Parkfield
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Parkfield clear sky chart from 2005-11-06 to 2024-01-13.

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
74%
23940
33%
74706
30%
23900
78%
23900
48%
36984

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
59%
756
20%
2588
22%
756
62%
756
27%
1544
January11th to 20thNight
66%
728
27%
2366
28%
728
70%
728
36%
1302
January21st to endNight
64%
792
29%
2574
32%
792
67%
792
35%
1427
February1st to 10thNight
64%
720
29%
2276
29%
720
70%
720
35%
1270
February11th to 20thNight
66%
700
31%
2099
31%
700
71%
700
43%
1091
February21st to endNight
61%
592
27%
1776
27%
592
66%
592
37%
1005
March1st to 10thNight
57%
720
21%
2124
19%
720
62%
720
33%
1272
March11th to 20thNight
64%
720
26%
1980
23%
720
68%
720
38%
1168
March21st to endNight
61%
792
25%
2070
18%
792
66%
792
43%
1194
April1st to 10thNight
65%
720
30%
1800
19%
720
68%
720
47%
1020
April11th to 20thNight
64%
711
35%
1779
18%
711
70%
711
54%
926
April21st to endNight
69%
720
33%
1800
17%
720
74%
720
59%
928
May1st to 10thNight
74%
720
31%
1800
18%
720
76%
720
63%
899
May11th to 20thNight
73%
569
37%
1632
27%
569
77%
569
65%
713
May21st to endNight
76%
388
36%
1552
36%
388
83%
388
56%
562
June1st to 10thNight
80%
360
36%
1440
40%
360
85%
360
59%
514
June11th to 20thNight
84%
360
42%
1440
49%
360
90%
360
78%
430
June21st to endNight
88%
360
43%
1440
50%
360
93%
360
82%
416
July1st to 10thNight
95%
350
41%
1400
50%
350
97%
350
83%
404
July11th to 20thNight
94%
445
40%
1489
40%
445
95%
445
76%
536
July21st to endNight
92%
591
41%
1674
35%
558
93%
558
70%
691
August1st to 10thNight
89%
630
41%
1695
29%
627
90%
627
79%
722
August11th to 20thNight
92%
712
42%
1780
26%
712
93%
712
84%
784
August21st to endNight
93%
792
46%
1980
31%
792
94%
792
85%
862
September1st to 10thNight
91%
720
47%
1800
34%
720
92%
720
82%
800
September11th to 20thNight
88%
720
50%
1810
40%
720
91%
720
81%
806
September21st to endNight
86%
720
45%
1980
42%
720
90%
720
75%
846
October1st to 10thNight
80%
720
35%
2142
37%
720
83%
720
59%
970
October11th to 20thNight
81%
720
40%
2160
42%
720
84%
720
59%
978
October21st to endNight
82%
792
43%
2376
46%
792
85%
792
61%
1060
November1st to 10thNight
77%
740
37%
2326
37%
740
81%
740
53%
1077
November11th to 20thNight
76%
760
33%
2470
34%
760
81%
760
49%
1172
November21st to endNight
73%
760
31%
2470
32%
760
76%
760
42%
1263
December1st to 10thNight
65%
760
28%
2583
29%
760
70%
760
35%
1387
December11th to 20thNight
60%
759
21%
3228
25%
759
64%
759
18%
2152
December21st to endNight
57%
821
15%
4807
23%
817
63%
817
16%
2793

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%
74733
Night
5%323323346%65%
75004
TransparencyDay
20%36%19%28%23%
74450
Night
22%38%19%27%22%
74809
SeeingDay
7%7%20%32%25%10%
14326
Night
7%310%35%36%9%
23965

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
12%7%25%5%345%5%6%45%
1574
11th to 20thDay
7%5%25%43445%7%55%
1639
21st to endDay
12%7%35%5%34446%47%
1782
February1st to 10thDay
13%6%23324446%54%
1683
11th to 20thDay
8%5%35%435%447%52%
1750
21st to endDay
11%7%35%4245%47%47%
1480
March1st to 10thDay
8%7%46%6%46%5%6%7%41%
1831
11th to 20thDay
9%7%35%6%35%5%6%8%44%
1980
21st to endDay
8%6%25%5%45%447%52%
2286
April1st to 10thDay
8%6%2442345%8%54%
2160
11th to 20thDay
5%43442445%7%59%
2129
21st to endDay
422333445%6%64%
2160
May1st to 10thDay
3213323347%69%
2160
11th to 20thDay
221232335%6%71%
2254
21st to endDay
3213324347%68%
2723
June1st to 10thDay
2212222348%71%
2520
11th to 20thDay
11111112388%
2520
21st to endDay
1111222387%
2520
July1st to 10thDay
1111112488%
2520
11th to 20thDay
11121233383%
2416
21st to endDay
1111222335%79%
2546
August1st to 10thDay
12211123384%
2232
11th to 20thDay
11111122288%
2122
21st to endDay
11111111388%
2376
September1st to 10thDay
1111121389%
2160
11th to 20thDay
11122222384%
2148
21st to endDay
121121234479%
1980
October1st to 10thDay
211342345%5%71%
1814
11th to 20thDay
221322435%5%72%
1800
21st to endDay
321321235%5%71%
1980
November1st to 10thDay
432432345%7%62%
1751
11th to 20thDay
5%5%23324446%61%
1710
21st to endDay
5%42442445%6%59%
1710
December1st to 10thDay
8%5%26%5%3446%8%50%
1595
11th to 20thDay
17%11%46%5%2445%7%35%
1928
21st to endDay
11%8%36%6%45%5%6%8%38%
2794
January1st to 10thNight
10%7%36%5%35%5%5%7%44%
2588
11th to 20thNight
7%5%25%5%35%45%8%52%
2366
21st to endNight
10%5%24434447%52%
2574
February1st to 10thNight
10%5%34334446%55%
2276
11th to 20thNight
5%42442445%8%58%
2098
21st to endNight
8%5%34423347%56%
1776
March1st to 10thNight
8%6%26%5%35%5%49%47%
2124
11th to 20thNight
6%5%345%345%5%7%52%
1980
21st to endNight
8%424433446%59%
2070
April1st to 10thNight
5%325%43435%7%60%
1800
11th to 20thNight
3213323336%69%
1779
21st to endNight
321232445%6%69%
1800
May1st to 10thNight
221321335%7%72%
1800
11th to 20thNight
3111212246%75%
1631
21st to endNight
2212212345%76%
1552
June1st to 10thNight
2212212345%76%
1440
11th to 20thNight
121122488%
1440
21st to endNight
1112490%
1440
July1st to 10thNight
11123488%
1440
11th to 20thNight
111121213386%
1538
21st to endNight
1112123245%78%
1773
August1st to 10thNight
11121212287%
1704
11th to 20thNight
11111233485%
1780
21st to endNight
1111111389%
1980
September1st to 10thNight
11111112288%
1800
11th to 20thNight
11111113386%
1810
21st to endNight
11121232383%
1980
October1st to 10thNight
321331324474%
2142
11th to 20thNight
2313322245%73%
2160
21st to endNight
3212223345%73%
2376
November1st to 10thNight
332332335%6%68%
2326
11th to 20thNight
432432345%7%63%
2470
21st to endNight
4425%4345%6%7%56%
2470
December1st to 10thNight
8%5%3443435%8%52%
2583
11th to 20thNight
17%9%45%5%35%45%7%36%
3276
21st to endNight
10%7%36%7%45%6%6%8%39%
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
37%6%10%23%17%7%
1574
11th to 20thDay
29%310%21%21%15%
1639
21st to endDay
37%410%16%22%11%
1782
February1st to 10thDay
32%37%20%24%14%
1683
11th to 20thDay
31%46%22%26%10%
1760
21st to endDay
36%410%20%24%7%
1480
March1st to 10thDay
40%6%10%17%19%8%
1831
11th to 20thDay
37%5%10%21%21%7%
1980
21st to endDay
33%5%10%26%19%7%
2286
April1st to 10thDay
29%411%26%20%10%
2160
11th to 20thDay
24%5%9%27%24%10%
2132
21st to endDay
21%49%28%29%8%
2160
May1st to 10thDay
17%49%22%35%13%
2160
11th to 20thDay
15%36%28%36%13%
2257
21st to endDay
17%48%30%34%7%
2724
June1st to 10thDay
14%310%20%36%18%
2520
11th to 20thDay
6%2415%41%33%
2520
21st to endDay
6%1210%34%46%
2520
July1st to 10thDay
4119%29%55%
2451
11th to 20thDay
8%238%29%50%
2342
21st to endDay
10%3312%28%45%
2405
August1st to 10thDay
8%219%31%49%
2216
11th to 20thDay
5%1212%35%45%
2122
21st to endDay
7%119%38%45%
2376
September1st to 10thDay
5%2211%30%50%
2160
11th to 20thDay
8%2218%42%29%
2148
21st to endDay
10%3218%39%28%
1980
October1st to 10thDay
14%35%20%24%34%
1814
11th to 20thDay
16%45%18%28%30%
1800
21st to endDay
17%25%16%31%29%
1980
November1st to 10thDay
22%48%19%29%18%
1751
11th to 20thDay
24%410%21%26%15%
1710
21st to endDay
26%47%17%27%20%
1710
December1st to 10thDay
31%5%10%18%22%14%
1595
11th to 20thDay
49%47%16%14%8%
1928
21st to endDay
41%6%10%25%13%5%
2794
January1st to 10thNight
38%5%10%20%21%6%
2588
11th to 20thNight
31%410%21%19%15%
2366
21st to endNight
31%5%11%19%22%13%
2574
February1st to 10thNight
32%46%20%25%14%
2276
11th to 20thNight
24%48%23%29%12%
2099
21st to endNight
30%48%24%26%7%
1776
March1st to 10thNight
35%412%23%18%8%
2124
11th to 20thNight
30%6%11%21%25%8%
1980
21st to endNight
27%5%14%25%22%8%
2070
April1st to 10thNight
24%414%27%19%12%
1800
11th to 20thNight
18%412%27%28%11%
1779
21st to endNight
16%310%29%32%9%
1800
May1st to 10thNight
14%310%25%31%16%
1800
11th to 20thNight
12%26%30%36%14%
1632
21st to endNight
12%310%30%34%12%
1552
June1st to 10thNight
12%210%20%36%21%
1440
11th to 20thNight
5%1415%39%35%
1440
21st to endNight
41110%35%49%
1440
July1st to 10thNight
4118%29%58%
1400
11th to 20thNight
7%127%30%53%
1489
21st to endNight
9%329%26%51%
1674
August1st to 10thNight
7%1110%27%54%
1695
11th to 20thNight
5%228%33%51%
1780
21st to endNight
5%117%36%50%
1980
September1st to 10thNight
6%228%26%57%
1800
11th to 20thNight
7%1216%35%39%
1810
21st to endNight
8%2216%41%31%
1980
October1st to 10thNight
15%36%18%25%34%
2142
11th to 20thNight
16%27%16%30%29%
2160
21st to endNight
15%2418%34%28%
2376
November1st to 10thNight
18%37%21%30%21%
2326
11th to 20thNight
21%311%21%27%18%
2470
21st to endNight
25%49%17%26%18%
2470
December1st to 10thNight
30%49%17%23%16%
2583
11th to 20thNight
48%5%9%15%15%8%
3276
21st to endNight
41%6%13%20%14%5%
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
21%7%31%26%11%3
235
11th to 20thDay
15%6%27%32%17%3
347
21st to endDay
12%7%26%31%21%3
374
February1st to 10thDay
16%10%23%27%18%5%
368
11th to 20thDay
12%12%26%32%15%3
415
21st to endDay
16%12%26%32%12%2
346
March1st to 10thDay
15%14%26%29%15%1
420
11th to 20thDay
17%10%25%28%17%3
420
21st to endDay
15%15%25%27%16%2
462
April1st to 10thDay
13%11%25%27%19%6%
420
11th to 20thDay
9%15%24%29%18%6%
412
21st to endDay
410%28%32%17%9%
420
May1st to 10thDay
7%8%26%36%17%6%
423
11th to 20thDay
311%21%32%24%9%
448
21st to endDay
6%10%21%31%22%11%
485
June1st to 10thDay
37%17%34%26%13%
450
11th to 20thDay
15%20%36%30%9%
450
21st to endDay
1319%32%29%16%
450
July1st to 10thDay
1113%40%29%16%
446
11th to 20thDay
27%34%34%24%
444
21st to endDay
1110%31%36%21%
487
August1st to 10thDay
2215%39%27%16%
447
11th to 20thDay
1212%30%34%21%
437
21st to endDay
118%32%36%23%
495
September1st to 10thDay
1213%28%35%21%
450
11th to 20thDay
2315%34%34%11%
450
21st to endDay
2412%32%39%11%
450
October1st to 10thDay
35%18%37%30%7%
450
11th to 20thDay
36%19%35%29%8%
450
21st to endDay
6%419%33%31%7%
495
November1st to 10thDay
6%5%17%36%31%5%
347
11th to 20thDay
6%5%19%39%23%9%
270
21st to endDay
7%6%23%38%23%4
270
December1st to 10thDay
14%425%37%18%2
215
11th to 20thDay
11%9%27%29%19%5%
180
21st to endDay
18%8%25%30%14%5%
198
January1st to 10thNight
16%310%38%25%7%
760
11th to 20thNight
9%311%41%28%7%
728
21st to endNight
13%5%10%39%27%6%
792
February1st to 10thNight
14%5%10%36%28%7%
720
11th to 20thNight
10%414%36%28%7%
704
21st to endNight
13%6%14%45%19%3
592
March1st to 10thNight
14%6%14%39%23%5%
720
11th to 20thNight
11%314%35%30%7%
720
21st to endNight
11%7%16%35%27%5%
792
April1st to 10thNight
5%8%14%41%28%4
720
11th to 20thNight
5%7%18%33%30%6%
711
21st to endNight
46%19%36%28%8%
720
May1st to 10thNight
3415%41%29%8%
720
11th to 20thNight
4415%36%34%7%
569
21st to endNight
45%12%39%33%6%
389
June1st to 10thNight
3311%38%43%4
360
11th to 20thNight
1212%41%40%5%
360
21st to endNight
119%34%49%7%
360
July1st to 10thNight
1229%57%10%
350
11th to 20thNight
2122%57%18%
445
21st to endNight
21117%58%21%
591
August1st to 10thNight
215%27%51%14%
630
11th to 20thNight
11422%59%13%
712
21st to endNight
1320%57%18%
792
September1st to 10thNight
12422%54%18%
720
11th to 20thNight
216%31%45%15%
720
21st to endNight
128%26%49%13%
720
October1st to 10thNight
336%37%38%13%
720
11th to 20thNight
6%27%36%38%11%
720
21st to endNight
5%27%34%39%14%
792
November1st to 10thNight
4311%34%36%11%
740
11th to 20thNight
6%29%41%35%7%
760
21st to endNight
5%310%41%32%9%
760
December1st to 10thNight
12%310%40%30%5%
760
11th to 20thNight
16%49%42%24%5%
760
21st to endNight
13%6%15%39%22%5%
836
Page generated at 2024-01-09 22:25:04. Version ac07

Copyright 2024 Attilla Danko


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