Wiarton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wiarton clear sky chart from 2005-11-06 to 2024-11-02.

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% 11% 4 9% 5% 4 4 3 5% 7% 33%	101498
	Night	15% 13% 5% 11% 6% 5% 4 3 5% 6% 28%	97492
Transparency	Day	51% 7% 13% 19% 10% 1	101255
	Night	57% 7% 11% 15% 9% 1	97354
Seeing	Day	18% 11% 27% 27% 14% 4	15175
	Night	20% 11% 28% 26% 12% 2	24354

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	15% 24% 15% 17% 8% 4 4 2 2 3 6%	2214
	11th to 20th	Day	11% 21% 11% 28% 8% 5% 4 2 2 1 5%	2591
	21st to end	Day	18% 21% 11% 15% 7% 6% 3 3 3 4 9%	3124
February	1st to 10th	Day	12% 22% 7% 19% 9% 5% 4 3 4 4 12%	1710
	11th to 20th	Day	12% 17% 7% 14% 8% 5% 5% 4 5% 5% 17%	1663
	21st to end	Day	14% 18% 7% 12% 6% 6% 5% 5% 5% 5% 19%	1527
March	1st to 10th	Day	16% 16% 4 9% 5% 5% 4 3 5% 5% 29%	3331
	11th to 20th	Day	11% 18% 9% 11% 6% 4 5% 4 4 5% 24%	3480
	21st to end	Day	15% 13% 5% 8% 5% 5% 4 4 6% 6% 30%	3815
April	1st to 10th	Day	19% 12% 4 9% 5% 4 4 3 5% 7% 29%	2189
	11th to 20th	Day	20% 10% 2 7% 4 3 3 3 4 6% 38%	2442
	21st to end	Day	21% 9% 4 7% 3 3 4 3 5% 7% 35%	2470
May	1st to 10th	Day	17% 7% 2 6% 4 4 4 3 5% 7% 40%	4108
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 5% 8% 42%	4260
	21st to end	Day	14% 5% 2 5% 4 3 4 4 5% 8% 46%	4837
June	1st to 10th	Day	13% 8% 2 5% 4 4 5% 4 7% 8% 39%	2802
	11th to 20th	Day	11% 5% 2 5% 4 5% 5% 4 6% 8% 44%	2850
	21st to end	Day	15% 7% 2 5% 5% 3 4 4 6% 8% 42%	2850
July	1st to 10th	Day	14% 7% 2 6% 4 4 4 4 6% 8% 39%	4760
	11th to 20th	Day	11% 6% 1 5% 3 3 4 3 6% 8% 50%	4662
	21st to end	Day	9% 5% 2 5% 3 4 3 4 6% 9% 50%	4466
August	1st to 10th	Day	12% 6% 2 5% 4 4 5% 4 7% 8% 44%	4104
	11th to 20th	Day	16% 7% 2 5% 3 4 5% 3 6% 8% 41%	4044
	21st to end	Day	10% 5% 2 6% 4 5% 4 4 6% 9% 46%	4505
September	1st to 10th	Day	13% 6% 3 7% 4 4 4 4 5% 8% 41%	2256
	11th to 20th	Day	13% 6% 2 6% 4 4 4 4 5% 9% 44%	2090
	21st to end	Day	18% 7% 3 8% 4 5% 4 4 5% 6% 35%	2090
October	1st to 10th	Day	19% 9% 2 8% 5% 5% 5% 3 5% 6% 34%	1926
	11th to 20th	Day	23% 14% 3 10% 5% 5% 4 3 5% 5% 22%	1900
	21st to end	Day	29% 15% 4 10% 5% 3 4 2 4 5% 18%	2014
November	1st to 10th	Day	18% 19% 4 10% 6% 4 4 4 4 7% 21%	1639
	11th to 20th	Day	16% 21% 4 11% 6% 5% 5% 5% 4 5% 18%	1520
	21st to end	Day	21% 25% 7% 11% 5% 4 4 4 4 4 11%	1520
December	1st to 10th	Day	16% 29% 9% 15% 6% 4 4 3 3 4 7%	1520
	11th to 20th	Day	18% 25% 7% 16% 6% 4 4 3 3 5% 9%	1788
	21st to end	Day	27% 23% 8% 15% 5% 4 4 2 3 3 6%	2431
January	1st to 10th	Night	15% 25% 11% 19% 7% 5% 4 2 3 3 7%	4739
	11th to 20th	Night	14% 18% 9% 24% 11% 5% 4 2 3 3 6%	4374
	21st to end	Night	17% 20% 10% 16% 7% 6% 4 3 3 4 12%	4532
February	1st to 10th	Night	13% 20% 5% 16% 10% 6% 5% 4 5% 3 14%	2470
	11th to 20th	Night	13% 16% 7% 15% 9% 5% 4 3 4 6% 19%	2403
	21st to end	Night	15% 14% 6% 11% 7% 5% 5% 4 5% 5% 22%	1922
March	1st to 10th	Night	12% 12% 5% 8% 5% 5% 4 3 5% 6% 35%	3509
	11th to 20th	Night	10% 14% 6% 10% 5% 4 4 3 4 6% 34%	3479
	21st to end	Night	13% 11% 5% 10% 5% 5% 5% 3 5% 6% 32%	3817
April	1st to 10th	Night	20% 11% 3 8% 5% 4 4 3 5% 6% 32%	1998
	11th to 20th	Night	19% 9% 3 6% 4 4 4 3 5% 6% 37%	1694
	21st to end	Night	20% 9% 3 8% 5% 4 4 4 5% 5% 33%	1710
May	1st to 10th	Night	15% 6% 3 8% 5% 4 4 3 6% 7% 39%	2833
	11th to 20th	Night	13% 7% 2 7% 5% 4 4 4 5% 7% 40%	2629
	21st to end	Night	11% 6% 2 7% 3 4 4 4 5% 7% 46%	2738
June	1st to 10th	Night	13% 8% 2 8% 5% 5% 4 3 6% 7% 39%	1373
	11th to 20th	Night	11% 5% 2 4 4 5% 5% 4 7% 10% 42%	1330
	21st to end	Night	14% 6% 3 6% 4 4 5% 4 6% 8% 40%	1330
July	1st to 10th	Night	12% 8% 3 6% 4 4 3 3 5% 7% 46%	2210
	11th to 20th	Night	12% 5% 2 5% 3 4 4 3 5% 7% 51%	2290
	21st to end	Night	7% 7% 3 5% 4 4 4 4 5% 7% 49%	3087
August	1st to 10th	Night	12% 7% 2 7% 4 4 4 4 6% 7% 43%	2825
	11th to 20th	Night	13% 7% 2 7% 4 5% 5% 4 5% 8% 41%	2785
	21st to end	Night	11% 6% 2 6% 4 4 4 4 5% 8% 46%	3124
September	1st to 10th	Night	11% 4 2 6% 4 3 4 5% 7% 7% 47%	1915
	11th to 20th	Night	11% 5% 2 6% 3 4 4 4 5% 7% 49%	2090
	21st to end	Night	17% 7% 2 8% 6% 5% 5% 3 4 6% 37%	2090
October	1st to 10th	Night	18% 8% 3 7% 5% 5% 4 3 6% 6% 35%	2253
	11th to 20th	Night	24% 11% 4 10% 5% 4 4 3 6% 6% 23%	2280
	21st to end	Night	26% 14% 4 10% 6% 4 5% 4 4 6% 20%	2581
November	1st to 10th	Night	19% 16% 4 9% 6% 4 4 3 4 5% 25%	2462
	11th to 20th	Night	17% 19% 5% 10% 6% 6% 4 4 5% 7% 17%	2660
	21st to end	Night	23% 22% 5% 9% 5% 5% 3 3 4 5% 14%	2660
December	1st to 10th	Night	19% 27% 8% 11% 5% 5% 4 3 4 4 7%	2660
	11th to 20th	Night	15% 24% 8% 17% 6% 4 5% 3 4 4 11%	3404
	21st to end	Night	24% 22% 9% 16% 6% 4 3 2 2 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	84% 7% 7% 3	2215
	11th to 20th	Day	88% 6% 4 2 1	2591
	21st to end	Day	79% 8% 9% 3 1	3124
February	1st to 10th	Day	77% 6% 8% 7% 1	1710
	11th to 20th	Day	69% 8% 11% 7% 4	1672
	21st to end	Day	66% 6% 11% 12% 4	1527
March	1st to 10th	Day	57% 6% 14% 14% 8% 1	3334
	11th to 20th	Day	59% 7% 12% 15% 6% 1	3480
	21st to end	Day	51% 7% 15% 16% 10% 1	3815
April	1st to 10th	Day	55% 6% 11% 18% 10%	2189
	11th to 20th	Day	48% 4 8% 22% 16% 1	2442
	21st to end	Day	48% 6% 12% 19% 11% 3	2470
May	1st to 10th	Day	41% 7% 13% 19% 17% 2	4120
	11th to 20th	Day	39% 8% 17% 23% 13% 1	4264
	21st to end	Day	35% 7% 13% 20% 19% 5%	4837
June	1st to 10th	Day	40% 8% 11% 25% 15% 1	2802
	11th to 20th	Day	36% 7% 13% 25% 18% 1	2850
	21st to end	Day	40% 7% 12% 25% 14% 2	2850
July	1st to 10th	Day	41% 6% 16% 20% 14% 1	4686
	11th to 20th	Day	31% 6% 15% 35% 12% 1	4581
	21st to end	Day	31% 6% 12% 33% 17% 1	4324
August	1st to 10th	Day	35% 7% 16% 26% 14% 1	4091
	11th to 20th	Day	40% 7% 17% 25% 11%	4083
	21st to end	Day	33% 7% 15% 33% 11% 1	4505
September	1st to 10th	Day	40% 8% 13% 25% 13% 1	2256
	11th to 20th	Day	36% 8% 15% 28% 13%	2090
	21st to end	Day	49% 8% 12% 22% 9%	2090
October	1st to 10th	Day	50% 7% 12% 20% 10% 1	1926
	11th to 20th	Day	63% 7% 12% 12% 5% 1	1900
	21st to end	Day	69% 6% 11% 11% 3	2014
November	1st to 10th	Day	63% 7% 12% 13% 5%	1639
	11th to 20th	Day	66% 10% 12% 7% 5%	1520
	21st to end	Day	75% 9% 10% 5%	1520
December	1st to 10th	Day	82% 8% 6% 3 1	1520
	11th to 20th	Day	79% 9% 8% 5%	1787
	21st to end	Day	84% 6% 7% 3	2431
January	1st to 10th	Night	82% 8% 7% 3	4739
	11th to 20th	Night	84% 7% 5% 2 1	4374
	21st to end	Night	78% 8% 9% 3 1	4532
February	1st to 10th	Night	73% 7% 8% 9% 2	2470
	11th to 20th	Night	67% 7% 11% 11% 4	2405
	21st to end	Night	61% 8% 13% 11% 6% 1	1922
March	1st to 10th	Night	49% 7% 16% 18% 9% 1	3519
	11th to 20th	Night	49% 8% 14% 18% 9% 2	3480
	21st to end	Night	50% 9% 12% 18% 10% 1	3817
April	1st to 10th	Night	53% 5% 10% 20% 11% 1	1998
	11th to 20th	Night	47% 5% 9% 20% 17% 2	1694
	21st to end	Night	52% 6% 10% 15% 15% 2	1710
May	1st to 10th	Night	42% 7% 13% 18% 18% 2	2840
	11th to 20th	Night	41% 8% 11% 21% 17% 2	2630
	21st to end	Night	36% 7% 12% 22% 20% 3	2739
June	1st to 10th	Night	42% 7% 11% 20% 18% 2	1373
	11th to 20th	Night	36% 6% 14% 24% 19% 2	1330
	21st to end	Night	40% 6% 12% 27% 13% 2	1330
July	1st to 10th	Night	38% 5% 13% 22% 17% 5%	2175
	11th to 20th	Night	33% 6% 10% 36% 15% 1	2248
	21st to end	Night	33% 7% 12% 25% 22% 1	2988
August	1st to 10th	Night	38% 5% 15% 25% 15% 1	2814
	11th to 20th	Night	40% 8% 18% 20% 14% 1	2812
	21st to end	Night	35% 7% 14% 31% 13% 1	3124
September	1st to 10th	Night	33% 9% 14% 28% 15% 1	1915
	11th to 20th	Night	34% 8% 15% 29% 14%	2090
	21st to end	Night	47% 8% 13% 23% 9%	2090
October	1st to 10th	Night	49% 9% 10% 20% 11% 1	2253
	11th to 20th	Night	60% 7% 12% 15% 5%	2280
	21st to end	Night	67% 7% 10% 11% 5%	2581
November	1st to 10th	Night	59% 7% 13% 16% 5%	2462
	11th to 20th	Night	65% 9% 14% 7% 3 1	2660
	21st to end	Night	72% 10% 12% 6% 1	2660
December	1st to 10th	Night	80% 9% 7% 3 1	2660
	11th to 20th	Night	77% 8% 10% 4	3404
	21st to end	Night	84% 5% 8% 2	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	22% 18% 37% 15% 5% 2	184
	11th to 20th	Day	20% 16% 36% 20% 7% 1	270
	21st to end	Day	26% 13% 32% 23% 6% 1	297
February	1st to 10th	Day	20% 25% 34% 17% 4	270
	11th to 20th	Day	18% 20% 39% 19% 4	270
	21st to end	Day	18% 26% 39% 16% 1	225
March	1st to 10th	Day	22% 14% 33% 24% 6% 1	393
	11th to 20th	Day	19% 15% 33% 26% 7% 1	460
	21st to end	Day	22% 12% 30% 27% 7% 1	506
April	1st to 10th	Day	19% 14% 33% 23% 11% 1	460
	11th to 20th	Day	26% 12% 27% 19% 10% 5%	452
	21st to end	Day	25% 9% 30% 25% 10% 1	460
May	1st to 10th	Day	21% 6% 27% 31% 14% 2	463
	11th to 20th	Day	16% 6% 26% 29% 18% 4	487
	21st to end	Day	13% 5% 22% 33% 20% 5%	529
June	1st to 10th	Day	13% 6% 25% 36% 17% 2	632
	11th to 20th	Day	12% 5% 26% 37% 16% 4	680
	21st to end	Day	17% 5% 25% 33% 16% 4	680
July	1st to 10th	Day	11% 3 23% 36% 22% 5%	671
	11th to 20th	Day	13% 4 25% 33% 18% 7%	666
	21st to end	Day	11% 3 19% 40% 19% 7%	532
August	1st to 10th	Day	13% 5% 19% 30% 25% 8%	486
	11th to 20th	Day	14% 4 14% 33% 26% 9%	479
	21st to end	Day	15% 8% 22% 30% 19% 7%	539
September	1st to 10th	Day	14% 9% 21% 30% 19% 7%	490
	11th to 20th	Day	11% 8% 18% 26% 26% 13%	490
	21st to end	Day	18% 11% 20% 26% 20% 5%	490
October	1st to 10th	Day	22% 13% 25% 21% 16% 4	490
	11th to 20th	Day	22% 18% 31% 22% 6% 1	490
	21st to end	Day	33% 17% 26% 19% 4	463
November	1st to 10th	Day	23% 19% 30% 19% 8% 2	253
	11th to 20th	Day	25% 18% 32% 19% 4 2	180
	21st to end	Day	23% 19% 40% 16% 2	180
December	1st to 10th	Day	23% 25% 33% 15% 4	180
	11th to 20th	Day	28% 23% 32% 13% 5%	180
	21st to end	Day	35% 20% 33% 9% 3	198
January	1st to 10th	Night	23% 17% 33% 21% 5% 1	950
	11th to 20th	Night	26% 17% 31% 18% 6% 1	910
	21st to end	Night	20% 12% 33% 27% 7% 1	836
February	1st to 10th	Night	20% 17% 37% 21% 4	760
	11th to 20th	Night	17% 16% 34% 25% 7%	743
	21st to end	Night	21% 15% 36% 24% 4	628
March	1st to 10th	Night	17% 13% 38% 25% 7%	760
	11th to 20th	Night	18% 13% 37% 25% 7% 1	760
	21st to end	Night	19% 10% 30% 29% 11% 1	836
April	1st to 10th	Night	23% 11% 29% 30% 6% 1	760
	11th to 20th	Night	21% 8% 30% 27% 12% 3	570
	21st to end	Night	24% 7% 25% 29% 15% 1	570
May	1st to 10th	Night	16% 4 22% 38% 17% 2	570
	11th to 20th	Night	18% 4 17% 39% 21% 1	456
	21st to end	Night	12% 3 23% 37% 22% 3	411
June	1st to 10th	Night	15% 4 26% 36% 16% 3	380
	11th to 20th	Night	11% 6% 23% 37% 22%	380
	21st to end	Night	13% 5% 21% 36% 23% 1	380
July	1st to 10th	Night	10% 2 16% 48% 22% 2	370
	11th to 20th	Night	10% 3 23% 31% 30% 3	409
	21st to end	Night	9% 3 18% 42% 25% 3	624
August	1st to 10th	Night	11% 2 20% 33% 31% 3	567
	11th to 20th	Night	10% 4 16% 33% 30% 7%	564
	21st to end	Night	14% 5% 19% 31% 26% 4	627
September	1st to 10th	Night	12% 6% 20% 35% 20% 7%	755
	11th to 20th	Night	13% 5% 19% 31% 25% 6%	760
	21st to end	Night	18% 8% 21% 26% 20% 7%	760
October	1st to 10th	Night	21% 9% 27% 26% 15% 3	760
	11th to 20th	Night	29% 15% 23% 23% 8% 2	760
	21st to end	Night	32% 14% 27% 21% 5%	836
November	1st to 10th	Night	26% 14% 29% 22% 8% 1	745
	11th to 20th	Night	25% 19% 31% 17% 8%	760
	21st to end	Night	32% 15% 31% 18% 3	760
December	1st to 10th	Night	28% 22% 32% 14% 4 1	760
	11th to 20th	Night	23% 20% 38% 15% 4	832
	21st to end	Night	33% 15% 32% 16% 4	1045

Page generated at 2024-10-30 01:22:59. Version ac07

Copyright © 2024 Attilla Danko.