Hwy 29 and Benndale Road
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hwy 29 and Benndale Road clear sky chart from 2005-11-06 to 2025-12-03.

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	12% 6% 2 6% 5% 5% 5% 4 6% 8% 42%	126408
	Night	13% 6% 2 6% 4 4 4 4 6% 8% 45%	124249
Transparency	Day	38% 7% 12% 18% 18% 8%	130195
	Night	37% 6% 12% 18% 18% 9%	128537
Seeing	Day	14% 9% 21% 25% 21% 10%	15857
	Night	14% 8% 21% 30% 22% 5%	25537

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% 6% 4 4 3 2 3 3 5% 6% 47%	4516
	11th to 20th	Day	12% 5% 2 5% 4 3 4 3 4 5% 52%	4520
	21st to end	Day	23% 7% 2 7% 4 3 4 3 4 6% 37%	4972
February	1st to 10th	Day	18% 8% 3 7% 5% 4 4 4 4 5% 38%	2000
	11th to 20th	Day	20% 6% 2 4 4 4 4 4 4 7% 42%	1948
	21st to end	Day	16% 9% 2 8% 5% 3 4 4 4 6% 39%	1650
March	1st to 10th	Day	17% 10% 2 7% 4 4 5% 4 5% 6% 36%	4480
	11th to 20th	Day	14% 5% 2 6% 4 3 4 2 5% 8% 48%	4877
	21st to end	Day	15% 6% 3 7% 5% 5% 4 3 4 5% 42%	5914
April	1st to 10th	Day	12% 6% 3 7% 5% 4 5% 4 6% 7% 42%	2400
	11th to 20th	Day	13% 6% 3 6% 5% 4 5% 4 5% 7% 42%	2374
	21st to end	Day	8% 5% 2 6% 5% 5% 4 4 5% 7% 49%	2400
May	1st to 10th	Day	16% 6% 2 6% 5% 5% 5% 4 7% 9% 35%	5405
	11th to 20th	Day	11% 5% 2 6% 4 4 5% 4 7% 9% 42%	5404
	21st to end	Day	7% 5% 2 6% 5% 5% 5% 4 7% 11% 42%	6424
June	1st to 10th	Day	9% 6% 3 7% 7% 5% 6% 6% 8% 10% 32%	2600
	11th to 20th	Day	5% 5% 2 8% 8% 7% 6% 6% 9% 9% 37%	2600
	21st to end	Day	6% 7% 2 8% 7% 8% 8% 6% 8% 9% 30%	2706
July	1st to 10th	Day	6% 5% 2 8% 6% 7% 8% 7% 9% 12% 30%	5842
	11th to 20th	Day	6% 5% 2 7% 6% 7% 8% 6% 9% 13% 33%	5440
	21st to end	Day	7% 5% 2 7% 7% 7% 8% 7% 10% 14% 26%	5922
August	1st to 10th	Day	4 3 2 5% 5% 5% 5% 4 7% 8% 52%	3905
	11th to 20th	Day	7% 4 2 6% 5% 6% 6% 5% 7% 10% 41%	3849
	21st to end	Day	8% 5% 3 9% 6% 6% 6% 5% 7% 9% 36%	4312
September	1st to 10th	Day	9% 6% 3 8% 6% 6% 6% 4 7% 8% 36%	2400
	11th to 20th	Day	12% 6% 2 7% 5% 4 5% 4 5% 7% 44%	2267
	21st to end	Day	9% 4 2 5% 4 5% 4 3 5% 6% 52%	2200
October	1st to 10th	Day	8% 4 2 5% 4 4 3 3 5% 6% 55%	2200
	11th to 20th	Day	8% 4 2 5% 3 4 3 3 4 6% 57%	2049
	21st to end	Day	10% 5% 2 5% 3 3 4 3 4 6% 56%	2200
November	1st to 10th	Day	10% 6% 2 5% 3 3 3 3 4 6% 55%	1974
	11th to 20th	Day	12% 5% 2 4 4 3 3 3 3 6% 56%	1890
	21st to end	Day	13% 6% 3 6% 3 3 4 4 5% 6% 47%	1890
December	1st to 10th	Day	18% 7% 2 4 3 3 4 3 4 6% 45%	2948
	11th to 20th	Day	11% 6% 2 6% 4 4 4 3 5% 5% 49%	3373
	21st to end	Day	18% 6% 2 5% 3 4 3 3 4 5% 45%	4557
January	1st to 10th	Night	18% 6% 4 5% 3 2 3 2 4 4 49%	5429
	11th to 20th	Night	17% 9% 3 5% 3 3 2 2 4 5% 48%	5440
	21st to end	Night	23% 9% 2 5% 4 3 3 3 4 5% 39%	5984
February	1st to 10th	Night	16% 8% 3 5% 4 4 4 3 4 6% 43%	2400
	11th to 20th	Night	22% 9% 2 6% 3 3 3 3 4 5% 41%	2338
	21st to end	Night	18% 9% 2 7% 4 4 4 3 4 6% 40%	1980
March	1st to 10th	Night	20% 9% 3 6% 3 4 4 3 5% 6% 36%	5373
	11th to 20th	Night	15% 7% 2 4 4 3 4 3 5% 6% 48%	5124
	21st to end	Night	15% 6% 2 5% 4 3 4 3 5% 6% 46%	5013
April	1st to 10th	Night	15% 7% 2 6% 4 4 4 3 5% 5% 44%	2000
	11th to 20th	Night	13% 7% 2 6% 3 3 3 3 6% 6% 48%	1975
	21st to end	Night	9% 4 2 5% 4 4 3 2 4 7% 58%	2000
May	1st to 10th	Night	16% 7% 3 8% 4 4 4 4 5% 8% 38%	4490
	11th to 20th	Night	12% 6% 2 6% 4 4 4 3 6% 8% 43%	4489
	21st to end	Night	7% 4 2 6% 5% 5% 5% 5% 8% 12% 41%	4425
June	1st to 10th	Night	7% 6% 2 6% 5% 6% 4 5% 8% 11% 39%	1800
	11th to 20th	Night	4 4 2 5% 5% 5% 6% 6% 8% 11% 44%	1800
	21st to end	Night	7% 6% 2 6% 6% 5% 5% 6% 8% 11% 40%	1672
July	1st to 10th	Night	5% 5% 2 7% 6% 6% 7% 5% 8% 11% 39%	4066
	11th to 20th	Night	4 4 2 6% 5% 6% 7% 6% 9% 12% 39%	4517
	21st to end	Night	5% 5% 2 8% 6% 6% 7% 6% 10% 12% 32%	4929
August	1st to 10th	Night	3 2 1 4 3 4 5% 5% 8% 13% 53%	3244
	11th to 20th	Night	4 3 2 5% 4 5% 6% 5% 8% 14% 43%	3200
	21st to end	Night	6% 4 3 7% 5% 6% 7% 5% 8% 10% 39%	3586
September	1st to 10th	Night	9% 6% 3 8% 5% 6% 5% 5% 7% 9% 37%	2000
	11th to 20th	Night	9% 6% 3 6% 4 4 4 4 7% 8% 46%	2110
	21st to end	Night	7% 5% 2 6% 3 4 4 4 6% 7% 51%	2200
October	1st to 10th	Night	8% 4 2 5% 4 4 4 4 5% 7% 53%	2200
	11th to 20th	Night	8% 4 1 3 3 3 3 2 5% 7% 61%	2346
	21st to end	Night	12% 5% 2 5% 3 3 3 2 4 5% 56%	2640
November	1st to 10th	Night	10% 4 1 5% 4 3 4 3 4 5% 57%	2540
	11th to 20th	Night	13% 5% 1 4 2 3 3 3 4 5% 56%	2730
	21st to end	Night	12% 7% 2 5% 3 3 4 3 5% 6% 49%	2730
December	1st to 10th	Night	15% 6% 2 5% 4 3 4 3 6% 5% 46%	4277
	11th to 20th	Night	13% 6% 2 5% 3 4 4 3 4 5% 50%	4822
	21st to end	Night	21% 8% 2 5% 3 3 3 2 3 5% 45%	6380

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	38% 3 5% 19% 27% 8%	4517
	11th to 20th	Day	35% 3 4 17% 31% 10%	4520
	21st to end	Day	50% 3 6% 12% 17% 12%	4972
February	1st to 10th	Day	48% 4 7% 12% 20% 10%	2000
	11th to 20th	Day	42% 5% 6% 16% 22% 10%	1958
	21st to end	Day	46% 4 6% 16% 17% 11%	1650
March	1st to 10th	Day	48% 4 7% 15% 18% 9%	4480
	11th to 20th	Day	36% 4 7% 17% 20% 17%	4877
	21st to end	Day	45% 4 9% 15% 18% 9%	5916
April	1st to 10th	Day	40% 6% 8% 17% 18% 10%	2400
	11th to 20th	Day	41% 5% 6% 17% 22% 9%	2374
	21st to end	Day	34% 6% 9% 21% 22% 7%	2400
May	1st to 10th	Day	44% 7% 12% 22% 13% 3	5440
	11th to 20th	Day	36% 7% 16% 23% 17% 2	5408
	21st to end	Day	33% 7% 14% 29% 13% 3	6438
June	1st to 10th	Day	43% 9% 15% 22% 10% 2	2600
	11th to 20th	Day	39% 9% 16% 22% 11% 3	2600
	21st to end	Day	45% 12% 18% 17% 8% 1	2706
July	1st to 10th	Day	41% 13% 23% 18% 4	5782
	11th to 20th	Day	39% 13% 32% 13% 2	5377
	21st to end	Day	42% 14% 21% 19% 3	5752
August	1st to 10th	Day	27% 8% 15% 25% 23% 2	3893
	11th to 20th	Day	35% 9% 17% 23% 15% 1	3885
	21st to end	Day	43% 10% 15% 15% 15% 2	4311
September	1st to 10th	Day	44% 8% 12% 18% 13% 5%	2400
	11th to 20th	Day	39% 8% 12% 17% 18% 7%	2267
	21st to end	Day	33% 5% 11% 22% 20% 9%	2200
October	1st to 10th	Day	27% 3 7% 11% 22% 29%	3590
	11th to 20th	Day	18% 3 5% 16% 27% 31%	3315
	21st to end	Day	22% 4 4 13% 37% 20%	3538
November	1st to 10th	Day	31% 3 7% 19% 25% 14%	1974
	11th to 20th	Day	31% 3 6% 17% 29% 13%	1890
	21st to end	Day	37% 4 8% 18% 21% 12%	1890
December	1st to 10th	Day	42% 3 7% 16% 23% 9%	2948
	11th to 20th	Day	37% 4 10% 17% 22% 10%	3370
	21st to end	Day	41% 4 6% 19% 26% 5%	4557
January	1st to 10th	Night	40% 3 5% 17% 29% 6%	5429
	11th to 20th	Night	40% 3 4 15% 29% 9%	5440
	21st to end	Night	49% 3 5% 13% 21% 10%	5984
February	1st to 10th	Night	42% 4 8% 16% 20% 10%	2400
	11th to 20th	Night	47% 4 4 13% 21% 12%	2339
	21st to end	Night	47% 4 8% 15% 13% 13%	1980
March	1st to 10th	Night	48% 4 8% 12% 20% 7%	5373
	11th to 20th	Night	38% 5% 7% 14% 21% 16%	5124
	21st to end	Night	39% 4 11% 20% 15% 10%	5013
April	1st to 10th	Night	41% 5% 9% 15% 19% 11%	2000
	11th to 20th	Night	36% 5% 9% 20% 21% 10%	1975
	21st to end	Night	28% 4 12% 23% 25% 8%	2000
May	1st to 10th	Night	44% 7% 13% 18% 14% 3	4520
	11th to 20th	Night	36% 7% 18% 24% 14% 1	4490
	21st to end	Night	32% 8% 20% 27% 11% 2	4433
June	1st to 10th	Night	35% 10% 19% 22% 12% 2	1800
	11th to 20th	Night	29% 11% 23% 25% 11% 2	1800
	21st to end	Night	34% 11% 22% 22% 8% 2	1672
July	1st to 10th	Night	36% 13% 28% 18% 4	4020
	11th to 20th	Night	33% 17% 35% 14% 1	4460
	21st to end	Night	40% 16% 18% 23% 2	4785
August	1st to 10th	Night	19% 8% 23% 29% 19% 1	3232
	11th to 20th	Night	28% 12% 22% 25% 12% 1	3230
	21st to end	Night	36% 14% 17% 18% 11% 3	3586
September	1st to 10th	Night	40% 10% 16% 15% 13% 5%	2000
	11th to 20th	Night	34% 7% 17% 17% 16% 8%	2110
	21st to end	Night	31% 7% 12% 23% 17% 10%	2200
October	1st to 10th	Night	30% 4 8% 11% 23% 24%	3590
	11th to 20th	Night	16% 3 5% 20% 23% 33%	3819
	21st to end	Night	21% 3 4 12% 37% 23%	4252
November	1st to 10th	Night	30% 3 8% 17% 25% 16%	2540
	11th to 20th	Night	31% 3 6% 17% 27% 16%	2730
	21st to end	Night	35% 4 7% 20% 20% 13%	2730
December	1st to 10th	Night	39% 4 6% 18% 24% 9%	4277
	11th to 20th	Night	37% 4 9% 20% 21% 9%	4824
	21st to end	Night	43% 3 5% 18% 24% 6%	6380

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	24% 18% 38% 14% 5% 1	300
	11th to 20th	Day	24% 18% 32% 18% 7% 1	300
	21st to end	Day	28% 23% 31% 15% 4	330
February	1st to 10th	Day	28% 20% 29% 15% 7% 1	300
	11th to 20th	Day	32% 19% 29% 14% 5%	300
	21st to end	Day	20% 28% 38% 9% 4	249
March	1st to 10th	Day	21% 20% 37% 17% 5%	300
	11th to 20th	Day	24% 26% 29% 17% 4	300
	21st to end	Day	19% 18% 29% 25% 9%	523
April	1st to 10th	Day	21% 14% 33% 21% 9% 2	500
	11th to 20th	Day	20% 16% 30% 22% 10% 2	492
	21st to end	Day	12% 11% 30% 27% 17% 3	500
May	1st to 10th	Day	12% 13% 28% 24% 18% 5%	503
	11th to 20th	Day	9% 7% 25% 29% 20% 8%	527
	21st to end	Day	8% 2 23% 31% 24% 11%	573
June	1st to 10th	Day	11% 4 17% 31% 25% 13%	530
	11th to 20th	Day	7% 2 13% 32% 30% 15%	530
	21st to end	Day	9% 3 11% 29% 29% 18%	636
July	1st to 10th	Day	7% 3 7% 31% 33% 20%	648
	11th to 20th	Day	6% 3 5% 16% 41% 28%	524
	21st to end	Day	7% 1 7% 24% 38% 22%	576
August	1st to 10th	Day	5% 2 7% 25% 34% 27%	526
	11th to 20th	Day	8% 2 6% 18% 37% 29%	519
	21st to end	Day	10% 3 10% 22% 33% 22%	583
September	1st to 10th	Day	9% 3 8% 29% 33% 18%	530
	11th to 20th	Day	13% 5% 8% 25% 34% 15%	530
	21st to end	Day	12% 4 13% 31% 30% 10%	530
October	1st to 10th	Day	9% 5% 23% 36% 21% 6%	530
	11th to 20th	Day	9% 7% 23% 32% 22% 7%	379
	21st to end	Day	17% 11% 20% 31% 17% 4	363
November	1st to 10th	Day	17% 9% 28% 30% 14% 3	330
	11th to 20th	Day	18% 12% 27% 28% 14% 2	330
	21st to end	Day	15% 18% 33% 22% 9% 3	330
December	1st to 10th	Day	21% 17% 33% 21% 8% 1	306
	11th to 20th	Day	24% 14% 39% 17% 5% 1	300
	21st to end	Day	29% 14% 27% 21% 8%	330
January	1st to 10th	Night	22% 14% 34% 26% 5%	800
	11th to 20th	Night	21% 14% 29% 30% 7%	800
	21st to end	Night	24% 14% 32% 27% 4	880
February	1st to 10th	Night	20% 13% 33% 30% 5%	800
	11th to 20th	Night	27% 16% 28% 23% 6%	783
	21st to end	Night	22% 19% 36% 20% 3	660
March	1st to 10th	Night	18% 15% 33% 27% 7%	800
	11th to 20th	Night	17% 11% 35% 31% 6% 1	666
	21st to end	Night	15% 11% 33% 32% 9%	660
April	1st to 10th	Night	18% 12% 29% 30% 12% 1	600
	11th to 20th	Night	15% 10% 34% 27% 13% 1	593
	21st to end	Night	10% 7% 27% 38% 18% 1	600
May	1st to 10th	Night	10% 6% 26% 39% 17% 2	600
	11th to 20th	Night	9% 4 20% 40% 23% 3	591
	21st to end	Night	6% 2 18% 38% 30% 7%	650
June	1st to 10th	Night	10% 3 13% 33% 35% 6%	600
	11th to 20th	Night	3 2 8% 34% 42% 10%	600
	21st to end	Night	8% 2 8% 27% 42% 13%	600
July	1st to 10th	Night	4 1 5% 21% 51% 17%	585
	11th to 20th	Night	4 1 4 16% 48% 27%	582
	21st to end	Night	5% 1 4 22% 49% 19%	657
August	1st to 10th	Night	4 1 3 20% 47% 26%	597
	11th to 20th	Night	8% 1 3 18% 47% 24%	594
	21st to end	Night	8% 2 6% 19% 44% 21%	660
September	1st to 10th	Night	11% 3 8% 24% 41% 14%	600
	11th to 20th	Night	11% 3 7% 30% 42% 7%	710
	21st to end	Night	10% 3 11% 34% 36% 7%	800
October	1st to 10th	Night	10% 2 20% 35% 30% 3	800
	11th to 20th	Night	10% 5% 22% 34% 26% 3	800
	21st to end	Night	13% 6% 22% 35% 22% 2	880
November	1st to 10th	Night	13% 7% 20% 39% 19% 2	820
	11th to 20th	Night	16% 9% 25% 36% 14% 1	840
	21st to end	Night	15% 9% 28% 32% 13% 2	840
December	1st to 10th	Night	19% 13% 26% 30% 12%	809
	11th to 20th	Night	21% 9% 30% 31% 9% 1	800
	21st to end	Night	24% 11% 29% 28% 8%	880

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