Martinez
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Martinez clear sky chart from 2005-11-05 to 2017-09-17.

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
50%
15724
22%
46915
15%
15681
57%
15681
28%
29406

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
31%
720
23%
2327
11%
716
46%
716
25%
1418
January16th to endNight
29%
768
24%
2496
13%
768
43%
768
24%
1542
February1st to 15thNight
34%
704
24%
2160
11%
701
49%
701
27%
1324
February16th to endNight
29%
631
25%
1891
9%
631
44%
631
29%
1142
March1st to 15thNight
36%
720
26%
1980
13%
720
48%
720
31%
1225
March16th to endNight
39%
768
21%
2112
11%
768
47%
768
30%
1339
April1st to 15thNight
42%
718
24%
1976
13%
718
51%
718
35%
1190
April16th to endNight
50%
603
26%
1683
16%
603
57%
603
34%
1033
May1st to 15thNight
53%
539
20%
1620
11%
539
60%
539
30%
1003
May16th to endNight
62%
561
19%
1682
14%
561
65%
561
27%
1087
June1st to 15thNight
63%
540
15%
1620
13%
540
64%
540
25%
1077
June16th to endNight
70%
540
14%
1620
12%
540
71%
540
28%
1036
July1st to 15thNight
68%
510
11%
1530
9%
510
68%
510
24%
1042
July16th to endNight
74%
564
11%
1595
10%
531
75%
531
23%
1101
August1st to 15thNight
70%
539
15%
1609
13%
536
70%
536
23%
1122
August16th to endNight
62%
642
14%
1872
13%
642
62%
642
22%
1311
September1st to 15thNight
67%
720
18%
1980
16%
720
68%
720
27%
1326
September16th to endNight
56%
665
18%
1837
14%
665
60%
665
25%
1262
October1st to 15thNight
55%
660
30%
1894
27%
660
61%
660
35%
1144
October16th to endNight
56%
704
34%
2112
27%
704
67%
704
40%
1157
November1st to 15thNight
55%
700
31%
2143
26%
700
64%
700
38%
1187
November16th to endNight
43%
720
26%
2340
18%
720
56%
720
30%
1333
December1st to 15thNight
44%
720
24%
2340
18%
720
53%
720
26%
1407
December16th to endNight
37%
768
23%
2496
16%
768
47%
768
22%
1598

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
12%5%245%345%5%8%42%
47851
Night
12%5%2442445%7%45%
47114
TransparencyDay
38%7%12%19%17%5%
47552
Night
36%6%11%18%18%7%
46917
SeeingDay
14%5%17%24%24%14%
5577
Night
14%5%22%31%22%3
15727

By Month

Percentage Cloud Cover SE (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
15%6%25%42445%5%45%
1611
16th to endDay
15%5%24423437%45%
1728
February1st to 15thDay
14%5%25%42345%6%45%
1699
16th to endDay
17%5%23324236%48%
1580
March1st to 15thDay
14%424423347%48%
1980
16th to endDay
15%5%24413346%47%
2111
April1st to 15thDay
10%42443445%7%49%
1972
16th to endDay
8%314435%45%8%49%
2286
May1st to 15thDay
9%4245%345%6%8%45%
2331
16th to endDay
10%5%35%6%45%6%6%9%37%
2431
June1st to 15thDay
10%5%25%5%35%6%7%10%37%
2340
16th to endDay
43145%37%7%9%11%40%
2340
July1st to 15thDay
8%5%26%8%46%6%8%9%32%
2340
16th to endDay
6%426%6%48%7%8%12%30%
2465
August1st to 15thDay
9%5%25%7%5%6%8%8%11%30%
2340
16th to endDay
12%5%27%7%47%7%7%9%27%
2313
September1st to 15thDay
10%425%5%45%6%6%9%40%
1980
16th to endDay
16%6%25%5%34437%39%
1829
October1st to 15thDay
15%5%14322335%52%
1735
16th to endDay
11%32341333359%
1760
November1st to 15thDay
13%5%22312245%55%
1712
16th to endDay
15%424323336%50%
1620
December1st to 15thDay
17%6%24423347%43%
1620
16th to endDay
21%7%24324336%39%
1728
January1st to 15thNight
14%6%25%32335%6%45%
2327
16th to endNight
17%6%25%32334446%
2496
February1st to 15thNight
16%5%14424346%47%
2151
16th to endNight
13%424423346%49%
1891
March1st to 15thNight
12%5%24414345%50%
1980
16th to endNight
13%42442445%7%46%
2112
April1st to 15thNight
11%323423446%52%
1976
16th to endNight
8%325%435%447%50%
1683
May1st to 15thNight
8%425%435%5%7%8%44%
1619
16th to endNight
6%425%5%36%6%8%7%42%
1682
June1st to 15thNight
11%5%25%5%36%6%6%11%35%
1620
16th to endNight
4315%6%36%6%11%12%38%
1620
July1st to 15thNight
7%435%6%47%6%8%11%33%
1620
16th to endNight
6%425%6%46%8%9%13%32%
1703
August1st to 15thNight
7%5%25%6%46%8%9%11%32%
1620
16th to endNight
11%6%35%7%345%6%12%32%
1872
September1st to 15thNight
9%425%6%45%5%7%8%40%
1980
16th to endNight
15%6%15%6%35%45%6%39%
1837
October1st to 15thNight
15%5%14412235%53%
1894
16th to endNight
8%314413245%58%
2112
November1st to 15thNight
11%413223246%57%
2143
16th to endNight
14%324423346%51%
2340
December1st to 15thNight
14%6%24333346%46%
2340
16th to endNight
19%6%23324345%42%
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
39%6%8%16%24%5%
1612
16th to endDay
39%47%18%23%7%
1728
February1st to 15thDay
38%37%21%21%6%
1701
16th to endDay
39%35%21%22%7%
1580
March1st to 15thDay
36%49%19%20%10%
1980
16th to endDay
37%5%11%21%18%5%
2112
April1st to 15thDay
33%5%10%20%23%7%
1972
16th to endDay
31%6%11%20%23%6%
2286
May1st to 15thDay
34%7%15%20%19%3
2331
16th to endDay
39%9%14%22%11%1
2435
June1st to 15thDay
38%10%17%22%10%
2340
16th to endDay
31%12%18%22%12%2
2340
July1st to 15thDay
41%12%18%17%7%3
2201
16th to endDay
40%13%19%17%6%1
2310
August1st to 15thDay
43%13%14%19%8%1
2327
16th to endDay
48%12%15%14%8%
2313
September1st to 15thDay
38%11%13%16%16%3
1980
16th to endDay
44%6%11%16%15%5%
1829
October1st to 15thDay
34%48%20%23%8%
1735
16th to endDay
30%3419%29%13%
1760
November1st to 15thDay
31%38%18%26%12%
1712
16th to endDay
36%48%19%22%10%
1620
December1st to 15thDay
41%49%18%18%7%
1620
16th to endDay
46%49%16%16%6%
1728
January1st to 15thNight
38%48%16%24%7%
2327
16th to endNight
41%35%16%22%10%
2496
February1st to 15thNight
38%37%18%20%11%
2160
16th to endNight
36%38%17%24%9%
1891
March1st to 15thNight
36%410%17%22%9%
1980
16th to endNight
36%5%11%18%19%8%
2112
April1st to 15thNight
32%5%8%21%23%9%
1976
16th to endNight
32%6%9%19%22%9%
1683
May1st to 15thNight
34%7%14%20%17%5%
1620
16th to endNight
35%10%13%22%16%1
1684
June1st to 15thNight
40%8%15%23%11%
1620
16th to endNight
33%12%19%19%11%2
1620
July1st to 15thNight
37%14%20%17%6%3
1530
16th to endNight
36%16%21%17%6%1
1595
August1st to 15thNight
39%13%17%19%8%
1609
16th to endNight
43%10%18%17%9%
1872
September1st to 15thNight
37%10%14%17%13%5%
1980
16th to endNight
44%6%11%17%14%5%
1837
October1st to 15thNight
35%39%18%24%9%
1894
16th to endNight
28%37%18%27%14%
2112
November1st to 15thNight
29%36%16%27%16%
2143
16th to endNight
34%38%14%25%14%
2340
December1st to 15thNight
37%5%10%18%20%8%
2340
16th to endNight
43%48%18%17%7%
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
20%13%34%22%10%
90
16th to endDay
12%30%37%13%6%
96
February1st to 15thDay
13%20%51%14%1
90
16th to endDay
13%16%41%25%2
81
March1st to 15thDay
14%13%29%30%11%
270
16th to endDay
14%5%35%26%16%
288
April1st to 15thDay
13%11%24%23%22%4
270
16th to endDay
11%320%31%25%8%
270
May1st to 15thDay
10%7%24%23%22%10%
288
16th to endDay
15%313%22%23%20%
331
June1st to 15thDay
16%16%22%28%24%
315
16th to endDay
7%11%28%23%28%
315
July1st to 15thDay
9%425%34%25%
305
16th to endDay
8%421%36%28%
326
August1st to 15thDay
15%6%22%32%22%
313
16th to endDay
12%26%21%29%28%
332
September1st to 15thDay
13%113%20%31%19%
315
16th to endDay
22%214%27%21%12%
259
October1st to 15thDay
22%215%28%23%7%
255
16th to endDay
11%421%22%29%10%
272
November1st to 15thDay
20%5%21%26%23%3
220
16th to endDay
10%8%28%22%25%4
90
December1st to 15thDay
25%7%33%20%12%1
90
16th to endDay
38%15%18%18%6%2
96
January1st to 15thNight
17%11%32%29%8%
720
16th to endNight
20%10%36%27%5%
768
February1st to 15thNight
17%11%32%32%6%
704
16th to endNight
16%12%36%30%3
631
March1st to 15thNight
14%10%35%31%7%
720
16th to endNight
14%8%31%30%13%
768
April1st to 15thNight
13%9%30%30%14%
718
16th to endNight
11%5%25%38%18%
603
May1st to 15thNight
11%425%35%20%2
540
16th to endNight
9%115%33%35%4
563
June1st to 15thNight
13%112%34%31%7%
540
16th to endNight
6%9%34%40%8%
540
July1st to 15thNight
10%7%31%41%8%
510
16th to endNight
7%6%32%45%7%
564
August1st to 15thNight
11%5%30%44%7%
539
16th to endNight
15%17%28%37%9%
642
September1st to 15thNight
10%10%30%41%5%
720
16th to endNight
18%113%32%29%4
665
October1st to 15thNight
18%317%29%26%4
660
16th to endNight
10%423%33%24%3
704
November1st to 15thNight
13%421%37%19%3
700
16th to endNight
15%9%27%28%18%1
720
December1st to 15thNight
17%7%26%30%15%1
720
16th to endNight
24%8%26%30%8%
768
Page generated at 2017-09-18 08:38:25. Version ac04

Copyright 2017 A. Danko


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