Prescott
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prescott clear sky chart from 2005-11-06 to 2024-01-10.

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
69%
24111
35%
74316
29%
24063
76%
24063
52%
35231

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
63%
759
34%
2456
29%
756
74%
756
45%
1188
January11th to 20thNight
62%
720
35%
2340
32%
720
70%
720
47%
1125
January21st to endNight
53%
792
35%
2574
28%
792
66%
792
38%
1371
February1st to 10thNight
59%
720
37%
2250
28%
720
73%
720
50%
1050
February11th to 20thNight
57%
700
34%
2099
26%
700
69%
700
47%
1058
February21st to endNight
56%
592
35%
1776
30%
592
65%
592
44%
918
March1st to 10thNight
55%
720
34%
2010
24%
720
66%
720
49%
1036
March11th to 20thNight
63%
720
35%
1980
27%
720
70%
720
48%
1031
March21st to endNight
58%
792
34%
2178
21%
792
69%
792
52%
1090
April1st to 10thNight
59%
720
32%
1980
18%
720
69%
720
57%
962
April11th to 20thNight
53%
628
38%
1815
21%
628
67%
628
57%
835
April21st to endNight
61%
540
44%
1620
28%
540
74%
540
67%
670
May1st to 10thNight
70%
540
39%
1620
29%
540
76%
540
59%
709
May11th to 20thNight
71%
531
40%
1594
31%
531
77%
531
66%
665
May21st to endNight
72%
582
39%
1746
28%
582
79%
582
73%
697
June1st to 10thNight
79%
540
36%
1620
31%
540
81%
540
69%
669
June11th to 20thNight
79%
540
37%
1620
31%
540
81%
540
75%
637
June21st to endNight
83%
540
33%
1620
30%
540
85%
540
65%
696
July1st to 10thNight
86%
525
28%
1575
24%
525
86%
525
52%
772
July11th to 20thNight
87%
522
25%
1566
21%
522
87%
522
48%
785
July21st to endNight
79%
591
23%
1674
21%
558
81%
558
37%
960
August1st to 10thNight
87%
537
28%
1602
24%
534
88%
534
51%
786
August11th to 20thNight
87%
534
33%
1602
29%
534
87%
534
48%
803
August21st to endNight
85%
730
33%
1985
28%
730
85%
730
50%
1066
September1st to 10thNight
82%
720
32%
1980
28%
720
83%
720
51%
1046
September11th to 20thNight
86%
720
42%
1980
36%
720
88%
720
68%
902
September21st to endNight
76%
720
41%
1980
30%
720
83%
720
67%
901
October1st to 10thNight
72%
720
38%
1988
28%
720
78%
720
57%
973
October11th to 20thNight
78%
720
43%
2160
37%
720
84%
720
68%
904
October21st to endNight
74%
792
45%
2376
35%
792
83%
792
66%
997
November1st to 10thNight
74%
740
41%
2262
35%
740
81%
740
60%
994
November11th to 20thNight
72%
760
40%
2470
36%
760
81%
760
60%
1041
November21st to endNight
63%
760
38%
2470
33%
760
73%
760
49%
1152
December1st to 10thNight
67%
760
36%
2470
33%
760
73%
760
45%
1207
December11th to 20thNight
60%
758
33%
2944
31%
758
69%
758
32%
1566
December21st to endNight
56%
826
22%
4334
29%
817
65%
817
27%
1969

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
332443445%6%62%
74904
Night
332342345%6%66%
74806
TransparencyDay
21%46%15%28%27%
74631
Night
19%36%15%28%28%
74601
SeeingDay
5%10%25%31%21%8%
13879
Night
4417%36%33%6%
24130

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
45%35%5%2335%7%59%
1699
11th to 20thDay
35%24423345%63%
1620
21st to endDay
6%6%244245%5%7%55%
1782
February1st to 10thDay
36%24424346%64%
1706
11th to 20thDay
5%6%25%5%3435%6%56%
1750
21st to endDay
27%244345%5%6%57%
1480
March1st to 10thDay
2424435%5%5%7%57%
1948
11th to 20thDay
45%245%345%46%59%
1980
21st to endDay
3424424445%64%
2178
April1st to 10thDay
231442445%7%64%
1980
11th to 20thDay
2313323336%72%
2086
21st to endDay
2213323447%69%
2340
May1st to 10thDay
3313323347%69%
2340
11th to 20thDay
321322445%5%70%
2301
21st to endDay
2212213235%75%
2530
June1st to 10thDay
1112323345%75%
2340
11th to 20thDay
211111122484%
2340
21st to endDay
121322334474%
2340
July1st to 10thDay
2224335%5%6%6%61%
2340
11th to 20thDay
4327%6%5%7%6%7%9%43%
2340
21st to endDay
6%436%8%6%7%8%9%10%32%
2545
August1st to 10thDay
5%4245%46%5%6%8%52%
2328
11th to 20thDay
4425%5%5%6%7%7%8%49%
2299
21st to endDay
5%4245%35%6%7%8%51%
2364
September1st to 10thDay
5%425%5%45%5%6%7%54%
1980
11th to 20thDay
3113323445%71%
1980
21st to endDay
3213333345%70%
1980
October1st to 10thDay
3313334445%68%
1971
11th to 20thDay
2112212225%80%
1800
21st to endDay
2113322335%75%
1980
November1st to 10thDay
1213324346%71%
1812
11th to 20thDay
2213323345%71%
1710
21st to endDay
5%423323346%65%
1710
December1st to 10thDay
5%6%235%34447%57%
1710
11th to 20thDay
37%45%5%345%7%8%48%
2169
21st to endDay
5%7%36%5%2345%6%52%
3146
January1st to 10thNight
34244345%5%6%60%
2456
11th to 20thNight
45%2442335%5%63%
2340
21st to endNight
5%7%35%5%23345%58%
2574
February1st to 10thNight
242342335%6%66%
2250
11th to 20thNight
3425%424447%60%
2098
21st to endNight
46%2433445%6%60%
1776
March1st to 10thNight
34244245%6%7%60%
2010
11th to 20thNight
5%42342345%6%63%
1980
21st to endNight
222342445%7%63%
2178
April1st to 10thNight
222332445%6%67%
1980
11th to 20thNight
232332334472%
1815
21st to endNight
1112313345%76%
1620
May1st to 10thNight
121221435%5%73%
1620
11th to 20thNight
2212222235%78%
1594
21st to endNight
21121223482%
1746
June1st to 10thNight
111131323479%
1620
11th to 20thNight
111111222285%
1620
21st to endNight
221232323477%
1620
July1st to 10thNight
2213435%5%5%7%64%
1620
11th to 20thNight
2214435%5%6%9%59%
1620
21st to endNight
4326%5%46%6%8%12%44%
1773
August1st to 10thNight
22134345%7%9%61%
1611
11th to 20thNight
22134346%7%11%57%
1602
21st to endNight
23134346%7%8%59%
1985
September1st to 10thNight
23244345%6%8%60%
1980
11th to 20thNight
2112212345%77%
1980
21st to endNight
211321233478%
1980
October1st to 10thNight
4212313446%70%
1988
11th to 20thNight
121231223480%
2160
21st to endNight
1212212235%78%
2376
November1st to 10thNight
2223323345%73%
2262
11th to 20thNight
1213323335%74%
2470
21st to endNight
4424323346%66%
2470
December1st to 10thNight
5%42343445%6%61%
2470
11th to 20thNight
46%26%5%446%5%8%51%
3041
21st to endNight
46%245%35%5%5%5%56%
4521

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
25%36%17%30%19%
1700
11th to 20thDay
24%26%17%32%19%
1620
21st to endDay
28%47%16%30%16%
1782
February1st to 10thDay
23%26%15%26%27%
1706
11th to 20thDay
29%35%14%25%24%
1760
21st to endDay
25%46%16%27%23%
1480
March1st to 10thDay
25%3417%30%22%
1948
11th to 20thDay
26%35%15%32%20%
1980
21st to endDay
22%35%17%38%15%
2178
April1st to 10thDay
19%25%18%33%22%
1980
11th to 20thDay
16%1413%34%32%
2089
21st to endDay
15%3415%37%27%
2340
May1st to 10thDay
17%25%15%32%29%
2340
11th to 20thDay
15%36%13%33%30%
2304
21st to endDay
14%2311%32%37%
2530
June1st to 10thDay
12%148%31%44%
2340
11th to 20thDay
8%12421%64%
2340
21st to endDay
13%248%21%51%
2340
July1st to 10thDay
20%5%7%12%19%37%
2276
11th to 20thDay
31%10%15%17%17%11%
2271
21st to endDay
37%13%16%15%13%7%
2404
August1st to 10thDay
27%7%10%15%18%23%
2313
11th to 20thDay
27%8%11%19%19%16%
2299
21st to endDay
27%7%10%16%26%15%
2364
September1st to 10thDay
26%6%10%14%22%23%
1980
11th to 20thDay
14%36%12%34%31%
1980
21st to endDay
15%35%12%31%34%
1980
October1st to 10thDay
19%36%16%23%33%
1971
11th to 20thDay
11%249%34%41%
1800
21st to endDay
13%25%13%32%36%
1980
November1st to 10thDay
16%2419%34%25%
1812
11th to 20thDay
15%2417%30%33%
1710
21st to endDay
22%2416%31%26%
1710
December1st to 10thDay
27%36%17%23%23%
1710
11th to 20thDay
31%49%20%19%17%
2168
21st to endDay
31%36%17%29%13%
3146
January1st to 10thNight
22%37%18%33%16%
2456
11th to 20thNight
22%35%18%31%22%
2340
21st to endNight
30%25%13%32%18%
2574
February1st to 10thNight
19%26%17%28%28%
2250
11th to 20thNight
23%37%17%26%24%
2099
21st to endNight
24%35%13%30%24%
1776
March1st to 10thNight
21%36%16%30%23%
2010
11th to 20thNight
22%35%15%33%22%
1980
21st to endNight
19%39%19%33%18%
2178
April1st to 10thNight
17%27%15%36%23%
1980
11th to 20thNight
16%25%10%34%33%
1815
21st to endNight
10%25%14%36%33%
1620
May1st to 10thNight
13%35%15%29%34%
1620
11th to 20thNight
11%2411%36%35%
1595
21st to endNight
9%1213%36%39%
1746
June1st to 10thNight
11%126%29%50%
1620
11th to 20thNight
8%12420%64%
1620
21st to endNight
13%236%19%58%
1620
July1st to 10thNight
17%6%8%10%19%40%
1575
11th to 20thNight
19%7%16%20%24%14%
1566
21st to endNight
27%9%18%22%15%9%
1674
August1st to 10thNight
17%6%14%16%21%26%
1602
11th to 20thNight
19%7%13%23%18%21%
1602
21st to endNight
21%6%10%20%26%17%
1985
September1st to 10thNight
20%6%11%19%21%25%
1980
11th to 20thNight
11%36%12%31%37%
1980
21st to endNight
11%3412%32%38%
1980
October1st to 10thNight
17%35%17%22%36%
1988
11th to 20thNight
11%2310%29%45%
2160
21st to endNight
11%25%12%28%42%
2376
November1st to 10thNight
15%2416%36%27%
2262
11th to 20thNight
15%2415%31%34%
2470
21st to endNight
21%2415%30%29%
2470
December1st to 10thNight
22%46%17%24%27%
2470
11th to 20thNight
30%47%17%25%18%
3041
21st to endNight
27%47%18%29%15%
4521

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
12%12%28%28%19%2
267
11th to 20thDay
12%6%28%32%18%5%
240
21st to endDay
414%29%28%19%6%
264
February1st to 10thDay
6%14%29%31%14%6%
326
11th to 20thDay
12%17%34%25%10%2
415
21st to endDay
11%24%31%24%9%1
346
March1st to 10thDay
7%23%33%25%10%1
420
11th to 20thDay
9%17%29%27%15%4
420
21st to endDay
8%27%33%20%10%2
462
April1st to 10thDay
7%16%33%23%15%5%
420
11th to 20thDay
7%22%36%20%11%4
412
21st to endDay
420%35%24%10%7%
420
May1st to 10thDay
6%17%34%27%13%4
423
11th to 20thDay
314%33%30%15%6%
448
21st to endDay
6%12%34%30%14%5%
485
June1st to 10thDay
29%28%37%17%7%
450
11th to 20thDay
36%30%35%17%9%
450
21st to endDay
2326%39%23%8%
450
July1st to 10thDay
2118%42%27%10%
446
11th to 20thDay
3110%34%34%18%
444
21st to endDay
5%17%33%34%20%
487
August1st to 10thDay
5%210%37%31%16%
447
11th to 20thDay
4111%35%33%16%
437
21st to endDay
5%19%31%34%20%
495
September1st to 10thDay
5%216%35%29%13%
450
11th to 20thDay
3421%37%28%8%
450
21st to endDay
49%21%33%23%10%
450
October1st to 10thDay
5%10%26%27%23%8%
441
11th to 20thDay
45%19%36%27%10%
270
21st to endDay
311%20%30%29%8%
297
November1st to 10thDay
38%24%34%25%7%
270
11th to 20thDay
39%21%31%26%10%
270
21st to endDay
5%12%24%31%22%7%
270
December1st to 10thDay
7%10%21%31%27%3
270
11th to 20thDay
11%27%39%19%4
270
21st to endDay
10%15%22%31%19%2
297
January1st to 10thNight
5%6%18%40%22%8%
760
11th to 20thNight
6%6%20%38%25%6%
720
21st to endNight
9%5%25%36%22%3
792
February1st to 10thNight
46%23%37%25%4
720
11th to 20thNight
5%7%27%41%19%2
704
21st to endNight
8%8%24%40%17%3
592
March1st to 10thNight
5%8%27%40%19%1
720
11th to 20thNight
7%7%17%35%27%6%
720
21st to endNight
47%24%40%22%2
792
April1st to 10thNight
35%26%43%21%3
720
11th to 20thNight
48%29%35%22%2
628
21st to endNight
16%29%36%23%4
540
May1st to 10thNight
36%17%46%26%2
540
11th to 20thNight
2319%40%33%3
531
21st to endNight
3319%44%28%4
584
June1st to 10thNight
1312%44%37%3
540
11th to 20thNight
1115%44%33%5%
540
21st to endNight
29%36%47%6%
540
July1st to 10thNight
3433%55%6%
525
11th to 20thNight
2219%61%15%
522
21st to endNight
31318%63%13%
591
August1st to 10thNight
3221%57%16%
537
11th to 20thNight
21321%60%13%
534
21st to endNight
3317%56%20%
730
September1st to 10thNight
315%25%52%14%
720
11th to 20thNight
27%33%51%6%
720
21st to endNight
2315%33%41%8%
720
October1st to 10thNight
5%316%36%36%4
720
11th to 20thNight
2213%43%33%7%
720
21st to endNight
25%16%36%31%11%
792
November1st to 10thNight
3215%42%30%7%
740
11th to 20thNight
2318%40%29%8%
760
21st to endNight
6%5%20%35%28%5%
760
December1st to 10thNight
6%6%16%40%29%3
760
11th to 20thNight
7%5%20%42%24%3
760
21st to endNight
7%7%22%41%19%4
836
Page generated at 2024-01-07 08:06:54. Version ac07

Copyright 2024 Attilla Danko


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