Mesa Vista Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mesa Vista Observatory clear sky chart from 2005-11-05 to 2018-11-30.

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
48%
17344
30%
51735
16%
17300
61%
17300
40%
27100

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
41%
841
32%
2583
16%
837
59%
837
47%
1219
January16th to endNight
39%
832
36%
2704
21%
832
58%
832
41%
1263
February1st to 15thNight
34%
762
29%
2383
14%
760
51%
760
38%
1217
February16th to endNight
25%
684
36%
2050
11%
684
50%
684
39%
1046
March1st to 15thNight
40%
780
32%
2233
14%
780
55%
780
40%
1176
March16th to endNight
36%
764
34%
2220
14%
764
54%
764
45%
1107
April1st to 15thNight
30%
584
31%
1948
11%
584
55%
584
34%
951
April16th to endNight
33%
579
32%
1929
15%
579
58%
579
35%
930
May1st to 15thNight
42%
584
26%
1949
16%
584
57%
584
37%
986
May16th to endNight
48%
611
29%
1673
15%
609
62%
609
43%
903
June1st to 15thNight
59%
585
26%
1560
15%
585
66%
585
47%
842
June16th to endNight
66%
585
24%
1560
19%
585
69%
585
47%
857
July1st to 15thNight
74%
555
17%
1522
15%
555
75%
555
34%
940
July16th to endNight
77%
612
13%
1737
13%
579
77%
579
29%
1074
August1st to 15thNight
76%
575
15%
1842
16%
572
76%
572
27%
1154
August16th to endNight
72%
621
19%
2070
21%
621
75%
621
31%
1216
September1st to 15thNight
70%
585
24%
1950
25%
585
72%
585
31%
1142
September16th to endNight
64%
585
33%
2082
28%
585
73%
585
40%
1013
October1st to 15thNight
55%
780
33%
2340
21%
780
64%
780
44%
1210
October16th to endNight
54%
832
37%
2496
19%
832
67%
832
50%
1172
November1st to 15thNight
48%
943
38%
2583
17%
943
61%
943
53%
1238
November16th to endNight
45%
1050
37%
2730
17%
1050
57%
1050
52%
1397
December1st to 15thNight
34%
975
31%
2679
11%
975
51%
975
40%
1444
December16th to endNight
30%
1040
31%
2912
12%
1040
47%
1040
37%
1603

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
431342445%7%56%
52559
Night
331332345%7%60%
51924
Cloud CoverDay
442342446%7%55%
52557
Night
331332345%7%59%
51924
TransparencyDay
24%6%11%20%24%12%
52249
Night
21%6%11%21%25%12%
51736
SeeingDay
8%17%30%28%13%2
7128
Night
5%12%29%32%18%2
17348

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 15thDay
2312213346%68%
1695
16th to endDay
3423213335%66%
1872
February1st to 15thDay
15%2331235%7%62%
1806
16th to endDay
37%321345%7%61%
1710
March1st to 15thDay
342332345%7%58%
2055
16th to endDay
4323323446%62%
2355
April1st to 15thDay
332442345%6%58%
2330
16th to endDay
3423323346%60%
2306
May1st to 15thDay
5%41343445%5%56%
2331
16th to endDay
421232346%7%61%
2788
June1st to 15thDay
211331445%8%62%
2730
16th to endDay
3223245%6%6%61%
2730
July1st to 15thDay
5%426%6%47%7%7%9%37%
2681
16th to endDay
6%425%6%47%8%10%10%34%
2675
August1st to 15thDay
6%3147%46%7%7%10%40%
2359
16th to endDay
6%425%5%36%6%7%9%41%
2484
September1st to 15thDay
8%5%25%5%35%5%7%7%43%
2340
16th to endDay
5%2133335%46%60%
2205
October1st to 15thDay
7%31331233463%
1950
16th to endDay
3312221245%69%
2080
November1st to 15thDay
12221235%8%68%
1919
16th to endDay
3312222345%68%
1885
December1st to 15thDay
3412313345%64%
1609
16th to endDay
46%24324348%57%
1664
January1st to 15thNight
2312222336%69%
2583
16th to endNight
3311223336%67%
2704
February1st to 15thNight
26%24222337%63%
2373
16th to endNight
35%12223447%62%
2050
March1st to 15thNight
241332335%6%63%
2233
16th to endNight
3313223245%67%
2220
April1st to 15thNight
441221345%8%61%
1948
16th to endNight
3313223335%65%
1929
May1st to 15thNight
331332345%8%59%
1949
16th to endNight
4212323436%64%
1672
June1st to 15thNight
112425%5%5%8%60%
1560
16th to endNight
2312435%5%5%7%59%
1560
July1st to 15thNight
43245%26%7%8%11%44%
1605
16th to endNight
33245%36%7%9%13%40%
1845
August1st to 15thNight
43145%46%7%9%11%41%
1851
16th to endNight
4225%5%35%6%8%11%44%
2070
September1st to 15thNight
7%2135%26%5%9%9%44%
1950
16th to endNight
4214324346%62%
2082
October1st to 15thNight
6%31322334465%
2340
16th to endNight
412222346%68%
2496
November1st to 15thNight
2112213336%70%
2583
16th to endNight
3212222345%69%
2730
December1st to 15thNight
4413213336%63%
2679
16th to endNight
45%13323346%60%
2912

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
2312213347%66%
1695
16th to endDay
4423312335%64%
1872
February1st to 15thDay
15%2432335%7%60%
1806
16th to endDay
37%1231346%7%58%
1710
March1st to 15thDay
342332436%7%56%
2055
16th to endDay
442332335%6%60%
2353
April1st to 15thDay
332442445%7%56%
2330
16th to endDay
45%24324446%57%
2306
May1st to 15thDay
6%424425%46%5%53%
2331
16th to endDay
421332445%7%60%
2788
June1st to 15thDay
21133245%5%7%61%
2730
16th to endDay
22123246%6%7%59%
2730
July1st to 15thDay
5%426%7%48%7%7%10%35%
2681
16th to endDay
6%425%7%5%8%8%10%10%31%
2675
August1st to 15thDay
5%4247%5%6%7%8%10%37%
2359
16th to endDay
6%425%6%37%7%8%8%39%
2484
September1st to 15thDay
8%5%35%5%35%5%7%8%41%
2340
16th to endDay
5%21343345%6%59%
2205
October1st to 15thDay
8%414312335%62%
1950
16th to endDay
4312321235%68%
2080
November1st to 15thDay
221221235%7%67%
1919
16th to endDay
4312312336%67%
1885
December1st to 15thDay
35%12323446%62%
1609
16th to endDay
36%24323349%55%
1664
January1st to 15thNight
2312313236%68%
2583
16th to endNight
3412313347%65%
2704
February1st to 15thNight
27%24222337%61%
2373
16th to endNight
35%22323447%61%
2050
March1st to 15thNight
241342345%7%61%
2233
16th to endNight
3312323236%65%
2220
April1st to 15thNight
3412322448%60%
1948
16th to endNight
4313323345%64%
1929
May1st to 15thNight
332242445%7%58%
1949
16th to endNight
4213314347%62%
1672
June1st to 15thNight
1113435%46%8%59%
1560
16th to endNight
2313435%5%5%8%58%
1560
July1st to 15thNight
4324436%7%8%11%42%
1605
16th to endNight
4314445%8%10%12%38%
1845
August1st to 15thNight
33146%46%8%8%12%39%
1851
16th to endNight
5%325%5%35%6%9%11%42%
2070
September1st to 15thNight
7%2136%25%7%8%10%43%
1950
16th to endNight
4313324346%61%
2082
October1st to 15thNight
6%313312345%64%
2340
16th to endNight
42221335%6%67%
2496
November1st to 15thNight
222223336%70%
2583
16th to endNight
3212222346%68%
2730
December1st to 15thNight
45%13323347%61%
2679
16th to endNight
45%14323346%60%
2912

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
15%5%11%26%34%6%
1696
16th to endDay
22%38%21%31%12%
1872
February1st to 15thDay
22%6%9%26%23%11%
1807
16th to endDay
21%37%24%30%12%
1710
March1st to 15thDay
21%49%22%28%13%
2055
16th to endDay
21%48%22%32%10%
2355
April1st to 15thDay
23%5%7%23%27%12%
2330
16th to endDay
22%48%20%30%12%
2306
May1st to 15thDay
26%5%9%17%27%12%
2331
16th to endDay
19%6%10%19%22%22%
2792
June1st to 15thDay
17%6%11%14%23%26%
2730
16th to endDay
18%5%11%16%22%24%
2730
July1st to 15thDay
36%10%15%14%12%9%
2535
16th to endDay
35%12%22%21%7%
2520
August1st to 15thDay
33%12%16%20%11%4
2344
16th to endDay
34%10%14%21%15%3
2484
September1st to 15thDay
34%8%15%19%14%8%
2340
16th to endDay
22%5%8%19%29%14%
2205
October1st to 15thDay
24%37%18%28%17%
1950
16th to endDay
17%38%19%34%15%
2080
November1st to 15thDay
13%310%22%36%13%
1919
16th to endDay
18%25%22%33%16%
1885
December1st to 15thDay
20%413%28%24%7%
1609
16th to endDay
25%412%26%25%4
1664
January1st to 15thNight
16%410%26%32%9%
2583
16th to endNight
18%48%23%32%11%
2704
February1st to 15thNight
23%411%25%24%10%
2383
16th to endNight
21%36%22%30%13%
2050
March1st to 15thNight
20%6%7%24%27%12%
2233
16th to endNight
19%38%21%34%12%
2220
April1st to 15thNight
20%5%9%22%27%13%
1948
16th to endNight
21%48%19%31%14%
1929
May1st to 15thNight
21%7%11%17%28%13%
1950
16th to endNight
20%7%12%18%20%21%
1673
June1st to 15thNight
19%7%12%15%19%25%
1560
16th to endNight
22%5%12%16%16%26%
1560
July1st to 15thNight
28%12%19%17%12%10%
1522
16th to endNight
29%14%27%19%8%
1737
August1st to 15thNight
31%14%19%18%11%5%
1842
16th to endNight
29%10%19%23%11%5%
2070
September1st to 15thNight
28%11%20%18%12%8%
1950
16th to endNight
22%5%10%18%28%14%
2082
October1st to 15thNight
22%47%17%28%18%
2340
16th to endNight
16%48%19%34%16%
2496
November1st to 15thNight
15%37%26%34%12%
2583
16th to endNight
17%37%23%31%17%
2730
December1st to 15thNight
21%5%10%28%23%9%
2679
16th to endNight
24%411%25%27%6%
2912

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
8%31%28%22%7%1
135
16th to endDay
6%30%29%18%13%1
144
February1st to 15thDay
6%28%32%31%
135
16th to endDay
12%41%25%17%2
120
March1st to 15thDay
8%29%39%17%5%
240
16th to endDay
15%34%34%11%2
352
April1st to 15thDay
14%38%33%10%3
329
16th to endDay
14%35%36%10%2
318
May1st to 15thDay
9%28%42%15%21
348
16th to endDay
6%15%38%28%9%1
588
June1st to 15thDay
49%29%36%18%2
570
16th to endDay
45%24%37%22%4
570
July1st to 15thDay
7%121%32%29%6%
504
16th to endDay
9%9%42%28%8%
391
August1st to 15thDay
6%220%48%18%3
359
16th to endDay
6%326%41%18%4
396
September1st to 15thDay
8%231%38%16%1
375
16th to endDay
9%9%35%32%10%2
245
October1st to 15thDay
12%25%36%16%8%1
180
16th to endDay
9%15%34%23%12%4
192
November1st to 15thDay
10%26%36%18%7%1
180
16th to endDay
11%27%31%19%10%
178
December1st to 15thDay
6%32%31%20%8%
135
16th to endDay
12%34%33%17%2
144
January1st to 15thNight
414%35%29%13%1
842
16th to endNight
6%17%35%26%12%2
832
February1st to 15thNight
6%16%39%28%7%
764
16th to endNight
7%21%43%24%2
684
March1st to 15thNight
420%32%33%8%
780
16th to endNight
5%16%38%30%8%
764
April1st to 15thNight
6%22%37%26%5%
584
16th to endNight
7%19%36%28%7%
579
May1st to 15thNight
412%38%30%13%
585
16th to endNight
5%11%30%37%14%1
611
June1st to 15thNight
2429%40%22%
585
16th to endNight
2321%43%26%2
585
July1st to 15thNight
5%9%36%42%4
555
16th to endNight
415%27%53%8%
612
August1st to 15thNight
5%7%31%46%8%
575
16th to endNight
49%37%39%8%
621
September1st to 15thNight
6%113%40%33%4
585
16th to endNight
5%5%19%40%26%3
585
October1st to 15thNight
7%6%26%38%17%2
780
16th to endNight
5%10%25%34%19%4
832
November1st to 15thNight
313%33%32%15%2
943
16th to endNight
5%14%33%30%13%3
1050
December1st to 15thNight
8%17%36%27%8%
975
16th to endNight
8%19%39%25%6%
1040
Page generated at 2018-12-01 09:35:32. Version ac04

Copyright 2018 A. Danko


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