%23%11%2
240
21st to endDay
13%10%43%25%9%2
264
April1st to 10thDay
11%10%42%24%13%1
276
11th to 20thDay
15%14%40%26%5%
412
21st to endDay
14%10%39%27%9%2
568
May1st to 10thDay
11%437%36%10%
603
11th to 20thDay
14%428%35%16%3
625
21st to endDay
11%5%26%34%19%5%
679
June1st to 10thDay
8%213%41%30%6%
630
11th to 20thDay
5%118%44%25%6%
630
21st to endDay
5%113%41%33%8%
630
July1st to 10thDay
6%15%33%40%16%
621
11th to 20thDay
416%29%45%15%
618
21st to endDay
31327%50%17%
684
August1st to 10thDay
5%1432%45%13%
626
11th to 20thDay
7%16%34%36%15%
481
21st to endDay
5%15%29%41%19%
495
September1st to 10thDay
11%1225%40%22%
295
11th to 20thDay
8%6%27%36%23%
270
21st to endDay
14%26%28%35%15%
270
October1st to 10thDay
4119%36%30%11%
270
11th to 20thDay
10%329%35%20%3
270
21st to endDay
21%7%22%30%17%3
297
November1st to 10thDay
15%328%29%21%4
270
11th to 20thDay
12%7%26%34%17%4
270
21st to endDay
19%7%31%26%11%4
270
December1st to 10thDay
10%340%32%14%1
270
11th to 20thDay
10%6%34%35%14%1
270
21st to endDay
19%9%37%26%8%1
297
January1st to 10thNight
9%6%37%38%10%
950
11th to 20thNight
9%8%33%40%9%
921
21st to endNight
9%6%37%40%8%
940
February1st to 10thNight
13%8%39%33%7%
720
11th to 20thNight
12%8%42%32%5%
704
21st to endNight
13%10%44%30%3
592
March1st to 10thNight
11%10%41%33%5%
666
11th to 20thNight
15%10%39%29%7%
540
21st to endNight
8%12%45%30%4
594
April1st to 10thNight
8%9%52%26%5%
540
11th to 20thNight
11%8%50%27%4
533
21st to endNight
10%8%46%29%6%
540
May1st to 10thNight
9%6%48%30%7%
540
11th to 20thNight
11%439%34%11%1
531
21st to endNight
7%435%40%12%1
584
June1st to 10thNight
5%228%46%19%1
540
11th to 20thNight
3235%51%9%
540
21st to endNight
3124%46%24%1
540
July1st to 10thNight
5%110%46%35%3
525
11th to 20thNight
319%49%36%2
522
21st to endNight
415%48%42%2
591
August1st to 10thNight
18%52%37%2
537
11th to 20thNight
6%19%49%34%1
534
21st to endNight
48%45%39%5%
594
September1st to 10thNight
9%212%43%33%2
540
11th to 20thNight
11%15%43%28%2
540
21st to endNight
9%117%44%27%2
540
October1st to 10thNight
8%324%42%22%1
540
11th to 20thNight
9%430%44%11%1
623
21st to endNight
10%7%31%36%15%1
792
November1st to 10thNight
9%432%39%14%2
911
11th to 20thNight
6%6%34%42%11%1
950
21st to endNight
12%7%33%35%12%1
950
December1st to 10thNight
12%6%31%41%10%
950
11th to 20thNight
13%7%35%38%7%
950
21st to endNight
12%5%38%38%7%
1045
Page generated at 2024-01-11 21:33:51. Version ac07

Copyright 2024 Attilla Danko


Vernon Clear Sky Chart |Charts Home