Huisache Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Huisache Observatory clear sky chart from 2005-11-05 to 2019-06-24.

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
58%
18137
29%
54042
20%
18094
67%
18094
41%
28652

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
57%
881
30%
2759
24%
878
66%
878
44%
1374
January16th to endNight
56%
896
32%
2912
26%
896
66%
896
43%
1421
February1st to 15thNight
49%
821
28%
2629
21%
820
59%
820
39%
1327
February16th to endNight
39%
736
34%
2206
17%
736
57%
736
39%
1164
March1st to 15thNight
47%
840
32%
2361
18%
840
59%
840
42%
1295
March16th to endNight
48%
852
32%
2420
16%
852
61%
852
45%
1246
April1st to 15thNight
39%
629
29%
2098
15%
629
58%
629
34%
1052
April16th to endNight
43%
624
29%
2079
17%
624
62%
624
36%
1027
May1st to 15thNight
52%
630
26%
2065
19%
629
64%
629
36%
1094
May16th to endNight
53%
659
30%
1793
17%
657
65%
657
47%
950
June1st to 15thNight
68%
630
29%
1680
20%
630
73%
630
55%
840
June16th to endNight
74%
609
26%
1624
19%
609
77%
609
50%
867
July1st to 15thNight
75%
555
14%
1550
12%
555
76%
555
29%
1007
July16th to endNight
76%
612
12%
1737
12%
579
77%
579
26%
1121
August1st to 15thNight
78%
575
16%
1787
16%
572
79%
572
30%
1089
August16th to endNight
77%
621
19%
2070
22%
621
79%
621
28%
1249
September1st to 15thNight
74%
585
25%
1950
27%
585
76%
585
30%
1135
September16th to endNight
74%
639
34%
2108
29%
639
79%
639
49%
985
October1st to 15thNight
60%
780
33%
2340
21%
780
69%
780
45%
1212
October16th to endNight
65%
832
37%
2496
25%
832
74%
832
52%
1194
November1st to 15thNight
63%
911
39%
2551
25%
911
71%
911
58%
1191
November16th to endNight
59%
1050
37%
2751
24%
1050
67%
1050
54%
1406
December1st to 15thNight
49%
1050
30%
2940
17%
1050
59%
1050
43%
1563
December16th to endNight
44%
1120
26%
3136
17%
1120
52%
1120
34%
1843

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
23134245%6%8%57%
54763
Night
221332345%7%61%
54234
TransparencyDay
24%8%12%22%23%9%
54455
Night
21%7%12%23%24%10%
54044
SeeingDay
6%15%27%29%17%3
7905
Night
48%23%37%22%2
18141

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
131332446%7%61%
1850
16th to endDay
1313324337%64%
2016
February1st to 15thDay
142442445%6%58%
1890
16th to endDay
3144346%6%9%55%
1840
March1st to 15thDay
132433446%8%57%
2257
16th to endDay
13233245%5%9%59%
2506
April1st to 15thDay
12133145%6%9%59%
2510
16th to endDay
2313323448%60%
2486
May1st to 15thDay
23134245%6%8%57%
2542
16th to endDay
2213325%5%5%7%61%
3021
June1st to 15thDay
11123235%6%7%63%
2940
16th to endDay
1122135%6%7%66%
2844
July1st to 15thDay
33146%47%8%9%11%40%
2651
16th to endDay
43245%47%8%10%12%35%
2675
August1st to 15thDay
4325%6%47%7%7%11%40%
2415
16th to endDay
4314435%6%8%10%45%
2484
September1st to 15thDay
5%4245%45%5%7%8%46%
2340
16th to endDay
22222245%45%65%
2179
October1st to 15thDay
3212323447%63%
1950
16th to endDay
211331234471%
2080
November1st to 15thDay
112212347%71%
1950
16th to endDay
1212323345%70%
1865
December1st to 15thDay
31341446%7%61%
1680
16th to endDay
26%244245%6%7%53%
1792
January1st to 15thNight
31331335%7%64%
2759
16th to endNight
121221335%8%65%
2912
February1st to 15thNight
1414313347%63%
2619
16th to endNight
131332445%8%62%
2206
March1st to 15thNight
131332345%7%63%
2361
16th to endNight
221221335%6%67%
2420
April1st to 15thNight
12123245%6%8%61%
2098
16th to endNight
231332345%6%63%
2079
May1st to 15thNight
331232446%8%59%
2065
16th to endNight
111221345%7%67%
1793
June1st to 15thNight
11121336%8%67%
1680
16th to endNight
123245%6%8%63%
1624
July1st to 15thNight
32146%47%7%7%10%42%
1635
16th to endNight
2425%5%47%7%10%11%39%
1845
August1st to 15thNight
43144347%7%10%48%
1796
16th to endNight
4314446%6%9%10%43%
2070
September1st to 15thNight
33146%36%6%7%9%47%
1950
16th to endNight
32321235%6%69%
2108
October1st to 15thNight
322323446%66%
2340
16th to endNight
212222346%70%
2496
November1st to 15thNight
11212347%73%
2551
16th to endNight
1212223345%72%
2751
December1st to 15thNight
121332345%6%66%
2940
16th to endNight
142442445%9%55%
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
22%7%13%31%23%2
1851
16th to endDay
23%6%10%30%24%5%
2016
February1st to 15thDay
27%6%13%26%18%7%
1891
16th to endDay
23%9%11%21%26%7%
1840
March1st to 15thDay
25%6%10%22%27%7%
2257
16th to endDay
24%6%9%26%26%7%
2506
April1st to 15thDay
23%6%10%25%24%9%
2510
16th to endDay
24%6%10%22%27%9%
2486
May1st to 15thDay
25%8%11%20%26%7%
2542
16th to endDay
21%8%10%17%26%15%
3024
June1st to 15thDay
17%7%10%18%22%24%
2940
16th to endDay
15%5%9%18%24%25%
2844
July1st to 15thDay
33%13%16%13%12%10%
2508
16th to endDay
34%15%23%19%5%
2520
August1st to 15thDay
36%14%15%15%11%5%
2400
16th to endDay
30%12%16%19%15%5%
2484
September1st to 15thDay
33%9%13%19%16%7%
2340
16th to endDay
20%5%9%18%33%12%
2179
October1st to 15thDay
21%6%10%19%28%13%
1950
16th to endDay
17%48%22%35%10%
2080
November1st to 15thDay
16%311%27%31%9%
1950
16th to endDay
17%47%28%32%9%
1865
December1st to 15thDay
22%8%14%28%19%5%
1680
16th to endDay
31%8%13%26%17%2
1792
January1st to 15thNight
19%6%12%30%24%5%
2759
16th to endNight
18%7%11%30%26%6%
2912
February1st to 15thNight
21%6%15%26%21%7%
2629
16th to endNight
21%7%8%24%31%6%
2206
March1st to 15thNight
21%7%9%27%28%5%
2361
16th to endNight
18%6%7%26%31%9%
2420
April1st to 15thNight
21%7%10%25%25%9%
2098
16th to endNight
21%6%10%22%29%10%
2079
May1st to 15thNight
24%8%9%19%28%9%
2066
16th to endNight
18%7%11%19%25%18%
1794
June1st to 15thNight
14%6%12%15%23%26%
1680
16th to endNight
19%6%10%12%22%28%
1624
July1st to 15thNight
32%13%18%14%8%12%
1550
16th to endNight
33%14%26%19%5%1
1737
August1st to 15thNight
28%14%20%17%10%8%
1787
16th to endNight
31%11%18%18%13%7%
2070
September1st to 15thNight
30%10%17%19%11%11%
1950
16th to endNight
16%6%10%16%30%19%
2108
October1st to 15thNight
20%6%7%20%28%15%
2340
16th to endNight
16%5%8%20%36%13%
2496
November1st to 15thNight
12%410%28%34%10%
2551
16th to endNight
16%46%26%34%11%
2751
December1st to 15thNight
19%7%13%32%23%4
2940
16th to endNight
27%8%12%26%21%2
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
11%17%25%28%15%2
180
16th to endDay
6%17%26%31%15%3
192
February1st to 15thDay
8%22%29%30%7%1
180
16th to endDay
9%28%30%22%9%
159
March1st to 15thDay
13%25%35%17%7%1
337
16th to endDay
12%33%31%14%6%2
416
April1st to 15thDay
10%36%29%17%5%1
389
16th to endDay
10%33%33%17%3
378
May1st to 15thDay
8%24%37%21%6%1
408
16th to endDay
7%17%34%27%12%1
634
June1st to 15thDay
29%29%32%23%2
645
16th to endDay
25%24%32%29%5%
611
July1st to 15thDay
3419%33%31%7%
477
16th to endDay
6%211%34%35%9%
391
August1st to 15thDay
5%416%41%25%6%
359
16th to endDay
6%418%40%23%5%
396
September1st to 15thDay
5%325%40%19%5%
375
16th to endDay
5%9%28%36%16%5%
274
October1st to 15thDay
5%19%30%26%14%4
180
16th to endDay
5%12%23%30%18%9%
192
November1st to 15thDay
6%14%25%35%16%2
180
16th to endDay
9%15%32%22%16%3
180
December1st to 15thDay
6%15%31%32%11%3
180
16th to endDay
10%23%25%30%9%
192
January1st to 15thNight
49%23%40%18%2
882
16th to endNight
411%26%36%18%2
896
February1st to 15thNight
6%11%29%38%12%1
824
16th to endNight
6%15%36%34%8%
736
March1st to 15thNight
5%12%31%37%12%
840
16th to endNight
5%11%32%36%12%
852
April1st to 15thNight
5%18%34%31%9%
629
16th to endNight
6%16%31%35%9%
624
May1st to 15thNight
5%8%30%39%15%
630
16th to endNight
27%31%39%16%1
659
June1st to 15thNight
25%21%49%20%
630
16th to endNight
1216%45%31%1
609
July1st to 15thNight
317%40%43%3
555
16th to endNight
215%26%55%8%
612
August1st to 15thNight
317%31%47%9%
575
16th to endNight
5%16%34%46%6%
621
September1st to 15thNight
5%19%41%36%5%
585
16th to endNight
5%313%40%33%3
639
October1st to 15thNight
4426%42%18%3
780
16th to endNight
6%5%19%36%27%5%
832
November1st to 15thNight
27%24%40%21%3
911
16th to endNight
5%9%23%33%22%4
1050
December1st to 15thNight
6%14%27%37%13%1
1050
16th to endNight
6%14%30%34%13%1
1120
Page generated at 2019-06-24 18:41:31. Version ac04

Copyright 2019 A. Danko


Huisache Observatory Clear Sky Chart |Charts Home