Velveeta Valley Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Velveeta Valley Observatory clear sky chart from 2005-11-05 to 2019-06-19.

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
37%
18435
17%
53964
10%
18392
44%
18392
24%
36092

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
23%
1050
14%
2926
5%
1045
32%
1045
19%
2126
January16th to endNight
22%
1120
12%
3058
5%
1120
28%
1120
17%
2281
February1st to 15thNight
21%
995
14%
2647
4%
995
28%
995
19%
1941
February16th to endNight
26%
735
17%
2205
8%
735
35%
735
18%
1537
March1st to 15thNight
30%
837
15%
2517
7%
837
37%
837
20%
1711
March16th to endNight
31%
672
16%
2332
11%
672
39%
672
18%
1586
April1st to 15thNight
26%
629
15%
2097
9%
629
37%
629
18%
1438
April16th to endNight
36%
624
18%
2043
12%
624
45%
624
22%
1358
May1st to 15thNight
37%
630
14%
1782
9%
630
42%
630
22%
1272
May16th to endNight
45%
659
17%
1753
8%
657
51%
657
31%
1136
June1st to 15thNight
54%
630
17%
1680
10%
630
58%
630
36%
1054
June16th to endNight
50%
597
15%
1592
8%
597
54%
597
30%
1048
July1st to 15thNight
67%
555
19%
1480
12%
555
69%
555
44%
856
July16th to endNight
69%
612
21%
1545
16%
579
71%
579
44%
886
August1st to 15thNight
74%
575
23%
1666
22%
572
75%
572
42%
920
August16th to endNight
63%
621
19%
2070
20%
621
67%
621
33%
1174
September1st to 15thNight
63%
585
29%
1950
29%
585
68%
585
36%
1043
September16th to endNight
56%
744
26%
2112
18%
744
61%
744
36%
1238
October1st to 15thNight
39%
780
22%
2304
14%
780
47%
780
27%
1476
October16th to endNight
32%
832
19%
2610
10%
832
42%
832
23%
1681
November1st to 15thNight
31%
820
23%
2666
16%
820
41%
820
24%
1664
November16th to endNight
26%
963
16%
2853
8%
963
35%
963
20%
1962
December1st to 15thNight
22%
1050
13%
2940
5%
1050
29%
1050
16%
2217
December16th to endNight
20%
1120
11%
3136
3%
1120
27%
1120
13%
2487

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
13%8%36%5%3445%7%36%
54768
Night
14%8%36%5%24446%40%
54133
Cloud CoverDay
14%8%36%5%3445%7%37%
54776
Night
14%7%35%424446%40%
54138
TransparencyDay
46%5%13%21%11%1
54454
Night
44%5%11%22%14%1
53965
SeeingDay
17%8%26%25%16%5%
8342
Night
17%7%30%30%12%1
18438

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
12%11%6%8%5%25%5%5%7%28%
1672
16th to endDay
13%13%6%11%6%25%346%26%
1869
February1st to 15thDay
13%14%6%8%5%34445%30%
1875
16th to endDay
15%11%47%6%24336%32%
1840
March1st to 15thDay
14%10%47%5%33448%34%
2105
16th to endDay
16%8%37%5%35%45%6%32%
2596
April1st to 15thDay
19%10%47%6%3445%6%29%
2511
16th to endDay
19%9%26%423446%34%
2521
May1st to 15thDay
19%9%37%6%3445%6%28%
2827
16th to endDay
13%6%26%5%35%6%6%7%36%
3065
June1st to 15thDay
12%5%245%35%46%8%39%
2940
16th to endDay
10%6%25%6%35%5%6%10%37%
2776
July1st to 15thDay
6%324435%6%7%9%46%
2730
16th to endDay
7%5%25%6%35%5%6%9%41%
2879
August1st to 15thDay
6%425%5%35%6%7%10%41%
2533
16th to endDay
11%5%244345%6%7%44%
2484
September1st to 15thDay
12%423324437%50%
2340
16th to endDay
10%5%25%5%24447%47%
2165
October1st to 15thDay
17%7%25%423346%41%
1983
16th to endDay
18%7%25%433446%39%
1966
November1st to 15thDay
13%9%35%5%35%35%6%38%
1852
16th to endDay
15%12%45%5%23336%37%
1767
December1st to 15thDay
16%12%48%434336%29%
1680
16th to endDay
20%14%6%7%6%33445%23%
1792
January1st to 15thNight
14%11%5%8%5%3334435%
2926
16th to endNight
13%10%5%10%5%3445%7%29%
3058
February1st to 15thNight
14%11%6%7%5%24335%34%
2645
16th to endNight
17%11%36%5%24445%35%
2205
March1st to 15thNight
15%9%25%434345%39%
2504
16th to endNight
17%8%36%5%24446%34%
2332
April1st to 15thNight
19%8%35%423345%36%
2097
16th to endNight
17%6%35%5%34446%37%
2043
May1st to 15thNight
18%6%35%5%25%46%7%33%
1782
16th to endNight
10%5%245%2445%10%42%
1752
June1st to 15thNight
10%5%235%235%6%8%47%
1680
16th to endNight
8%5%25%5%35%5%7%8%41%
1592
July1st to 15thNight
6%21332346%9%56%
1560
16th to endNight
6%3133235%7%9%51%
1641
August1st to 15thNight
43145%244410%54%
1675
16th to endNight
9%423424347%51%
2070
September1st to 15thNight
9%423333246%57%
1950
16th to endNight
8%42443445%7%51%
2112
October1st to 15thNight
14%6%24424436%45%
2304
16th to endNight
17%7%24433336%43%
2610
November1st to 15thNight
13%8%35%423345%46%
2666
16th to endNight
18%8%35%424446%37%
2853
December1st to 15thNight
18%11%48%5%34446%29%
2940
16th to endNight
21%12%49%5%2444424%
3136

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 15thDay
13%11%6%7%5%35%5%5%7%28%
1672
16th to endDay
13%14%6%11%6%3435%5%25%
1869
February1st to 15thDay
13%14%6%6%6%25%436%29%
1875
16th to endDay
15%12%47%6%24336%32%
1840
March1st to 15thDay
15%10%37%5%33348%34%
2115
16th to endDay
17%9%36%5%35%45%6%32%
2594
April1st to 15thDay
19%9%47%5%35%446%29%
2511
16th to endDay
20%9%25%5%23346%34%
2521
May1st to 15thDay
20%7%37%6%3445%6%29%
2827
16th to endDay
14%6%25%5%35%5%6%7%37%
3065
June1st to 15thDay
13%425%5%35%5%6%7%40%
2940
16th to endDay
11%5%25%5%35%5%6%9%38%
2776
July1st to 15thDay
6%424435%5%7%9%46%
2730
16th to endDay
8%5%26%5%35%47%9%41%
2879
August1st to 15thDay
6%315%6%36%6%7%10%41%
2533
16th to endDay
12%5%245%2446%7%44%
2484
September1st to 15thDay
13%413424347%50%
2340
16th to endDay
10%5%25%42445%7%46%
2165
October1st to 15thDay
18%7%15%423346%41%
1983
16th to endDay
18%7%245%33446%39%
1966
November1st to 15thDay
14%8%45%5%2445%6%38%
1852
16th to endDay
16%12%45%423336%38%
1767
December1st to 15thDay
17%12%48%5%34336%30%
1680
16th to endDay
20%14%6%7%6%23445%23%
1792
January1st to 15thNight
14%10%5%7%5%3434435%
2926
16th to endNight
13%10%5%9%6%3445%6%29%
3058
February1st to 15thNight
15%12%5%7%5%24235%35%
2638
16th to endNight
17%11%45%5%24345%35%
2205
March1st to 15thNight
15%9%35%5%2435%5%39%
2517
16th to endNight
17%8%36%5%24437%34%
2332
April1st to 15thNight
20%8%35%424445%37%
2097
16th to endNight
18%7%26%43445%6%37%
2043
May1st to 15thNight
17%7%26%5%245%6%7%34%
1781
16th to endNight
11%5%1442445%10%42%
1752
June1st to 15thNight
11%4135%2346%8%47%
1680
16th to endNight
9%5%26%445%5%6%9%41%
1592
July1st to 15thNight
5%21332345%9%56%
1560
16th to endNight
6%2233235%6%10%51%
1641
August1st to 15thNight
5%3135%2445%8%55%
1675
16th to endNight
10%324423447%51%
2070
September1st to 15thNight
9%413323246%57%
1950
16th to endNight
8%424434447%52%
2112
October1st to 15thNight
15%5%245%24345%45%
2304
16th to endNight
17%7%14423336%43%
2610
November1st to 15thNight
14%8%25%413345%45%
2666
16th to endNight
18%8%35%424446%37%
2853
December1st to 15thNight
18%11%48%6%34345%29%
2940
16th to endNight
21%13%48%5%34445%24%
3136

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
53%6%14%15%9%
1673
16th to endDay
60%412%14%7%
1869
February1st to 15thDay
57%411%17%8%
1877
16th to endDay
54%5%10%21%7%1
1840
March1st to 15thDay
49%5%13%21%9%
2115
16th to endDay
51%6%12%20%7%
2596
April1st to 15thDay
55%410%19%8%
2511
16th to endDay
50%5%10%18%12%2
2521
May1st to 15thDay
54%6%12%20%5%
2827
16th to endDay
44%7%12%20%13%1
3069
June1st to 15thDay
40%7%13%23%13%1
2940
16th to endDay
39%7%14%22%13%1
2776
July1st to 15thDay
31%7%17%25%14%3
2581
16th to endDay
36%6%17%23%13%2
2712
August1st to 15thDay
34%6%15%28%13%1
2518
16th to endDay
37%6%13%26%14%1
2484
September1st to 15thDay
34%5%8%27%20%3
2340
16th to endDay
35%5%12%28%16%1
2165
October1st to 15thDay
44%410%24%14%
1983
16th to endDay
46%412%23%11%1
1966
November1st to 15thDay
46%412%22%12%1
1852
16th to endDay
49%415%23%6%
1767
December1st to 15thDay
57%414%16%7%
1680
16th to endDay
63%5%11%12%7%
1792
January1st to 15thNight
52%410%19%12%
2926
16th to endNight
55%413%16%9%
3058
February1st to 15thNight
53%311%19%11%
2647
16th to endNight
50%412%22%8%2
2205
March1st to 15thNight
47%5%13%19%12%1
2517
16th to endNight
49%412%20%11%1
2332
April1st to 15thNight
49%5%9%21%13%1
2097
16th to endNight
45%410%22%12%4
2043
May1st to 15thNight
47%7%13%20%10%
1782
16th to endNight
35%8%14%22%16%2
1754
June1st to 15thNight
33%6%12%26%19%1
1680
16th to endNight
37%8%12%21%18%3
1592
July1st to 15thNight
25%6%13%29%20%4
1480
16th to endNight
24%7%16%28%18%4
1545
August1st to 15thNight
26%5%14%31%19%2
1666
16th to endNight
32%5%14%26%17%3
2070
September1st to 15thNight
28%410%26%25%3
1950
16th to endNight
31%5%10%31%18%2
2112
October1st to 15thNight
40%5%9%23%20%1
2304
16th to endNight
43%411%25%13%1
2610
November1st to 15thNight
41%410%23%17%2
2666
16th to endNight
47%5%13%23%10%
2853
December1st to 15thNight
57%49%19%7%
2940
16th to endNight
62%5%10%13%7%
3136

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
19%13%31%27%7%
180
16th to endDay
20%10%34%26%7%
192
February1st to 15thDay
27%14%35%18%4
180
16th to endDay
30%16%27%20%5%
159
March1st to 15thDay
22%17%35%17%6%1
180
16th to endDay
25%8%32%18%12%2
324
April1st to 15thDay
29%10%31%20%8%
390
16th to endDay
21%11%24%24%13%4
379
May1st to 15thDay
24%10%27%23%9%3
514
16th to endDay
17%11%26%22%15%6%
677
June1st to 15thDay
12%5%30%30%17%3
645
16th to endDay
15%5%27%30%14%5%
587
July1st to 15thDay
8%221%30%24%12%
550
16th to endDay
10%320%32%24%8%
595
August1st to 15thDay
6%220%31%28%10%
508
16th to endDay
14%417%26%25%12%
396
September1st to 15thDay
14%216%25%27%13%
375
16th to endDay
9%6%21%30%23%7%
374
October1st to 15thDay
21%11%26%24%14%1
213
16th to endDay
24%14%27%26%8%
192
November1st to 15thDay
20%11%31%20%13%4
180
16th to endDay
29%10%33%20%6%
180
December1st to 15thDay
18%12%36%21%7%2
180
16th to endDay
27%13%41%15%2
192
January1st to 15thNight
20%11%36%24%6%
1050
16th to endNight
18%10%37%28%4
1120
February1st to 15thNight
22%10%36%25%5%
998
16th to endNight
22%11%34%24%6%
735
March1st to 15thNight
19%10%33%28%7%
837
16th to endNight
19%7%34%27%9%1
672
April1st to 15thNight
23%10%34%26%5%
629
16th to endNight
20%9%29%29%10%
624
May1st to 15thNight
21%5%29%31%11%
630
16th to endNight
13%330%36%15%
659
June1st to 15thNight
12%224%45%14%
630
16th to endNight
9%330%38%17%
597
July1st to 15thNight
7%118%41%29%2
555
16th to endNight
8%15%44%28%2
612
August1st to 15thNight
5%9%47%31%4
575
16th to endNight
11%213%37%28%5%
621
September1st to 15thNight
10%218%34%28%5%
585
16th to endNight
9%5%21%34%26%2
744
October1st to 15thNight
17%7%31%28%15%1
780
16th to endNight
21%9%33%26%9%
832
November1st to 15thNight
17%8%36%26%10%
820
16th to endNight
22%10%34%25%6%
963
December1st to 15thNight
23%10%35%23%6%
1050
16th to endNight
25%10%33%25%3
1120
Page generated at 2019-06-20 07:02:31. Version ac04

Copyright 2019 A. Danko


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