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 2026-08-30.

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	14% 11% 4 10% 6% 5% 5% 4 5% 7% 30%	144744
	Night	13% 12% 5% 11% 6% 5% 5% 4 5% 6% 29%	137370
Transparency	Day	51% 6% 12% 19% 11% 1	148310
	Night	52% 6% 11% 18% 11% 1	141893
Seeing	Day	19% 13% 29% 23% 12% 5%	17353
	Night	19% 12% 30% 27% 11% 1	26275

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	14% 16% 9% 18% 7% 5% 4 3 3 4 15%	4451
	11th to 20th	Day	9% 21% 11% 24% 11% 10% 4 2 2 2 5%	5246
	21st to end	Day	13% 15% 7% 19% 10% 9% 6% 4 4 5% 9%	5780
February	1st to 10th	Day	14% 19% 6% 15% 10% 7% 4 3 3 3 15%	1890
	11th to 20th	Day	14% 12% 8% 17% 9% 5% 5% 4 5% 5% 16%	1843
	21st to end	Day	15% 17% 6% 12% 9% 5% 5% 4 5% 5% 18%	1679
March	1st to 10th	Day	17% 12% 5% 13% 8% 4 3 2 4 5% 26%	4952
	11th to 20th	Day	11% 13% 6% 10% 6% 5% 5% 4 6% 7% 27%	5090
	21st to end	Day	17% 14% 6% 11% 5% 5% 4 3 4 5% 26%	5586
April	1st to 10th	Day	17% 16% 4 8% 5% 3 5% 4 5% 6% 27%	2420
	11th to 20th	Day	19% 11% 3 7% 4 4 4 3 4 7% 33%	2660
	21st to end	Day	19% 12% 4 7% 4 4 4 3 5% 7% 32%	2730
May	1st to 10th	Day	16% 9% 3 8% 5% 5% 5% 4 5% 8% 33%	7642
	11th to 20th	Day	14% 10% 3 8% 4 5% 5% 4 6% 8% 33%	7882
	21st to end	Day	17% 7% 2 6% 4 4 4 3 5% 6% 42%	9060
June	1st to 10th	Day	13% 8% 2 6% 6% 4 5% 4 6% 8% 37%	2940
	11th to 20th	Day	11% 7% 2 7% 5% 4 6% 5% 7% 8% 38%	3136
	21st to end	Day	14% 6% 3 6% 5% 5% 4 4 7% 7% 38%	3150
July	1st to 10th	Day	10% 6% 3 7% 4 5% 5% 5% 7% 10% 38%	8879
	11th to 20th	Day	7% 5% 2 6% 4 5% 5% 4 7% 10% 45%	8170
	21st to end	Day	8% 5% 2 6% 4 5% 5% 4 6% 9% 45%	8340
August	1st to 10th	Day	14% 7% 2 6% 5% 5% 5% 5% 6% 9% 35%	4364
	11th to 20th	Day	11% 8% 3 9% 5% 5% 5% 5% 7% 10% 32%	4304
	21st to end	Day	9% 6% 2 7% 5% 5% 6% 5% 7% 10% 39%	4703
September	1st to 10th	Day	11% 6% 2 8% 5% 4 5% 4 7% 8% 39%	2390
	11th to 20th	Day	11% 7% 2 6% 4 4 4 4 6% 9% 43%	2200
	21st to end	Day	16% 8% 3 7% 5% 6% 6% 4 6% 7% 34%	2200
October	1st to 10th	Day	17% 9% 3 7% 6% 4 5% 4 4 7% 34%	2015
	11th to 20th	Day	21% 11% 4 8% 5% 4 4 3 7% 6% 27%	2000
	21st to end	Day	23% 14% 4 9% 5% 6% 5% 4 5% 6% 18%	2175
November	1st to 10th	Day	16% 16% 3 8% 6% 4 4 4 4 6% 28%	1820
	11th to 20th	Day	13% 17% 5% 10% 6% 4 6% 3 7% 6% 22%	1680
	21st to end	Day	16% 21% 8% 12% 7% 5% 4 4 5% 5% 14%	1680
December	1st to 10th	Day	16% 25% 9% 15% 7% 5% 4 3 4 4 9%	2680
	11th to 20th	Day	20% 20% 7% 13% 8% 4 5% 3 5% 5% 13%	3066
	21st to end	Day	25% 20% 8% 14% 6% 4 4 2 3 3 11%	3941
January	1st to 10th	Night	12% 15% 8% 20% 9% 6% 5% 3 5% 5% 13%	8399
	11th to 20th	Night	9% 18% 9% 20% 12% 7% 6% 4 4 3 7%	7639
	21st to end	Night	12% 13% 7% 16% 11% 7% 8% 4 5% 5% 11%	8401
February	1st to 10th	Night	13% 18% 6% 13% 10% 6% 5% 3 5% 5% 17%	2730
	11th to 20th	Night	13% 13% 6% 13% 7% 6% 5% 4 6% 7% 19%	2663
	21st to end	Night	13% 14% 5% 13% 7% 6% 5% 4 6% 6% 22%	2123
March	1st to 10th	Night	13% 10% 4 11% 7% 5% 5% 4 5% 6% 29%	5096
	11th to 20th	Night	9% 9% 4 11% 5% 5% 5% 4 7% 8% 32%	5089
	21st to end	Night	18% 11% 5% 9% 4 4 4 3 4 5% 33%	5588
April	1st to 10th	Night	19% 11% 4 9% 5% 4 5% 3 6% 6% 29%	2200
	11th to 20th	Night	16% 11% 3 7% 4 4 4 4 5% 6% 36%	1925
	21st to end	Night	14% 10% 4 8% 6% 5% 5% 3 5% 7% 33%	1890
May	1st to 10th	Night	17% 8% 3 6% 4 4 4 3 5% 7% 38%	5257
	11th to 20th	Night	14% 10% 3 8% 5% 4 4 3 5% 6% 39%	4963
	21st to end	Night	17% 6% 2 5% 3 3 4 3 5% 7% 46%	5114
June	1st to 10th	Night	12% 6% 2 6% 4 4 4 4 6% 7% 44%	1680
	11th to 20th	Night	10% 6% 3 6% 5% 4 5% 4 7% 10% 41%	1477
	21st to end	Night	11% 6% 2 6% 5% 4 4 4 5% 8% 45%	1470
July	1st to 10th	Night	7% 5% 2 6% 5% 4 4 4 6% 9% 47%	4110
	11th to 20th	Night	8% 5% 2 5% 5% 4 4 3 5% 8% 50%	4777
	21st to end	Night	8% 6% 2 6% 4 4 4 4 5% 6% 50%	5737
August	1st to 10th	Night	11% 6% 3 7% 4 4 4 3 6% 7% 45%	3005
	11th to 20th	Night	11% 7% 3 6% 4 4 5% 4 6% 8% 42%	2965
	21st to end	Night	10% 6% 2 6% 4 4 5% 4 5% 7% 47%	3360
September	1st to 10th	Night	8% 7% 2 7% 5% 5% 4 4 6% 6% 46%	2005
	11th to 20th	Night	9% 5% 2 5% 4 3 3 4 4 7% 54%	2200
	21st to end	Night	16% 8% 3 6% 4 5% 4 3 5% 7% 39%	2200
October	1st to 10th	Night	15% 8% 3 8% 4 4 4 3 6% 6% 39%	2385
	11th to 20th	Night	18% 11% 3 8% 5% 4 4 4 4 7% 31%	2400
	21st to end	Night	20% 12% 4 9% 5% 5% 4 4 5% 6% 26%	2661
November	1st to 10th	Night	15% 11% 4 8% 5% 4 5% 4 6% 5% 33%	2697
	11th to 20th	Night	15% 14% 5% 11% 6% 5% 5% 4 5% 6% 22%	2940
	21st to end	Night	19% 16% 6% 10% 6% 5% 4 3 6% 7% 18%	2940
December	1st to 10th	Night	14% 20% 9% 15% 7% 6% 5% 4 5% 5% 12%	4720
	11th to 20th	Night	12% 23% 8% 14% 7% 4 4 3 4 4 16%	5348
	21st to end	Night	22% 20% 9% 14% 6% 4 4 3 3 4 12%	7216

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	70% 6% 7% 8% 8%	4452
	11th to 20th	Day	85% 5% 5% 3 2	5280
	21st to end	Day	75% 6% 8% 6% 5%	5780
February	1st to 10th	Day	72% 6% 7% 11% 4	1890
	11th to 20th	Day	66% 7% 9% 12% 5% 1	1852
	21st to end	Day	65% 6% 11% 12% 5% 1	1679
March	1st to 10th	Day	60% 5% 14% 13% 8% 1	4955
	11th to 20th	Day	53% 6% 15% 18% 6% 2	5090
	21st to end	Day	58% 6% 11% 16% 9% 1	5586
April	1st to 10th	Day	56% 6% 10% 17% 10% 1	2420
	11th to 20th	Day	51% 6% 11% 21% 11% 1	2660
	21st to end	Day	52% 5% 12% 19% 10% 2	2730
May	1st to 10th	Day	47% 6% 13% 19% 11% 4	7651
	11th to 20th	Day	47% 7% 12% 19% 14% 1	7886
	21st to end	Day	41% 6% 9% 25% 16% 3	9061
June	1st to 10th	Day	42% 8% 12% 21% 16% 1	2940
	11th to 20th	Day	39% 8% 14% 23% 14% 1	3136
	21st to end	Day	41% 7% 13% 25% 13%	3150
July	1st to 10th	Day	39% 7% 14% 24% 15% 1	8806
	11th to 20th	Day	31% 6% 12% 34% 15% 1	8092
	21st to end	Day	34% 7% 14% 27% 18% 1	8156
August	1st to 10th	Day	42% 7% 14% 23% 12% 1	4351
	11th to 20th	Day	43% 9% 15% 24% 9%	4343
	21st to end	Day	38% 7% 13% 31% 10% 1	4703
September	1st to 10th	Day	40% 8% 15% 25% 11% 1	2390
	11th to 20th	Day	35% 7% 14% 29% 14% 1	2200
	21st to end	Day	47% 7% 14% 22% 9% 1	2200
October	1st to 10th	Day	43% 7% 11% 22% 16% 1	3275
	11th to 20th	Day	42% 6% 14% 22% 16%	3240
	21st to end	Day	55% 6% 14% 18% 7%	3489
November	1st to 10th	Day	54% 8% 12% 19% 7% 1	1820
	11th to 20th	Day	58% 7% 14% 13% 7% 1	1680
	21st to end	Day	68% 8% 11% 10% 3	1680
December	1st to 10th	Day	76% 6% 8% 8% 2	2680
	11th to 20th	Day	73% 5% 9% 9% 4	3066
	21st to end	Day	78% 6% 5% 6% 5%	3941
January	1st to 10th	Night	68% 8% 8% 12% 4	8399
	11th to 20th	Night	76% 8% 6% 6% 3	7680
	21st to end	Night	70% 6% 10% 8% 6%	8401
February	1st to 10th	Night	66% 6% 11% 13% 4 1	2730
	11th to 20th	Night	60% 7% 12% 15% 6% 1	2665
	21st to end	Night	60% 6% 13% 13% 7%	2123
March	1st to 10th	Night	53% 6% 14% 16% 10% 1	5106
	11th to 20th	Night	44% 8% 18% 20% 9% 1	5090
	21st to end	Night	51% 6% 10% 17% 14% 2	5588
April	1st to 10th	Night	54% 5% 10% 16% 13% 1	2200
	11th to 20th	Night	47% 6% 9% 20% 15% 2	1925
	21st to end	Night	48% 6% 11% 19% 15% 2	1890
May	1st to 10th	Night	45% 6% 11% 17% 15% 6%	5264
	11th to 20th	Night	45% 8% 12% 20% 14% 2	4964
	21st to end	Night	37% 6% 10% 25% 19% 2	5115
June	1st to 10th	Night	37% 6% 11% 25% 18% 2	1680
	11th to 20th	Night	36% 7% 14% 25% 16% 2	1477
	21st to end	Night	37% 7% 13% 25% 17% 1	1470
July	1st to 10th	Night	31% 7% 16% 26% 16% 3	4075
	11th to 20th	Night	32% 4 10% 31% 20% 2	4732
	21st to end	Night	32% 7% 10% 27% 22% 2	5606
August	1st to 10th	Night	37% 6% 13% 26% 16% 2	2994
	11th to 20th	Night	36% 8% 16% 27% 12% 1	2992
	21st to end	Night	34% 7% 11% 32% 14% 1	3360
September	1st to 10th	Night	35% 8% 13% 29% 14% 1	2005
	11th to 20th	Night	29% 6% 13% 31% 20% 1	2200
	21st to end	Night	43% 7% 13% 25% 12%	2200
October	1st to 10th	Night	34% 5% 10% 26% 24% 1	3905
	11th to 20th	Night	44% 6% 14% 20% 15%	3899
	21st to end	Night	44% 6% 17% 23% 9%	4297
November	1st to 10th	Night	49% 7% 13% 20% 10% 1	2697
	11th to 20th	Night	58% 7% 14% 14% 6% 1	2940
	21st to end	Night	62% 8% 15% 11% 4	2940
December	1st to 10th	Night	72% 7% 11% 9% 2	4720
	11th to 20th	Night	70% 5% 9% 10% 6%	5348
	21st to end	Night	76% 6% 7% 7% 4	7216

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	23% 20% 36% 14% 6% 1	243
	11th to 20th	Day	21% 22% 41% 12% 3 1	330
	21st to end	Day	24% 20% 32% 19% 4 1	363
February	1st to 10th	Day	23% 22% 35% 15% 4	330
	11th to 20th	Day	23% 22% 38% 16% 1	330
	21st to end	Day	27% 26% 32% 14% 1	273
March	1st to 10th	Day	25% 14% 39% 16% 6% 1	498
	11th to 20th	Day	22% 18% 34% 20% 6% 1	540
	21st to end	Day	27% 13% 36% 19% 4 1	594
April	1st to 10th	Day	24% 18% 33% 18% 6% 1	540
	11th to 20th	Day	28% 17% 24% 17% 10% 3	532
	21st to end	Day	26% 12% 34% 21% 7% 1	540
May	1st to 10th	Day	21% 13% 30% 23% 10% 3	543
	11th to 20th	Day	19% 11% 28% 23% 14% 5%	567
	21st to end	Day	17% 9% 28% 26% 15% 6%	617
June	1st to 10th	Day	14% 10% 29% 31% 14% 2	570
	11th to 20th	Day	13% 11% 30% 28% 15% 2	766
	21st to end	Day	15% 7% 30% 32% 13% 3	780
July	1st to 10th	Day	9% 8% 24% 30% 21% 8%	771
	11th to 20th	Day	13% 7% 24% 29% 20% 7%	619
	21st to end	Day	10% 3 26% 34% 19% 8%	620
August	1st to 10th	Day	11% 6% 20% 27% 24% 11%	566
	11th to 20th	Day	13% 4 21% 29% 19% 14%	559
	21st to end	Day	15% 6% 22% 28% 18% 11%	619
September	1st to 10th	Day	13% 8% 24% 23% 19% 14%	530
	11th to 20th	Day	9% 5% 17% 27% 26% 16%	530
	21st to end	Day	16% 11% 24% 26% 15% 7%	530
October	1st to 10th	Day	18% 11% 27% 23% 15% 6%	530
	11th to 20th	Day	20% 18% 32% 23% 5% 2	530
	21st to end	Day	28% 18% 29% 20% 5% 1	558
November	1st to 10th	Day	27% 21% 27% 17% 8% 1	313
	11th to 20th	Day	24% 18% 35% 16% 4 2	220
	21st to end	Day	21% 25% 35% 15% 4	220
December	1st to 10th	Day	26% 25% 30% 14% 5%	220
	11th to 20th	Day	28% 25% 31% 13% 3	220
	21st to end	Day	32% 20% 33% 12% 2	242
January	1st to 10th	Night	22% 19% 37% 17% 5% 1	951
	11th to 20th	Night	25% 17% 34% 20% 3	840
	21st to end	Night	19% 12% 40% 23% 6%	924
February	1st to 10th	Night	22% 17% 38% 21% 2	840
	11th to 20th	Night	21% 16% 36% 22% 5%	823
	21st to end	Night	21% 18% 36% 23% 2	692
March	1st to 10th	Night	17% 16% 37% 22% 7%	840
	11th to 20th	Night	17% 20% 37% 21% 6%	840
	21st to end	Night	21% 14% 32% 24% 9%	924
April	1st to 10th	Night	23% 16% 33% 24% 4	840
	11th to 20th	Night	22% 13% 31% 23% 9% 1	681
	21st to end	Night	17% 13% 29% 32% 8%	630
May	1st to 10th	Night	17% 7% 32% 30% 13% 1	630
	11th to 20th	Night	19% 4 30% 35% 11% 1	532
	21st to end	Night	13% 5% 28% 38% 16%	455
June	1st to 10th	Night	13% 5% 30% 39% 12% 1	420
	11th to 20th	Night	11% 7% 30% 40% 12%	420
	21st to end	Night	14% 4 27% 43% 12% 1	420
July	1st to 10th	Night	5% 3 18% 51% 22% 1	410
	11th to 20th	Night	10% 2 24% 39% 23% 1	494
	21st to end	Night	9% 3 20% 46% 20% 1	690
August	1st to 10th	Night	11% 3 15% 42% 26% 2	627
	11th to 20th	Night	8% 3 19% 40% 27% 3	624
	21st to end	Night	11% 5% 21% 33% 27% 3	717
September	1st to 10th	Night	12% 5% 23% 34% 22% 4	800
	11th to 20th	Night	10% 4 21% 33% 27% 5%	800
	21st to end	Night	18% 8% 22% 31% 17% 4	800
October	1st to 10th	Night	18% 8% 27% 30% 16% 2	800
	11th to 20th	Night	22% 14% 28% 26% 10% 1	800
	21st to end	Night	26% 11% 32% 25% 5%	880
November	1st to 10th	Night	22% 12% 30% 27% 8% 1	820
	11th to 20th	Night	21% 16% 34% 21% 7% 1	840
	21st to end	Night	26% 16% 32% 22% 4	840
December	1st to 10th	Night	25% 18% 33% 19% 5%	840
	11th to 20th	Night	21% 20% 38% 17% 3	840
	21st to end	Night	28% 16% 36% 17% 2	951

Page generated at 2026-08-27 04:07:16. Version ac07

Copyright © 2026 Attilla Danko.