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 2025-02-25.

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% 7% 2 6% 4 4 4 3 5% 7% 39%	108435
	Night	18% 7% 2 6% 4 4 4 3 5% 6% 41%	110245
Transparency	Day	43% 5% 12% 22% 15% 2	112002
	Night	43% 5% 12% 22% 15% 2	114842
Seeing	Day	22% 15% 31% 21% 9% 3	15281
	Night	21% 11% 33% 27% 7%	24433

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	12% 8% 4 9% 5% 5% 4 3 4 5% 42%	3597
	11th to 20th	Day	14% 8% 3 8% 4 4 5% 4 5% 6% 41%	3570
	21st to end	Day	18% 8% 3 6% 4 4 4 3 4 6% 40%	4023
February	1st to 10th	Day	17% 8% 3 6% 5% 5% 5% 4 6% 6% 36%	1865
	11th to 20th	Day	14% 8% 2 7% 5% 5% 4 4 5% 6% 40%	1948
	21st to end	Day	20% 9% 3 6% 3 4 4 3 6% 5% 38%	1610
March	1st to 10th	Day	25% 10% 3 8% 4 3 3 2 4 5% 33%	3116
	11th to 20th	Day	12% 8% 3 6% 5% 5% 5% 3 5% 7% 41%	3258
	21st to end	Day	21% 7% 3 6% 4 3 3 3 5% 6% 39%	4166
April	1st to 10th	Day	19% 8% 3 6% 4 4 5% 3 6% 6% 37%	2280
	11th to 20th	Day	18% 6% 2 6% 4 4 4 3 5% 6% 41%	2254
	21st to end	Day	21% 6% 2 5% 4 4 4 3 4 6% 39%	2403
May	1st to 10th	Day	26% 8% 2 6% 4 3 4 3 6% 7% 30%	4106
	11th to 20th	Day	23% 7% 3 7% 4 3 4 3 5% 6% 35%	4288
	21st to end	Day	14% 5% 2 5% 3 4 4 4 6% 8% 45%	4837
June	1st to 10th	Day	16% 6% 2 5% 6% 5% 5% 4 6% 8% 36%	2660
	11th to 20th	Day	15% 5% 2 7% 5% 5% 4 4 6% 10% 38%	2660
	21st to end	Day	14% 6% 3 7% 5% 4 5% 4 7% 10% 36%	2660
July	1st to 10th	Day	11% 6% 2 7% 6% 6% 5% 4 7% 9% 37%	4440
	11th to 20th	Day	12% 5% 2 6% 5% 5% 6% 5% 7% 10% 39%	4440
	21st to end	Day	17% 8% 3 7% 5% 5% 5% 3 5% 7% 35%	4814
August	1st to 10th	Day	17% 7% 3 8% 6% 5% 5% 5% 7% 8% 31%	4270
	11th to 20th	Day	11% 6% 3 7% 5% 5% 5% 4 5% 8% 41%	3797
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 4 7% 9% 45%	4180
September	1st to 10th	Day	14% 6% 2 5% 5% 5% 4 4 4 6% 45%	2280
	11th to 20th	Day	14% 5% 2 5% 3 3 3 3 5% 6% 51%	2142
	21st to end	Day	18% 6% 2 6% 4 4 4 3 5% 7% 42%	2090
October	1st to 10th	Day	22% 7% 3 5% 3 4 3 3 5% 5% 40%	2066
	11th to 20th	Day	14% 6% 2 5% 4 4 4 3 5% 7% 46%	1867
	21st to end	Day	22% 6% 2 5% 4 3 4 3 4 5% 41%	1881
November	1st to 10th	Day	14% 6% 2 6% 4 3 4 3 4 5% 49%	1761
	11th to 20th	Day	19% 5% 2 4 3 3 3 3 5% 6% 46%	1800
	21st to end	Day	18% 7% 2 6% 4 4 3 3 4 6% 42%	1760
December	1st to 10th	Day	16% 7% 2 5% 4 4 4 3 5% 7% 44%	2600
	11th to 20th	Day	21% 6% 2 4 3 2 3 3 5% 5% 45%	2986
	21st to end	Day	21% 11% 2 7% 4 4 3 3 4 5% 38%	3960
January	1st to 10th	Night	15% 6% 2 8% 4 4 4 3 5% 6% 43%	6349
	11th to 20th	Night	14% 8% 3 8% 4 4 3 3 4 6% 42%	6315
	21st to end	Night	17% 10% 3 6% 5% 5% 4 3 5% 5% 37%	6932
February	1st to 10th	Night	17% 9% 3 5% 4 4 4 4 5% 5% 40%	2534
	11th to 20th	Night	15% 8% 3 6% 5% 5% 4 4 5% 6% 39%	2338
	21st to end	Night	19% 8% 2 6% 5% 3 3 3 5% 6% 40%	1939
March	1st to 10th	Night	29% 8% 2 6% 4 3 3 3 4 5% 33%	3724
	11th to 20th	Night	13% 8% 2 6% 5% 5% 4 4 5% 6% 42%	3695
	21st to end	Night	23% 7% 2 6% 3 3 3 3 6% 5% 38%	3466
April	1st to 10th	Night	20% 7% 2 6% 5% 5% 4 4 6% 5% 37%	1900
	11th to 20th	Night	21% 7% 2 6% 5% 4 4 3 5% 5% 39%	1875
	21st to end	Night	22% 8% 2 6% 4 3 3 2 4 5% 41%	1776
May	1st to 10th	Night	25% 8% 3 7% 4 4 4 3 5% 6% 30%	2834
	11th to 20th	Night	22% 8% 3 7% 5% 4 5% 4 5% 7% 30%	2633
	21st to end	Night	17% 5% 2 5% 4 4 3 3 6% 8% 43%	2738
June	1st to 10th	Night	18% 5% 2 6% 4 5% 3 4 5% 6% 42%	1520
	11th to 20th	Night	18% 6% 2 5% 3 5% 4 4 6% 7% 40%	1520
	21st to end	Night	15% 5% 2 5% 5% 4 4 3 6% 8% 43%	1520
July	1st to 10th	Night	13% 5% 2 6% 5% 4 6% 5% 7% 9% 38%	2520
	11th to 20th	Night	15% 6% 2 7% 4 4 4 4 6% 9% 38%	2520
	21st to end	Night	16% 9% 3 7% 4 4 5% 3 6% 7% 35%	2739
August	1st to 10th	Night	22% 6% 3 7% 6% 3 4 3 7% 8% 31%	2629
	11th to 20th	Night	13% 7% 3 7% 5% 5% 5% 4 5% 7% 39%	3027
	21st to end	Night	10% 4 2 5% 4 3 4 4 5% 8% 52%	3476
September	1st to 10th	Night	15% 5% 2 6% 4 4 4 3 4 6% 46%	1900
	11th to 20th	Night	14% 5% 2 4 4 3 3 3 3 6% 53%	2038
	21st to end	Night	17% 7% 2 5% 4 3 4 4 5% 6% 44%	2090
October	1st to 10th	Night	21% 7% 2 5% 4 3 4 3 4 6% 42%	2110
	11th to 20th	Night	16% 5% 2 5% 3 3 4 3 4 6% 48%	2311
	21st to end	Night	25% 5% 2 5% 3 3 4 3 4 5% 40%	2717
November	1st to 10th	Night	14% 5% 2 6% 3 4 4 3 5% 6% 49%	2537
	11th to 20th	Night	19% 6% 2 5% 3 3 3 4 4 5% 45%	2600
	21st to end	Night	17% 6% 2 6% 4 3 4 3 5% 5% 45%	2639
December	1st to 10th	Night	19% 7% 2 5% 4 4 3 3 4 5% 45%	4580
	11th to 20th	Night	26% 7% 2 4 3 3 3 3 4 4 41%	5208
	21st to end	Night	20% 10% 3 7% 4 3 3 2 4 5% 39%	6996

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	45% 4 9% 27% 13% 2	3598
	11th to 20th	Day	43% 6% 10% 21% 14% 6%	3600
	21st to end	Day	46% 4 10% 23% 16% 1	4023
February	1st to 10th	Day	46% 6% 14% 19% 13% 2	1865
	11th to 20th	Day	45% 5% 10% 23% 14% 3	1957
	21st to end	Day	46% 5% 12% 20% 14% 2	1610
March	1st to 10th	Day	55% 4 12% 17% 10% 2	3119
	11th to 20th	Day	38% 7% 17% 26% 10% 2	3258
	21st to end	Day	46% 4 7% 18% 20% 5%	4166
April	1st to 10th	Day	46% 5% 11% 20% 14% 3	2280
	11th to 20th	Day	43% 5% 11% 21% 18% 3	2254
	21st to end	Day	45% 5% 10% 20% 16% 4	2403
May	1st to 10th	Day	53% 6% 15% 14% 11% 1	4120
	11th to 20th	Day	50% 7% 13% 19% 10% 1	4292
	21st to end	Day	35% 7% 15% 24% 18% 2	4837
June	1st to 10th	Day	44% 7% 13% 23% 12% 1	2660
	11th to 20th	Day	42% 7% 15% 21% 13% 2	2660
	21st to end	Day	42% 8% 13% 21% 14% 1	2660
July	1st to 10th	Day	43% 7% 12% 20% 16% 2	4370
	11th to 20th	Day	39% 7% 16% 23% 13% 2	4365
	21st to end	Day	49% 5% 12% 18% 15% 1	4661
August	1st to 10th	Day	50% 6% 15% 20% 8%	4256
	11th to 20th	Day	41% 5% 14% 29% 10% 1	3835
	21st to end	Day	35% 6% 11% 29% 16% 2	4180
September	1st to 10th	Day	40% 5% 11% 23% 18% 2	2280
	11th to 20th	Day	34% 5% 10% 26% 23% 3	2142
	21st to end	Day	42% 5% 10% 22% 18% 3	2090
October	1st to 10th	Day	41% 4 9% 19% 23% 3	3430
	11th to 20th	Day	30% 4 9% 27% 28% 3	3083
	21st to end	Day	34% 4 13% 25% 20% 4	3081
November	1st to 10th	Day	38% 4 13% 24% 18% 2	1761
	11th to 20th	Day	38% 4 11% 23% 20% 4	1800
	21st to end	Day	44% 4 12% 26% 11% 3	1760
December	1st to 10th	Day	41% 5% 16% 27% 11% 1	2600
	11th to 20th	Day	42% 3 15% 20% 17% 3	2986
	21st to end	Day	49% 5% 9% 19% 14% 4	3960
January	1st to 10th	Night	42% 3 10% 28% 14% 2	6349
	11th to 20th	Night	44% 5% 13% 20% 14% 5%	6360
	21st to end	Night	48% 4 11% 16% 16% 4	6932
February	1st to 10th	Night	46% 5% 13% 23% 11% 2	2534
	11th to 20th	Night	45% 6% 10% 20% 16% 3	2340
	21st to end	Night	45% 4 11% 23% 12% 4	1939
March	1st to 10th	Night	53% 5% 11% 18% 11% 2	3734
	11th to 20th	Night	40% 7% 16% 22% 13% 2	3696
	21st to end	Night	47% 5% 8% 13% 22% 5%	3466
April	1st to 10th	Night	47% 5% 11% 20% 14% 3	1900
	11th to 20th	Night	46% 6% 9% 19% 19% 1	1875
	21st to end	Night	46% 5% 10% 20% 14% 5%	1776
May	1st to 10th	Night	53% 9% 14% 13% 10% 2	2840
	11th to 20th	Night	53% 8% 14% 15% 9% 2	2634
	21st to end	Night	38% 7% 18% 22% 13% 1	2739
June	1st to 10th	Night	42% 8% 13% 22% 15% 1	1520
	11th to 20th	Night	42% 7% 16% 23% 11% 1	1520
	21st to end	Night	38% 8% 15% 25% 14%	1520
July	1st to 10th	Night	42% 7% 17% 20% 14% 1	2480
	11th to 20th	Night	42% 7% 16% 23% 11% 1	2472
	21st to end	Night	48% 6% 13% 15% 15% 2	2651
August	1st to 10th	Night	51% 8% 14% 17% 9% 1	2619
	11th to 20th	Night	44% 6% 15% 27% 8%	3055
	21st to end	Night	30% 6% 15% 33% 16% 1	3476
September	1st to 10th	Night	40% 7% 10% 24% 18% 1	1900
	11th to 20th	Night	34% 5% 11% 23% 25% 2	2038
	21st to end	Night	40% 6% 10% 23% 19% 2	2090
October	1st to 10th	Night	39% 6% 13% 22% 18% 2	3526
	11th to 20th	Night	28% 3 10% 28% 30% 2	3834
	21st to end	Night	34% 4 13% 30% 18% 2	4467
November	1st to 10th	Night	37% 5% 12% 23% 20% 4	2537
	11th to 20th	Night	41% 4 11% 21% 19% 4	2600
	21st to end	Night	41% 5% 15% 27% 11% 1	2639
December	1st to 10th	Night	44% 3 13% 30% 10% 1	4580
	11th to 20th	Night	47% 3 14% 17% 17% 2	5208
	21st to end	Night	48% 4 8% 21% 15% 4	6996

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	26% 24% 30% 17% 5%	200
	11th to 20th	Day	27% 28% 30% 13% 3	200
	21st to end	Day	22% 24% 35% 13% 6%	233
February	1st to 10th	Day	30% 23% 31% 13% 3	365
	11th to 20th	Day	29% 23% 34% 13% 2	496
	21st to end	Day	29% 18% 34% 15% 4	398
March	1st to 10th	Day	25% 21% 34% 17% 3	460
	11th to 20th	Day	27% 23% 32% 15% 3 1	460
	21st to end	Day	29% 20% 33% 12% 5% 2	506
April	1st to 10th	Day	29% 20% 30% 13% 7% 1	460
	11th to 20th	Day	29% 19% 31% 15% 6% 1	452
	21st to end	Day	30% 17% 31% 14% 6% 1	460
May	1st to 10th	Day	33% 17% 27% 14% 7% 1	463
	11th to 20th	Day	22% 16% 37% 17% 7% 1	487
	21st to end	Day	18% 15% 33% 23% 9% 3	529
June	1st to 10th	Day	18% 14% 31% 25% 9% 3	490
	11th to 20th	Day	16% 15% 35% 25% 8% 2	490
	21st to end	Day	16% 14% 32% 25% 10% 3	490
July	1st to 10th	Day	15% 9% 30% 28% 14% 3	485
	11th to 20th	Day	14% 6% 29% 32% 15% 4	484
	21st to end	Day	16% 9% 33% 30% 11% 2	532
August	1st to 10th	Day	14% 7% 30% 32% 12% 5%	486
	11th to 20th	Day	13% 7% 32% 27% 15% 6%	479
	21st to end	Day	13% 9% 28% 26% 19% 5%	539
September	1st to 10th	Day	19% 10% 23% 25% 16% 7%	490
	11th to 20th	Day	17% 10% 27% 23% 12% 12%	490
	21st to end	Day	21% 12% 28% 24% 9% 7%	490
October	1st to 10th	Day	27% 10% 25% 20% 12% 6%	490
	11th to 20th	Day	18% 15% 31% 25% 9% 3	473
	21st to end	Day	29% 12% 27% 23% 9% 1	429
November	1st to 10th	Day	18% 17% 29% 24% 10% 2	395
	11th to 20th	Day	29% 17% 29% 19% 7% 1	400
	21st to end	Day	25% 15% 33% 19% 8%	360
December	1st to 10th	Day	20% 23% 36% 14% 8% 1	200
	11th to 20th	Day	31% 22% 33% 11% 4	200
	21st to end	Day	25% 18% 36% 14% 6% 1	220
January	1st to 10th	Night	21% 17% 39% 21% 3	800
	11th to 20th	Night	27% 16% 32% 23% 2	800
	21st to end	Night	20% 14% 40% 23% 3	880
February	1st to 10th	Night	23% 14% 37% 25% 2	800
	11th to 20th	Night	23% 18% 40% 18% 2	783
	21st to end	Night	25% 14% 38% 20% 3	647
March	1st to 10th	Night	24% 18% 36% 20% 3	760
	11th to 20th	Night	22% 17% 39% 20% 3	760
	21st to end	Night	25% 16% 36% 20% 5%	836
April	1st to 10th	Night	23% 17% 35% 22% 3	760
	11th to 20th	Night	24% 17% 34% 21% 5%	751
	21st to end	Night	26% 17% 32% 20% 4	636
May	1st to 10th	Night	28% 15% 31% 22% 4	570
	11th to 20th	Night	20% 14% 41% 20% 4	460
	21st to end	Night	20% 8% 31% 35% 6% 1	411
June	1st to 10th	Night	19% 7% 34% 33% 8%	380
	11th to 20th	Night	19% 7% 31% 34% 8% 1	380
	21st to end	Night	16% 4 33% 39% 8%	380
July	1st to 10th	Night	13% 4 30% 39% 14%	370
	11th to 20th	Night	16% 3 24% 42% 15% 1	368
	21st to end	Night	11% 4 27% 44% 13%	416
August	1st to 10th	Night	13% 4 26% 44% 12%	449
	11th to 20th	Night	13% 5% 23% 38% 19% 1	704
	21st to end	Night	14% 4 24% 38% 19% 1	836
September	1st to 10th	Night	17% 4 30% 33% 15% 1	760
	11th to 20th	Night	16% 5% 24% 33% 19% 3	760
	21st to end	Night	18% 6% 28% 32% 14% 2	760
October	1st to 10th	Night	25% 7% 26% 28% 12% 2	760
	11th to 20th	Night	19% 11% 31% 29% 10% 1	760
	21st to end	Night	28% 10% 30% 24% 7%	836
November	1st to 10th	Night	17% 12% 34% 28% 9% 1	780
	11th to 20th	Night	24% 11% 35% 24% 6% 1	800
	21st to end	Night	23% 14% 32% 26% 5%	800
December	1st to 10th	Night	26% 11% 35% 22% 6%	800
	11th to 20th	Night	25% 14% 32% 26% 3	800
	21st to end	Night	26% 13% 36% 23% 3	880

Page generated at 2025-02-22 06:51:34. Version ac07

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