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 2024-01-12.

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	16% 11% 5% 7% 6% 3 4 4 5% 7% 32%	74704
	Night	18% 14% 6% 9% 6% 3 4 4 4 5% 27%	74998
Transparency	Day	52% 7% 12% 18% 9% 1	74415
	Night	58% 7% 10% 15% 9% 1	74822
Seeing	Day	19% 10% 26% 26% 14% 5%	14021
	Night	22% 11% 27% 27% 11% 2	23481

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	18% 20% 11% 13% 9% 4 4 2 3 3 11%	1435
	11th to 20th	Day	17% 19% 13% 18% 8% 4 4 2 3 3 9%	1507
	21st to end	Day	15% 19% 10% 16% 10% 4 4 4 4 4 10%	1782
February	1st to 10th	Day	16% 18% 8% 15% 10% 5% 3 3 3 4 13%	1620
	11th to 20th	Day	14% 13% 9% 17% 11% 4 4 3 3 4 16%	1582
	21st to end	Day	16% 18% 7% 9% 7% 3 5% 3 4 5% 23%	1480
March	1st to 10th	Day	15% 12% 7% 11% 7% 3 5% 4 3 6% 27%	1900
	11th to 20th	Day	14% 12% 7% 10% 6% 2 4 4 5% 6% 31%	1980
	21st to end	Day	19% 10% 6% 7% 7% 3 4 4 4 5% 31%	2178
April	1st to 10th	Day	17% 13% 7% 7% 4 3 5% 3 5% 7% 30%	2058
	11th to 20th	Day	18% 9% 4 5% 5% 3 4 4 5% 8% 36%	2312
	21st to end	Day	20% 8% 4 5% 5% 2 4 4 5% 6% 36%	2340
May	1st to 10th	Day	16% 9% 3 6% 6% 3 5% 5% 5% 8% 35%	2340
	11th to 20th	Day	17% 6% 3 5% 6% 2 4 4 5% 6% 42%	2305
	21st to end	Day	13% 6% 3 5% 4 2 4 5% 5% 9% 45%	2725
June	1st to 10th	Day	13% 6% 2 5% 6% 3 5% 5% 6% 9% 41%	2623
	11th to 20th	Day	11% 6% 3 5% 4 3 4 5% 6% 9% 43%	2700
	21st to end	Day	14% 6% 2 4 4 3 4 5% 5% 8% 44%	2700
July	1st to 10th	Day	8% 4 2 4 4 3 4 4 6% 9% 51%	2700
	11th to 20th	Day	11% 5% 3 5% 4 3 5% 4 7% 9% 46%	2521
	21st to end	Day	10% 5% 2 4 4 3 5% 5% 7% 10% 45%	2547
August	1st to 10th	Day	10% 5% 2 5% 4 3 5% 6% 7% 10% 43%	2327
	11th to 20th	Day	11% 5% 3 6% 5% 4 4 6% 7% 9% 42%	2303
	21st to end	Day	12% 6% 2 5% 5% 3 5% 4 6% 9% 44%	2571
September	1st to 10th	Day	13% 6% 3 6% 6% 3 4 5% 5% 8% 41%	2090
	11th to 20th	Day	13% 5% 2 5% 4 3 5% 5% 5% 9% 44%	1980
	21st to end	Day	18% 6% 3 5% 5% 3 5% 5% 6% 8% 35%	1980
October	1st to 10th	Day	20% 8% 3 6% 5% 3 4 5% 5% 6% 35%	1852
	11th to 20th	Day	26% 14% 4 7% 6% 4 4 4 5% 7% 20%	1800
	21st to end	Day	30% 14% 5% 7% 5% 4 4 4 4 5% 18%	1904
November	1st to 10th	Day	19% 17% 4 7% 5% 3 4 4 4 6% 26%	1672
	11th to 20th	Day	20% 20% 5% 10% 6% 3 4 4 5% 5% 19%	1558
	21st to end	Day	21% 26% 9% 8% 6% 2 3 4 4 4 13%	1520
December	1st to 10th	Day	18% 29% 13% 12% 5% 3 3 3 2 3 7%	1520
	11th to 20th	Day	20% 21% 12% 14% 8% 3 3 3 3 3 9%	1861
	21st to end	Day	28% 23% 10% 9% 5% 3 4 3 3 4 8%	2431
January	1st to 10th	Night	19% 18% 11% 17% 10% 3 3 3 2 3 9%	2729
	11th to 20th	Night	21% 20% 10% 15% 8% 3 4 3 3 3 10%	2477
	21st to end	Night	14% 18% 10% 16% 10% 5% 4 3 3 4 12%	2574
February	1st to 10th	Night	17% 19% 6% 15% 12% 3 4 4 3 3 13%	2340
	11th to 20th	Night	17% 15% 8% 14% 10% 4 4 4 4 5% 15%	2261
	21st to end	Night	16% 15% 8% 13% 7% 3 5% 5% 4 4 21%	1776
March	1st to 10th	Night	15% 12% 5% 11% 7% 4 4 4 4 6% 28%	2047
	11th to 20th	Night	15% 12% 6% 8% 7% 4 4 4 4 6% 31%	1979
	21st to end	Night	19% 11% 5% 8% 6% 3 4 5% 4 5% 31%	2178
April	1st to 10th	Night	22% 12% 4 6% 4 3 3 5% 5% 6% 31%	1918
	11th to 20th	Night	18% 9% 3 6% 5% 3 4 4 5% 7% 37%	1597
	21st to end	Night	18% 11% 4 6% 6% 3 3 4 6% 5% 34%	1620
May	1st to 10th	Night	17% 9% 4 5% 4 3 4 5% 5% 8% 35%	1620
	11th to 20th	Night	16% 7% 3 6% 5% 3 3 4 5% 6% 41%	1584
	21st to end	Night	11% 3 2 4 5% 3 4 5% 6% 8% 49%	1550
June	1st to 10th	Night	14% 5% 3 5% 5% 3 5% 4 5% 7% 43%	1332
	11th to 20th	Night	12% 6% 2 7% 4 2 4 4 8% 9% 41%	1260
	21st to end	Night	13% 6% 2 4 5% 4 4 4 5% 8% 45%	1260
July	1st to 10th	Night	7% 4 2 3 5% 2 4 5% 6% 7% 54%	1260
	11th to 20th	Night	11% 4 2 4 4 3 5% 6% 5% 9% 48%	1434
	21st to end	Night	9% 4 3 6% 6% 3 5% 5% 6% 6% 47%	1771
August	1st to 10th	Night	10% 4 2 5% 6% 3 5% 6% 5% 8% 48%	1611
	11th to 20th	Night	10% 5% 2 4 4 2 4 6% 7% 9% 47%	1598
	21st to end	Night	12% 6% 2 5% 4 3 4 5% 5% 7% 46%	1782
September	1st to 10th	Night	12% 5% 3 6% 4 3 4 4 6% 7% 45%	1851
	11th to 20th	Night	14% 4 2 4 4 3 4 4 5% 7% 50%	1980
	21st to end	Night	17% 7% 3 6% 6% 3 4 5% 5% 6% 39%	1980
October	1st to 10th	Night	20% 8% 3 7% 5% 2 3 3 5% 7% 37%	2106
	11th to 20th	Night	29% 10% 4 6% 6% 3 5% 4 4 5% 23%	2160
	21st to end	Night	30% 13% 4 7% 7% 4 4 4 4 4 20%	2451
November	1st to 10th	Night	21% 16% 4 7% 5% 3 3 4 3 5% 29%	2406
	11th to 20th	Night	20% 23% 6% 8% 5% 3 4 4 4 5% 18%	2621
	21st to end	Night	24% 24% 8% 9% 5% 3 3 3 3 4 14%	2660
December	1st to 10th	Night	21% 29% 13% 10% 6% 2 3 2 2 3 9%	2660
	11th to 20th	Night	16% 23% 11% 14% 7% 3 4 3 4 4 12%	3329
	21st to end	Night	27% 25% 9% 10% 6% 3 3 3 3 3 8%	5236

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	78% 6% 7% 6% 2	1436
	11th to 20th	Day	82% 5% 6% 4 3	1507
	21st to end	Day	79% 6% 7% 6% 2	1782
February	1st to 10th	Day	76% 6% 7% 9% 2	1620
	11th to 20th	Day	73% 5% 7% 10% 3 1	1591
	21st to end	Day	65% 6% 11% 12% 6% 1	1480
March	1st to 10th	Day	60% 5% 14% 14% 7% 1	1903
	11th to 20th	Day	54% 7% 10% 18% 8% 2	1980
	21st to end	Day	55% 5% 12% 17% 9% 1	2178
April	1st to 10th	Day	55% 6% 13% 17% 9%	2058
	11th to 20th	Day	46% 7% 12% 19% 13% 2	2312
	21st to end	Day	48% 7% 14% 17% 11% 2	2340
May	1st to 10th	Day	47% 6% 11% 22% 13% 1	2340
	11th to 20th	Day	42% 7% 11% 23% 14% 3	2309
	21st to end	Day	38% 7% 15% 22% 15% 2	2725
June	1st to 10th	Day	40% 7% 13% 24% 14% 2	2623
	11th to 20th	Day	36% 8% 14% 25% 16% 1	2700
	21st to end	Day	38% 7% 14% 26% 15% 1	2700
July	1st to 10th	Day	29% 8% 15% 25% 21% 2	2626
	11th to 20th	Day	33% 8% 15% 28% 13% 2	2444
	21st to end	Day	34% 9% 15% 28% 13% 2	2405
August	1st to 10th	Day	34% 10% 18% 27% 10% 2	2314
	11th to 20th	Day	36% 9% 18% 24% 11% 1	2303
	21st to end	Day	37% 7% 16% 27% 13% 1	2571
September	1st to 10th	Day	40% 8% 17% 22% 11% 2	2090
	11th to 20th	Day	37% 7% 16% 29% 11% 1	1980
	21st to end	Day	45% 9% 14% 23% 8% 1	1980
October	1st to 10th	Day	49% 7% 11% 21% 11% 1	1852
	11th to 20th	Day	64% 6% 12% 12% 5% 1	1800
	21st to end	Day	68% 8% 10% 10% 4	1904
November	1st to 10th	Day	59% 8% 9% 17% 7% 1	1672
	11th to 20th	Day	66% 8% 11% 9% 5% 1	1558
	21st to end	Day	76% 7% 8% 8% 2	1520
December	1st to 10th	Day	84% 5% 5% 5% 1	1520
	11th to 20th	Day	80% 7% 8% 5% 1	1861
	21st to end	Day	82% 6% 9% 3	2431
January	1st to 10th	Night	81% 5% 7% 5% 1	2729
	11th to 20th	Night	79% 7% 7% 4 2	2477
	21st to end	Night	76% 7% 7% 6% 3 1	2574
February	1st to 10th	Night	77% 6% 7% 9% 1	2340
	11th to 20th	Night	71% 6% 10% 10% 3	2263
	21st to end	Night	65% 6% 10% 12% 6%	1776
March	1st to 10th	Night	56% 8% 11% 17% 7% 1	2057
	11th to 20th	Night	54% 6% 10% 18% 10% 2	1980
	21st to end	Night	55% 5% 9% 17% 11% 2	2178
April	1st to 10th	Night	54% 6% 9% 19% 12% 1	1918
	11th to 20th	Night	46% 7% 10% 19% 17% 2	1597
	21st to end	Night	50% 6% 9% 17% 15% 3	1620
May	1st to 10th	Night	46% 6% 10% 21% 15% 2	1620
	11th to 20th	Night	43% 6% 10% 21% 17% 4	1585
	21st to end	Night	31% 10% 14% 26% 16% 4	1551
June	1st to 10th	Night	40% 5% 11% 25% 16% 2	1332
	11th to 20th	Night	37% 6% 13% 24% 17% 3	1260
	21st to end	Night	37% 6% 12% 25% 18% 2	1260
July	1st to 10th	Night	26% 9% 11% 26% 24% 4	1225
	11th to 20th	Night	31% 8% 13% 27% 18% 2	1388
	21st to end	Night	34% 10% 15% 24% 15% 2	1672
August	1st to 10th	Night	34% 9% 13% 29% 14% 1	1600
	11th to 20th	Night	31% 8% 16% 28% 15% 2	1598
	21st to end	Night	36% 9% 13% 27% 14% 2	1782
September	1st to 10th	Night	37% 8% 13% 25% 14% 2	1851
	11th to 20th	Night	34% 7% 15% 27% 17% 1	1980
	21st to end	Night	44% 8% 14% 22% 12% 1	1980
October	1st to 10th	Night	48% 8% 9% 21% 14% 1	2106
	11th to 20th	Night	61% 9% 10% 16% 4	2160
	21st to end	Night	68% 6% 9% 11% 6%	2451
November	1st to 10th	Night	57% 8% 11% 17% 8%	2406
	11th to 20th	Night	68% 6% 10% 11% 4 1	2621
	21st to end	Night	74% 6% 10% 8% 2	2660
December	1st to 10th	Night	82% 5% 6% 5% 1	2660
	11th to 20th	Night	76% 8% 9% 5% 1	3329
	21st to end	Night	83% 6% 8% 3	5236

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	25% 19% 32% 17% 6% 1	231
	11th to 20th	Day	24% 16% 40% 14% 5% 1	243
	21st to end	Day	25% 14% 37% 19% 5%	264
February	1st to 10th	Day	27% 23% 39% 10% 2	240
	11th to 20th	Day	18% 20% 50% 11% 2	240
	21st to end	Day	24% 29% 33% 13% 2	198
March	1st to 10th	Day	24% 13% 38% 18% 6% 1	343
	11th to 20th	Day	21% 13% 30% 27% 9% 1	420
	21st to end	Day	27% 11% 31% 24% 7% 1	462
April	1st to 10th	Day	23% 14% 32% 21% 9% 1	420
	11th to 20th	Day	25% 12% 25% 22% 10% 6%	412
	21st to end	Day	24% 9% 31% 25% 10% 2	420
May	1st to 10th	Day	19% 10% 27% 27% 13% 3	423
	11th to 20th	Day	19% 6% 25% 26% 18% 6%	447
	21st to end	Day	16% 5% 21% 30% 21% 7%	485
June	1st to 10th	Day	13% 5% 28% 33% 19% 3	553
	11th to 20th	Day	13% 5% 27% 33% 17% 4	630
	21st to end	Day	15% 4 22% 38% 16% 4	630
July	1st to 10th	Day	8% 5% 18% 33% 27% 10%	621
	11th to 20th	Day	13% 4 23% 31% 22% 7%	596
	21st to end	Day	10% 2 20% 38% 22% 8%	488
August	1st to 10th	Day	11% 2 19% 31% 26% 12%	446
	11th to 20th	Day	13% 3 15% 33% 24% 12%	439
	21st to end	Day	16% 4 19% 29% 24% 7%	495
September	1st to 10th	Day	13% 6% 21% 29% 23% 8%	450
	11th to 20th	Day	10% 6% 19% 27% 26% 13%	450
	21st to end	Day	19% 9% 23% 23% 18% 7%	450
October	1st to 10th	Day	22% 10% 24% 24% 16% 6%	450
	11th to 20th	Day	30% 16% 27% 21% 6% 1	450
	21st to end	Day	32% 16% 30% 17% 4 1	419
November	1st to 10th	Day	23% 19% 30% 18% 10% 1	270
	11th to 20th	Day	28% 22% 29% 16% 4 1	198
	21st to end	Day	28% 22% 33% 15% 2	180
December	1st to 10th	Day	28% 28% 27% 15% 2 1	180
	11th to 20th	Day	28% 26% 29% 13% 3 1	180
	21st to end	Day	34% 18% 35% 11% 2	198
January	1st to 10th	Night	24% 19% 33% 18% 5% 1	950
	11th to 20th	Night	27% 17% 32% 18% 5%	844
	21st to end	Night	20% 14% 35% 25% 6% 1	792
February	1st to 10th	Night	28% 15% 32% 22% 3	720
	11th to 20th	Night	23% 16% 33% 23% 5% 1	703
	21st to end	Night	25% 15% 36% 21% 4	592
March	1st to 10th	Night	20% 13% 34% 25% 8%	720
	11th to 20th	Night	20% 13% 34% 24% 7% 1	720
	21st to end	Night	24% 8% 28% 29% 9% 1	792
April	1st to 10th	Night	25% 13% 28% 28% 6%	712
	11th to 20th	Night	22% 9% 29% 27% 11% 2	533
	21st to end	Night	23% 10% 26% 30% 11% 1	540
May	1st to 10th	Night	21% 4 27% 32% 15% 1	540
	11th to 20th	Night	20% 5% 22% 37% 15% 1	523
	21st to end	Night	12% 3 25% 39% 20% 1	389
June	1st to 10th	Night	16% 4 22% 40% 16% 1	360
	11th to 20th	Night	14% 4 24% 41% 18% 1	360
	21st to end	Night	13% 4 19% 41% 21% 1	360
July	1st to 10th	Night	7% 4 14% 50% 23% 3	350
	11th to 20th	Night	11% 2 16% 42% 24% 5%	496
	21st to end	Night	10% 3 15% 48% 23% 2	591
August	1st to 10th	Night	11% 2 14% 39% 30% 4	537
	11th to 20th	Night	11% 3 15% 36% 30% 5%	534
	21st to end	Night	14% 2 18% 34% 28% 4	594
September	1st to 10th	Night	13% 4 20% 37% 19% 7%	704
	11th to 20th	Night	14% 4 19% 33% 26% 4	720
	21st to end	Night	19% 8% 20% 31% 17% 5%	720
October	1st to 10th	Night	23% 8% 25% 26% 16% 2	720
	11th to 20th	Night	30% 14% 24% 24% 7% 1	720
	21st to end	Night	35% 13% 27% 21% 3	792
November	1st to 10th	Night	28% 13% 25% 26% 8% 1	740
	11th to 20th	Night	29% 18% 31% 16% 5% 1	760
	21st to end	Night	33% 17% 27% 18% 4	760
December	1st to 10th	Night	34% 22% 26% 15% 3	760
	11th to 20th	Night	24% 23% 34% 15% 3 1	788
	21st to end	Night	34% 15% 33% 16% 2	1045

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