Mano Prieto Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mano Prieto Observatory clear sky chart from 2005-11-05 to 2017-10-06.

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
63%
15447
31%
47273
23%
15406
71%
15406
44%
24373

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
52%
716
34%
2148
21%
716
65%
716
43%
1130
January16th to endNight
52%
768
38%
2304
23%
768
66%
768
45%
1171
February1st to 15thNight
56%
701
36%
2107
22%
696
70%
696
49%
1022
February16th to endNight
45%
632
35%
1894
18%
632
60%
632
49%
921
March1st to 15thNight
52%
720
34%
2139
19%
720
64%
720
46%
1073
March16th to endNight
50%
650
37%
1994
22%
650
65%
650
48%
964
April1st to 15thNight
46%
539
34%
1798
20%
539
64%
539
42%
865
April16th to endNight
51%
540
36%
1800
26%
540
69%
540
49%
795
May1st to 15thNight
50%
539
28%
1799
22%
539
64%
539
44%
870
May16th to endNight
63%
561
26%
1766
25%
561
70%
561
40%
938
June1st to 15thNight
75%
540
24%
1620
23%
540
80%
540
50%
811
June16th to endNight
77%
540
24%
1620
26%
540
79%
540
42%
881
July1st to 15thNight
80%
510
19%
1694
23%
510
81%
510
37%
933
July16th to endNight
82%
564
22%
1771
25%
531
83%
531
34%
984
August1st to 15thNight
86%
539
23%
1789
30%
536
86%
536
40%
935
August16th to endNight
80%
573
20%
1910
24%
573
80%
573
29%
1140
September1st to 15thNight
77%
540
20%
1810
22%
540
77%
540
31%
1051
September16th to endNight
75%
537
26%
1980
29%
537
77%
537
28%
1137
October1st to 15thNight
73%
529
32%
1897
32%
529
76%
529
42%
919
October16th to endNight
71%
704
37%
2112
26%
704
77%
704
55%
998
November1st to 15thNight
67%
781
38%
2181
24%
781
73%
781
60%
1035
November16th to endNight
63%
900
38%
2340
21%
900
71%
900
56%
1202
December1st to 15thNight
56%
900
37%
2340
21%
900
64%
900
48%
1292
December16th to endNight
50%
924
38%
2460
19%
924
61%
924
47%
1306

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
43134245%5%7%56%
47883
Night
321332445%7%59%
47498
Cloud CoverDay
43133245%5%7%56%
47881
Night
321332445%7%59%
47498
TransparencyDay
24%5%9%17%24%18%
47603
Night
22%5%9%18%24%19%
47280
SeeingDay
6%6%21%30%26%8%
5288
Night
5%422%38%26%2
15457

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
45%14322346%60%
1790
16th to endDay
3423213346%63%
1920
February1st to 15thDay
22121145%46%67%
1750
16th to endDay
1212312347%69%
1580
March1st to 15thDay
132343445%7%59%
1818
16th to endDay
2312323346%65%
2229
April1st to 15thDay
221231445%7%63%
2150
16th to endDay
1212212336%71%
2160
May1st to 15thDay
2212323346%65%
2151
16th to endDay
321222445%8%62%
2345
June1st to 15thDay
123235%7%8%62%
2340
16th to endDay
4313426%6%7%9%48%
2340
July1st to 15thDay
7%4245%5%7%8%7%10%36%
2160
16th to endDay
6%425%7%48%8%7%9%35%
2277
August1st to 15thDay
5%3146%38%8%9%11%37%
2160
16th to endDay
7%5%36%6%5%7%8%8%7%33%
2292
September1st to 15thDay
10%5%25%6%37%7%6%7%36%
2148
16th to endDay
7%6%25%6%3445%7%46%
1980
October1st to 15thDay
441232345%6%60%
1857
16th to endDay
32321233471%
1760
November1st to 15thDay
3312212245%69%
1663
16th to endDay
4212212235%70%
1620
December1st to 15thDay
3323313347%63%
1620
16th to endDay
332322345%6%62%
1773
January1st to 15thNight
4324433445%59%
2148
16th to endNight
5%21332345%7%60%
2304
February1st to 15thNight
121232435%6%65%
2102
16th to endNight
222233446%66%
1894
March1st to 15thNight
331242335%7%61%
2139
16th to endNight
2313423335%66%
1994
April1st to 15thNight
4213313446%63%
1798
16th to endNight
21222434470%
1800
May1st to 15thNight
321332445%5%62%
1799
16th to endNight
3214325%5%6%7%57%
1765
June1st to 15thNight
112235%6%9%10%56%
1620
16th to endNight
3213335%6%8%11%50%
1620
July1st to 15thNight
3214426%6%8%11%49%
1794
16th to endNight
3314335%6%7%13%46%
1891
August1st to 15thNight
3112435%6%8%17%45%
1800
16th to endNight
42146%35%6%8%12%42%
1910
September1st to 15thNight
6%4134346%7%10%46%
1810
16th to endNight
5%5%24435%5%6%9%45%
1980
October1st to 15thNight
431341345%7%60%
1897
16th to endNight
2312313335%70%
2112
November1st to 15thNight
2212212346%71%
2181
16th to endNight
3212323335%70%
2340
December1st to 15thNight
4213423347%61%
2340
16th to endNight
341332333466%
2460

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
5%5%23323336%60%
1790
16th to endDay
4413223346%63%
1920
February1st to 15thDay
22121145%5%5%67%
1750
16th to endDay
122212347%69%
1580
March1st to 15thDay
13135%2435%7%59%
1818
16th to endDay
2312323346%66%
2227
April1st to 15thDay
221231445%7%63%
2150
16th to endDay
222212346%71%
2160
May1st to 15thDay
3212323346%65%
2151
16th to endDay
32222345%9%62%
2345
June1st to 15thDay
1113245%7%8%62%
2340
16th to endDay
4313436%6%7%9%48%
2340
July1st to 15thDay
7%425%5%47%7%7%9%37%
2160
16th to endDay
6%425%7%47%8%7%9%35%
2277
August1st to 15thDay
6%2145%48%7%9%11%37%
2160
16th to endDay
7%5%35%6%5%7%7%8%8%33%
2292
September1st to 15thDay
11%5%25%6%46%7%7%7%35%
2148
16th to endDay
9%5%25%5%345%5%7%45%
1980
October1st to 15thDay
6%31232445%6%61%
1857
16th to endDay
32231233471%
1760
November1st to 15thDay
3312212335%69%
1663
16th to endDay
4212212136%70%
1620
December1st to 15thDay
3324223347%63%
1620
16th to endDay
3322223447%62%
1773
January1st to 15thNight
4424424345%60%
2148
16th to endNight
5%212413447%60%
2304
February1st to 15thNight
132324346%65%
2102
16th to endNight
222224347%65%
1894
March1st to 15thNight
331332335%7%61%
2139
16th to endNight
3213423345%66%
1994
April1st to 15thNight
4313313446%63%
1798
16th to endNight
2212314345%70%
1800
May1st to 15thNight
321242445%5%63%
1799
16th to endNight
4213325%5%6%7%57%
1765
June1st to 15thNight
2123347%8%9%56%
1620
16th to endNight
4113335%6%8%11%50%
1620
July1st to 15thNight
3214426%6%7%10%49%
1794
16th to endNight
4314435%6%7%13%46%
1891
August1st to 15thNight
3212335%6%8%17%45%
1800
16th to endNight
43136%45%6%8%12%42%
1910
September1st to 15thNight
7%423435%6%6%11%45%
1810
16th to endNight
7%424435%6%6%9%45%
1980
October1st to 15thNight
5%214422447%60%
1897
16th to endNight
231231234471%
2112
November1st to 15thNight
3212112345%72%
2181
16th to endNight
321232323470%
2340
December1st to 15thNight
4313324346%61%
2340
16th to endNight
341332333466%
2460

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
25%3417%30%17%
1791
16th to endDay
21%36%14%33%20%
1920
February1st to 15thDay
16%46%14%26%31%
1751
16th to endDay
15%2416%35%26%
1580
March1st to 15thDay
22%36%16%26%25%
1818
16th to endDay
18%35%12%29%30%
2229
April1st to 15thDay
18%47%9%28%30%
2150
16th to endDay
14%25%9%32%35%
2160
May1st to 15thDay
19%36%12%25%31%
2151
16th to endDay
18%49%17%24%25%
2348
June1st to 15thDay
14%5%11%20%27%20%
2340
16th to endDay
26%7%12%21%20%11%
2340
July1st to 15thDay
37%10%13%22%14%1
2031
16th to endDay
38%10%16%24%8%1
2134
August1st to 15thDay
34%9%17%25%11%1
2147
16th to endDay
41%11%15%17%11%2
2292
September1st to 15thDay
41%9%13%18%12%3
2148
16th to endDay
35%6%11%19%19%7%
1980
October1st to 15thDay
21%5%10%23%20%17%
1857
16th to endDay
17%15%16%28%29%
1760
November1st to 15thDay
17%37%19%29%23%
1663
16th to endDay
18%16%15%32%26%
1620
December1st to 15thDay
21%36%18%32%18%
1620
16th to endDay
20%36%21%32%15%
1773
January1st to 15thNight
25%36%14%29%20%
2148
16th to endNight
22%35%15%33%19%
2304
February1st to 15thNight
18%45%11%26%33%
2112
16th to endNight
19%35%9%32%29%
1894
March1st to 15thNight
21%35%15%27%26%
2139
16th to endNight
20%35%13%28%29%
1994
April1st to 15thNight
21%46%12%27%28%
1798
16th to endNight
16%36%12%25%35%
1800
May1st to 15thNight
21%5%6%15%21%30%
1800
16th to endNight
24%7%9%17%18%22%
1767
June1st to 15thNight
17%7%14%24%23%13%
1620
16th to endNight
23%7%15%20%20%12%
1620
July1st to 15thNight
25%9%16%30%15%2
1694
16th to endNight
25%11%19%30%12%1
1771
August1st to 15thNight
21%9%22%29%16%
1789
16th to endNight
30%11%16%25%13%2
1910
September1st to 15thNight
29%10%19%23%11%5%
1810
16th to endNight
31%9%13%21%17%6%
1980
October1st to 15thNight
22%5%12%23%18%17%
1897
16th to endNight
17%35%13%28%31%
2112
November1st to 15thNight
15%36%18%34%22%
2181
16th to endNight
18%25%13%30%30%
2340
December1st to 15thNight
23%4420%28%19%
2340
16th to endNight
22%25%18%34%16%
2460

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
10%14%35%25%14%
90
16th to endDay
8%25%28%23%9%5%
96
February1st to 15thDay
310%23%23%37%2
90
16th to endDay
11%14%28%28%14%2
81
March1st to 15thDay
5%43%30%15%3
108
16th to endDay
315%45%23%10%2
288
April1st to 15thDay
415%45%24%10%
269
16th to endDay
221%40%27%7%1
270
May1st to 15thDay
214%44%29%8%
288
16th to endDay
35%32%40%16%1
432
June1st to 15thDay
2112%42%36%6%
495
16th to endDay
5%6%33%44%8%
495
July1st to 15thDay
8%430%37%18%
305
16th to endDay
5%1326%41%20%
327
August1st to 15thDay
8%5%18%42%24%
315
16th to endDay
12%428%36%17%
332
September1st to 15thDay
8%19%30%34%15%
303
16th to endDay
13%215%28%30%9%
135
October1st to 15thDay
19%114%24%28%10%
107
16th to endDay
5%420%23%25%20%
96
November1st to 15thDay
16%8%25%21%18%8%
90
16th to endDay
13%14%24%32%11%4
90
December1st to 15thDay
10%8%23%41%15%1
90
16th to endDay
8%16%36%27%11%
96
January1st to 15thNight
6%430%38%17%2
720
16th to endNight
6%7%29%39%15%1
768
February1st to 15thNight
36%31%36%19%1
704
16th to endNight
48%39%37%9%
632
March1st to 15thNight
48%31%36%16%1
720
16th to endNight
38%33%37%14%2
650
April1st to 15thNight
6%8%35%39%9%
539
16th to endNight
37%34%43%10%
540
May1st to 15thNight
5%5%35%42%11%
540
16th to endNight
3325%47%18%
563
June1st to 15thNight
116%54%25%
540
16th to endNight
49%51%33%1
540
July1st to 15thNight
35%42%45%2
510
16th to endNight
4239%48%3
564
August1st to 15thNight
3122%64%8%
539
16th to endNight
5%227%60%4
573
September1st to 15thNight
7%1428%51%5%
540
16th to endNight
9%7%39%37%4
537
October1st to 15thNight
7%111%44%31%3
529
16th to endNight
5%217%35%30%8%
704
November1st to 15thNight
4222%36%28%5%
781
16th to endNight
45%21%39%25%3
900
December1st to 15thNight
6%427%40%18%2
900
16th to endNight
5%9%30%37%13%2
924
Page generated at 2017-10-07 13:07:47. Version ac04

Copyright 2017 A. Danko


Mano Prieto Observatory Clear Sky Chart | Charts Home