Fountain Hills
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fountain Hills clear sky chart from 2005-11-05 to 2018-04-23.

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
80%
16483
37%
49509
34%
16445
83%
16445
56%
23242

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
73%
778
32%
2522
33%
776
78%
776
46%
1225
January16th to endNight
70%
832
37%
2704
37%
832
77%
832
45%
1348
February1st to 15thNight
75%
758
36%
2376
36%
758
81%
758
54%
1105
February16th to endNight
73%
684
37%
2034
38%
684
77%
684
46%
1061
March1st to 15thNight
74%
780
41%
2145
35%
780
79%
780
59%
1035
March16th to endNight
80%
832
40%
2288
33%
832
84%
832
62%
1081
April1st to 15thNight
77%
762
35%
2126
29%
762
81%
762
58%
1044
April16th to endNight
77%
558
46%
1762
40%
558
84%
558
70%
691
May1st to 15thNight
79%
539
40%
1619
34%
539
84%
539
68%
679
May16th to endNight
82%
561
41%
1684
34%
561
85%
561
74%
673
June1st to 15thNight
88%
540
35%
1620
31%
540
88%
540
73%
651
June16th to endNight
93%
540
35%
1620
32%
540
93%
540
74%
647
July1st to 15thNight
84%
510
24%
1530
21%
510
84%
510
49%
765
July16th to endNight
82%
564
27%
1593
23%
531
82%
531
41%
874
August1st to 15thNight
84%
539
30%
1611
26%
536
84%
536
47%
837
August16th to endNight
84%
630
33%
1860
32%
630
84%
630
45%
1002
September1st to 15thNight
84%
720
34%
1980
29%
720
85%
720
54%
1026
September16th to endNight
85%
716
45%
1980
36%
716
88%
716
67%
892
October1st to 15thNight
84%
720
41%
2068
35%
720
87%
720
66%
920
October16th to endNight
87%
768
47%
2304
42%
768
90%
768
69%
961
November1st to 15thNight
84%
760
41%
2309
39%
760
86%
760
63%
1010
November16th to endNight
78%
780
42%
2535
43%
780
82%
780
55%
1117
December1st to 15thNight
74%
780
37%
2535
37%
780
78%
780
48%
1207
December16th to endNight
71%
832
37%
2704
38%
832
75%
832
42%
1391

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
3212213346%69%
50003
Night
3212213345%68%
49705
TransparencyDay
17%1312%25%38%
49698
Night
18%1311%24%40%
49511
SeeingDay
4415%34%29%10%
6181
Night
417%42%38%5%
16494

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
5%222313345%65%
1746
16th to endDay
7%312222235%65%
1872
February1st to 15thDay
4313212235%67%
1813
16th to endDay
7%313222337%60%
1725
March1st to 15thDay
4212323346%66%
2145
16th to endDay
3113322335%69%
2288
April1st to 15thDay
311113446%70%
2151
16th to endDay
11121222479%
2309
May1st to 15thDay
11112235%80%
2331
16th to endDay
2111112381%
2429
June1st to 15thDay
11111112482%
2340
16th to endDay
111222481%
2340
July1st to 15thDay
22124245%6%9%57%
2340
16th to endDay
5%214436%7%7%11%44%
2467
August1st to 15thDay
2213325%5%6%9%56%
2340
16th to endDay
21134245%7%8%58%
2339
September1st to 15thDay
3212424445%64%
1980
16th to endDay
211111125%80%
1980
October1st to 15thDay
21121223477%
1890
16th to endDay
11111222479%
1920
November1st to 15thDay
112222245%73%
1876
16th to endDay
5%11231123472%
1755
December1st to 15thDay
7%313323335%62%
1755
16th to endDay
7%414313445%60%
1872
January1st to 15thNight
6%213323435%63%
2522
16th to endNight
8%31331333464%
2704
February1st to 15thNight
5%213212246%67%
2365
16th to endNight
7%21232343461%
2034
March1st to 15thNight
4212212346%69%
2145
16th to endNight
2111213236%72%
2288
April1st to 15thNight
3112213345%69%
2126
16th to endNight
2111212381%
1762
May1st to 15thNight
111112345%76%
1619
16th to endNight
2111112383%
1684
June1st to 15thNight
1111223480%
1620
16th to endNight
111123481%
1620
July1st to 15thNight
12124246%7%10%55%
1620
16th to endNight
32145%35%6%8%12%46%
1701
August1st to 15thNight
12145%245%7%9%54%
1620
16th to endNight
2214435%6%6%8%54%
1860
September1st to 15thNight
221332445%7%61%
1980
16th to endNight
21121223477%
1980
October1st to 15thNight
2111212235%76%
2068
16th to endNight
12111223479%
2304
November1st to 15thNight
2112112345%72%
2309
16th to endNight
412322225%71%
2535
December1st to 15thNight
7%22223336%63%
2535
16th to endNight
8%213413335%60%
2704

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%1415%29%26%
1747
16th to endDay
22%1216%26%29%
1872
February1st to 15thDay
20%1416%27%29%
1813
16th to endDay
24%1216%30%24%
1725
March1st to 15thDay
20%119%31%35%
2145
16th to endDay
18%1210%33%34%
2288
April1st to 15thDay
14%1110%34%37%
2151
16th to endDay
11%117%25%53%
2309
May1st to 15thDay
9%19%26%53%
2331
16th to endDay
10%16%23%57%
2432
June1st to 15thDay
9%1317%68%
2340
16th to endDay
8%11412%72%
2340
July1st to 15thDay
20%39%17%17%31%
2201
16th to endDay
28%5%13%24%17%9%
2312
August1st to 15thDay
21%49%19%18%26%
2325
16th to endDay
20%45%20%26%22%
2339
September1st to 15thDay
19%35%15%25%30%
1980
16th to endDay
10%16%29%51%
1980
October1st to 15thDay
12%129%26%47%
1890
16th to endDay
11%138%26%48%
1920
November1st to 15thDay
13%2112%32%37%
1876
16th to endDay
17%1111%25%42%
1755
December1st to 15thDay
25%1416%26%25%
1755
16th to endDay
26%2420%29%17%
1872
January1st to 15thNight
24%1412%26%30%
2522
16th to endNight
25%1212%27%29%
2704
February1st to 15thNight
19%1414%26%32%
2376
16th to endNight
26%1214%27%27%
2034
March1st to 15thNight
17%1110%27%41%
2145
16th to endNight
15%1110%32%37%
2288
April1st to 15thNight
18%117%28%41%
2126
16th to endNight
9%116%22%58%
1762
May1st to 15thNight
10%117%27%51%
1620
16th to endNight
9%17%17%63%
1685
June1st to 15thNight
9%1413%70%
1620
16th to endNight
8%1139%75%
1620
July1st to 15thNight
21%311%15%15%33%
1530
16th to endNight
26%5%13%21%21%12%
1593
August1st to 15thNight
23%48%20%14%29%
1611
16th to endNight
24%47%16%22%23%
1860
September1st to 15thNight
20%37%20%22%27%
1980
16th to endNight
12%16%23%54%
1980
October1st to 15thNight
13%119%22%50%
2068
16th to endNight
11%128%19%56%
2304
November1st to 15thNight
14%1111%30%40%
2309
16th to endNight
17%129%25%43%
2535
December1st to 15thNight
22%1314%26%30%
2535
16th to endNight
27%1416%27%21%
2704

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
20%12%34%28%3
135
16th to endDay
8%13%36%30%11%
144
February1st to 15thDay
7%215%35%31%7%
238
16th to endDay
10%7%24%40%13%2
290
March1st to 15thDay
5%8%22%35%15%11%
330
16th to endDay
39%26%29%22%8%
352
April1st to 15thDay
6%10%22%35%18%6%
329
16th to endDay
414%29%32%14%3
288
May1st to 15thDay
311%25%35%19%4
288
16th to endDay
25%26%36%24%3
330
June1st to 15thDay
3121%38%27%6%
315
16th to endDay
110%43%30%13%
315
July1st to 15thDay
29%37%37%13%
305
16th to endDay
4329%34%26%
327
August1st to 15thDay
1328%43%20%
315
16th to endDay
329%44%20%
332
September1st to 15thDay
6%18%31%42%9%
315
16th to endDay
5%115%36%34%5%
315
October1st to 15thDay
3115%34%35%10%
225
16th to endDay
3323%47%21%
144
November1st to 15thDay
3113%36%34%10%
135
16th to endDay
7%11%41%31%8%
135
December1st to 15thDay
7%8%42%37%3
135
16th to endDay
12%13%36%29%7%
144
January1st to 15thNight
7%110%51%25%3
780
16th to endNight
10%111%47%25%4
832
February1st to 15thNight
6%19%53%27%2
764
16th to endNight
9%110%54%22%1
684
March1st to 15thNight
6%112%48%27%3
780
16th to endNight
329%46%32%5%
832
April1st to 15thNight
339%51%28%2
762
16th to endNight
2215%49%26%3
558
May1st to 15thNight
2311%45%33%3
540
16th to endNight
3110%41%39%4
563
June1st to 15thNight
16%47%39%3
540
16th to endNight
1233%57%5%
540
July1st to 15thNight
1427%59%6%
510
16th to endNight
41113%64%15%
564
August1st to 15thNight
2117%64%13%
539
16th to endNight
3119%65%10%
630
September1st to 15thNight
21329%54%8%
720
16th to endNight
216%38%44%5%
716
October1st to 15thNight
37%46%38%2
720
16th to endNight
15%42%43%6%
768
November1st to 15thNight
37%50%34%4
760
16th to endNight
5%9%44%35%4
780
December1st to 15thNight
9%9%47%30%2
780
16th to endNight
10%18%49%26%3
832
Page generated at 2018-04-24 07:03:06. Version ac04

Copyright 2018 A. Danko


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