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 2026-07-01.

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%	137531
	Night	18% 7% 2 6% 4 4 4 3 5% 6% 40%	134855
Transparency	Day	44% 5% 12% 22% 15% 2	141052
	Night	44% 5% 12% 22% 15% 2	139423
Seeing	Day	22% 15% 31% 21% 8% 3	17070
	Night	21% 12% 33% 27% 7%	26085

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	11% 8% 4 9% 5% 5% 5% 3 4 5% 40%	4661
	11th to 20th	Day	14% 9% 3 7% 4 4 4 3 4 6% 42%	4650
	21st to end	Day	15% 9% 2 5% 3 3 4 3 5% 6% 43%	5201
February	1st to 10th	Day	16% 7% 3 6% 5% 5% 5% 4 6% 6% 37%	1958
	11th to 20th	Day	14% 7% 2 7% 5% 5% 4 4 5% 6% 40%	2048
	21st to end	Day	19% 10% 3 6% 4 4 4 3 6% 5% 39%	1730
March	1st to 10th	Day	22% 8% 2 7% 4 3 3 3 4 5% 38%	4576
	11th to 20th	Day	16% 8% 2 6% 4 5% 4 3 5% 6% 40%	4762
	21st to end	Day	22% 7% 2 6% 4 4 4 3 5% 6% 37%	6102
April	1st to 10th	Day	20% 8% 3 6% 4 4 4 3 5% 6% 37%	2520
	11th to 20th	Day	18% 6% 2 6% 5% 4 4 3 5% 6% 41%	2494
	21st to end	Day	20% 6% 2 5% 4 4 4 3 4 6% 40%	2656
May	1st to 10th	Day	28% 8% 2 6% 3 3 4 3 5% 7% 30%	7639
	11th to 20th	Day	19% 7% 3 7% 4 4 4 3 5% 6% 38%	8014
	21st to end	Day	21% 7% 3 7% 4 4 4 4 6% 8% 31%	9060
June	1st to 10th	Day	16% 6% 2 5% 6% 5% 5% 4 6% 9% 36%	2940
	11th to 20th	Day	15% 5% 2 7% 5% 5% 4 4 6% 10% 38%	2940
	21st to end	Day	15% 6% 3 6% 5% 4 5% 3 7% 10% 37%	2940
July	1st to 10th	Day	13% 6% 3 7% 5% 5% 5% 4 7% 10% 35%	6360
	11th to 20th	Day	10% 5% 3 7% 5% 5% 6% 5% 8% 11% 36%	6360
	21st to end	Day	15% 6% 3 6% 4 4 4 3 5% 7% 43%	6926
August	1st to 10th	Day	16% 7% 3 7% 6% 5% 5% 5% 7% 8% 31%	4405
	11th to 20th	Day	11% 6% 3 7% 5% 5% 5% 4 5% 8% 41%	3919
	21st to end	Day	8% 5% 2 6% 5% 5% 5% 4 7% 9% 45%	4312
September	1st to 10th	Day	14% 6% 2 5% 5% 5% 4 4 4 6% 45%	2400
	11th to 20th	Day	14% 5% 2 5% 4 3 3 2 5% 6% 52%	2255
	21st to end	Day	18% 6% 2 6% 4 4 4 3 5% 7% 41%	2200
October	1st to 10th	Day	21% 6% 3 5% 3 4 3 3 5% 5% 42%	2175
	11th to 20th	Day	15% 6% 2 5% 4 4 3 3 5% 8% 45%	1965
	21st to end	Day	21% 6% 2 5% 4 3 5% 3 4 5% 42%	1980
November	1st to 10th	Day	13% 6% 2 6% 4 3 4 3 4 5% 48%	1851
	11th to 20th	Day	18% 6% 2 4 3 3 3 3 6% 7% 46%	1890
	21st to end	Day	19% 8% 2 6% 4 4 3 3 4 6% 41%	1848
December	1st to 10th	Day	16% 7% 2 5% 4 4 4 3 5% 7% 44%	2680
	11th to 20th	Day	21% 6% 2 4 3 2 3 3 5% 5% 46%	3066
	21st to end	Day	21% 10% 3 7% 4 4 3 3 4 6% 37%	4048
January	1st to 10th	Night	15% 8% 3 8% 5% 4 4 3 5% 6% 41%	8234
	11th to 20th	Night	16% 10% 3 8% 5% 4 3 3 4 5% 40%	8235
	21st to end	Night	16% 8% 3 7% 5% 4 4 3 5% 6% 41%	8979
February	1st to 10th	Night	16% 9% 3 5% 4 4 4 4 5% 6% 40%	2660
	11th to 20th	Night	15% 8% 3 6% 5% 5% 4 4 5% 6% 39%	2458
	21st to end	Night	18% 8% 2 6% 5% 4 3 3 5% 6% 40%	2076
March	1st to 10th	Night	24% 7% 3 5% 3 3 3 3 4 5% 39%	5484
	11th to 20th	Night	18% 9% 3 6% 4 4 3 3 4 6% 40%	5411
	21st to end	Night	23% 8% 2 7% 4 4 3 3 5% 5% 37%	5072
April	1st to 10th	Night	21% 7% 2 6% 4 5% 4 3 6% 5% 37%	2100
	11th to 20th	Night	21% 7% 2 6% 4 4 4 3 5% 5% 39%	2075
	21st to end	Night	22% 8% 2 6% 4 3 3 2 5% 5% 42%	1962
May	1st to 10th	Night	28% 9% 3 6% 3 4 3 3 4 6% 31%	5259
	11th to 20th	Night	20% 8% 3 7% 4 4 4 4 5% 7% 33%	4901
	21st to end	Night	22% 7% 3 8% 4 5% 4 4 5% 7% 31%	5114
June	1st to 10th	Night	18% 5% 2 6% 4 5% 3 4 5% 6% 43%	1680
	11th to 20th	Night	17% 7% 3 5% 4 5% 4 4 6% 7% 39%	1680
	21st to end	Night	15% 5% 2 5% 5% 4 4 3 6% 9% 43%	1680
July	1st to 10th	Night	14% 6% 2 7% 5% 4 5% 4 6% 9% 39%	3600
	11th to 20th	Night	14% 7% 3 7% 4 4 4 4 6% 9% 37%	3600
	21st to end	Night	12% 7% 2 5% 4 4 5% 3 5% 7% 45%	3926
August	1st to 10th	Night	22% 5% 3 7% 6% 3 4 3 7% 7% 32%	2713
	11th to 20th	Night	13% 7% 3 7% 5% 5% 5% 4 5% 7% 40%	3125
	21st to end	Night	10% 4 2 5% 4 3 4 4 5% 8% 52%	3586
September	1st to 10th	Night	15% 5% 2 6% 4 4 4 3 5% 6% 46%	2000
	11th to 20th	Night	13% 5% 2 4 4 3 3 3 4 6% 53%	2145
	21st to end	Night	17% 7% 2 5% 4 3 4 4 5% 6% 44%	2200
October	1st to 10th	Night	20% 7% 2 4 4 3 4 3 4 6% 44%	2221
	11th to 20th	Night	17% 5% 2 5% 3 3 4 3 4 6% 47%	2433
	21st to end	Night	24% 5% 2 5% 3 3 4 3 5% 5% 40%	2860
November	1st to 10th	Night	14% 5% 2 6% 3 4 4 3 5% 6% 49%	2667
	11th to 20th	Night	18% 6% 2 5% 3 3 3 4 4 5% 45%	2730
	21st to end	Night	17% 6% 2 6% 4 3 4 3 5% 5% 45%	2771
December	1st to 10th	Night	19% 8% 2 5% 4 4 3 3 4 5% 44%	4720
	11th to 20th	Night	25% 7% 2 4 3 3 3 3 4 4 42%	5348
	21st to end	Night	20% 9% 3 7% 4 3 3 3 4 5% 39%	7150

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	46% 4 11% 25% 13% 2	4662
	11th to 20th	Day	43% 5% 9% 21% 16% 6%	4680
	21st to end	Day	42% 4 12% 24% 18% 1	5201
February	1st to 10th	Day	45% 6% 14% 19% 14% 2	1958
	11th to 20th	Day	45% 5% 10% 23% 14% 3	2057
	21st to end	Day	46% 5% 12% 20% 15% 2	1730
March	1st to 10th	Day	49% 3 11% 16% 12% 8%	4579
	11th to 20th	Day	41% 5% 16% 27% 9% 2	4762
	21st to end	Day	48% 4 7% 16% 19% 6%	6102
April	1st to 10th	Day	47% 5% 11% 20% 14% 4	2520
	11th to 20th	Day	43% 4 12% 20% 18% 2	2494
	21st to end	Day	45% 5% 10% 20% 17% 4	2656
May	1st to 10th	Day	53% 5% 13% 16% 12% 1	7651
	11th to 20th	Day	47% 5% 12% 21% 13% 1	8018
	21st to end	Day	50% 5% 12% 20% 12% 1	9061
June	1st to 10th	Day	44% 7% 12% 23% 13% 1	2940
	11th to 20th	Day	42% 7% 15% 21% 14% 2	2940
	21st to end	Day	41% 8% 13% 22% 15% 1	2940
July	1st to 10th	Day	45% 7% 12% 20% 15% 1	6290
	11th to 20th	Day	41% 6% 17% 23% 11% 1	6285
	21st to end	Day	41% 4 11% 25% 18% 1	6728
August	1st to 10th	Day	50% 6% 15% 20% 9% 1	4391
	11th to 20th	Day	41% 5% 14% 29% 10% 1	3957
	21st to end	Day	35% 6% 11% 29% 17% 2	4312
September	1st to 10th	Day	40% 5% 10% 24% 18% 2	2400
	11th to 20th	Day	33% 5% 10% 25% 23% 3	2255
	21st to end	Day	42% 5% 10% 22% 18% 3	2200
October	1st to 10th	Day	40% 4 9% 20% 24% 3	3539
	11th to 20th	Day	31% 4 9% 27% 28% 3	3181
	21st to end	Day	34% 4 13% 25% 20% 4	3180
November	1st to 10th	Day	39% 4 13% 23% 18% 2	1851
	11th to 20th	Day	38% 4 11% 24% 19% 3	1890
	21st to end	Day	45% 4 11% 27% 10% 2	1848
December	1st to 10th	Day	41% 5% 15% 27% 11% 1	2680
	11th to 20th	Day	42% 3 15% 20% 17% 3	3066
	21st to end	Day	50% 4 9% 19% 14% 4	4048
January	1st to 10th	Night	45% 3 11% 25% 14% 2	8234
	11th to 20th	Night	47% 4 11% 19% 14% 5%	8280
	21st to end	Night	45% 3 10% 19% 19% 3	8979
February	1st to 10th	Night	46% 4 13% 23% 12% 2	2660
	11th to 20th	Night	45% 6% 10% 20% 16% 3	2460
	21st to end	Night	46% 4 10% 23% 12% 4	2076
March	1st to 10th	Night	47% 5% 11% 17% 15% 5%	5494
	11th to 20th	Night	44% 5% 17% 20% 10% 3	5412
	21st to end	Night	50% 4 6% 13% 23% 5%	5072
April	1st to 10th	Night	48% 5% 11% 20% 14% 3	2100
	11th to 20th	Night	46% 6% 9% 19% 18% 2	2075
	21st to end	Night	45% 5% 10% 20% 15% 5%	1962
May	1st to 10th	Night	54% 6% 14% 13% 11% 1	5265
	11th to 20th	Night	51% 5% 12% 19% 10% 2	4902
	21st to end	Night	52% 5% 13% 20% 8% 1	5115
June	1st to 10th	Night	42% 7% 12% 23% 16% 1	1680
	11th to 20th	Night	42% 7% 16% 23% 11% 1	1680
	21st to end	Night	37% 8% 15% 26% 13% 1	1680
July	1st to 10th	Night	43% 6% 15% 21% 14% 1	3560
	11th to 20th	Night	44% 6% 18% 21% 10% 1	3552
	21st to end	Night	39% 5% 12% 25% 17% 1	3809
August	1st to 10th	Night	50% 8% 13% 18% 9% 1	2703
	11th to 20th	Night	43% 6% 15% 27% 9%	3153
	21st to end	Night	29% 6% 15% 33% 16% 1	3586
September	1st to 10th	Night	39% 7% 10% 25% 18% 1	2000
	11th to 20th	Night	33% 5% 11% 23% 26% 2	2145
	21st to end	Night	40% 6% 10% 23% 19% 2	2200
October	1st to 10th	Night	39% 5% 13% 23% 18% 2	3637
	11th to 20th	Night	29% 3 10% 28% 29% 2	3956
	21st to end	Night	34% 4 13% 30% 18% 2	4610
November	1st to 10th	Night	37% 5% 11% 23% 20% 3	2667
	11th to 20th	Night	41% 4 11% 21% 19% 4	2730
	21st to end	Night	41% 5% 14% 27% 12% 1	2771
December	1st to 10th	Night	44% 3 13% 30% 10% 1	4720
	11th to 20th	Night	47% 3 14% 17% 17% 2	5348
	21st to end	Night	48% 4 8% 21% 15% 4	7150

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% 23% 31% 17% 5%	220
	11th to 20th	Day	25% 30% 29% 13% 3	220
	21st to end	Day	23% 25% 34% 13% 5%	256
February	1st to 10th	Day	28% 23% 32% 14% 3	398
	11th to 20th	Day	28% 22% 35% 13% 2	536
	21st to end	Day	29% 18% 35% 15% 4	446
March	1st to 10th	Day	26% 20% 33% 17% 3	540
	11th to 20th	Day	29% 22% 31% 15% 3 1	540
	21st to end	Day	30% 21% 32% 11% 4 2	594
April	1st to 10th	Day	31% 21% 29% 12% 6% 1	540
	11th to 20th	Day	30% 19% 29% 15% 5% 1	532
	21st to end	Day	30% 18% 30% 15% 5% 1	540
May	1st to 10th	Day	33% 18% 29% 13% 6% 1	543
	11th to 20th	Day	21% 18% 37% 17% 6% 1	567
	21st to end	Day	21% 14% 33% 22% 7% 2	617
June	1st to 10th	Day	17% 14% 31% 25% 10% 3	570
	11th to 20th	Day	17% 15% 34% 25% 7% 2	570
	21st to end	Day	16% 13% 32% 27% 10% 2	570
July	1st to 10th	Day	15% 9% 30% 29% 14% 3	525
	11th to 20th	Day	14% 6% 30% 31% 15% 4	524
	21st to end	Day	16% 9% 32% 30% 11% 2	576
August	1st to 10th	Day	13% 7% 29% 33% 13% 6%	526
	11th to 20th	Day	13% 7% 30% 28% 16% 6%	519
	21st to end	Day	12% 9% 30% 26% 18% 5%	583
September	1st to 10th	Day	18% 10% 24% 25% 16% 7%	530
	11th to 20th	Day	15% 9% 26% 24% 13% 12%	530
	21st to end	Day	20% 11% 28% 24% 10% 6%	530
October	1st to 10th	Day	25% 10% 24% 20% 12% 7%	530
	11th to 20th	Day	19% 15% 30% 24% 9% 3	511
	21st to end	Day	28% 13% 27% 22% 8% 2	462
November	1st to 10th	Day	19% 18% 28% 24% 10% 2	425
	11th to 20th	Day	28% 17% 28% 19% 7% 1	430
	21st to end	Day	27% 16% 32% 18% 7%	388
December	1st to 10th	Day	20% 23% 35% 14% 7%	220
	11th to 20th	Day	30% 22% 34% 10% 4	220
	21st to end	Day	28% 18% 35% 13% 5% 1	242
January	1st to 10th	Night	21% 16% 39% 21% 3	840
	11th to 20th	Night	27% 16% 31% 23% 2	840
	21st to end	Night	20% 15% 40% 23% 3	924
February	1st to 10th	Night	22% 14% 37% 25% 2	840
	11th to 20th	Night	22% 18% 39% 19% 2	823
	21st to end	Night	24% 15% 38% 20% 2	692
March	1st to 10th	Night	24% 18% 36% 20% 3	840
	11th to 20th	Night	22% 17% 38% 20% 3	840
	21st to end	Night	25% 16% 35% 19% 4	924
April	1st to 10th	Night	25% 16% 35% 21% 3	840
	11th to 20th	Night	24% 16% 35% 20% 5%	831
	21st to end	Night	26% 17% 32% 21% 4	702
May	1st to 10th	Night	29% 15% 31% 22% 4	630
	11th to 20th	Night	20% 14% 40% 21% 4	509
	21st to end	Night	21% 8% 31% 34% 5% 1	455
June	1st to 10th	Night	18% 6% 32% 36% 8%	420
	11th to 20th	Night	20% 8% 32% 32% 8%	420
	21st to end	Night	16% 5% 33% 39% 8%	420
July	1st to 10th	Night	13% 4 29% 40% 13%	390
	11th to 20th	Night	15% 3 25% 41% 15% 1	388
	21st to end	Night	11% 4 28% 45% 13%	438
August	1st to 10th	Night	14% 4 25% 44% 12%	473
	11th to 20th	Night	13% 5% 23% 39% 19% 1	742
	21st to end	Night	14% 4 25% 38% 19% 1	880
September	1st to 10th	Night	17% 5% 30% 33% 15% 1	800
	11th to 20th	Night	15% 5% 24% 34% 20% 3	800
	21st to end	Night	19% 6% 27% 32% 15% 2	800
October	1st to 10th	Night	24% 7% 25% 29% 13% 2	800
	11th to 20th	Night	19% 11% 31% 29% 10% 1	800
	21st to end	Night	28% 10% 30% 25% 7%	880
November	1st to 10th	Night	18% 12% 33% 28% 8% 1	820
	11th to 20th	Night	23% 11% 35% 24% 6% 1	840
	21st to end	Night	23% 14% 32% 27% 5%	840
December	1st to 10th	Night	26% 11% 35% 22% 5%	840
	11th to 20th	Night	25% 14% 32% 26% 3	840
	21st to end	Night	26% 14% 35% 22% 2	924

Page generated at 2026-06-28 02:10:47. Version ac07

Copyright © 2026 Attilla Danko.