Springfield
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Springfield clear sky chart from 2005-11-05 to 2018-01-12.

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
29%
15378
19%
48335
9%
15347
40%
15347
20%
31306

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
22%
765
20%
2662
9%
761
36%
761
17%
1687
January16th to endNight
19%
768
19%
2681
7%
768
36%
768
16%
1714
February1st to 15thNight
18%
703
17%
2190
6%
701
32%
701
17%
1479
February16th to endNight
19%
631
23%
1893
8%
631
37%
631
17%
1258
March1st to 15thNight
17%
720
17%
2160
6%
720
30%
720
15%
1476
March16th to endNight
21%
768
24%
2009
7%
768
35%
768
23%
1330
April1st to 15thNight
19%
718
17%
1796
4%
718
26%
718
18%
1298
April16th to endNight
23%
634
19%
1714
3%
634
34%
634
20%
1164
May1st to 15thNight
19%
534
17%
1614
6%
534
30%
534
15%
1125
May16th to endNight
31%
375
12%
1497
10%
374
39%
374
15%
938
June1st to 15thNight
33%
360
13%
1440
11%
360
44%
360
16%
918
June16th to endNight
37%
360
13%
1440
11%
360
48%
360
21%
841
July1st to 15thNight
45%
340
13%
1360
15%
340
50%
340
21%
806
July16th to endNight
48%
376
15%
1418
16%
354
56%
354
21%
837
August1st to 15thNight
47%
485
17%
1556
12%
483
52%
483
26%
929
August16th to endNight
55%
764
21%
1910
11%
764
58%
764
32%
1233
September1st to 15thNight
41%
720
20%
1830
10%
720
46%
720
30%
1197
September16th to endNight
46%
717
27%
1980
16%
717
54%
717
31%
1211
October1st to 15thNight
38%
720
22%
2049
14%
720
46%
720
25%
1328
October16th to endNight
28%
768
17%
2461
8%
768
40%
768
20%
1618
November1st to 15thNight
28%
760
20%
2472
11%
760
42%
760
21%
1555
November16th to endNight
25%
780
22%
2561
9%
780
40%
780
18%
1629
December1st to 15thNight
22%
780
16%
2730
6%
780
36%
780
15%
1786
December16th to endNight
18%
832
18%
2912
6%
832
33%
832
14%
1949

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
16%5%25%42445%7%39%
49009
Night
17%6%24424446%41%
48505
Cloud CoverDay
17%6%25%5%2445%7%39%
49019
Night
17%6%25%42445%6%40%
48510
TransparencyDay
43%411%23%14%2
48697
Night
43%411%22%14%1
48335
SeeingDay
20%17%26%20%10%4
6159
Night
18%21%25%25%7%
15379

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
16%5%25%4245%7%6%40%
1520
16th to endDay
15%6%25%32446%8%40%
1542
February1st to 15thDay
15%7%26%6%35%45%7%34%
1669
16th to endDay
15%8%35%5%24346%38%
1580
March1st to 15thDay
19%7%35%42445%7%35%
1790
16th to endDay
17%6%25%433346%42%
2214
April1st to 15thDay
18%5%35%5%24346%38%
2152
16th to endDay
18%414324347%44%
2244
May1st to 15thDay
23%7%35%42335%6%33%
2346
16th to endDay
17%4345%345%5%7%39%
2618
June1st to 15thDay
22%6%24423448%35%
2520
16th to endDay
14%4245%35%6%7%9%36%
2520
July1st to 15thDay
11%5%25%6%35%5%5%8%38%
2520
16th to endDay
12%436%5%35%5%6%9%38%
2654
August1st to 15thDay
13%425%6%35%5%6%7%39%
2380
16th to endDay
10%4145%345%5%7%45%
2292
September1st to 15thDay
14%5%25%424446%44%
2130
16th to endDay
14%5%2431345%6%49%
1980
October1st to 15thDay
20%6%23423445%42%
1908
16th to endDay
17%6%25%5%24345%41%
1761
November1st to 15thDay
19%6%24423336%42%
1716
16th to endDay
18%5%23323445%44%
1729
December1st to 15thDay
19%6%26%42345%5%38%
1560
16th to endDay
21%7%2443345%8%33%
1664
January1st to 15thNight
17%7%25%424346%41%
2662
16th to endNight
15%8%35%42335%6%39%
2681
February1st to 15thNight
14%8%35%5%35%46%6%37%
2189
16th to endNight
16%7%35%424345%41%
1893
March1st to 15thNight
19%7%2442445%7%37%
2147
16th to endNight
17%6%25%314246%45%
2009
April1st to 15thNight
18%7%26%6%34335%37%
1796
16th to endNight
21%5%24423336%41%
1714
May1st to 15thNight
21%5%25%5%35%345%36%
1614
16th to endNight
19%4235%245%5%9%37%
1495
June1st to 15thNight
22%41442446%7%37%
1440
16th to endNight
15%5%334245%5%9%42%
1440
July1st to 15thNight
13%325%5%35%46%8%41%
1440
16th to endNight
10%5%25%436%5%7%9%39%
1514
August1st to 15thNight
10%4244345%6%9%44%
1566
16th to endNight
12%4144345%5%7%44%
1910
September1st to 15thNight
15%5%24424336%47%
1830
16th to endNight
13%5%23423345%51%
1980
October1st to 15thNight
18%5%24423335%45%
2049
16th to endNight
20%6%25%323445%40%
2461
November1st to 15thNight
18%6%24323345%45%
2472
16th to endNight
18%6%25%424445%42%
2561
December1st to 15thNight
21%6%25%423446%37%
2730
16th to endNight
21%7%2443445%5%37%
2912

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
16%5%245%235%6%6%40%
1520
16th to endDay
15%7%25%32445%7%39%
1542
February1st to 15thDay
16%7%37%6%245%47%33%
1669
16th to endDay
16%8%26%5%34346%38%
1580
March1st to 15thDay
19%7%45%424347%35%
1800
16th to endDay
17%6%34423346%42%
2214
April1st to 15thDay
19%6%35%5%24446%38%
2152
16th to endDay
18%424424447%43%
2244
May1st to 15thDay
24%7%35%42435%6%32%
2346
16th to endDay
17%435%5%2445%7%38%
2618
June1st to 15thDay
22%6%35%42445%7%34%
2520
16th to endDay
14%5%24435%6%7%10%35%
2520
July1st to 15thDay
11%5%35%6%46%5%5%8%37%
2520
16th to endDay
13%435%6%35%5%6%8%38%
2654
August1st to 15thDay
13%425%5%35%5%6%8%37%
2380
16th to endDay
10%5%245%3446%7%45%
2292
September1st to 15thDay
14%5%25%423446%45%
2130
16th to endDay
14%5%1332335%6%49%
1980
October1st to 15thDay
20%6%23433346%42%
1908
16th to endDay
17%6%35%424445%41%
1761
November1st to 15thDay
18%8%24423345%42%
1716
16th to endDay
19%5%23324446%43%
1729
December1st to 15thDay
19%7%35%42445%6%38%
1560
16th to endDay
22%8%2442445%6%34%
1664
January1st to 15thNight
18%6%35%424346%40%
2662
16th to endNight
16%9%36%42335%5%39%
2681
February1st to 15thNight
14%8%36%5%345%5%5%37%
2182
16th to endNight
16%8%26%325%346%39%
1893
March1st to 15thNight
19%8%25%5%2435%6%36%
2160
16th to endNight
17%6%25%323246%44%
2008
April1st to 15thNight
19%7%36%6%24335%37%
1796
16th to endNight
21%6%34423335%41%
1714
May1st to 15thNight
20%5%26%5%3435%5%36%
1614
16th to endNight
19%4244245%6%8%37%
1495
June1st to 15thNight
22%5%24325%45%7%37%
1440
16th to endNight
15%42442446%8%42%
1440
July1st to 15thNight
13%3145%35%5%6%8%40%
1440
16th to endNight
10%435%5%35%5%7%9%39%
1514
August1st to 15thNight
10%415%4245%6%9%43%
1566
16th to endNight
12%3145%3446%8%44%
1910
September1st to 15thNight
14%5%24424436%46%
1830
16th to endNight
13%5%23423345%51%
1980
October1st to 15thNight
17%5%24424435%45%
2049
16th to endNight
20%6%24323446%39%
2461
November1st to 15thNight
18%7%24413345%44%
2472
16th to endNight
18%7%35%423445%41%
2561
December1st to 15thNight
21%6%25%42345%6%37%
2730
16th to endNight
21%7%25%42445%5%35%
2912

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
41%414%25%11%2
1521
16th to endDay
42%414%25%12%1
1542
February1st to 15thDay
49%412%21%11%
1672
16th to endDay
47%210%23%13%2
1580
March1st to 15thDay
48%313%22%10%2
1800
16th to endDay
43%310%22%16%4
2214
April1st to 15thDay
47%210%21%15%2
2152
16th to endDay
41%49%22%19%3
2244
May1st to 15thDay
52%37%20%13%2
2346
16th to endDay
44%5%13%21%13%2
2622
June1st to 15thDay
48%5%13%20%10%1
2520
16th to endDay
41%6%14%22%13%1
2520
July1st to 15thDay
43%5%11%23%14%1
2371
16th to endDay
41%414%22%13%2
2487
August1st to 15thDay
42%413%24%13%1
2366
16th to endDay
36%5%8%29%18%1
2292
September1st to 15thDay
39%311%24%18%2
2130
16th to endDay
34%37%25%25%1
1980
October1st to 15thDay
43%39%25%14%2
1908
16th to endDay
44%312%23%14%2
1761
November1st to 15thDay
44%413%21%14%2
1716
16th to endDay
42%310%26%15%1
1729
December1st to 15thDay
46%316%19%12%
1560
16th to endDay
49%414%19%10%
1664
January1st to 15thNight
44%312%23%12%2
2662
16th to endNight
45%311%23%14%1
2681
February1st to 15thNight
47%412%21%11%1
2190
16th to endNight
46%38%23%14%2
1893
March1st to 15thNight
47%411%20%13%2
2160
16th to endNight
41%210%21%17%5%
2009
April1st to 15thNight
50%29%19%16%1
1796
16th to endNight
46%27%21%17%4
1714
May1st to 15thNight
49%49%19%14%3
1614
16th to endNight
43%6%17%19%10%1
1497
June1st to 15thNight
46%414%21%11%
1440
16th to endNight
38%5%14%25%14%
1440
July1st to 15thNight
38%6%13%26%14%
1360
16th to endNight
39%5%15%25%11%2
1418
August1st to 15thNight
35%6%14%26%15%2
1556
16th to endNight
36%5%11%28%17%
1910
September1st to 15thNight
39%411%24%19%
1830
16th to endNight
35%37%24%27%2
1980
October1st to 15thNight
42%311%23%16%3
2049
16th to endNight
46%312%24%12%
2461
November1st to 15thNight
42%412%20%17%2
2472
16th to endNight
44%312%23%13%1
2561
December1st to 15thNight
47%415%21%11%
2730
16th to endNight
48%411%21%12%
2912

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
17%25%34%17%6%
82
16th to endDay
26%16%38%16%1
65
February1st to 15thDay
23%26%28%16%4
185
16th to endDay
19%28%30%17%4
239
March1st to 15thDay
28%26%21%19%3
270
16th to endDay
20%27%26%15%7%2
288
April1st to 15thDay
22%22%30%15%8%
270
16th to endDay
20%22%24%20%8%3
270
May1st to 15thDay
32%20%21%13%9%2
288
16th to endDay
19%20%29%18%9%2
331
June1st to 15thDay
22%18%23%21%11%2
315
16th to endDay
13%19%32%22%9%2
315
July1st to 15thDay
15%13%28%24%14%4
305
16th to endDay
14%14%22%26%17%4
326
August1st to 15thDay
15%11%21%30%14%7%
313
16th to endDay
10%9%22%25%22%9%
332
September1st to 15thDay
17%11%22%25%12%10%
315
16th to endDay
16%8%24%17%15%17%
314
October1st to 15thDay
23%8%20%22%16%8%
315
16th to endDay
19%19%27%21%10%
296
November1st to 15thDay
22%15%26%23%8%3
280
16th to endDay
23%18%27%17%9%2
259
December1st to 15thDay
20%21%37%12%7%1
90
16th to endDay
31%18%38%10%1
96
January1st to 15thNight
17%25%29%23%3
765
16th to endNight
18%24%30%23%1
768
February1st to 15thNight
18%24%32%22%1
704
16th to endNight
20%27%28%20%3
631
March1st to 15thNight
23%28%25%20%1
720
16th to endNight
19%25%29%19%5%
768
April1st to 15thNight
20%27%27%20%3
718
16th to endNight
20%27%25%19%7%
634
May1st to 15thNight
18%28%29%17%5%
534
16th to endNight
19%22%24%28%5%
375
June1st to 15thNight
20%20%23%28%7%
360
16th to endNight
14%18%25%33%8%
360
July1st to 15thNight
12%13%22%39%12%
340
16th to endNight
10%17%17%40%12%
376
August1st to 15thNight
11%11%22%38%14%
485
16th to endNight
11%10%15%38%21%2
764
September1st to 15thNight
16%12%23%31%14%
720
16th to endNight
16%12%17%29%19%4
717
October1st to 15thNight
21%13%21%31%11%1
720
16th to endNight
22%17%28%23%7%
768
November1st to 15thNight
19%20%26%23%9%
760
16th to endNight
17%25%27%22%6%
780
December1st to 15thNight
23%21%28%20%5%
780
16th to endNight
24%25%27%21%1
832
Page generated at 2018-01-12 22:01:25. Version ac04

Copyright 2018 A. Danko


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