Conestogo Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Conestogo Lake clear sky chart from 2005-11-06 to 2025-04-26.

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% 12% 4 10% 6% 5% 5% 4 5% 7% 28%	114155
	Night	14% 12% 5% 11% 6% 5% 5% 4 5% 6% 28%	114365
Transparency	Day	52% 7% 12% 18% 10% 1	117764
	Night	52% 7% 12% 18% 10% 1	118920
Seeing	Day	19% 12% 29% 23% 12% 5%	15508
	Night	19% 12% 30% 27% 11% 1	24694

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% 16% 9% 18% 7% 5% 4 3 3 4 19%	3435
	11th to 20th	Day	10% 21% 9% 23% 10% 10% 5% 2 3 2 6%	4026
	21st to end	Day	16% 17% 8% 20% 8% 5% 5% 4 3 4 10%	4466
February	1st to 10th	Day	14% 19% 6% 15% 10% 7% 4 3 3 3 15%	1800
	11th to 20th	Day	14% 13% 8% 17% 9% 5% 4 4 5% 6% 16%	1753
	21st to end	Day	16% 17% 6% 12% 9% 5% 5% 4 5% 5% 18%	1601
March	1st to 10th	Day	17% 12% 5% 13% 8% 4 4 2 3 5% 26%	4844
	11th to 20th	Day	11% 13% 6% 10% 6% 5% 5% 4 6% 7% 28%	4980
	21st to end	Day	17% 14% 6% 11% 5% 5% 4 3 4 5% 26%	5465
April	1st to 10th	Day	17% 16% 4 8% 5% 3 5% 4 5% 6% 27%	2305
	11th to 20th	Day	18% 12% 3 6% 4 4 5% 3 5% 7% 34%	2532
	21st to end	Day	20% 12% 4 7% 4 4 4 3 5% 7% 32%	2535
May	1st to 10th	Day	18% 9% 3 7% 5% 4 4 4 5% 8% 33%	4108
	11th to 20th	Day	17% 9% 3 8% 5% 5% 5% 4 6% 8% 31%	4225
	21st to end	Day	14% 5% 2 6% 5% 4 4 3 5% 7% 46%	4837
June	1st to 10th	Day	14% 8% 2 6% 6% 4 5% 4 6% 8% 36%	2660
	11th to 20th	Day	11% 7% 2 6% 5% 4 6% 5% 7% 8% 39%	2837
	21st to end	Day	14% 6% 3 6% 5% 5% 5% 4 7% 7% 38%	2850
July	1st to 10th	Day	11% 5% 2 6% 5% 5% 6% 6% 8% 10% 36%	4760
	11th to 20th	Day	10% 6% 2 6% 5% 5% 5% 5% 7% 9% 40%	4372
	21st to end	Day	9% 6% 2 7% 5% 5% 5% 5% 7% 9% 41%	4466
August	1st to 10th	Day	14% 7% 2 6% 5% 5% 5% 5% 7% 9% 34%	4104
	11th to 20th	Day	11% 8% 3 9% 5% 5% 5% 5% 7% 10% 31%	4044
	21st to end	Day	8% 6% 2 7% 5% 5% 6% 5% 7% 9% 39%	4446
September	1st to 10th	Day	12% 7% 2 8% 5% 4 5% 4 7% 8% 39%	2271
	11th to 20th	Day	11% 7% 2 7% 4 4 4 4 6% 9% 42%	2090
	21st to end	Day	16% 8% 3 7% 5% 6% 6% 4 6% 7% 34%	2090
October	1st to 10th	Day	17% 10% 3 8% 6% 4 5% 4 4 7% 32%	1914
	11th to 20th	Day	22% 11% 4 8% 5% 4 4 3 6% 6% 26%	1900
	21st to end	Day	24% 14% 4 8% 5% 6% 5% 4 5% 6% 18%	2066
November	1st to 10th	Day	15% 16% 3 8% 6% 4 4 4 5% 7% 28%	1732
	11th to 20th	Day	14% 17% 5% 10% 6% 4 6% 3 7% 6% 21%	1600
	21st to end	Day	17% 20% 8% 12% 7% 5% 4 4 5% 5% 14%	1600
December	1st to 10th	Day	16% 25% 9% 15% 7% 5% 4 3 4 4 9%	2600
	11th to 20th	Day	20% 20% 7% 12% 7% 4 5% 2 5% 5% 13%	2986
	21st to end	Day	25% 20% 8% 14% 6% 4 4 2 3 3 11%	3855
January	1st to 10th	Night	12% 15% 7% 19% 8% 6% 5% 3 5% 6% 15%	6474
	11th to 20th	Night	11% 14% 8% 20% 12% 8% 7% 4 5% 4 7%	5859
	21st to end	Night	14% 15% 8% 17% 7% 6% 7% 4 5% 5% 12%	6490
February	1st to 10th	Night	14% 18% 6% 13% 10% 6% 5% 3 5% 5% 16%	2600
	11th to 20th	Night	13% 13% 7% 13% 8% 6% 5% 4 6% 7% 18%	2533
	21st to end	Night	14% 14% 4 13% 7% 5% 5% 4 6% 6% 22%	2025
March	1st to 10th	Night	13% 10% 4 11% 7% 5% 5% 4 5% 6% 29%	4984
	11th to 20th	Night	9% 9% 4 11% 5% 5% 5% 4 7% 8% 33%	4979
	21st to end	Night	18% 11% 5% 9% 4 4 4 3 4 5% 34%	5467
April	1st to 10th	Night	19% 11% 4 9% 4 4 5% 3 6% 6% 29%	2095
	11th to 20th	Night	16% 11% 3 7% 4 4 3 4 5% 6% 36%	1832
	21st to end	Night	14% 10% 4 8% 6% 5% 5% 4 5% 7% 33%	1761
May	1st to 10th	Night	16% 7% 2 6% 4 4 4 3 5% 7% 41%	2833
	11th to 20th	Night	14% 10% 3 8% 5% 5% 5% 3 5% 6% 36%	2667
	21st to end	Night	9% 6% 2 5% 4 4 4 4 6% 8% 50%	2738
June	1st to 10th	Night	12% 6% 2 7% 5% 4 4 4 6% 7% 42%	1520
	11th to 20th	Night	10% 6% 2 6% 5% 3 5% 4 7% 10% 42%	1337
	21st to end	Night	12% 6% 2 6% 5% 4 4 4 5% 8% 45%	1330
July	1st to 10th	Night	6% 4 2 6% 5% 4 4 4 6% 9% 50%	2210
	11th to 20th	Night	10% 5% 2 5% 4 4 4 3 4 8% 53%	2583
	21st to end	Night	6% 6% 2 6% 5% 5% 5% 4 6% 7% 49%	3087
August	1st to 10th	Night	12% 6% 3 7% 4 4 4 3 6% 7% 45%	2825
	11th to 20th	Night	11% 7% 3 6% 4 4 5% 4 6% 8% 42%	2785
	21st to end	Night	10% 6% 2 6% 4 4 4 3 5% 7% 48%	3178
September	1st to 10th	Night	9% 7% 2 7% 5% 5% 4 4 6% 7% 46%	1905
	11th to 20th	Night	10% 6% 2 5% 4 3 3 4 4 7% 52%	2090
	21st to end	Night	16% 8% 3 6% 4 5% 4 3 5% 8% 39%	2090
October	1st to 10th	Night	15% 8% 3 8% 5% 4 4 3 6% 6% 38%	2266
	11th to 20th	Night	18% 11% 3 8% 5% 4 5% 4 5% 7% 31%	2280
	21st to end	Night	21% 12% 4 10% 5% 5% 4 4 5% 6% 25%	2528
November	1st to 10th	Night	15% 11% 4 8% 5% 4 5% 4 6% 5% 33%	2565
	11th to 20th	Night	15% 14% 5% 11% 6% 5% 5% 4 5% 6% 23%	2800
	21st to end	Night	19% 16% 5% 10% 6% 5% 4 3 7% 7% 19%	2800
December	1st to 10th	Night	14% 20% 9% 14% 7% 6% 5% 4 5% 5% 11%	4580
	11th to 20th	Night	12% 23% 8% 14% 7% 4 4 3 4 4 16%	5208
	21st to end	Night	22% 20% 9% 14% 6% 4 4 3 3 4 11%	7061

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	66% 7% 8% 10% 9% 1	3436
	11th to 20th	Day	82% 7% 6% 3 2	4060
	21st to end	Day	75% 6% 8% 6% 4	4466
February	1st to 10th	Day	72% 6% 7% 11% 3 1	1800
	11th to 20th	Day	66% 7% 9% 12% 5% 1	1762
	21st to end	Day	65% 6% 10% 12% 5% 1	1601
March	1st to 10th	Day	60% 5% 14% 13% 8% 1	4847
	11th to 20th	Day	52% 6% 15% 18% 6% 2	4980
	21st to end	Day	57% 6% 11% 16% 9% 1	5465
April	1st to 10th	Day	56% 6% 10% 17% 10% 1	2305
	11th to 20th	Day	50% 6% 11% 21% 12% 1	2532
	21st to end	Day	52% 6% 12% 18% 10% 2	2535
May	1st to 10th	Day	46% 8% 14% 19% 12% 2	4120
	11th to 20th	Day	47% 10% 15% 20% 7% 1	4229
	21st to end	Day	36% 8% 13% 21% 18% 5%	4837
June	1st to 10th	Day	43% 8% 13% 21% 14% 1	2660
	11th to 20th	Day	38% 8% 14% 24% 15% 1	2837
	21st to end	Day	42% 8% 13% 24% 13%	2850
July	1st to 10th	Day	38% 8% 15% 22% 15% 2	4686
	11th to 20th	Day	35% 7% 13% 32% 11% 1	4294
	21st to end	Day	36% 8% 14% 23% 18% 1	4324
August	1st to 10th	Day	43% 7% 14% 23% 12% 1	4091
	11th to 20th	Day	44% 9% 16% 23% 9%	4083
	21st to end	Day	38% 7% 13% 31% 10% 1	4446
September	1st to 10th	Day	40% 8% 15% 24% 11% 1	2271
	11th to 20th	Day	36% 7% 14% 28% 14% 1	2090
	21st to end	Day	47% 7% 14% 23% 9% 1	2090
October	1st to 10th	Day	44% 7% 11% 21% 16% 1	3174
	11th to 20th	Day	43% 6% 14% 21% 16%	3140
	21st to end	Day	55% 6% 14% 18% 6%	3380
November	1st to 10th	Day	53% 8% 12% 18% 7% 1	1732
	11th to 20th	Day	58% 8% 14% 12% 7% 1	1600
	21st to end	Day	67% 8% 11% 10% 3	1600
December	1st to 10th	Day	76% 7% 8% 7% 2	2600
	11th to 20th	Day	73% 5% 9% 9% 4	2986
	21st to end	Day	78% 6% 5% 6% 5%	3855
January	1st to 10th	Night	65% 8% 8% 13% 5%	6474
	11th to 20th	Night	74% 10% 7% 6% 3	5900
	21st to end	Night	70% 6% 10% 8% 5% 1	6490
February	1st to 10th	Night	67% 6% 11% 13% 3	2600
	11th to 20th	Night	61% 7% 12% 14% 6% 1	2535
	21st to end	Night	59% 7% 13% 13% 8%	2025
March	1st to 10th	Night	53% 6% 14% 16% 10% 1	4994
	11th to 20th	Night	43% 8% 18% 20% 10% 1	4980
	21st to end	Night	50% 6% 10% 17% 15% 2	5467
April	1st to 10th	Night	54% 5% 10% 16% 13% 1	2095
	11th to 20th	Night	47% 6% 9% 20% 15% 2	1832
	21st to end	Night	49% 6% 11% 18% 14% 2	1761
May	1st to 10th	Night	41% 8% 11% 19% 15% 5%	2840
	11th to 20th	Night	44% 9% 15% 19% 11% 2	2668
	21st to end	Night	29% 9% 14% 22% 22% 3	2739
June	1st to 10th	Night	38% 7% 12% 25% 17% 2	1520
	11th to 20th	Night	35% 7% 14% 25% 17% 2	1337
	21st to end	Night	37% 7% 13% 25% 17% 1	1330
July	1st to 10th	Night	28% 7% 14% 25% 20% 5%	2175
	11th to 20th	Night	31% 5% 13% 32% 18% 1	2538
	21st to end	Night	32% 9% 13% 27% 17% 2	2988
August	1st to 10th	Night	37% 6% 12% 26% 16% 2	2814
	11th to 20th	Night	36% 9% 16% 27% 12% 1	2812
	21st to end	Night	34% 7% 11% 32% 15% 1	3178
September	1st to 10th	Night	35% 8% 13% 27% 15% 2	1905
	11th to 20th	Night	30% 6% 13% 30% 20% 1	2090
	21st to end	Night	43% 7% 13% 25% 12%	2090
October	1st to 10th	Night	35% 5% 11% 25% 23% 1	3786
	11th to 20th	Night	44% 6% 14% 21% 15%	3779
	21st to end	Night	44% 6% 17% 23% 9%	4164
November	1st to 10th	Night	49% 7% 14% 20% 10% 1	2565
	11th to 20th	Night	58% 8% 14% 14% 6% 1	2800
	21st to end	Night	61% 9% 16% 11% 4	2800
December	1st to 10th	Night	72% 7% 11% 9% 1	4580
	11th to 20th	Night	71% 5% 9% 10% 5%	5208
	21st to end	Night	76% 6% 8% 7% 4	7061

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	22% 20% 35% 16% 7% 1	221
	11th to 20th	Day	20% 20% 42% 13% 4 1	300
	21st to end	Day	24% 21% 32% 20% 4 1	330
February	1st to 10th	Day	24% 23% 37% 13% 3	300
	11th to 20th	Day	24% 22% 38% 15% 1	300
	21st to end	Day	29% 25% 31% 15% 1	249
March	1st to 10th	Day	24% 14% 39% 16% 6% 1	460
	11th to 20th	Day	20% 16% 36% 21% 6% 1	500
	21st to end	Day	27% 12% 36% 20% 5% 1	550
April	1st to 10th	Day	23% 17% 34% 18% 7% 1	500
	11th to 20th	Day	27% 16% 25% 17% 10% 3	492
	21st to end	Day	26% 12% 33% 20% 7% 2	480
May	1st to 10th	Day	22% 13% 27% 24% 11% 3	463
	11th to 20th	Day	20% 8% 28% 23% 15% 5%	487
	21st to end	Day	15% 7% 25% 28% 17% 7%	529
June	1st to 10th	Day	15% 10% 27% 30% 15% 3	490
	11th to 20th	Day	13% 10% 28% 29% 17% 2	667
	21st to end	Day	16% 7% 30% 30% 13% 3	680
July	1st to 10th	Day	9% 7% 23% 30% 22% 9%	671
	11th to 20th	Day	14% 7% 23% 27% 21% 8%	533
	21st to end	Day	11% 3 25% 34% 19% 9%	532
August	1st to 10th	Day	11% 6% 21% 26% 24% 12%	486
	11th to 20th	Day	14% 4 18% 28% 20% 15%	479
	21st to end	Day	14% 6% 22% 27% 18% 12%	539
September	1st to 10th	Day	13% 8% 24% 24% 19% 13%	490
	11th to 20th	Day	9% 5% 18% 28% 24% 16%	490
	21st to end	Day	16% 12% 25% 25% 15% 7%	490
October	1st to 10th	Day	19% 12% 27% 23% 13% 6%	490
	11th to 20th	Day	20% 18% 30% 23% 6% 2	490
	21st to end	Day	29% 18% 27% 20% 5% 1	515
November	1st to 10th	Day	26% 20% 28% 17% 8% 1	285
	11th to 20th	Day	23% 18% 37% 17% 4 3	200
	21st to end	Day	21% 24% 37% 15% 5%	200
December	1st to 10th	Day	27% 26% 30% 13% 5%	200
	11th to 20th	Day	28% 25% 31% 14% 3	200
	21st to end	Day	32% 19% 34% 12% 2	220
January	1st to 10th	Night	22% 19% 37% 17% 5% 1	906
	11th to 20th	Night	26% 16% 33% 21% 4	800
	21st to end	Night	19% 12% 40% 23% 6%	880
February	1st to 10th	Night	23% 17% 38% 21% 2	800
	11th to 20th	Night	21% 16% 36% 22% 5%	783
	21st to end	Night	22% 17% 36% 23% 3	660
March	1st to 10th	Night	17% 16% 38% 21% 7%	800
	11th to 20th	Night	16% 20% 37% 21% 6%	800
	21st to end	Night	22% 13% 31% 25% 9%	880
April	1st to 10th	Night	24% 16% 32% 25% 4	800
	11th to 20th	Night	22% 13% 31% 23% 9% 1	648
	21st to end	Night	18% 13% 30% 31% 8%	587
May	1st to 10th	Night	17% 6% 32% 30% 14% 1	570
	11th to 20th	Night	18% 4 30% 36% 11% 1	481
	21st to end	Night	11% 4 27% 40% 18%	411
June	1st to 10th	Night	13% 5% 29% 39% 13% 1	380
	11th to 20th	Night	11% 6% 30% 40% 13%	380
	21st to end	Night	15% 4 27% 41% 13% 1	380
July	1st to 10th	Night	5% 3 19% 49% 23% 1	370
	11th to 20th	Night	10% 2 24% 38% 24% 2	446
	21st to end	Night	9% 3 20% 47% 21% 1	624
August	1st to 10th	Night	11% 3 15% 43% 26% 2	567
	11th to 20th	Night	8% 3 19% 38% 29% 4	564
	21st to end	Night	11% 5% 20% 33% 27% 3	655
September	1st to 10th	Night	12% 5% 23% 34% 21% 4	760
	11th to 20th	Night	10% 4 22% 33% 26% 5%	760
	21st to end	Night	18% 8% 23% 30% 18% 4	760
October	1st to 10th	Night	19% 8% 28% 29% 15% 2	760
	11th to 20th	Night	22% 14% 27% 26% 10% 1	760
	21st to end	Night	26% 11% 32% 25% 5%	836
November	1st to 10th	Night	22% 12% 29% 28% 8% 1	780
	11th to 20th	Night	21% 16% 34% 21% 7% 1	800
	21st to end	Night	26% 16% 32% 23% 4	800
December	1st to 10th	Night	26% 19% 33% 18% 5%	800
	11th to 20th	Night	22% 20% 37% 17% 3	800
	21st to end	Night	28% 16% 36% 18% 2	906

Page generated at 2025-04-23 09:25:08. Version ac07

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