Mendota Wildlife Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mendota Wildlife Area clear sky chart from 2005-11-06 to 2024-02-10.

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
68%
23869
31%
80057
27%
23793
75%
23793
45%
40089

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
56%
747
18%
4347
18%
736
58%
736
15%
2491
January11th to 20thNight
64%
747
18%
4060
23%
740
69%
740
18%
2523
January21st to endNight
62%
828
16%
4404
27%
814
66%
814
17%
2798
February1st to 10thNight
63%
758
28%
2409
29%
758
67%
758
35%
1344
February11th to 20thNight
64%
700
32%
2099
29%
700
71%
700
44%
1088
February21st to endNight
61%
592
27%
1776
27%
592
66%
592
39%
976
March1st to 10thNight
57%
720
22%
2146
20%
720
63%
720
34%
1255
March11th to 20thNight
60%
720
25%
1980
21%
720
65%
720
39%
1152
March21st to endNight
57%
792
26%
2060
15%
792
66%
792
47%
1153
April1st to 10thNight
54%
720
30%
1800
13%
720
63%
720
49%
1017
April11th to 20thNight
54%
711
35%
1779
13%
711
65%
711
57%
920
April21st to endNight
60%
720
34%
1800
13%
720
68%
720
65%
882
May1st to 10thNight
61%
720
33%
1800
15%
720
68%
720
67%
875
May11th to 20thNight
61%
493
39%
1556
26%
493
71%
493
66%
631
May21st to endNight
59%
388
36%
1552
28%
388
76%
388
56%
559
June1st to 10thNight
58%
360
36%
1440
30%
360
74%
360
58%
514
June11th to 20thNight
69%
360
42%
1440
40%
360
85%
360
77%
426
June21st to endNight
74%
360
43%
1440
42%
360
89%
360
83%
411
July1st to 10thNight
79%
350
40%
1400
40%
350
91%
350
82%
399
July11th to 20thNight
85%
377
41%
1421
46%
377
87%
377
73%
461
July21st to endNight
85%
591
41%
1674
31%
558
90%
558
73%
681
August1st to 10thNight
81%
616
40%
1681
26%
613
85%
613
80%
699
August11th to 20thNight
85%
712
40%
1780
21%
712
89%
712
83%
785
August21st to endNight
89%
792
46%
1980
29%
792
91%
792
87%
857
September1st to 10thNight
87%
720
47%
1800
32%
720
91%
720
86%
783
September11th to 20thNight
80%
720
50%
1818
36%
720
87%
720
81%
811
September21st to endNight
81%
720
47%
1980
40%
720
89%
720
81%
809
October1st to 10thNight
75%
720
36%
2132
33%
720
82%
720
64%
928
October11th to 20thNight
78%
720
41%
2160
41%
720
85%
720
64%
925
October21st to endNight
80%
792
45%
2376
45%
792
85%
792
68%
983
November1st to 10thNight
74%
740
35%
2362
36%
740
79%
740
52%
1096
November11th to 20thNight
74%
760
32%
2470
33%
760
78%
760
50%
1157
November21st to endNight
70%
760
32%
2470
32%
760
75%
760
44%
1224
December1st to 10thNight
61%
760
25%
2612
24%
760
66%
760
31%
1462
December11th to 20thNight
61%
759
20%
3220
23%
758
65%
758
20%
2057
December21st to endNight
55%
824
12%
4833
20%
817
61%
817
14%
2957

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
5%323323346%66%
78437
Night
7%423323346%64%
80561
TransparencyDay
20%5%9%19%25%22%
78153
Night
21%6%10%20%23%20%
80367
SeeingDay
5%415%27%32%18%
14299
Night
6%317%40%30%4
23921

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 10thDay
10%10%48%9%46%5%6%7%32%
2539
11th to 20thDay
9%7%5%9%9%45%6%6%7%33%
2859
21st to endDay
14%9%5%8%7%46%5%6%7%30%
3146
February1st to 10thDay
13%5%24435%45%8%48%
1753
11th to 20thDay
10%424433447%55%
1750
21st to endDay
11%5%25%424446%53%
1480
March1st to 10thDay
10%5%35%4245%6%9%47%
1810
11th to 20thDay
9%425%5%25%36%9%49%
1980
21st to endDay
8%32342345%8%57%
2294
April1st to 10thDay
7%423423348%61%
2160
11th to 20thDay
6%22232335%6%66%
2129
21st to endDay
4213322246%71%
2160
May1st to 10thDay
1213212336%75%
2160
11th to 20thDay
2112213336%75%
2330
21st to endDay
3212221236%76%
2723
June1st to 10thDay
2211212236%77%
2520
11th to 20thDay
11111112390%
2520
21st to endDay
111211111288%
2520
July1st to 10thDay
111212389%
2520
11th to 20thDay
111111122386%
2486
21st to endDay
111121233481%
2546
August1st to 10thDay
21111123285%
2249
11th to 20thDay
1111112389%
2122
21st to endDay
11111112289%
2376
September1st to 10thDay
11111112290%
2160
11th to 20thDay
1112112287%
2142
21st to endDay
121111223483%
1980
October1st to 10thDay
2112212335%78%
1823
11th to 20thDay
2212223335%77%
1800
21st to endDay
3213322246%71%
1980
November1st to 10thDay
5%32442445%7%61%
1715
11th to 20thDay
7%4244245%6%6%57%
1710
21st to endDay
6%5%25%43345%7%55%
1710
December1st to 10thDay
9%7%47%6%345%6%8%42%
1563
11th to 20thDay
16%8%48%7%445%5%7%32%
1928
21st to endDay
12%9%47%7%46%5%7%8%32%
2794
January1st to 10thNight
12%8%36%6%34446%42%
4405
11th to 20thNight
12%7%37%7%445%6%7%39%
4110
21st to endNight
15%7%36%5%35%45%7%38%
4521
February1st to 10thNight
12%423434447%54%
2409
11th to 20thNight
8%213334448%59%
2098
21st to endNight
10%5%2342435%5%58%
1776
March1st to 10thNight
9%5%25%5%3445%7%51%
2146
11th to 20thNight
9%424425%5%5%8%53%
1980
21st to endNight
9%32332335%6%61%
2060
April1st to 10thNight
7%41322445%7%62%
1800
11th to 20thNight
4212323346%70%
1779
21st to endNight
322222337%74%
1800
May1st to 10thNight
1212213345%78%
1800
11th to 20thNight
2112212235%79%
1555
21st to endNight
321221222480%
1552
June1st to 10thNight
221221223380%
1440
11th to 20thNight
11122389%
1440
21st to endNight
11111292%
1440
July1st to 10thNight
11112389%
1440
11th to 20thNight
211111221385%
1469
21st to endNight
11122334480%
1773
August1st to 10thNight
11111112288%
1690
11th to 20thNight
1121223286%
1780
21st to endNight
11111111390%
1980
September1st to 10thNight
11111111291%
1800
11th to 20thNight
111111111288%
1818
21st to endNight
11111112487%
1980
October1st to 10thNight
221222222478%
2132
11th to 20thNight
3112112445%76%
2160
21st to endNight
3111111235%79%
2376
November1st to 10thNight
5%213323346%68%
2362
11th to 20thNight
5%323323347%66%
2470
21st to endNight
6%32342345%7%61%
2470
December1st to 10thNight
9%6%35%5%34347%51%
2612
11th to 20thNight
12%6%35%6%36%5%7%9%38%
3276
21st to endNight
13%7%37%7%46%5%6%7%37%
4862

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
42%14%17%21%6%1
2539
11th to 20thDay
45%11%13%17%13%3
2859
21st to endDay
47%11%13%16%11%1
3146
February1st to 10thDay
31%7%11%26%17%7%
1753
11th to 20thDay
28%6%11%26%23%6%
1760
21st to endDay
31%7%12%24%22%4
1480
March1st to 10thDay
31%8%14%24%18%4
1810
11th to 20thDay
32%6%13%24%21%5%
1980
21st to endDay
25%6%17%27%19%6%
2294
April1st to 10thDay
24%5%13%27%22%9%
2160
11th to 20thDay
20%412%27%27%9%
2132
21st to endDay
15%411%31%32%8%
2160
May1st to 10thDay
12%410%23%39%12%
2160
11th to 20thDay
12%36%25%37%17%
2333
21st to endDay
12%38%31%33%12%
2724
June1st to 10thDay
10%49%21%33%24%
2520
11th to 20thDay
415%15%38%38%
2520
21st to endDay
6%128%28%55%
2520
July1st to 10thDay
4126%21%66%
2451
11th to 20thDay
6%138%23%59%
2411
21st to endDay
8%328%24%55%
2405
August1st to 10thDay
7%228%27%54%
2233
11th to 20thDay
4128%33%53%
2122
21st to endDay
5%118%34%50%
2376
September1st to 10thDay
5%128%28%57%
2160
11th to 20thDay
6%2318%42%30%
2142
21st to endDay
8%2417%40%30%
1980
October1st to 10thDay
10%37%19%30%30%
1823
11th to 20thDay
12%35%25%30%26%
1800
21st to endDay
15%47%22%31%21%
1980
November1st to 10thDay
21%5%11%25%27%10%
1715
11th to 20thDay
23%8%14%26%25%4
1710
21st to endDay
26%6%12%24%24%8%
1710
December1st to 10thDay
37%8%11%19%18%8%
1563
11th to 20thDay
49%8%11%18%11%3
1928
21st to endDay
40%14%17%18%9%1
2794
January1st to 10thNight
36%12%16%26%10%1
4405
11th to 20thNight
40%10%15%19%10%6%
4110
21st to endNight
41%10%14%19%13%3
4521
February1st to 10thNight
30%6%10%24%22%8%
2409
11th to 20thNight
23%5%10%27%28%7%
2099
21st to endNight
27%5%11%28%23%6%
1776
March1st to 10thNight
30%8%14%22%20%7%
2146
11th to 20thNight
28%7%13%23%22%7%
1980
21st to endNight
23%5%15%27%21%8%
2060
April1st to 10thNight
22%5%14%29%20%10%
1800
11th to 20thNight
16%413%29%29%11%
1779
21st to endNight
12%410%31%34%9%
1800
May1st to 10thNight
10%5%8%24%35%18%
1800
11th to 20thNight
10%35%26%39%17%
1556
21st to endNight
12%38%29%36%13%
1552
June1st to 10thNight
12%28%20%33%25%
1440
11th to 20thNight
42416%35%39%
1440
21st to endNight
4118%29%58%
1440
July1st to 10thNight
412421%68%
1400
11th to 20thNight
7%226%21%62%
1421
21st to endNight
8%336%22%57%
1674
August1st to 10thNight
7%119%25%57%
1681
11th to 20thNight
5%237%27%56%
1780
21st to endNight
4118%30%56%
1980
September1st to 10thNight
5%127%24%62%
1800
11th to 20thNight
6%2215%38%37%
1818
21st to endNight
6%1314%40%36%
1980
October1st to 10thNight
12%36%18%25%35%
2132
11th to 20thNight
11%46%21%29%29%
2160
21st to endNight
10%25%22%34%26%
2376
November1st to 10thNight
17%5%9%25%29%15%
2362
11th to 20thNight
18%5%13%25%31%8%
2470
21st to endNight
22%5%10%24%29%10%
2470
December1st to 10thNight
31%7%11%23%18%11%
2612
11th to 20thNight
39%11%13%19%15%3
3276
21st to endNight
40%11%17%19%10%3
4862

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
20%9%17%31%16%7%
180
11th to 20thDay
9%5%18%29%26%13%
369
21st to endDay
12%418%22%27%17%
407
February1st to 10thDay
13%6%20%20%22%19%
391
11th to 20thDay
10%8%18%32%17%15%
415
21st to endDay
8%11%22%27%25%6%
346
March1st to 10thDay
12%7%19%32%23%6%
420
11th to 20thDay
10%8%22%28%22%10%
420
21st to endDay
11%11%22%28%19%8%
462
April1st to 10thDay
9%8%27%25%21%11%
420
11th to 20thDay
6%8%26%33%17%10%
412
21st to endDay
37%25%30%20%15%
420
May1st to 10thDay
37%21%34%25%10%
423
11th to 20thDay
26%19%32%29%12%
448
21st to endDay
46%17%26%30%17%
485
June1st to 10thDay
2415%31%31%17%
450
11th to 20thDay
1217%29%37%14%
450
21st to endDay
110%28%41%20%
450
July1st to 10thDay
16%24%44%25%
446
11th to 20thDay
1116%44%37%
444
21st to endDay
1218%49%30%
487
August1st to 10thDay
316%24%43%23%
447
11th to 20thDay
15%23%44%26%
437
21st to endDay
1322%44%30%
495
September1st to 10thDay
115%24%47%22%
450
11th to 20thDay
2210%36%34%16%
450
21st to endDay
2211%24%42%20%
450
October1st to 10thDay
1318%27%31%19%
450
11th to 20thDay
2413%26%33%22%
450
21st to endDay
3413%23%35%23%
495
November1st to 10thDay
6%215%22%33%23%
311
11th to 20thDay
3412%27%31%22%
270
21st to endDay
8%114%29%34%14%
270
December1st to 10thDay
11%321%25%27%12%
201
11th to 20thDay
10%7%14%31%23%16%
180
21st to endDay
15%10%20%23%25%7%
198
January1st to 10thNight
16%414%34%27%6%
760
11th to 20thNight
9%313%38%32%6%
760
21st to endNight
13%214%36%32%4
836
February1st to 10thNight
12%314%35%29%6%
758
11th to 20thNight
8%5%18%33%31%5%
704
21st to endNight
11%6%18%41%22%3
592
March1st to 10thNight
10%5%20%40%23%3
720
11th to 20thNight
8%6%19%34%28%4
720
21st to endNight
8%5%26%38%21%2
792
April1st to 10thNight
7%5%29%37%21%2
720
11th to 20thNight
48%29%35%21%3
711
21st to endNight
35%30%38%21%4
720
May1st to 10thNight
2430%40%21%3
720
11th to 20thNight
2432%45%17%
493
21st to endNight
36%29%44%17%1
389
June1st to 10thNight
3433%45%14%1
360
11th to 20thNight
425%53%18%1
360
21st to endNight
1123%55%19%1
360
July1st to 10thNight
19%53%27%
350
11th to 20thNight
210%58%31%1
377
21st to endNight
1110%43%43%3
591
August1st to 10thNight
215%49%31%3
616
11th to 20thNight
112%48%37%2
712
21st to endNight
18%43%46%3
792
September1st to 10thNight
118%45%41%4
720
11th to 20thNight
1116%44%32%5%
720
21st to endNight
1114%36%41%6%
720
October1st to 10thNight
3316%37%34%7%
720
11th to 20thNight
3214%34%39%8%
720
21st to endNight
4311%32%37%15%
792
November1st to 10thNight
5%313%32%38%10%
740
11th to 20thNight
5%111%40%35%8%
760
21st to endNight
7%213%37%34%7%
760
December1st to 10thNight
11%313%36%31%5%
760
11th to 20thNight
13%414%39%26%4
760
21st to endNight
13%6%15%40%22%3
836
Page generated at 2024-02-07 03:11:56. Version ac07

Copyright 2024 Attilla Danko


Mendota Wildlife Area Clear Sky Chart |Charts Home