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 2017-09-16.

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
79%
15622
37%
46903
34%
15584
83%
15584
56%
22046

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%
718
32%
2327
33%
716
78%
716
47%
1119
January16th to endNight
69%
768
36%
2496
36%
768
75%
768
43%
1265
February1st to 15thNight
75%
698
36%
2190
36%
698
81%
698
54%
1016
February16th to endNight
73%
632
37%
1879
38%
632
76%
632
47%
974
March1st to 15thNight
73%
720
41%
1980
35%
720
79%
720
60%
951
March16th to endNight
79%
768
40%
2112
33%
768
85%
768
63%
991
April1st to 15thNight
77%
703
34%
1962
27%
703
80%
703
57%
971
April16th to endNight
77%
540
45%
1704
40%
540
84%
540
71%
665
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%
660
42%
1826
34%
660
88%
660
66%
830
October1st to 15thNight
83%
660
42%
1895
36%
660
86%
660
64%
860
October16th to endNight
86%
704
44%
2112
40%
704
89%
704
68%
893
November1st to 15thNight
84%
700
42%
2127
40%
700
87%
700
66%
901
November16th to endNight
77%
720
40%
2340
40%
720
82%
720
55%
1032
December1st to 15thNight
74%
720
37%
2340
37%
720
78%
720
48%
1115
December16th to endNight
69%
768
35%
2496
36%
768
73%
768
40%
1309

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%
47852
Night
3212213345%68%
47099
TransparencyDay
17%2312%25%38%
47547
Night
18%2311%23%39%
46905
SeeingDay
4416%35%29%10%
5441
Night
418%42%38%5%
15633

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%222312245%66%
1611
16th to endDay
7%312222236%64%
1728
February1st to 15thDay
4313312246%67%
1670
16th to endDay
7%323222338%60%
1594
March1st to 15thDay
4212213346%67%
1980
16th to endDay
3113312335%70%
2112
April1st to 15thDay
312113446%70%
1985
16th to endDay
11121222479%
2253
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
211111135%79%
1823
October1st to 15thDay
21121233475%
1733
16th to endDay
11111222479%
1760
November1st to 15thDay
112212245%74%
1729
16th to endDay
5%11231123472%
1620
December1st to 15thDay
7%313323335%63%
1620
16th to endDay
7%414313445%59%
1728
January1st to 15thNight
6%212323335%64%
2327
16th to endNight
8%31332333462%
2496
February1st to 15thNight
4213212245%67%
2179
16th to endNight
7%212323445%62%
1879
March1st to 15thNight
4212212345%69%
1980
16th to endNight
2111212245%73%
2112
April1st to 15thNight
3212213345%68%
1962
16th to endNight
1111212382%
1704
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
21131233476%
1826
October1st to 15thNight
2111212235%74%
1895
16th to endNight
121111223478%
2112
November1st to 15thNight
2111112345%74%
2127
16th to endNight
41232222471%
2340
December1st to 15thNight
7%22223436%64%
2340
16th to endNight
9%313423335%58%
2496

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
21%1415%28%27%
1612
16th to endDay
23%1217%25%29%
1728
February1st to 15thDay
20%15%17%27%28%
1670
16th to endDay
24%1216%30%24%
1594
March1st to 15thDay
19%118%32%36%
1980
16th to endDay
18%129%32%35%
2112
April1st to 15thDay
15%1110%34%36%
1985
16th to endDay
11%117%25%52%
2253
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%17%29%50%
1823
October1st to 15thDay
13%1210%26%44%
1733
16th to endDay
11%138%26%48%
1760
November1st to 15thDay
12%2111%33%39%
1729
16th to endDay
17%1211%24%42%
1620
December1st to 15thDay
25%15%16%28%23%
1620
16th to endDay
26%2421%28%16%
1728
January1st to 15thNight
23%2412%26%31%
2327
16th to endNight
26%1212%27%28%
2496
February1st to 15thNight
19%1415%25%32%
2190
16th to endNight
25%1214%27%27%
1879
March1st to 15thNight
17%119%27%43%
1980
16th to endNight
14%1210%32%39%
2112
April1st to 15thNight
18%117%29%40%
1962
16th to endNight
9%116%22%59%
1704
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
13%16%24%53%
1826
October1st to 15thNight
14%1110%24%47%
1895
16th to endNight
11%128%19%55%
2112
November1st to 15thNight
12%1110%30%43%
2127
16th to endNight
17%129%23%44%
2340
December1st to 15thNight
22%1414%28%28%
2340
16th to endNight
29%1416%27%19%
2496

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
28%16%34%17%2
90
16th to endDay
9%12%40%23%13%
96
February1st to 15thDay
4317%38%31%3
185
16th to endDay
10%7%23%39%15%3
238
March1st to 15thDay
410%22%34%14%14%
270
16th to endDay
39%27%28%21%8%
288
April1st to 15thDay
6%11%23%34%16%6%
269
16th to endDay
314%30%33%14%2
270
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
6%215%39%32%4
258
October1st to 15thDay
4218%32%31%10%
173
16th to endDay
4323%52%16%
96
November1st to 15thDay
3116%33%31%14%
90
16th to endDay
8%15%47%25%2
90
December1st to 15thDay
5%444%41%4
90
16th to endDay
16%17%41%22%1
96
January1st to 15thNight
7%111%53%23%3
720
16th to endNight
10%111%47%24%3
768
February1st to 15thNight
6%19%54%26%2
704
16th to endNight
9%110%53%23%1
632
March1st to 15thNight
6%113%47%27%3
720
16th to endNight
229%46%32%5%
768
April1st to 15thNight
3210%52%27%2
703
16th to endNight
2215%49%26%3
540
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%6%
660
October1st to 15thNight
48%46%37%3
660
16th to endNight
15%43%41%6%
704
November1st to 15thNight
38%48%35%4
700
16th to endNight
5%10%46%33%4
720
December1st to 15thNight
9%9%46%30%2
720
16th to endNight
11%18%50%24%3
768
Page generated at 2017-09-17 09:05:41. Version ac04

Copyright 2017 A. Danko


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