Milton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Milton clear sky chart from 2005-11-05 to 2017-03-22.

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
41%
14690
20%
45260
12%
14654
50%
14654
25%
28619

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
27%
719
21%
2497
9%
716
43%
716
20%
1535
January16th to endNight
22%
768
22%
2496
7%
768
40%
768
22%
1563
February1st to 15thNight
24%
703
20%
2240
8%
701
40%
701
22%
1409
February16th to endNight
23%
631
27%
1893
10%
631
45%
631
24%
1169
March1st to 15thNight
29%
720
20%
2088
10%
720
41%
720
25%
1332
March16th to endNight
29%
732
20%
1939
9%
732
38%
732
25%
1316
April1st to 15thNight
32%
658
20%
1646
6%
658
40%
658
30%
1099
April16th to endNight
46%
660
19%
1650
9%
660
48%
660
31%
1103
May1st to 15thNight
43%
530
17%
1520
9%
530
48%
530
24%
1043
May16th to endNight
57%
342
14%
1369
14%
342
61%
342
19%
852
June1st to 15thNight
57%
330
16%
1320
17%
330
62%
330
20%
829
June16th to endNight
62%
330
13%
1320
16%
330
64%
330
22%
781
July1st to 15thNight
66%
310
14%
1240
18%
310
68%
310
21%
761
July16th to endNight
69%
414
15%
1366
16%
386
72%
386
26%
813
August1st to 15thNight
71%
554
17%
1534
12%
551
71%
551
32%
958
August16th to endNight
66%
700
17%
1750
10%
700
67%
700
33%
1152
September1st to 15thNight
60%
660
24%
1650
16%
660
63%
660
33%
1095
September16th to endNight
54%
657
19%
1776
16%
657
56%
657
28%
1182
October1st to 15thNight
49%
660
24%
1974
22%
660
55%
660
27%
1253
October16th to endNight
38%
704
26%
2128
16%
704
51%
704
29%
1285
November1st to 15thNight
35%
700
22%
2277
13%
700
49%
700
25%
1396
November16th to endNight
34%
720
22%
2379
13%
720
47%
720
22%
1468
December1st to 15thNight
28%
720
19%
2520
9%
720
41%
720
19%
1582
December16th to endNight
24%
768
22%
2688
9%
768
42%
768
21%
1643

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
13%5%2442445%7%43%
45620
Night
14%5%25%42445%7%44%
45437
Cloud CoverDay
13%5%2442445%7%43%
45629
Night
14%5%24424446%44%
45443
TransparencyDay
38%6%12%23%16%2
45315
Night
39%5%11%22%16%2
45260
SeeingDay
16%6%22%27%20%6%
5104
Night
17%7%27%30%15%1
14693

By Month

Percentage Cloud Cover NE (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
14%7%2442435%6%44%
1438
16th to endDay
17%6%23414446%44%
1728
February1st to 15thDay
14%7%2442445%6%42%
1621
16th to endDay
13%7%35%334446%43%
1580
March1st to 15thDay
16%5%2442345%6%44%
1859
16th to endDay
15%6%25%425%336%43%
2081
April1st to 15thDay
14%7%23223447%47%
1972
16th to endDay
13%5%145%24446%47%
1980
May1st to 15thDay
14%5%25%4245%6%8%40%
2110
16th to endDay
11%5%244345%6%8%43%
2394
June1st to 15thDay
13%424435%5%6%9%40%
2310
16th to endDay
10%414425%6%6%10%41%
2310
July1st to 15thDay
9%5%25%435%5%6%10%41%
2310
16th to endDay
7%4245%37%6%8%12%36%
2390
August1st to 15thDay
9%5%25%5%345%7%9%40%
2072
16th to endDay
9%4245%45%6%6%8%43%
2100
September1st to 15thDay
12%5%245%3346%7%43%
1980
16th to endDay
15%6%25%435%5%46%39%
1854
October1st to 15thDay
17%424433346%44%
1653
16th to endDay
15%5%14313346%49%
1743
November1st to 15thDay
17%5%2322335%6%46%
1581
16th to endDay
14%5%14424447%47%
1578
December1st to 15thDay
13%5%36%4245%5%6%43%
1440
16th to endDay
18%7%24423346%42%
1536
January1st to 15thNight
15%5%3442445%6%43%
2497
16th to endNight
15%7%34423445%44%
2496
February1st to 15thNight
15%6%25%433345%44%
2239
16th to endNight
15%5%24323346%47%
1893
March1st to 15thNight
16%5%24323346%45%
2075
16th to endNight
18%7%34323346%42%
1939
April1st to 15thNight
15%5%25%42435%6%45%
1646
16th to endNight
16%425%424346%44%
1650
May1st to 15thNight
15%7%25%4335%6%6%39%
1520
16th to endNight
10%5%35%6%35%448%41%
1367
June1st to 15thNight
13%6%245%25%45%8%42%
1320
16th to endNight
8%336%445%6%5%10%41%
1320
July1st to 15thNight
7%435%6%35%6%6%10%40%
1320
16th to endNight
5%3347%36%6%6%10%41%
1468
August1st to 15thNight
6%425%6%35%5%6%9%44%
1545
16th to endNight
8%6%25%5%3446%9%43%
1750
September1st to 15thNight
13%5%3442445%7%45%
1650
16th to endNight
16%5%144236%5%7%41%
1776
October1st to 15thNight
16%5%24423446%45%
1974
16th to endNight
15%424323346%49%
2128
November1st to 15thNight
15%6%24313335%49%
2277
16th to endNight
14%5%25%42445%6%44%
2379
December1st to 15thNight
17%6%3442445%6%41%
2520
16th to endNight
17%5%25%32335%6%44%
2688

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
14%7%24325%446%44%
1438
16th to endDay
17%6%245%24346%43%
1728
February1st to 15thDay
15%6%35%42346%6%42%
1621
16th to endDay
13%6%35%4245%45%43%
1580
March1st to 15thDay
16%425%42345%6%44%
1869
16th to endDay
16%6%24425%335%44%
2080
April1st to 15thDay
15%6%2332335%6%47%
1972
16th to endDay
13%5%245%14346%47%
1980
May1st to 15thDay
15%42442445%9%40%
2110
16th to endDay
11%5%244345%5%7%44%
2394
June1st to 15thDay
15%424326%5%6%9%39%
2310
16th to endDay
10%324435%5%7%9%42%
2310
July1st to 15thDay
9%425%4345%6%10%42%
2310
16th to endDay
7%325%5%37%7%8%12%36%
2390
August1st to 15thDay
9%435%5%35%6%6%9%39%
2072
16th to endDay
9%325%5%45%6%5%7%44%
2100
September1st to 15thDay
12%425%42445%8%43%
1980
16th to endDay
15%7%26%5%345%46%39%
1854
October1st to 15thDay
16%5%24434445%44%
1653
16th to endDay
15%424413246%50%
1743
November1st to 15thDay
17%5%1331335%6%46%
1581
16th to endDay
14%324324448%46%
1578
December1st to 15thDay
13%6%35%42436%7%42%
1440
16th to endDay
18%6%44423246%42%
1536
January1st to 15thNight
15%5%3443345%6%43%
2497
16th to endNight
16%6%24423445%44%
2496
February1st to 15thNight
15%6%25%423345%45%
2232
16th to endNight
15%5%23323446%47%
1893
March1st to 15thNight
16%6%24323346%45%
2088
16th to endNight
18%8%34324245%42%
1939
April1st to 15thNight
16%425%424347%44%
1646
16th to endNight
16%425%335%347%43%
1650
May1st to 15thNight
15%6%445%245%5%6%39%
1520
16th to endNight
11%6%345%36%447%42%
1367
June1st to 15thNight
13%6%25%4245%48%41%
1320
16th to endNight
8%336%5%45%6%6%9%41%
1320
July1st to 15thNight
8%436%5%346%5%10%40%
1320
16th to endNight
5%3246%37%6%6%11%41%
1468
August1st to 15thNight
6%425%5%345%6%9%44%
1545
16th to endNight
9%6%25%425%5%5%9%44%
1750
September1st to 15thNight
12%5%25%42446%6%45%
1650
16th to endNight
16%5%144245%5%8%40%
1776
October1st to 15thNight
16%5%24423435%46%
1974
16th to endNight
16%424312446%48%
2128
November1st to 15thNight
15%5%24323335%49%
2277
16th to endNight
14%5%25%42445%6%44%
2379
December1st to 15thNight
16%7%25%42445%6%41%
2520
16th to endNight
18%5%25%42335%5%44%
2688

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%13%21%15%3
1439
16th to endDay
42%410%25%15%2
1728
February1st to 15thDay
41%412%24%14%2
1624
16th to endDay
41%5%11%25%15%2
1580
March1st to 15thDay
39%5%12%23%16%2
1869
16th to endDay
42%6%7%24%17%2
2081
April1st to 15thDay
37%5%11%22%17%5%
1972
16th to endDay
37%5%11%18%21%6%
1980
May1st to 15thDay
39%7%16%21%12%1
2110
16th to endDay
36%7%15%25%13%1
2398
June1st to 15thDay
38%10%13%23%12%1
2310
16th to endDay
34%10%15%21%17%1
2310
July1st to 15thDay
35%8%13%23%15%2
2161
16th to endDay
33%10%17%24%13%1
2229
August1st to 15thDay
37%7%14%25%13%1
2059
16th to endDay
35%9%11%22%18%3
2100
September1st to 15thDay
36%7%12%21%18%3
1980
16th to endDay
44%6%8%18%19%1
1854
October1st to 15thDay
40%6%10%24%14%3
1653
16th to endDay
35%48%27%21%2
1743
November1st to 15thDay
38%5%12%23%17%2
1581
16th to endDay
36%5%11%26%17%2
1578
December1st to 15thDay
40%5%15%22%12%3
1440
16th to endDay
44%312%25%13%1
1536
January1st to 15thNight
41%411%21%18%2
2497
16th to endNight
41%410%26%14%2
2496
February1st to 15thNight
41%39%26%15%2
2240
16th to endNight
37%49%25%20%2
1893
March1st to 15thNight
40%411%25%15%2
2088
16th to endNight
44%49%19%18%2
1939
April1st to 15thNight
39%5%10%20%19%4
1646
16th to endNight
40%49%17%21%6%
1650
May1st to 15thNight
44%7%11%21%13%2
1520
16th to endNight
40%8%15%18%15%1
1369
June1st to 15thNight
40%9%12%19%16%
1320
16th to endNight
37%8%14%21%15%2
1320
July1st to 15thNight
38%9%15%20%13%2
1240
16th to endNight
33%9%16%25%12%1
1366
August1st to 15thNight
34%7%18%21%18%
1534
16th to endNight
35%8%14%19%20%2
1750
September1st to 15thNight
38%6%13%21%17%3
1650
16th to endNight
40%7%10%19%19%3
1776
October1st to 15thNight
40%5%9%23%17%2
1974
16th to endNight
36%410%25%19%3
2128
November1st to 15thNight
39%410%21%18%6%
2277
16th to endNight
40%410%23%16%3
2379
December1st to 15thNight
43%5%12%23%12%2
2520
16th to endNight
41%414%22%14%2
2688

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
16%13%37%26%41
61
16th to endDay
22%12%41%16%6%
96
February1st to 15thDay
24%18%33%19%3
137
16th to endDay
15%13%39%27%4
239
March1st to 15thDay
21%11%29%31%6%
270
16th to endDay
16%8%40%25%44
250
April1st to 15thDay
20%9%27%28%10%2
210
16th to endDay
17%9%20%30%18%3
210
May1st to 15thDay
26%6%21%26%15%3
228
16th to endDay
13%119%25%29%10%
267
June1st to 15thDay
21%116%27%27%5%
255
16th to endDay
16%112%38%25%5%
255
July1st to 15thDay
11%11%33%34%8%
245
16th to endDay
5%16%34%37%13%
270
August1st to 15thDay
10%19%28%38%11%
253
16th to endDay
7%18%25%42%14%
268
September1st to 15thDay
14%117%23%24%17%
255
16th to endDay
25%212%27%21%9%
254
October1st to 15thDay
19%318%30%20%7%
255
16th to endDay
14%7%32%23%20%1
269
November1st to 15thDay
17%8%27%24%18%2
235
16th to endDay
12%16%32%21%16%1
198
December1st to 15thDay
15%16%23%33%11%
60
16th to endDay
32%9%35%17%4
64
January1st to 15thNight
17%14%36%25%5%
720
16th to endNight
20%13%39%23%2
768
February1st to 15thNight
19%13%37%28%1
704
16th to endNight
18%16%37%24%3
631
March1st to 15thNight
19%11%35%26%7%
720
16th to endNight
22%8%33%23%8%2
732
April1st to 15thNight
18%5%37%30%6%
658
16th to endNight
19%425%37%11%1
660
May1st to 15thNight
19%426%34%13%1
530
16th to endNight
14%216%38%24%2
343
June1st to 15thNight
14%117%39%25%1
330
16th to endNight
10%111%44%28%2
330
July1st to 15thNight
8%113%42%31%1
310
16th to endNight
4210%35%41%5%
414
August1st to 15thNight
10%6%44%35%2
554
16th to endNight
12%110%35%34%5%
700
September1st to 15thNight
16%112%30%33%4
660
16th to endNight
18%216%30%27%4
657
October1st to 15thNight
19%5%17%34%20%2
660
16th to endNight
18%8%30%25%15%
704
November1st to 15thNight
18%9%30%25%14%2
700
16th to endNight
15%14%30%28%10%1
720
December1st to 15thNight
21%10%35%19%10%1
720
16th to endNight
20%11%39%25%3
768
Page generated at 2017-03-23 07:36:14. Version ac04

Copyright 2017 A. Danko


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