Fresno
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fresno clear sky chart from 2005-11-05 to

2017-09-12
.

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
71%
15426
31%
46818
28%
15392
75%
15392
50%
23035

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
67%
716
20%
2471
23%
716
69%
716
31%
1403
January16th to endNight
65%
768
24%
2496
28%
768
66%
768
31%
1479
February1st to 15thNight
68%
699
26%
2175
28%
699
70%
699
35%
1242
February16th to endNight
63%
632
25%
1895
26%
632
66%
632
36%
1090
March1st to 15thNight
66%
720
22%
2116
21%
720
69%
720
40%
1171
March16th to endNight
61%
768
26%
2016
20%
768
66%
768
48%
1117
April1st to 15thNight
51%
719
28%
1799
14%
719
58%
719
45%
1051
April16th to endNight
59%
720
30%
1800
12%
720
66%
720
56%
952
May1st to 15thNight
63%
638
31%
1718
16%
638
69%
638
66%
794
May16th to endNight
57%
425
35%
1549
26%
425
70%
425
54%
608
June1st to 15thNight
58%
360
34%
1440
29%
360
73%
360
57%
510
June16th to endNight
75%
360
41%
1440
43%
360
86%
360
84%
404
July1st to 15thNight
84%
340
37%
1360
42%
340
89%
340
76%
412
July16th to endNight
87%
491
41%
1522
38%
460
90%
460
68%
588
August1st to 15thNight
85%
672
39%
1746
24%
669
88%
669
82%
749
August16th to endNight
91%
764
45%
1910
29%
764
92%
764
85%
834
September1st to 15thNight
90%
706
45%
1765
31%
706
93%
706
81%
794
September16th to endNight
83%
656
46%
1785
40%
656
88%
656
79%
751
October1st to 15thNight
77%
660
34%
1939
33%
660
82%
660
56%
914
October16th to endNight
79%
704
40%
2112
43%
704
83%
704
61%
950
November1st to 15thNight
80%
700
33%
2270
37%
700
81%
700
51%
1049
November16th to endNight
73%
720
28%
2340
30%
720
76%
720
42%
1196
December1st to 15thNight
67%
720
23%
2466
25%
720
70%
720
31%
1402
December16th to endNight
61%
768
23%
2688
25%
768
65%
768
28%
1575

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%212212335%68%
47848
Night
6%212212235%67%
47000
TransparencyDay
20%38%19%25%22%
47530
Night
20%39%21%25%20%
46819
SeeingDay
6%415%29%29%13%
5864
Night
7%214%38%31%6%
15437

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
10%7%36%43345%6%43%
1465
16th to endDay
15%7%345%25%346%40%
1728
February1st to 15thDay
14%5%34424346%46%
1688
16th to endDay
15%4245%23446%48%
1579
March1st to 15thDay
9%32342345%9%51%
1842
16th to endDay
9%413313446%55%
2208
April1st to 15thDay
10%323312335%59%
2149
16th to endDay
5%212223346%65%
2160
May1st to 15thDay
1112212235%75%
2230
16th to endDay
311212235%73%
2562
June1st to 15thDay
21111223478%
2520
16th to endDay
1111289%
2520
July1st to 15thDay
111112485%
2520
16th to endDay
111111222381%
2539
August1st to 15thDay
1111288%
2202
16th to endDay
111111386%
2292
September1st to 15thDay
11122286%
2114
16th to endDay
1111123481%
1845
October1st to 15thDay
312212335%72%
1689
16th to endDay
321212335%70%
1760
November1st to 15thDay
8%213313345%61%
1587
16th to endDay
9%423324446%54%
1620
December1st to 15thDay
13%6%25%433446%44%
1493
16th to endDay
14%6%36%41335%6%43%
1536
January1st to 15thNight
12%6%23323346%51%
2471
16th to endNight
14%424323447%48%
2496
February1st to 15thNight
10%423323446%54%
2164
16th to endNight
15%412312346%53%
1895
March1st to 15thNight
8%324423346%57%
2116
16th to endNight
9%312222348%59%
2016
April1st to 15thNight
8%313323347%59%
1799
16th to endNight
4122222235%70%
1800
May1st to 15thNight
2112245%76%
1718
16th to endNight
312111235%75%
1548
June1st to 15thNight
21112222378%
1440
16th to endNight
111291%
1440
July1st to 15thNight
112111485%
1440
16th to endNight
1112222380%
1627
August1st to 15thNight
11111188%
1755
16th to endNight
1122287%
1910
September1st to 15thNight
1111387%
1765
16th to endNight
11112285%
1785
October1st to 15thNight
3212213346%69%
1939
16th to endNight
322112235%74%
2112
November1st to 15thNight
6%312112236%68%
2270
16th to endNight
7%313212346%60%
2340
December1st to 15thNight
11%42332345%6%51%
2466
16th to endNight
16%423323336%50%
2688

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
41%5%13%20%16%3
1465
16th to endDay
44%7%10%16%15%6%
1728
February1st to 15thDay
38%7%12%22%16%2
1688
16th to endDay
37%5%13%28%13%1
1579
March1st to 15thDay
29%7%16%23%18%4
1842
16th to endDay
29%5%15%26%19%4
2208
April1st to 15thDay
27%411%28%20%7%
2149
16th to endDay
20%411%26%27%9%
2160
May1st to 15thDay
13%27%23%36%15%
2230
16th to endDay
13%27%28%34%12%
2566
June1st to 15thDay
10%28%17%31%29%
2520
16th to endDay
5%128%31%51%
2520
July1st to 15thDay
6%26%20%62%
2371
16th to endDay
10%139%20%55%
2382
August1st to 15thDay
5%18%28%54%
2186
16th to endDay
6%16%37%46%
2292
September1st to 15thDay
7%149%31%45%
2114
16th to endDay
7%1318%40%27%
1845
October1st to 15thDay
15%27%25%27%20%
1689
16th to endDay
15%37%26%28%17%
1760
November1st to 15thDay
25%5%13%26%26%3
1587
16th to endDay
30%6%12%25%21%3
1620
December1st to 15thDay
39%6%10%20%19%2
1493
16th to endDay
42%6%14%21%13%1
1536
January1st to 15thNight
32%6%12%24%19%4
2471
16th to endNight
34%5%12%18%17%10%
2496
February1st to 15thNight
31%5%12%27%18%4
2175
16th to endNight
31%413%29%18%2
1895
March1st to 15thNight
27%415%23%22%6%
2116
16th to endNight
24%316%28%21%5%
2016
April1st to 15thNight
26%411%30%19%6%
1799
16th to endNight
16%412%25%31%8%
1800
May1st to 15thNight
11%38%23%35%17%
1719
16th to endNight
13%27%25%36%14%
1549
June1st to 15thNight
11%26%21%29%29%
1440
16th to endNight
327%26%58%
1440
July1st to 15thNight
6%2423%62%
1360
16th to endNight
10%129%20%55%
1522
August1st to 15thNight
7%17%25%57%
1746
16th to endNight
5%127%31%52%
1910
September1st to 15thNight
6%119%29%51%
1765
16th to endNight
7%1216%40%31%
1785
October1st to 15thNight
16%36%22%28%22%
1939
16th to endNight
14%26%25%32%18%
2112
November1st to 15thNight
18%311%27%30%7%
2270
16th to endNight
24%412%25%25%6%
2340
December1st to 15thNight
31%6%12%23%18%6%
2466
16th to endNight
36%5%15%22%16%3
2688

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
30%116%24%18%9%
93
16th to endDay
18%113%24%24%16%
256
February1st to 15thDay
15%315%23%23%17%
255
16th to endDay
16%5%18%28%20%10%
238
March1st to 15thDay
10%8%17%25%23%14%
270
16th to endDay
12%8%23%25%22%7%
288
April1st to 15thDay
15%13%24%22%17%7%
269
16th to endDay
6%12%29%27%16%6%
270
May1st to 15thDay
46%21%36%21%9%
288
16th to endDay
37%22%26%29%10%
330
June1st to 15thDay
423%35%25%10%
315
16th to endDay
112%27%39%18%
315
July1st to 15thDay
17%29%37%23%
305
16th to endDay
16%29%45%17%
327
August1st to 15thDay
218%42%33%11%
315
16th to endDay
17%30%39%21%
332
September1st to 15thDay
19%39%37%12%
300
16th to endDay
1317%30%32%13%
255
October1st to 15thDay
2418%36%27%10%
255
16th to endDay
5%5%15%29%33%11%
272
November1st to 15thDay
6%15%8%40%37%
93
16th to endDay
6%5%13%32%32%10%
90
December1st to 15thDay
20%10%37%30%1
69
16th to endDay
15%115%25%28%14%
64
January1st to 15thNight
15%9%33%30%11%
720
16th to endNight
15%110%31%31%9%
768
February1st to 15thNight
13%110%35%31%8%
704
16th to endNight
15%214%34%27%6%
632
March1st to 15thNight
9%115%37%30%5%
720
16th to endNight
10%321%36%26%2
768
April1st to 15thNight
8%6%27%33%20%2
719
16th to endNight
45%27%35%23%3
720
May1st to 15thNight
2328%42%21%1
639
16th to endNight
47%27%41%18%
426
June1st to 15thNight
3432%49%11%
360
16th to endNight
2120%58%17%
360
July1st to 15thNight
12%60%25%
340
16th to endNight
27%45%42%2
491
August1st to 15thNight
210%48%34%4
672
16th to endNight
5%39%49%4
764
September1st to 15thNight
6%40%44%6%
706
16th to endNight
111%38%38%9%
656
October1st to 15thNight
5%113%34%36%9%
660
16th to endNight
4110%33%36%13%
704
November1st to 15thNight
7%16%34%37%12%
700
16th to endNight
8%10%35%33%10%
720
December1st to 15thNight
13%18%38%31%6%
720
16th to endNight
17%111%39%24%4
768
Page generated at 2017-09-13 04:39:13. Version ac04

Copyright 2017 A. Danko


Fresno Clear Sky Chart | Charts Home