Goderich
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Goderich clear sky chart from 2005-11-06 to 2025-10-19.

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% 5% 10% 5% 4 4 3 5% 6% 32%	126532
	Night	16% 15% 5% 11% 5% 4 4 3 4 5% 27%	123239
Transparency	Day	52% 7% 12% 19% 10% 1	130084
	Night	57% 6% 10% 16% 9% 1	127775
Seeing	Day	19% 11% 27% 25% 14% 4	16458
	Night	22% 11% 27% 27% 11% 1	25703

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	13% 22% 12% 29% 5% 3 2 1 2 3 7%	3414
	11th to 20th	Day	10% 23% 12% 28% 13% 5% 2 1 1 1 4	3738
	21st to end	Day	16% 19% 9% 24% 8% 6% 4 2 3 2 7%	4466
February	1st to 10th	Day	15% 20% 6% 17% 9% 5% 3 3 3 4 15%	1800
	11th to 20th	Day	14% 15% 9% 19% 9% 5% 4 2 3 4 15%	1763
	21st to end	Day	15% 19% 5% 12% 6% 5% 4 3 4 4 22%	1650
March	1st to 10th	Day	16% 12% 7% 13% 7% 3 4 2 4 5% 27%	4748
	11th to 20th	Day	13% 15% 6% 9% 4 4 3 3 6% 8% 29%	4980
	21st to end	Day	19% 14% 7% 10% 5% 4 4 3 4 5% 26%	5465
April	1st to 10th	Day	17% 15% 5% 8% 4 4 4 2 5% 6% 30%	2288
	11th to 20th	Day	18% 10% 3 6% 4 4 3 3 5% 7% 36%	2572
	21st to end	Day	19% 9% 4 6% 4 3 4 3 5% 6% 36%	2600
May	1st to 10th	Day	17% 8% 3 7% 4 4 4 4 5% 7% 36%	5888
	11th to 20th	Day	15% 9% 3 7% 4 4 4 4 5% 8% 38%	5893
	21st to end	Day	19% 8% 2 5% 3 3 3 3 4 7% 43%	6949
June	1st to 10th	Day	12% 6% 2 6% 5% 5% 4 4 6% 9% 40%	2915
	11th to 20th	Day	11% 6% 2 6% 4 4 5% 5% 6% 9% 42%	3000
	21st to end	Day	15% 6% 2 5% 4 4 4 4 6% 8% 43%	3000
July	1st to 10th	Day	11% 7% 2 6% 4 4 5% 3 6% 9% 42%	6819
	11th to 20th	Day	11% 5% 2 5% 3 4 4 3 5% 8% 50%	6333
	21st to end	Day	8% 5% 2 5% 3 4 4 4 6% 9% 49%	6424
August	1st to 10th	Day	11% 6% 2 6% 4 5% 5% 4 7% 9% 41%	4234
	11th to 20th	Day	11% 6% 2 6% 4 5% 5% 5% 7% 10% 38%	4174
	21st to end	Day	9% 5% 2 6% 5% 5% 5% 4 6% 8% 45%	4658
September	1st to 10th	Day	12% 6% 3 6% 5% 4 4 4 5% 8% 42%	2322
	11th to 20th	Day	12% 5% 2 5% 4 4 4 3 5% 8% 47%	2200
	21st to end	Day	17% 7% 3 6% 4 4 5% 4 6% 8% 35%	2200
October	1st to 10th	Day	18% 8% 3 6% 4 4 4 4 5% 6% 38%	2057
	11th to 20th	Day	24% 14% 3 8% 5% 4 4 3 5% 7% 23%	1980
	21st to end	Day	29% 15% 4 8% 5% 5% 4 3 4 6% 18%	2009
November	1st to 10th	Day	19% 18% 4 7% 5% 4 4 4 4 5% 26%	1762
	11th to 20th	Day	19% 21% 5% 10% 5% 4 4 3 5% 5% 19%	1640
	21st to end	Day	20% 29% 7% 9% 5% 3 3 3 4 3 12%	1600
December	1st to 10th	Day	17% 37% 12% 13% 5% 3 3 2 2 2 5%	2600
	11th to 20th	Day	22% 25% 9% 18% 6% 3 3 2 3 3 8%	2915
	21st to end	Day	27% 22% 8% 13% 5% 4 4 2 4 4 9%	3476
January	1st to 10th	Night	14% 22% 11% 30% 6% 4 2 2 2 2 6%	6550
	11th to 20th	Night	13% 22% 12% 24% 12% 4 3 2 2 2 5%	6155
	21st to end	Night	16% 19% 9% 20% 7% 9% 4 2 3 3 9%	6490
February	1st to 10th	Night	16% 21% 5% 16% 10% 5% 4 3 3 3 15%	2600
	11th to 20th	Night	15% 17% 7% 17% 8% 5% 4 3 4 5% 15%	2520
	21st to end	Night	15% 16% 6% 14% 6% 4 5% 3 5% 4 22%	1980
March	1st to 10th	Night	15% 13% 4 9% 6% 4 4 3 4 6% 30%	5092
	11th to 20th	Night	10% 13% 5% 8% 5% 4 4 4 6% 8% 32%	4979
	21st to end	Night	20% 10% 5% 10% 5% 4 4 3 4 4 31%	5467
April	1st to 10th	Night	21% 13% 4 8% 4 4 3 4 5% 5% 30%	2130
	11th to 20th	Night	19% 10% 3 7% 4 4 4 4 5% 6% 36%	1777
	21st to end	Night	17% 12% 4 7% 5% 4 3 4 5% 5% 33%	1800
May	1st to 10th	Night	18% 9% 3 7% 4 4 4 3 5% 7% 37%	4053
	11th to 20th	Night	15% 9% 3 9% 5% 4 4 3 4 5% 39%	3996
	21st to end	Night	19% 7% 2 4 3 3 4 3 4 7% 44%	3926
June	1st to 10th	Night	14% 6% 3 6% 5% 4 4 3 5% 7% 42%	1480
	11th to 20th	Night	11% 6% 2 8% 4 3 5% 4 8% 10% 39%	1400
	21st to end	Night	13% 6% 2 6% 5% 5% 4 3 5% 8% 45%	1400
July	1st to 10th	Night	8% 7% 3 7% 5% 3 5% 4 7% 8% 44%	3160
	11th to 20th	Night	11% 5% 2 5% 3 4 5% 4 4 7% 50%	3625
	21st to end	Night	9% 6% 2 5% 4 4 4 4 6% 7% 49%	4428
August	1st to 10th	Night	11% 6% 2 6% 5% 4 5% 4 5% 7% 46%	2915
	11th to 20th	Night	13% 7% 2 6% 3 4 4 4 6% 8% 43%	2875
	21st to end	Night	11% 6% 2 6% 4 4 4 3 6% 6% 47%	3223
September	1st to 10th	Night	12% 5% 3 7% 4 4 4 4 6% 7% 46%	2058
	11th to 20th	Night	12% 5% 2 5% 3 4 3 3 5% 7% 53%	2200
	21st to end	Night	18% 8% 2 7% 5% 4 4 3 5% 7% 38%	2200
October	1st to 10th	Night	18% 7% 3 7% 5% 3 3 2 5% 7% 40%	2341
	11th to 20th	Night	27% 11% 3 7% 5% 4 5% 3 3 5% 26%	2377
	21st to end	Night	28% 14% 3 8% 5% 4 4 3 4 5% 21%	2588
November	1st to 10th	Night	20% 17% 3 8% 4 4 4 3 4 5% 28%	2536
	11th to 20th	Night	19% 24% 5% 9% 5% 4 3 3 4 5% 18%	2759
	21st to end	Night	23% 27% 7% 10% 4 4 3 2 3 4 13%	2800
December	1st to 10th	Night	15% 33% 13% 13% 6% 4 3 2 2 2 6%	4580
	11th to 20th	Night	16% 29% 9% 17% 6% 3 3 2 3 3 10%	5277
	21st to end	Night	23% 23% 8% 13% 5% 4 4 3 4 4 9%	7502

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	82% 8% 6% 3 1	3415
	11th to 20th	Day	91% 3 3 1 1	3770
	21st to end	Day	84% 6% 6% 3 1	4466
February	1st to 10th	Day	74% 6% 8% 10% 2	1800
	11th to 20th	Day	74% 6% 7% 10% 3 1	1772
	21st to end	Day	64% 7% 11% 12% 5%	1650
March	1st to 10th	Day	60% 4 16% 14% 5%	4751
	11th to 20th	Day	52% 7% 14% 19% 6% 2	4980
	21st to end	Day	58% 7% 12% 14% 8% 1	5465
April	1st to 10th	Day	55% 6% 12% 17% 9%	2288
	11th to 20th	Day	46% 7% 12% 21% 13% 1	2572
	21st to end	Day	47% 7% 13% 18% 12% 2	2600
May	1st to 10th	Day	45% 7% 13% 17% 12% 5%	5897
	11th to 20th	Day	43% 10% 12% 19% 14% 2	5897
	21st to end	Day	42% 6% 11% 20% 17% 5%	6949
June	1st to 10th	Day	41% 7% 13% 24% 14% 2	2915
	11th to 20th	Day	36% 7% 14% 25% 16% 1	3000
	21st to end	Day	39% 7% 14% 25% 14% 1	3000
July	1st to 10th	Day	37% 6% 15% 23% 18% 1	6746
	11th to 20th	Day	32% 6% 12% 33% 16% 1	6256
	21st to end	Day	30% 7% 15% 30% 18% 1	6240
August	1st to 10th	Day	38% 8% 15% 24% 14% 1	4221
	11th to 20th	Day	38% 8% 18% 26% 9%	4213
	21st to end	Day	35% 7% 15% 30% 13% 1	4658
September	1st to 10th	Day	38% 7% 17% 25% 11% 2	2322
	11th to 20th	Day	34% 7% 16% 29% 13% 1	2200
	21st to end	Day	45% 9% 13% 22% 10%	2200
October	1st to 10th	Day	42% 6% 12% 26% 12% 2	3343
	11th to 20th	Day	47% 7% 12% 24% 10%	3220
	21st to end	Day	58% 7% 14% 16% 4	3285
November	1st to 10th	Day	59% 8% 9% 17% 7% 1	1762
	11th to 20th	Day	66% 8% 10% 9% 6% 1	1640
	21st to end	Day	77% 6% 8% 8% 1	1600
December	1st to 10th	Day	87% 5% 4 3 1	2600
	11th to 20th	Day	82% 5% 6% 6% 1	2915
	21st to end	Day	80% 6% 7% 6% 1	3476
January	1st to 10th	Night	82% 7% 5% 4 1	6550
	11th to 20th	Night	88% 4 4 2 1	6198
	21st to end	Night	80% 6% 7% 4 2	6490
February	1st to 10th	Night	75% 6% 7% 10% 2	2600
	11th to 20th	Night	71% 7% 10% 10% 3	2522
	21st to end	Night	63% 7% 11% 13% 6%	1980
March	1st to 10th	Night	55% 6% 14% 17% 7% 1	5102
	11th to 20th	Night	47% 7% 17% 20% 8% 1	4980
	21st to end	Night	54% 7% 12% 16% 10% 1	5467
April	1st to 10th	Night	55% 6% 9% 18% 12% 1	2130
	11th to 20th	Night	48% 7% 9% 18% 16% 2	1777
	21st to end	Night	50% 6% 9% 17% 16% 3	1800
May	1st to 10th	Night	46% 6% 11% 15% 14% 7%	4060
	11th to 20th	Night	45% 8% 11% 19% 15% 2	3997
	21st to end	Night	39% 8% 10% 24% 16% 3	3927
June	1st to 10th	Night	40% 6% 11% 24% 16% 3	1480
	11th to 20th	Night	38% 6% 12% 25% 16% 3	1400
	21st to end	Night	38% 6% 12% 25% 18% 2	1400
July	1st to 10th	Night	36% 6% 13% 23% 18% 4	3125
	11th to 20th	Night	33% 6% 11% 28% 20% 2	3579
	21st to end	Night	34% 7% 10% 26% 22% 2	4297
August	1st to 10th	Night	38% 7% 11% 27% 16% 1	2904
	11th to 20th	Night	38% 7% 14% 25% 15% 1	2902
	21st to end	Night	35% 7% 11% 33% 13% 1	3223
September	1st to 10th	Night	36% 8% 12% 27% 14% 2	2058
	11th to 20th	Night	31% 6% 15% 27% 19% 1	2200
	21st to end	Night	45% 8% 13% 22% 12% 1	2200
October	1st to 10th	Night	37% 7% 9% 26% 20% 1	3835
	11th to 20th	Night	50% 7% 13% 20% 10%	3876
	21st to end	Night	53% 6% 14% 20% 7%	4262
November	1st to 10th	Night	57% 7% 10% 17% 8%	2536
	11th to 20th	Night	68% 6% 10% 11% 4 1	2759
	21st to end	Night	75% 6% 9% 8% 2	2800
December	1st to 10th	Night	85% 5% 6% 3 1	4580
	11th to 20th	Night	80% 7% 6% 6% 1	5277
	21st to end	Night	78% 6% 8% 6% 2	7502

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% 21% 33% 16% 5% 1	257
	11th to 20th	Day	22% 22% 37% 13% 4 1	300
	21st to end	Day	24% 16% 36% 19% 4	330
February	1st to 10th	Day	25% 25% 36% 12% 3	300
	11th to 20th	Day	21% 21% 45% 11% 2	300
	21st to end	Day	24% 26% 34% 14% 2	249
March	1st to 10th	Day	23% 16% 37% 18% 5% 1	415
	11th to 20th	Day	22% 15% 29% 26% 8% 1	500
	21st to end	Day	27% 14% 30% 22% 6% 1	550
April	1st to 10th	Day	24% 16% 32% 20% 8% 1	500
	11th to 20th	Day	26% 14% 23% 22% 9% 5%	492
	21st to end	Day	24% 9% 32% 24% 9% 2	500
May	1st to 10th	Day	18% 12% 28% 27% 12% 3	503
	11th to 20th	Day	18% 8% 24% 26% 19% 6%	527
	21st to end	Day	17% 6% 23% 28% 20% 6%	573
June	1st to 10th	Day	13% 6% 30% 31% 17% 3	645
	11th to 20th	Day	12% 6% 29% 32% 16% 4	730
	21st to end	Day	16% 6% 23% 37% 15% 4	730
July	1st to 10th	Day	9% 5% 20% 33% 24% 8%	721
	11th to 20th	Day	13% 4 24% 31% 22% 7%	692
	21st to end	Day	10% 3 21% 36% 22% 7%	576
August	1st to 10th	Day	10% 3 20% 31% 26% 11%	526
	11th to 20th	Day	12% 4 17% 32% 23% 12%	519
	21st to end	Day	15% 5% 19% 32% 23% 8%	583
September	1st to 10th	Day	12% 8% 21% 27% 23% 9%	530
	11th to 20th	Day	9% 5% 16% 26% 29% 15%	530
	21st to end	Day	19% 9% 23% 24% 19% 6%	530
October	1st to 10th	Day	20% 10% 25% 24% 17% 5%	530
	11th to 20th	Day	27% 15% 29% 22% 6% 1	522
	21st to end	Day	31% 18% 29% 17% 5% 1	458
November	1st to 10th	Day	25% 20% 30% 17% 9% 1	300
	11th to 20th	Day	29% 22% 29% 15% 4 1	220
	21st to end	Day	29% 22% 34% 14% 2	200
December	1st to 10th	Day	29% 28% 26% 15% 3 1	200
	11th to 20th	Day	29% 26% 29% 13% 3 1	200
	21st to end	Day	36% 16% 35% 11% 1	220
January	1st to 10th	Night	24% 19% 33% 18% 5% 1	1000
	11th to 20th	Night	27% 19% 31% 18% 5%	929
	21st to end	Night	22% 14% 35% 24% 5%	880
February	1st to 10th	Night	27% 15% 33% 22% 3	800
	11th to 20th	Night	23% 17% 33% 22% 5% 1	783
	21st to end	Night	23% 15% 37% 20% 4	660
March	1st to 10th	Night	20% 13% 35% 23% 8%	800
	11th to 20th	Night	20% 16% 34% 24% 7% 1	800
	21st to end	Night	24% 9% 28% 29% 8% 1	880
April	1st to 10th	Night	25% 13% 29% 27% 5%	790
	11th to 20th	Night	22% 10% 29% 27% 11% 1	593
	21st to end	Night	23% 11% 26% 29% 10% 1	600
May	1st to 10th	Night	20% 5% 27% 33% 14% 1	600
	11th to 20th	Night	19% 6% 24% 35% 15% 1	581
	21st to end	Night	14% 3 25% 38% 19% 1	433
June	1st to 10th	Night	16% 5% 24% 39% 15% 1	400
	11th to 20th	Night	13% 4 25% 42% 17% 1	400
	21st to end	Night	13% 5% 20% 42% 20% 1	400
July	1st to 10th	Night	7% 4 15% 50% 21% 3	390
	11th to 20th	Night	11% 3 16% 42% 23% 5%	554
	21st to end	Night	10% 3 15% 48% 23% 2	657
August	1st to 10th	Night	11% 3 14% 39% 30% 4	597
	11th to 20th	Night	12% 3 16% 36% 29% 4	594
	21st to end	Night	14% 3 17% 34% 28% 3	660
September	1st to 10th	Night	13% 5% 20% 35% 20% 6%	783
	11th to 20th	Night	12% 4 17% 33% 30% 4	800
	21st to end	Night	20% 8% 20% 31% 16% 5%	800
October	1st to 10th	Night	21% 8% 27% 28% 15% 2	800
	11th to 20th	Night	29% 14% 24% 25% 8% 1	793
	21st to end	Night	34% 13% 27% 23% 3	836
November	1st to 10th	Night	28% 14% 25% 26% 8% 1	780
	11th to 20th	Night	30% 18% 30% 17% 5% 1	800
	21st to end	Night	33% 18% 27% 18% 4	800
December	1st to 10th	Night	33% 22% 27% 15% 4	800
	11th to 20th	Night	24% 24% 34% 15% 3 1	830
	21st to end	Night	33% 15% 33% 16% 2	1100

Page generated at 2025-10-16 01:50:22. Version ac07

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