39 Bradley Park Rd
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the 39 Bradley Park Rd clear sky chart from 2005-11-06 to 2024-02-05.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	17% 6% 3 5% 5% 3 4 4 5% 7% 40%	78085
	Night	18% 7% 3 5% 5% 3 4 4 5% 6% 41%	80767
Transparency	Day	43% 6% 12% 22% 14% 2	77790
	Night	44% 6% 13% 22% 14% 2	80596
Seeing	Day	22% 15% 31% 21% 9% 3	13913
	Night	21% 11% 33% 27% 7%	23084

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	15% 7% 2 5% 4 3 5% 4 4 5% 46%	2517
	11th to 20th	Day	17% 8% 3 8% 5% 4 5% 4 5% 6% 35%	2520
	21st to end	Day	22% 11% 4 6% 5% 3 4 4 4 5% 32%	2807
February	1st to 10th	Day	18% 7% 4 6% 5% 3 6% 5% 6% 6% 35%	1714
	11th to 20th	Day	14% 7% 3 7% 5% 3 5% 4 5% 6% 41%	1748
	21st to end	Day	21% 9% 3 5% 4 3 4 4 6% 5% 37%	1480
March	1st to 10th	Day	16% 7% 3 6% 6% 3 4 4 4 7% 41%	1797
	11th to 20th	Day	17% 6% 3 6% 6% 4 4 5% 5% 7% 38%	1842
	21st to end	Day	20% 7% 3 5% 5% 3 4 3 4 5% 41%	2376
April	1st to 10th	Day	19% 6% 3 5% 5% 3 5% 4 5% 7% 38%	2160
	11th to 20th	Day	18% 5% 2 5% 5% 2 4 4 5% 6% 43%	2134
	21st to end	Day	22% 5% 3 5% 5% 3 4 4 4 7% 39%	2276
May	1st to 10th	Day	24% 7% 3 6% 5% 3 4 4 5% 7% 33%	2340
	11th to 20th	Day	18% 5% 3 6% 4 2 4 4 6% 6% 41%	2410
	21st to end	Day	15% 5% 3 5% 5% 3 5% 4 6% 8% 43%	2725
June	1st to 10th	Day	17% 6% 3 5% 6% 4 5% 5% 6% 8% 35%	2520
	11th to 20th	Day	16% 5% 2 6% 5% 4 4 5% 6% 9% 38%	2520
	21st to end	Day	15% 5% 3 6% 6% 3 5% 5% 6% 10% 37%	2520
July	1st to 10th	Day	12% 5% 3 5% 6% 4 5% 5% 5% 9% 41%	2520
	11th to 20th	Day	12% 4 3 5% 5% 3 6% 6% 6% 9% 40%	2520
	21st to end	Day	13% 5% 3 6% 6% 3 6% 5% 6% 8% 39%	2744
August	1st to 10th	Day	10% 6% 3 5% 7% 4 5% 6% 8% 8% 38%	2422
	11th to 20th	Day	12% 5% 2 6% 5% 3 6% 5% 5% 9% 41%	2167
	21st to end	Day	12% 5% 2 4 5% 4 4 6% 6% 7% 45%	2376
September	1st to 10th	Day	14% 6% 2 4 6% 3 6% 5% 4 6% 44%	2160
	11th to 20th	Day	15% 5% 2 4 3 2 3 3 4 6% 52%	2030
	21st to end	Day	18% 5% 2 4 4 3 4 4 5% 7% 44%	1980
October	1st to 10th	Day	23% 6% 3 4 4 3 3 3 5% 5% 40%	1958
	11th to 20th	Day	15% 6% 2 5% 5% 3 4 4 5% 7% 45%	1769
	21st to end	Day	23% 6% 2 4 5% 2 5% 4 4 5% 40%	1782
November	1st to 10th	Day	14% 6% 3 5% 5% 2 4 4 4 5% 49%	1671
	11th to 20th	Day	20% 5% 2 4 3 3 3 4 5% 6% 45%	1710
	21st to end	Day	18% 7% 2 5% 4 3 4 4 4 6% 43%	1672
December	1st to 10th	Day	19% 6% 3 6% 6% 3 5% 5% 4 6% 37%	1520
	11th to 20th	Day	24% 5% 2 4 3 2 3 4 4 5% 44%	1906
	21st to end	Day	22% 11% 3 6% 5% 3 4 4 4 5% 33%	2772
January	1st to 10th	Night	18% 6% 2 4 5% 3 4 4 4 6% 45%	4429
	11th to 20th	Night	17% 8% 3 7% 5% 3 4 3 4 5% 41%	4440
	21st to end	Night	24% 12% 4 6% 5% 3 3 3 4 5% 31%	4848
February	1st to 10th	Night	18% 9% 3 5% 4 2 5% 5% 5% 5% 39%	2340
	11th to 20th	Night	15% 8% 3 5% 5% 4 5% 5% 6% 6% 39%	2098
	21st to end	Night	19% 7% 3 5% 6% 3 4 3 5% 5% 40%	1776
March	1st to 10th	Night	16% 7% 3 6% 5% 2 3 4 5% 6% 41%	2150
	11th to 20th	Night	16% 8% 2 5% 5% 3 4 4 4 7% 40%	2111
	21st to end	Night	19% 6% 2 6% 4 2 3 4 5% 6% 42%	1980
April	1st to 10th	Night	20% 7% 2 5% 5% 4 4 4 6% 5% 38%	1800
	11th to 20th	Night	20% 6% 2 5% 5% 2 4 4 5% 6% 40%	1775
	21st to end	Night	23% 7% 2 5% 4 2 3 3 4 6% 40%	1683
May	1st to 10th	Night	23% 7% 3 6% 5% 3 5% 5% 4 5% 32%	1620
	11th to 20th	Night	20% 6% 2 4 5% 2 4 5% 5% 8% 38%	1497
	21st to end	Night	17% 6% 3 4 4 3 4 3 6% 8% 42%	1550
June	1st to 10th	Night	18% 4 3 5% 4 3 4 5% 5% 7% 42%	1440
	11th to 20th	Night	18% 6% 3 4 4 4 5% 4 6% 7% 40%	1440
	21st to end	Night	15% 4 2 4 5% 3 4 4 6% 8% 44%	1440
July	1st to 10th	Night	13% 4 2 4 5% 3 6% 5% 7% 9% 42%	1440
	11th to 20th	Night	15% 4 3 5% 5% 3 5% 6% 6% 9% 39%	1440
	21st to end	Night	11% 4 2 5% 5% 3 6% 5% 6% 9% 43%	1574
August	1st to 10th	Night	10% 6% 2 5% 6% 3 4 4 7% 9% 44%	1499
	11th to 20th	Night	13% 6% 2 5% 5% 3 6% 6% 6% 8% 39%	1730
	21st to end	Night	14% 5% 2 4 5% 3 4 5% 5% 7% 46%	1980
September	1st to 10th	Night	15% 5% 3 5% 5% 3 4 4 5% 6% 45%	1800
	11th to 20th	Night	15% 5% 2 4 4 2 3 4 3 6% 53%	1930
	21st to end	Night	17% 6% 2 4 4 3 3 5% 5% 6% 46%	1980
October	1st to 10th	Night	22% 7% 2 4 4 3 3 4 4 6% 42%	1998
	11th to 20th	Night	17% 5% 2 5% 4 3 4 4 4 6% 47%	2189
	21st to end	Night	25% 5% 2 5% 4 3 3 5% 4 5% 38%	2574
November	1st to 10th	Night	15% 5% 2 5% 4 2 4 4 4 6% 48%	2407
	11th to 20th	Night	20% 6% 2 5% 4 2 3 4 4 5% 44%	2470
	21st to end	Night	17% 6% 2 5% 4 2 4 4 5% 5% 46%	2507
December	1st to 10th	Night	20% 7% 3 5% 4 2 4 4 5% 6% 39%	2660
	11th to 20th	Night	22% 6% 2 4 3 3 3 4 5% 6% 41%	3288
	21st to end	Night	24% 9% 3 6% 5% 2 4 3 4 4 35%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	39% 5% 13% 32% 9% 2	2518
	11th to 20th	Day	48% 7% 11% 23% 9% 1	2520
	21st to end	Day	54% 5% 10% 20% 9% 1	2807
February	1st to 10th	Day	47% 6% 14% 19% 12% 2	1714
	11th to 20th	Day	44% 5% 11% 22% 15% 3	1757
	21st to end	Day	48% 5% 11% 19% 15% 2	1480
March	1st to 10th	Day	44% 4 14% 22% 14% 3	1800
	11th to 20th	Day	45% 5% 12% 22% 13% 3	1842
	21st to end	Day	47% 4 8% 19% 18% 5%	2376
April	1st to 10th	Day	46% 5% 11% 21% 14% 4	2160
	11th to 20th	Day	42% 5% 11% 21% 19% 3	2134
	21st to end	Day	46% 5% 10% 20% 15% 4	2276
May	1st to 10th	Day	51% 5% 10% 19% 13% 2	2340
	11th to 20th	Day	42% 6% 9% 23% 17% 3	2414
	21st to end	Day	39% 7% 16% 21% 14% 3	2725
June	1st to 10th	Day	46% 7% 13% 22% 11% 1	2520
	11th to 20th	Day	43% 7% 14% 21% 14% 1	2520
	21st to end	Day	41% 8% 14% 22% 14% 1	2520
July	1st to 10th	Day	40% 8% 12% 20% 17% 2	2450
	11th to 20th	Day	38% 8% 15% 24% 13% 2	2445
	21st to end	Day	40% 8% 14% 19% 17% 2	2591
August	1st to 10th	Day	40% 8% 15% 23% 13%	2408
	11th to 20th	Day	40% 7% 15% 23% 13% 1	2167
	21st to end	Day	37% 7% 11% 25% 18% 2	2376
September	1st to 10th	Day	41% 5% 11% 23% 17% 2	2160
	11th to 20th	Day	34% 5% 10% 25% 23% 3	2030
	21st to end	Day	40% 5% 10% 23% 19% 3	1980
October	1st to 10th	Day	47% 4 11% 20% 14% 3	1958
	11th to 20th	Day	38% 5% 13% 27% 15% 2	1769
	21st to end	Day	46% 6% 12% 19% 13% 3	1782
November	1st to 10th	Day	39% 4 13% 23% 18% 3	1671
	11th to 20th	Day	40% 4 11% 24% 18% 3	1710
	21st to end	Day	43% 4 12% 26% 11% 3	1672
December	1st to 10th	Day	48% 6% 14% 17% 14% 1	1520
	11th to 20th	Day	43% 4 15% 20% 15% 2	1906
	21st to end	Day	54% 6% 12% 19% 9% 1	2772
January	1st to 10th	Night	41% 3 13% 29% 11% 3	4429
	11th to 20th	Night	46% 5% 13% 22% 12% 3	4440
	21st to end	Night	56% 4 10% 18% 11% 1	4848
February	1st to 10th	Night	47% 5% 14% 22% 11% 2	2340
	11th to 20th	Night	45% 6% 10% 20% 15% 3	2100
	21st to end	Night	46% 4 10% 23% 12% 4	1776
March	1st to 10th	Night	43% 6% 12% 22% 14% 3	2160
	11th to 20th	Night	45% 4 12% 20% 15% 3	2112
	21st to end	Night	43% 5% 10% 19% 18% 5%	1980
April	1st to 10th	Night	47% 5% 10% 21% 14% 3	1800
	11th to 20th	Night	45% 6% 9% 19% 19% 1	1775
	21st to end	Night	46% 5% 10% 20% 13% 5%	1683
May	1st to 10th	Night	52% 7% 10% 15% 13% 3	1620
	11th to 20th	Night	44% 7% 10% 20% 15% 3	1498
	21st to end	Night	40% 8% 18% 19% 13% 1	1551
June	1st to 10th	Night	43% 8% 13% 21% 15% 1	1440
	11th to 20th	Night	43% 7% 15% 23% 11% 1	1440
	21st to end	Night	36% 8% 16% 26% 14%	1440
July	1st to 10th	Night	38% 7% 17% 21% 16% 1	1400
	11th to 20th	Night	40% 9% 17% 26% 8% 1	1392
	21st to end	Night	36% 9% 17% 21% 15% 2	1486
August	1st to 10th	Night	35% 9% 17% 24% 13% 2	1489
	11th to 20th	Night	41% 7% 16% 23% 11% 1	1730
	21st to end	Night	36% 7% 13% 25% 18% 1	1980
September	1st to 10th	Night	40% 7% 11% 24% 17% 1	1800
	11th to 20th	Night	34% 5% 11% 22% 26% 2	1930
	21st to end	Night	39% 6% 10% 23% 20% 2	1980
October	1st to 10th	Night	44% 6% 12% 21% 13% 3	1998
	11th to 20th	Night	38% 6% 14% 27% 14% 1	2189
	21st to end	Night	48% 5% 12% 20% 13% 1	2574
November	1st to 10th	Night	38% 5% 12% 22% 20% 4	2407
	11th to 20th	Night	42% 4 12% 21% 18% 3	2470
	21st to end	Night	41% 5% 15% 26% 12% 1	2507
December	1st to 10th	Night	46% 4 15% 21% 13% 1	2660
	11th to 20th	Night	44% 5% 15% 19% 15% 2	3288
	21st to end	Night	52% 5% 10% 23% 10% 1	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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	25% 20% 32% 18% 5%	180
	11th to 20th	Day	27% 27% 29% 13% 3	180
	21st to end	Day	21% 24% 35% 13% 6%	209
February	1st to 10th	Day	32% 20% 31% 14% 3	310
	11th to 20th	Day	27% 22% 36% 13% 2	416
	21st to end	Day	31% 18% 34% 15% 3	346
March	1st to 10th	Day	24% 21% 35% 18% 3	420
	11th to 20th	Day	27% 22% 33% 15% 3 1	420
	21st to end	Day	28% 19% 32% 13% 5% 2	462
April	1st to 10th	Day	28% 20% 31% 13% 7% 1	420
	11th to 20th	Day	28% 18% 31% 16% 6% 1	412
	21st to end	Day	31% 18% 30% 14% 5% 1	420
May	1st to 10th	Day	35% 17% 28% 13% 7% 1	423
	11th to 20th	Day	22% 16% 38% 17% 6% 1	447
	21st to end	Day	19% 15% 31% 24% 9% 3	485
June	1st to 10th	Day	18% 14% 31% 24% 10% 3	450
	11th to 20th	Day	17% 15% 36% 23% 6% 2	450
	21st to end	Day	16% 14% 31% 26% 10% 3	450
July	1st to 10th	Day	15% 8% 30% 28% 15% 4	445
	11th to 20th	Day	15% 6% 27% 33% 15% 4	444
	21st to end	Day	14% 10% 33% 30% 11% 2	488
August	1st to 10th	Day	13% 8% 29% 33% 12% 5%	446
	11th to 20th	Day	13% 7% 32% 27% 15% 6%	439
	21st to end	Day	14% 9% 29% 25% 18% 5%	495
September	1st to 10th	Day	20% 9% 23% 25% 15% 7%	450
	11th to 20th	Day	18% 10% 28% 22% 11% 10%	450
	21st to end	Day	20% 13% 28% 22% 10% 7%	450
October	1st to 10th	Day	29% 9% 25% 19% 12% 6%	450
	11th to 20th	Day	18% 14% 31% 25% 9% 2	435
	21st to end	Day	31% 11% 27% 23% 8% 1	396
November	1st to 10th	Day	19% 15% 28% 24% 11% 2	365
	11th to 20th	Day	29% 17% 27% 18% 7% 1	370
	21st to end	Day	23% 15% 33% 20% 8%	332
December	1st to 10th	Day	22% 22% 35% 15% 7%	180
	11th to 20th	Day	31% 22% 35% 10% 3	180
	21st to end	Day	25% 19% 36% 14% 4 1	198
January	1st to 10th	Night	21% 15% 39% 22% 3	760
	11th to 20th	Night	28% 16% 32% 23% 2	760
	21st to end	Night	20% 15% 40% 23% 3	836
February	1st to 10th	Night	23% 14% 36% 25% 2	739
	11th to 20th	Night	22% 18% 40% 19% 2	703
	21st to end	Night	26% 15% 38% 19% 2	592
March	1st to 10th	Night	23% 18% 37% 20% 2	720
	11th to 20th	Night	23% 16% 39% 20% 3	720
	21st to end	Night	24% 15% 36% 20% 5%	792
April	1st to 10th	Night	23% 17% 34% 22% 3	720
	11th to 20th	Night	23% 16% 34% 21% 5%	711
	21st to end	Night	27% 17% 31% 21% 4	603
May	1st to 10th	Night	28% 15% 31% 21% 4	540
	11th to 20th	Night	21% 14% 41% 20% 4	436
	21st to end	Night	20% 8% 30% 36% 6% 1	389
June	1st to 10th	Night	19% 7% 32% 33% 8%	360
	11th to 20th	Night	20% 7% 31% 34% 8%	360
	21st to end	Night	15% 4 33% 40% 8%	360
July	1st to 10th	Night	13% 5% 29% 39% 14%	350
	11th to 20th	Night	16% 2 24% 41% 15% 1	348
	21st to end	Night	11% 4 28% 45% 13%	394
August	1st to 10th	Night	12% 4 27% 45% 12%	425
	11th to 20th	Night	13% 5% 23% 39% 19% 1	666
	21st to end	Night	15% 4 24% 37% 19% 1	792
September	1st to 10th	Night	17% 4 30% 33% 14% 1	720
	11th to 20th	Night	16% 6% 25% 33% 18% 2	720
	21st to end	Night	19% 7% 28% 30% 15% 2	720
October	1st to 10th	Night	26% 7% 26% 28% 12% 2	720
	11th to 20th	Night	19% 11% 31% 29% 9% 1	720
	21st to end	Night	29% 10% 31% 23% 6%	792
November	1st to 10th	Night	18% 11% 33% 28% 9% 1	740
	11th to 20th	Night	24% 10% 34% 24% 6% 1	760
	21st to end	Night	23% 14% 32% 26% 5%	760
December	1st to 10th	Night	26% 12% 35% 21% 6%	760
	11th to 20th	Night	24% 14% 33% 26% 3	760
	21st to end	Night	26% 13% 36% 22% 2	836

Page generated at 2024-02-02 05:20:28. Version ac07

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