Brady's Run Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Brady's Run Park clear sky chart from 2005-11-06 to 2026-03-03.

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	15% 11% 4 9% 5% 5% 5% 4 5% 7% 30%	130927
	Night	16% 12% 4 10% 5% 4 4 3 5% 6% 30%	130215
Transparency	Day	52% 5% 11% 20% 10% 1	134533
	Night	53% 5% 11% 19% 11% 1	134680
Seeing	Day	22% 15% 27% 20% 11% 4	16293
	Night	22% 12% 26% 27% 12% 1	26137

By Month

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	17% 19% 7% 21% 6% 4 4 2 4 4 13%	5258
	11th to 20th	Day	12% 21% 8% 18% 8% 6% 4 2 3 4 15%	5280
	21st to end	Day	19% 16% 5% 13% 9% 7% 4 3 4 4 15%	5780
February	1st to 10th	Day	18% 18% 5% 10% 7% 5% 4 3 3 5% 22%	1890
	11th to 20th	Day	17% 14% 6% 14% 6% 5% 4 4 4 5% 21%	1843
	21st to end	Day	19% 16% 4 9% 5% 4 4 4 5% 5% 25%	1732
March	1st to 10th	Day	17% 12% 5% 11% 5% 4 4 3 5% 6% 29%	4957
	11th to 20th	Day	12% 8% 4 9% 6% 5% 5% 4 5% 6% 37%	4980
	21st to end	Day	18% 10% 4 9% 5% 4 4 4 5% 6% 30%	5465
April	1st to 10th	Day	16% 12% 4 9% 5% 4 4 4 6% 6% 29%	2292
	11th to 20th	Day	16% 11% 4 7% 5% 4 5% 3 5% 6% 33%	2437
	21st to end	Day	21% 10% 3 7% 5% 4 4 3 5% 6% 33%	2600
May	1st to 10th	Day	20% 9% 3 8% 6% 5% 5% 4 6% 6% 27%	5862
	11th to 20th	Day	18% 9% 3 8% 5% 5% 5% 4 6% 8% 30%	5861
	21st to end	Day	18% 7% 2 6% 5% 5% 5% 4 7% 8% 32%	6752
June	1st to 10th	Day	13% 7% 3 8% 5% 5% 5% 5% 6% 8% 35%	2800
	11th to 20th	Day	14% 7% 3 7% 5% 5% 5% 4 7% 9% 34%	2800
	21st to end	Day	13% 6% 2 6% 5% 5% 5% 4 7% 9% 38%	2800
July	1st to 10th	Day	8% 6% 3 8% 5% 5% 5% 4 7% 9% 41%	6116
	11th to 20th	Day	10% 7% 3 8% 5% 5% 5% 5% 7% 10% 34%	5900
	21st to end	Day	11% 6% 2 7% 6% 5% 5% 4 6% 8% 39%	6424
August	1st to 10th	Day	13% 8% 3 8% 6% 6% 6% 5% 6% 7% 31%	4234
	11th to 20th	Day	11% 6% 3 8% 5% 5% 6% 5% 6% 9% 35%	4174
	21st to end	Day	7% 5% 2 7% 5% 6% 6% 5% 7% 10% 40%	4483
September	1st to 10th	Day	14% 6% 2 6% 4 4 4 3 5% 8% 44%	2384
	11th to 20th	Day	10% 5% 2 6% 5% 4 4 4 7% 9% 44%	2200
	21st to end	Day	18% 8% 3 8% 6% 4 4 3 5% 5% 35%	2200
October	1st to 10th	Day	14% 7% 2 6% 4 4 5% 4 5% 8% 41%	2011
	11th to 20th	Day	18% 8% 3 8% 5% 5% 5% 3 5% 6% 34%	2000
	21st to end	Day	21% 11% 3 7% 4 4 4 4 5% 6% 31%	2200
November	1st to 10th	Day	11% 8% 3 6% 6% 5% 6% 3 5% 6% 42%	1942
	11th to 20th	Day	17% 14% 4 9% 4 4 4 3 4 6% 30%	1768
	21st to end	Day	17% 16% 6% 9% 5% 3 5% 4 5% 5% 24%	1680
December	1st to 10th	Day	19% 15% 6% 15% 6% 4 3 3 4 5% 20%	2680
	11th to 20th	Day	24% 17% 7% 11% 4 3 3 2 4 4 21%	3070
	21st to end	Day	24% 21% 6% 12% 6% 5% 4 3 4 5% 12%	4072
January	1st to 10th	Night	14% 19% 7% 20% 6% 6% 4 3 3 4 13%	7635
	11th to 20th	Night	13% 17% 9% 16% 10% 6% 5% 3 3 4 14%	7680
	21st to end	Night	19% 15% 5% 12% 8% 6% 4 2 3 4 21%	8401
February	1st to 10th	Night	19% 13% 6% 11% 6% 5% 4 3 5% 4 23%	2730
	11th to 20th	Night	19% 13% 5% 13% 6% 6% 4 3 4 5% 23%	2663
	21st to end	Night	19% 13% 5% 13% 5% 4 5% 4 4 4 24%	2071
March	1st to 10th	Night	22% 11% 5% 9% 5% 3 3 2 4 5% 31%	4941
	11th to 20th	Night	14% 10% 4 7% 4 4 3 3 5% 7% 39%	4980
	21st to end	Night	17% 11% 4 9% 5% 4 4 3 4 5% 34%	5467
April	1st to 10th	Night	19% 12% 3 7% 6% 4 3 3 5% 6% 33%	2106
	11th to 20th	Night	16% 10% 3 8% 4 5% 5% 3 5% 7% 34%	1929
	21st to end	Night	15% 9% 3 7% 4 4 4 3 6% 9% 36%	1800
May	1st to 10th	Night	26% 11% 4 7% 4 4 4 4 5% 7% 25%	4033
	11th to 20th	Night	16% 10% 3 8% 4 4 4 3 5% 7% 36%	4032
	21st to end	Night	17% 8% 3 6% 4 4 4 4 6% 9% 36%	4084
June	1st to 10th	Night	10% 6% 3 6% 5% 4 5% 5% 6% 8% 43%	1600
	11th to 20th	Night	12% 5% 3 7% 5% 5% 3 3 6% 9% 42%	1600
	21st to end	Night	9% 4 2 8% 6% 5% 5% 4 7% 10% 42%	1600
July	1st to 10th	Night	9% 8% 2 8% 4 4 5% 4 5% 8% 42%	3822
	11th to 20th	Night	10% 7% 3 7% 5% 5% 5% 5% 8% 9% 38%	4057
	21st to end	Night	8% 6% 3 8% 5% 5% 4 4 6% 8% 44%	4427
August	1st to 10th	Night	12% 9% 3 8% 5% 4 5% 4 6% 7% 37%	2915
	11th to 20th	Night	12% 8% 2 8% 4 4 4 3 5% 7% 43%	2875
	21st to end	Night	8% 5% 2 6% 4 5% 6% 5% 7% 9% 44%	3380
September	1st to 10th	Night	12% 5% 2 5% 4 4 4 4 5% 7% 49%	2012
	11th to 20th	Night	9% 4 2 4 3 3 4 4 6% 9% 52%	2200
	21st to end	Night	16% 8% 2 7% 4 4 4 3 5% 7% 39%	2200
October	1st to 10th	Night	14% 6% 2 6% 3 4 4 3 5% 6% 47%	2388
	11th to 20th	Night	17% 7% 2 7% 5% 3 5% 3 5% 6% 39%	2400
	21st to end	Night	23% 9% 3 6% 3 3 4 3 5% 6% 37%	2640
November	1st to 10th	Night	14% 8% 2 6% 4 4 4 3 5% 6% 44%	2571
	11th to 20th	Night	18% 11% 4 8% 6% 4 4 4 5% 6% 30%	2850
	21st to end	Night	20% 14% 4 9% 4 4 4 4 5% 5% 28%	2940
December	1st to 10th	Night	16% 17% 10% 14% 5% 4 4 3 4 5% 18%	4720
	11th to 20th	Night	21% 18% 6% 11% 5% 4 3 3 4 5% 21%	5345
	21st to end	Night	24% 18% 6% 12% 6% 4 4 3 4 5% 16%	7121

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	76% 3 8% 9% 3	5259
	11th to 20th	Day	75% 3 6% 9% 5% 1	5280
	21st to end	Day	73% 3 7% 13% 4	5780
February	1st to 10th	Day	66% 3 9% 15% 7%	1890
	11th to 20th	Day	65% 5% 9% 14% 7%	1852
	21st to end	Day	60% 4 12% 16% 7% 1	1732
March	1st to 10th	Day	55% 4 10% 22% 8% 1	4957
	11th to 20th	Day	47% 5% 13% 25% 9% 2	4980
	21st to end	Day	53% 4 9% 20% 12% 1	5465
April	1st to 10th	Day	54% 5% 11% 18% 11% 2	2292
	11th to 20th	Day	51% 6% 10% 18% 13% 2	2437
	21st to end	Day	51% 5% 10% 22% 10% 2	2600
May	1st to 10th	Day	55% 6% 10% 17% 8% 3	5897
	11th to 20th	Day	50% 7% 11% 22% 9% 1	5865
	21st to end	Day	46% 7% 13% 21% 10% 3	6767
June	1st to 10th	Day	45% 7% 13% 23% 12% 1	2800
	11th to 20th	Day	45% 7% 14% 21% 12% 1	2800
	21st to end	Day	41% 8% 12% 25% 13% 1	2800
July	1st to 10th	Day	39% 5% 12% 27% 15% 2	6051
	11th to 20th	Day	43% 7% 13% 25% 12%	5831
	21st to end	Day	40% 7% 10% 24% 18% 1	6240
August	1st to 10th	Day	48% 8% 12% 22% 9%	4221
	11th to 20th	Day	42% 6% 11% 29% 10% 1	4213
	21st to end	Day	37% 8% 12% 28% 13% 2	4483
September	1st to 10th	Day	38% 6% 10% 23% 20% 3	2384
	11th to 20th	Day	36% 6% 14% 27% 16% 1	2200
	21st to end	Day	49% 5% 11% 21% 13% 1	2200
October	1st to 10th	Day	32% 5% 10% 32% 20% 1	3271
	11th to 20th	Day	45% 5% 10% 22% 14% 4	3240
	21st to end	Day	40% 4 13% 27% 16% 1	3538
November	1st to 10th	Day	43% 5% 12% 22% 17% 2	1942
	11th to 20th	Day	56% 4 11% 18% 10% 2	1768
	21st to end	Day	61% 5% 12% 16% 6% 1	1680
December	1st to 10th	Day	68% 5% 11% 12% 3	2680
	11th to 20th	Day	68% 3 11% 14% 4	3066
	21st to end	Day	76% 3 9% 10% 3	4072
January	1st to 10th	Night	75% 3 9% 10% 3	7636
	11th to 20th	Night	75% 4 8% 10% 4	7680
	21st to end	Night	69% 3 8% 14% 6% 1	8401
February	1st to 10th	Night	63% 4 9% 18% 6%	2730
	11th to 20th	Night	63% 4 10% 16% 6%	2665
	21st to end	Night	62% 5% 9% 15% 9% 1	2071
March	1st to 10th	Night	57% 3 10% 21% 9%	4941
	11th to 20th	Night	45% 4 13% 26% 8% 3	4980
	21st to end	Night	51% 5% 10% 18% 15% 1	5467
April	1st to 10th	Night	53% 4 10% 18% 13% 2	2106
	11th to 20th	Night	49% 5% 12% 17% 14% 3	1929
	21st to end	Night	44% 6% 12% 23% 13% 2	1800
May	1st to 10th	Night	58% 6% 9% 15% 9% 3	4060
	11th to 20th	Night	47% 6% 9% 24% 12% 1	4033
	21st to end	Night	43% 8% 12% 24% 11% 3	4091
June	1st to 10th	Night	37% 8% 13% 23% 17% 2	1600
	11th to 20th	Night	38% 7% 15% 23% 15% 2	1600
	21st to end	Night	37% 8% 13% 24% 17% 2	1600
July	1st to 10th	Night	40% 6% 9% 24% 19% 2	3780
	11th to 20th	Night	40% 7% 17% 24% 12% 1	4006
	21st to end	Night	37% 6% 11% 19% 24% 2	4297
August	1st to 10th	Night	44% 8% 12% 22% 12% 1	2904
	11th to 20th	Night	40% 6% 10% 29% 15% 1	2902
	21st to end	Night	34% 8% 13% 30% 13% 2	3380
September	1st to 10th	Night	33% 7% 11% 24% 20% 5%	2012
	11th to 20th	Night	28% 7% 14% 27% 22% 1	2200
	21st to end	Night	44% 5% 12% 21% 17% 1	2200
October	1st to 10th	Night	35% 5% 8% 27% 24% 1	3908
	11th to 20th	Night	38% 5% 12% 23% 15% 7%	3899
	21st to end	Night	36% 3 9% 30% 19% 2	4252
November	1st to 10th	Night	41% 4 12% 24% 16% 3	2571
	11th to 20th	Night	53% 4 11% 20% 9% 3	2850
	21st to end	Night	58% 4 11% 20% 5% 1	2940
December	1st to 10th	Night	70% 3 10% 13% 3	4720
	11th to 20th	Night	66% 4 12% 15% 3	5348
	21st to end	Night	71% 4 10% 12% 2	7121

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	30% 29% 27% 10% 3 1	330
	11th to 20th	Day	34% 30% 28% 7% 1	330
	21st to end	Day	31% 29% 31% 7% 2 1	363
February	1st to 10th	Day	32% 20% 36% 9% 3	330
	11th to 20th	Day	36% 28% 28% 7% 1	330
	21st to end	Day	33% 25% 34% 7%	287
March	1st to 10th	Day	30% 21% 30% 16% 3	508
	11th to 20th	Day	32% 21% 29% 12% 5% 1	500
	21st to end	Day	34% 19% 28% 15% 4 1	550
April	1st to 10th	Day	31% 21% 26% 15% 7% 1	500
	11th to 20th	Day	27% 20% 27% 15% 8% 3	492
	21st to end	Day	29% 16% 31% 17% 6% 1	500
May	1st to 10th	Day	26% 20% 26% 18% 7% 3	503
	11th to 20th	Day	22% 16% 30% 20% 9% 3	527
	21st to end	Day	17% 9% 28% 25% 17% 5%	573
June	1st to 10th	Day	13% 14% 31% 25% 12% 4	530
	11th to 20th	Day	18% 13% 24% 28% 14% 4	530
	21st to end	Day	13% 9% 32% 27% 15% 3	530
July	1st to 10th	Day	13% 6% 22% 27% 22% 10%	525
	11th to 20th	Day	12% 7% 26% 28% 19% 8%	524
	21st to end	Day	13% 7% 24% 29% 19% 8%	576
August	1st to 10th	Day	11% 6% 23% 31% 19% 10%	526
	11th to 20th	Day	14% 5% 23% 28% 20% 10%	519
	21st to end	Day	11% 6% 24% 26% 21% 11%	583
September	1st to 10th	Day	17% 8% 20% 26% 20% 8%	530
	11th to 20th	Day	11% 4 18% 31% 25% 12%	530
	21st to end	Day	22% 13% 24% 23% 15% 4	530
October	1st to 10th	Day	15% 9% 27% 25% 18% 5%	530
	11th to 20th	Day	22% 17% 30% 22% 7% 2	530
	21st to end	Day	28% 16% 32% 17% 6%	583
November	1st to 10th	Day	20% 19% 34% 16% 9% 2	420
	11th to 20th	Day	32% 17% 33% 12% 6% 1	266
	21st to end	Day	28% 24% 37% 11%	220
December	1st to 10th	Day	31% 27% 30% 9% 3 1	220
	11th to 20th	Day	31% 24% 32% 11% 2	220
	21st to end	Day	38% 21% 29% 12% 1	248
January	1st to 10th	Night	29% 21% 33% 14% 2	840
	11th to 20th	Night	29% 21% 32% 16% 2	840
	21st to end	Night	27% 22% 29% 19% 3	924
February	1st to 10th	Night	29% 17% 28% 24% 3	840
	11th to 20th	Night	30% 19% 33% 16% 1	823
	21st to end	Night	28% 18% 33% 18% 3	692
March	1st to 10th	Night	26% 18% 31% 23% 2	809
	11th to 20th	Night	26% 19% 27% 23% 5% 1	800
	21st to end	Night	25% 16% 33% 21% 5% 1	880
April	1st to 10th	Night	26% 16% 29% 23% 6%	800
	11th to 20th	Night	22% 14% 32% 23% 8% 1	745
	21st to end	Night	21% 10% 35% 29% 6%	600
May	1st to 10th	Night	21% 12% 24% 33% 8% 2	600
	11th to 20th	Night	20% 8% 28% 31% 13% 1	591
	21st to end	Night	13% 3 25% 35% 21% 3	507
June	1st to 10th	Night	11% 5% 25% 40% 19%	400
	11th to 20th	Night	13% 5% 24% 39% 19% 1	400
	21st to end	Night	8% 5% 27% 35% 24% 1	400
July	1st to 10th	Night	8% 3 18% 41% 25% 6%	480
	11th to 20th	Night	8% 2 19% 36% 30% 5%	582
	21st to end	Night	10% 4 14% 42% 27% 2	657
August	1st to 10th	Night	10% 2 18% 39% 29% 3	597
	11th to 20th	Night	11% 4 13% 40% 29% 4	594
	21st to end	Night	12% 4 20% 32% 26% 5%	752
September	1st to 10th	Night	15% 4 18% 34% 25% 4	800
	11th to 20th	Night	11% 3 15% 36% 32% 4	800
	21st to end	Night	18% 9% 23% 27% 19% 4	800
October	1st to 10th	Night	17% 6% 23% 29% 22% 2	800
	11th to 20th	Night	21% 11% 31% 25% 11% 1	800
	21st to end	Night	28% 12% 26% 26% 8%	880
November	1st to 10th	Night	19% 11% 27% 31% 12%	820
	11th to 20th	Night	28% 16% 26% 22% 7% 1	840
	21st to end	Night	29% 17% 27% 21% 6%	840
December	1st to 10th	Night	32% 17% 27% 20% 4	840
	11th to 20th	Night	29% 19% 29% 20% 3	840
	21st to end	Night	30% 18% 29% 22% 2	924

Page generated at 2026-02-28 01:40:22. Version ac07

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