Tiplady Farms Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tiplady Farms Observatory clear sky chart from 2005-11-06 to 2024-01-12.

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
28%
22806
13%
74684
8%
22764
35%
22764
15%
53937

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
13%
760
9%
2649
4%
757
20%
757
8%
2070
January11th to 20thNight
16%
728
8%
2546
4%
728
22%
728
7%
2025
January21st to endNight
17%
792
11%
2759
6%
792
25%
792
10%
2097
February1st to 10thNight
10%
720
8%
2340
2%
720
18%
720
8%
1871
February11th to 20thNight
13%
703
11%
2109
3%
700
23%
700
11%
1629
February21st to endNight
16%
592
14%
1776
5%
592
28%
592
12%
1343
March1st to 10thNight
18%
720
15%
2160
8%
720
28%
720
13%
1640
March11th to 20thNight
18%
720
13%
2101
5%
720
28%
720
13%
1572
March21st to endNight
22%
792
19%
1980
5%
792
32%
792
18%
1471
April1st to 10thNight
21%
720
14%
1800
4%
720
27%
720
16%
1372
April11th to 20thNight
24%
711
13%
1775
5%
711
28%
711
18%
1331
April21st to endNight
24%
603
15%
1683
5%
603
30%
603
17%
1232
May1st to 10thNight
25%
526
12%
1606
7%
526
30%
526
14%
1200
May11th to 20thNight
30%
354
16%
1416
13%
354
41%
354
16%
947
May21st to endNight
43%
388
13%
1551
13%
388
50%
388
18%
978
June1st to 10thNight
38%
360
13%
1440
13%
360
46%
360
16%
962
June11th to 20thNight
45%
360
12%
1440
14%
360
52%
360
19%
905
June21st to endNight
46%
360
12%
1440
15%
360
51%
360
19%
917
July1st to 10thNight
51%
350
12%
1400
17%
350
56%
350
21%
850
July11th to 20thNight
50%
348
14%
1392
18%
348
54%
348
22%
857
July21st to endNight
52%
394
17%
1486
20%
372
57%
372
24%
881
August1st to 10thNight
54%
358
17%
1422
19%
356
58%
356
24%
837
August11th to 20thNight
51%
655
13%
1719
8%
655
52%
655
26%
1199
August21st to endNight
50%
792
18%
1980
9%
792
54%
792
31%
1325
September1st to 10thNight
47%
720
17%
1800
7%
720
50%
720
31%
1218
September11th to 20thNight
49%
720
24%
1899
15%
720
53%
720
32%
1203
September21st to endNight
40%
720
21%
1980
14%
720
46%
720
27%
1329
October1st to 10thNight
34%
720
15%
2052
10%
720
39%
720
18%
1484
October11th to 20thNight
30%
720
15%
2182
9%
720
38%
720
19%
1533
October21st to endNight
21%
792
11%
2574
5%
792
28%
792
12%
1968
November1st to 10thNight
24%
740
16%
2407
11%
740
33%
740
17%
1676
November11th to 20thNight
23%
760
18%
2470
9%
760
35%
760
16%
1736
November21st to endNight
19%
760
13%
2607
7%
760
28%
760
12%
1883
December1st to 10thNight
13%
760
8%
2660
3%
760
20%
760
7%
2118
December11th to 20thNight
17%
760
10%
3248
4%
759
24%
759
7%
2476
December21st to endNight
13%
828
6%
4835
2%
817
21%
817
5%
3802

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
18%9%46%5%345%5%7%33%
74768
Night
19%10%47%5%3445%6%32%
74944
TransparencyDay
52%5%12%19%10%1
74473
Night
54%5%11%18%10%1
74773
SeeingDay
26%17%28%19%8%2
13687
Night
25%15%27%25%8%1
22815

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 10thDay
16%15%7%10%8%345%5%423%
1517
11th to 20thDay
18%15%48%6%45%46%6%25%
1454
21st to endDay
12%14%8%11%6%35%45%6%26%
1593
February1st to 10thDay
16%14%6%9%9%45%5%5%5%21%
1620
11th to 20thDay
15%14%8%11%6%44345%26%
1737
21st to endDay
19%13%5%9%6%33445%27%
1480
March1st to 10thDay
16%12%7%8%6%3445%6%29%
1797
11th to 20thDay
18%14%6%7%5%23445%32%
1853
21st to endDay
20%11%36%5%34445%35%
2376
April1st to 10thDay
21%12%5%6%434445%33%
2160
11th to 20thDay
18%8%36%6%45%45%5%35%
2134
21st to endDay
23%11%36%5%345%5%5%31%
2276
May1st to 10thDay
25%10%36%5%24445%32%
2369
11th to 20thDay
20%7%36%5%345%5%6%38%
2478
21st to endDay
17%6%35%5%35%46%7%38%
2725
June1st to 10thDay
19%6%36%5%46%6%6%8%29%
2520
11th to 20thDay
20%5%36%435%5%6%8%34%
2520
21st to endDay
18%8%37%6%45%5%6%9%30%
2520
July1st to 10thDay
15%6%25%6%35%6%7%7%39%
2520
11th to 20thDay
12%5%35%5%46%6%7%9%38%
2520
21st to endDay
14%6%36%6%35%6%6%8%36%
2744
August1st to 10thDay
14%5%25%6%45%6%7%10%36%
2493
11th to 20thDay
15%6%25%6%46%5%7%9%35%
2173
21st to endDay
15%5%34445%5%7%8%41%
2376
September1st to 10thDay
15%5%26%5%345%6%8%42%
2160
11th to 20thDay
17%5%243235%5%7%47%
2059
21st to endDay
17%7%245%245%48%42%
1980
October1st to 10thDay
24%8%36%5%44445%33%
1907
11th to 20thDay
17%9%45%5%35%447%36%
1777
21st to endDay
29%9%36%4345%45%28%
1782
November1st to 10thDay
15%10%45%5%3345%7%39%
1671
11th to 20thDay
20%11%47%5%34446%33%
1710
21st to endDay
20%12%47%6%35%346%30%
1569
December1st to 10thDay
22%17%5%8%5%34445%23%
1520
11th to 20thDay
22%15%6%7%6%2334429%
1906
21st to endDay
25%17%5%8%5%3334323%
2772
January1st to 10thNight
17%15%6%9%6%35%445%25%
2649
11th to 20thNight
19%16%5%9%6%4445%5%22%
2546
21st to endNight
14%13%5%11%7%45%5%5%5%27%
2759
February1st to 10thNight
17%15%5%11%8%45%5%4422%
2340
11th to 20thNight
14%12%5%10%8%46%5%5%6%25%
2107
21st to endNight
16%14%5%10%6%35%45%5%28%
1776
March1st to 10thNight
17%12%5%9%6%45%445%29%
2150
11th to 20thNight
18%12%6%7%6%345%45%31%
2100
21st to endNight
20%11%37%5%34345%36%
1980
April1st to 10thNight
22%11%36%5%35%5%46%32%
1800
11th to 20thNight
22%10%36%6%2345%6%34%
1775
21st to endNight
23%10%36%5%24445%33%
1683
May1st to 10thNight
24%10%37%6%345%35%30%
1606
11th to 20thNight
20%7%45%6%35%45%7%35%
1415
21st to endNight
17%6%36%5%345%5%9%38%
1550
June1st to 10thNight
21%6%35%5%35%5%6%8%34%
1440
11th to 20thNight
21%5%34325%46%8%38%
1440
21st to endNight
16%6%25%6%35%46%7%40%
1440
July1st to 10thNight
15%6%25%5%35%5%6%8%41%
1440
11th to 20thNight
14%5%36%5%36%5%6%8%41%
1440
21st to endNight
14%5%245%35%5%5%8%43%
1574
August1st to 10thNight
13%5%245%4446%10%42%
1432
11th to 20thNight
14%5%36%5%45%6%6%8%37%
1719
21st to endNight
16%6%2443446%7%45%
1980
September1st to 10thNight
15%7%343345%5%6%45%
1800
11th to 20thNight
17%5%145%24346%50%
1899
21st to endNight
18%5%245%345%5%5%44%
1980
October1st to 10thNight
24%7%37%5%3345%5%34%
2052
11th to 20thNight
18%8%37%6%345%5%6%35%
2182
21st to endNight
28%10%36%6%34445%27%
2574
November1st to 10thNight
16%11%36%6%34445%37%
2407
11th to 20thNight
20%11%36%5%3445%6%34%
2470
21st to endNight
18%12%47%5%3445%7%31%
2607
December1st to 10thNight
22%17%6%7%5%35%5%5%5%22%
2660
11th to 20thNight
23%14%5%7%5%2445%5%26%
3288
21st to endNight
25%17%7%8%5%3433421%
4884

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
66%48%16%6%
1518
11th to 20thDay
62%6%10%13%7%2
1454
21st to endDay
60%5%12%14%7%2
1593
February1st to 10thDay
65%5%10%13%6%
1620
11th to 20thDay
63%5%8%15%8%1
1746
21st to endDay
62%39%14%11%1
1480
March1st to 10thDay
58%410%15%10%2
1800
11th to 20thDay
56%411%13%13%2
1853
21st to endDay
54%47%17%14%4
2376
April1st to 10thDay
55%48%20%10%2
2160
11th to 20thDay
51%410%20%13%1
2134
21st to endDay
56%5%10%16%11%3
2276
May1st to 10thDay
56%48%18%12%2
2369
11th to 20thDay
49%5%10%21%15%2
2482
21st to endDay
46%6%15%22%10%1
2725
June1st to 10thDay
52%7%15%17%9%1
2520
11th to 20thDay
48%6%13%20%12%1
2520
21st to endDay
52%7%13%19%9%
2520
July1st to 10thDay
43%7%13%22%14%1
2450
11th to 20thDay
42%7%16%28%7%
2445
21st to endDay
45%6%14%24%10%1
2591
August1st to 10thDay
43%8%17%22%9%
2479
11th to 20thDay
46%7%17%22%8%1
2173
21st to endDay
42%6%15%26%11%1
2376
September1st to 10thDay
41%6%13%28%11%1
2160
11th to 20thDay
39%5%10%27%18%1
2059
21st to endDay
42%5%13%26%13%1
1980
October1st to 10thDay
55%48%19%12%1
1907
11th to 20thDay
49%6%14%23%7%1
1777
21st to endDay
60%5%10%15%8%1
1782
November1st to 10thDay
46%5%14%22%12%1
1671
11th to 20thDay
55%411%17%12%1
1710
21st to endDay
58%415%16%5%1
1569
December1st to 10thDay
66%410%13%5%1
1520
11th to 20thDay
63%312%16%5%1
1906
21st to endDay
67%48%15%6%
2772
January1st to 10thNight
65%410%12%8%
2649
11th to 20thNight
65%6%10%11%6%1
2546
21st to endNight
61%5%9%14%10%2
2759
February1st to 10thNight
67%410%12%6%1
2340
11th to 20thNight
62%410%14%9%1
2109
21st to endNight
59%410%17%8%2
1776
March1st to 10thNight
59%5%9%18%8%1
2160
11th to 20thNight
57%49%16%10%3
2101
21st to endNight
53%48%16%15%3
1980
April1st to 10thNight
56%5%9%18%10%2
1800
11th to 20thNight
53%5%9%21%12%1
1775
21st to endNight
55%49%17%12%3
1683
May1st to 10thNight
58%5%8%14%14%2
1606
11th to 20thNight
50%5%11%19%13%2
1416
21st to endNight
45%6%14%22%11%2
1551
June1st to 10thNight
50%6%14%19%11%1
1440
11th to 20thNight
44%6%17%21%11%1
1440
21st to endNight
45%6%14%24%10%1
1440
July1st to 10thNight
41%6%16%22%13%1
1400
11th to 20thNight
41%7%17%26%9%1
1392
21st to endNight
38%7%15%27%12%2
1486
August1st to 10thNight
37%7%16%27%11%1
1422
11th to 20thNight
44%7%16%23%10%
1719
21st to endNight
40%6%14%27%13%
1980
September1st to 10thNight
40%6%14%27%14%
1800
11th to 20thNight
37%411%28%19%1
1899
21st to endNight
43%5%11%25%15%2
1980
October1st to 10thNight
52%5%10%21%10%2
2052
11th to 20thNight
49%6%14%21%9%1
2182
21st to endNight
61%5%11%15%7%1
2574
November1st to 10thNight
51%5%10%19%12%2
2407
11th to 20thNight
52%411%19%10%3
2470
21st to endNight
55%5%14%18%7%
2607
December1st to 10thNight
66%5%11%14%4
2660
11th to 20thNight
63%5%11%12%8%
3288
21st to endNight
69%48%16%3
4884

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
32%21%27%16%31
180
11th to 20thDay
38%23%29%7%21
164
21st to endDay
24%26%33%13%41
180
February1st to 10thDay
38%33%23%6%
240
11th to 20thDay
26%33%27%11%2
405
21st to endDay
33%21%31%14%2
346
March1st to 10thDay
27%25%30%15%2
420
11th to 20thDay
31%25%27%14%31
420
21st to endDay
32%23%24%12%6%2
462
April1st to 10thDay
35%19%25%14%6%1
420
11th to 20thDay
34%21%23%14%7%2
412
21st to endDay
33%19%29%12%5%3
420
May1st to 10thDay
32%20%25%13%8%2
423
11th to 20thDay
23%16%35%19%5%2
447
21st to endDay
22%13%33%19%10%2
485
June1st to 10thDay
20%16%34%20%9%2
450
11th to 20thDay
23%11%33%22%9%2
450
21st to endDay
21%14%32%21%10%2
450
July1st to 10thDay
17%9%30%27%14%2
445
11th to 20thDay
15%6%35%30%13%2
444
21st to endDay
17%6%38%28%8%2
488
August1st to 10thDay
15%9%26%31%15%4
446
11th to 20thDay
17%7%28%26%15%6%
439
21st to endDay
16%12%27%27%13%6%
495
September1st to 10thDay
16%12%24%25%16%6%
450
11th to 20thDay
17%14%26%17%16%10%
450
21st to endDay
19%11%30%22%12%6%
450
October1st to 10thDay
32%11%23%16%15%3
450
11th to 20thDay
24%18%26%22%9%1
438
21st to endDay
37%14%25%20%4
396
November1st to 10thDay
27%18%25%19%10%1
365
11th to 20thDay
31%21%24%18%5%1
370
21st to endDay
31%23%30%13%3
229
December1st to 10thDay
36%19%30%11%31
180
11th to 20thDay
33%29%27%7%3
180
21st to endDay
37%23%25%13%3
198
January1st to 10thNight
25%24%31%18%2
760
11th to 20thNight
29%21%27%20%21
728
21st to endNight
21%21%34%20%4
792
February1st to 10thNight
27%22%35%15%2
720
11th to 20thNight
23%23%34%18%2
703
21st to endNight
25%25%29%18%3
592
March1st to 10thNight
23%22%32%20%3
720
11th to 20thNight
28%20%30%17%4
720
21st to endNight
28%20%26%19%8%
792
April1st to 10thNight
29%19%26%21%4
720
11th to 20thNight
27%19%26%20%8%
711
21st to endNight
30%16%26%23%5%
603
May1st to 10thNight
28%15%26%23%9%
526
11th to 20thNight
23%12%31%28%6%
354
21st to endNight
19%8%23%36%13%1
389
June1st to 10thNight
23%8%25%32%13%1
360
11th to 20thNight
23%6%20%39%12%
360
21st to endNight
17%7%24%43%9%1
360
July1st to 10thNight
18%5%21%43%13%1
350
11th to 20thNight
17%322%41%17%1
348
21st to endNight
15%422%45%13%2
394
August1st to 10thNight
15%420%40%20%
358
11th to 20thNight
17%5%19%37%18%4
655
21st to endNight
18%5%20%33%21%2
792
September1st to 10thNight
18%6%22%35%17%2
720
11th to 20thNight
20%8%20%29%19%5%
720
21st to endNight
20%8%26%29%15%2
720
October1st to 10thNight
27%11%20%25%14%1
720
11th to 20thNight
23%13%26%29%9%
720
21st to endNight
33%13%28%22%5%
792
November1st to 10thNight
25%17%29%23%6%1
740
11th to 20thNight
26%18%29%20%6%2
760
21st to endNight
26%19%30%18%5%1
760
December1st to 10thNight
33%21%26%16%4
760
11th to 20thNight
29%22%27%18%4
760
21st to endNight
31%20%31%16%2
836
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