Barrie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Barrie clear sky chart from 2005-11-06 to 2024-12-06.

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% 10% 4 9% 5% 5% 5% 4 5% 7% 32%	102333
	Night	15% 11% 4 9% 6% 5% 5% 4 5% 6% 31%	97387
Transparency	Day	49% 7% 12% 20% 10% 1	105932
	Night	51% 7% 13% 19% 10% 1	101877
Seeing	Day	17% 10% 28% 25% 14% 5%	14930
	Night	19% 9% 29% 29% 12% 1	23867

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% 15% 7% 11% 6% 5% 5% 3 5% 5% 24%	2517
	11th to 20th	Day	9% 16% 6% 18% 9% 7% 6% 4 5% 5% 15%	2721
	21st to end	Day	17% 22% 8% 13% 6% 5% 5% 3 4 4 14%	3124
February	1st to 10th	Day	12% 15% 6% 14% 9% 7% 6% 4 4 5% 18%	1710
	11th to 20th	Day	11% 13% 6% 14% 8% 6% 5% 4 5% 5% 23%	1663
	21st to end	Day	14% 17% 6% 13% 6% 6% 5% 3 5% 6% 21%	1452
March	1st to 10th	Day	18% 13% 5% 10% 5% 4 4 3 4 5% 30%	3432
	11th to 20th	Day	11% 14% 6% 11% 7% 6% 5% 4 4 5% 26%	3480
	21st to end	Day	15% 10% 4 10% 5% 4 4 4 4 5% 35%	3815
April	1st to 10th	Day	18% 13% 4 8% 6% 5% 5% 3 4 6% 29%	2239
	11th to 20th	Day	21% 10% 3 6% 4 4 4 3 4 6% 36%	2355
	21st to end	Day	20% 10% 4 7% 5% 4 3 2 5% 6% 35%	2470
May	1st to 10th	Day	17% 9% 3 8% 6% 4 4 3 6% 7% 35%	4108
	11th to 20th	Day	16% 8% 3 7% 5% 5% 4 4 6% 7% 36%	4393
	21st to end	Day	13% 6% 2 5% 4 4 4 4 5% 7% 45%	4837
June	1st to 10th	Day	18% 7% 3 6% 5% 4 4 4 6% 7% 37%	2660
	11th to 20th	Day	13% 5% 2 5% 4 4 5% 4 7% 9% 40%	2782
	21st to end	Day	15% 7% 3 6% 4 5% 4 4 6% 8% 39%	2850
July	1st to 10th	Day	11% 6% 2 7% 5% 5% 6% 5% 7% 10% 36%	4739
	11th to 20th	Day	10% 6% 2 5% 4 4 5% 4 6% 9% 45%	4440
	21st to end	Day	9% 6% 2 6% 4 4 5% 4 6% 8% 45%	4538
August	1st to 10th	Day	14% 7% 3 6% 5% 4 4 4 6% 8% 39%	4104
	11th to 20th	Day	11% 8% 3 7% 4 5% 5% 4 7% 10% 36%	4044
	21st to end	Day	10% 5% 2 7% 4 4 5% 4 6% 8% 44%	4386
September	1st to 10th	Day	14% 7% 3 7% 4 4 5% 4 5% 7% 40%	2280
	11th to 20th	Day	13% 5% 2 6% 4 4 5% 4 5% 8% 44%	2157
	21st to end	Day	15% 6% 3 7% 5% 5% 5% 4 6% 6% 37%	2058
October	1st to 10th	Day	18% 8% 3 9% 4 4 5% 4 5% 7% 33%	1900
	11th to 20th	Day	20% 10% 3 9% 6% 6% 6% 4 5% 6% 25%	1900
	21st to end	Day	24% 15% 3 11% 6% 5% 4 3 5% 5% 19%	2090
November	1st to 10th	Day	16% 13% 4 10% 6% 4 5% 3 5% 6% 27%	1651
	11th to 20th	Day	15% 15% 5% 10% 6% 6% 6% 4 5% 7% 20%	1600
	21st to end	Day	18% 19% 5% 10% 8% 6% 5% 4 6% 4 15%	1600
December	1st to 10th	Day	14% 22% 7% 14% 7% 5% 5% 4 5% 5% 11%	1560
	11th to 20th	Day	16% 17% 5% 12% 7% 5% 5% 5% 5% 5% 18%	1906
	21st to end	Day	27% 18% 6% 15% 6% 4 4 3 3 4 11%	2772
January	1st to 10th	Night	15% 19% 7% 14% 7% 6% 5% 3 5% 5% 15%	4429
	11th to 20th	Night	13% 11% 6% 16% 11% 9% 7% 5% 5% 5% 13%	4234
	21st to end	Night	18% 16% 8% 12% 7% 5% 5% 4 5% 6% 14%	4532
February	1st to 10th	Night	12% 17% 6% 14% 9% 6% 5% 5% 5% 5% 17%	2470
	11th to 20th	Night	12% 13% 6% 13% 7% 6% 5% 3 5% 6% 23%	2403
	21st to end	Night	15% 13% 5% 12% 6% 4 5% 4 5% 5% 25%	1997
March	1st to 10th	Night	16% 11% 4 9% 6% 5% 5% 3 4 6% 31%	3408
	11th to 20th	Night	11% 12% 4 10% 6% 5% 5% 4 6% 6% 31%	3479
	21st to end	Night	15% 8% 4 12% 7% 5% 6% 3 5% 5% 30%	3817
April	1st to 10th	Night	18% 12% 3 9% 6% 5% 4 4 5% 5% 30%	1940
	11th to 20th	Night	17% 9% 3 7% 5% 4 4 4 5% 6% 36%	1791
	21st to end	Night	18% 9% 4 8% 5% 4 3 4 4 6% 35%	1710
May	1st to 10th	Night	17% 6% 2 7% 4 5% 5% 4 6% 6% 40%	2833
	11th to 20th	Night	15% 7% 3 6% 4 5% 4 4 6% 7% 40%	2499
	21st to end	Night	10% 5% 2 6% 4 4 4 3 5% 9% 48%	2738
June	1st to 10th	Night	14% 6% 2 7% 6% 4 4 4 7% 7% 39%	1520
	11th to 20th	Night	9% 4 2 6% 4 5% 6% 5% 6% 10% 42%	1392
	21st to end	Night	11% 7% 3 7% 5% 5% 5% 4 4 8% 42%	1330
July	1st to 10th	Night	6% 5% 2 6% 5% 5% 4 4 5% 7% 49%	2226
	11th to 20th	Night	11% 6% 2 5% 4 3 3 3 5% 7% 51%	2520
	21st to end	Night	7% 6% 2 6% 3 5% 5% 3 7% 7% 49%	3012
August	1st to 10th	Night	10% 6% 3 6% 4 5% 4 4 6% 7% 46%	2825
	11th to 20th	Night	12% 6% 3 7% 4 3 4 3 5% 7% 47%	2785
	21st to end	Night	11% 6% 2 5% 3 4 5% 4 6% 8% 46%	3238
September	1st to 10th	Night	10% 6% 2 6% 4 4 4 4 5% 8% 46%	1900
	11th to 20th	Night	12% 5% 2 5% 3 3 4 3 6% 7% 51%	2019
	21st to end	Night	16% 7% 3 7% 4 4 4 4 5% 5% 41%	2121
October	1st to 10th	Night	18% 6% 3 8% 5% 5% 4 4 5% 6% 36%	2280
	11th to 20th	Night	19% 10% 3 7% 5% 5% 6% 4 4 5% 31%	2280
	21st to end	Night	22% 12% 3 9% 6% 5% 5% 4 5% 6% 23%	2508
November	1st to 10th	Night	18% 10% 3 7% 5% 5% 4 3 6% 5% 33%	2642
	11th to 20th	Night	15% 17% 4 10% 6% 5% 6% 4 6% 6% 22%	2800
	21st to end	Night	19% 16% 5% 9% 7% 6% 5% 4 6% 5% 19%	2800
December	1st to 10th	Night	17% 19% 6% 12% 7% 5% 4 4 5% 5% 15%	2737
	11th to 20th	Night	16% 18% 5% 12% 6% 5% 5% 3 6% 6% 17%	3288
	21st to end	Night	26% 20% 6% 15% 5% 5% 3 3 3 4 10%	4884

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	61% 8% 16% 10% 4	2518
	11th to 20th	Day	70% 8% 11% 8% 4	2721
	21st to end	Day	72% 7% 9% 8% 3 1	3124
February	1st to 10th	Day	67% 8% 8% 13% 4	1710
	11th to 20th	Day	62% 5% 11% 14% 7% 1	1672
	21st to end	Day	62% 6% 10% 14% 7%	1452
March	1st to 10th	Day	55% 7% 12% 16% 9%	3435
	11th to 20th	Day	58% 5% 12% 16% 7% 1	3480
	21st to end	Day	50% 5% 11% 18% 15% 2	3815
April	1st to 10th	Day	57% 5% 9% 18% 10% 1	2239
	11th to 20th	Day	49% 6% 9% 21% 15% 1	2355
	21st to end	Day	51% 5% 10% 18% 12% 3	2470
May	1st to 10th	Day	46% 6% 12% 21% 13% 2	4120
	11th to 20th	Day	45% 9% 13% 22% 10% 1	4397
	21st to end	Day	36% 7% 13% 23% 17% 3	4837
June	1st to 10th	Day	43% 8% 11% 22% 15% 1	2660
	11th to 20th	Day	37% 9% 12% 25% 16% 1	2782
	21st to end	Day	41% 8% 13% 23% 14% 1	2850
July	1st to 10th	Day	40% 8% 15% 20% 15% 1	4665
	11th to 20th	Day	34% 7% 14% 33% 10% 1	4365
	21st to end	Day	36% 8% 11% 27% 17% 1	4393
August	1st to 10th	Day	42% 8% 14% 24% 12% 1	4091
	11th to 20th	Day	40% 9% 17% 25% 10%	4083
	21st to end	Day	36% 7% 13% 33% 11% 1	4386
September	1st to 10th	Day	41% 7% 14% 26% 10% 2	2280
	11th to 20th	Day	38% 7% 14% 28% 13% 1	2157
	21st to end	Day	45% 9% 12% 25% 9%	2058
October	1st to 10th	Day	44% 6% 13% 25% 12%	3160
	11th to 20th	Day	44% 6% 15% 23% 12%	3140
	21st to end	Day	59% 7% 14% 15% 5%	3428
November	1st to 10th	Day	54% 8% 14% 17% 6%	1651
	11th to 20th	Day	60% 8% 12% 13% 6% 1	1600
	21st to end	Day	68% 9% 11% 10% 2	1600
December	1st to 10th	Day	72% 8% 11% 7% 1	1560
	11th to 20th	Day	67% 9% 12% 9% 3	1906
	21st to end	Day	79% 6% 8% 6% 1	2772
January	1st to 10th	Night	67% 9% 13% 8% 2	4429
	11th to 20th	Night	70% 9% 10% 8% 2	4234
	21st to end	Night	71% 7% 10% 8% 3 1	4532
February	1st to 10th	Night	65% 7% 10% 16% 3	2470
	11th to 20th	Night	60% 6% 12% 16% 6%	2405
	21st to end	Night	58% 6% 12% 16% 8%	1997
March	1st to 10th	Night	53% 6% 12% 20% 8% 1	3418
	11th to 20th	Night	49% 7% 16% 19% 8% 1	3480
	21st to end	Night	50% 6% 13% 18% 12% 1	3817
April	1st to 10th	Night	54% 6% 9% 18% 12% 1	1940
	11th to 20th	Night	47% 6% 10% 19% 16% 2	1791
	21st to end	Night	51% 5% 11% 16% 16% 2	1710
May	1st to 10th	Night	43% 8% 12% 18% 16% 3	2840
	11th to 20th	Night	40% 9% 14% 23% 12% 2	2500
	21st to end	Night	32% 8% 13% 26% 19% 2	2739
June	1st to 10th	Night	42% 7% 11% 23% 15% 2	1520
	11th to 20th	Night	35% 7% 14% 22% 20% 1	1392
	21st to end	Night	38% 9% 12% 25% 15% 1	1330
July	1st to 10th	Night	32% 6% 14% 26% 18% 3	2191
	11th to 20th	Night	33% 5% 12% 35% 15% 1	2472
	21st to end	Night	32% 8% 12% 30% 16% 1	2916
August	1st to 10th	Night	35% 6% 13% 28% 16% 1	2814
	11th to 20th	Night	34% 7% 18% 27% 14% 1	2812
	21st to end	Night	34% 8% 13% 31% 12% 1	3238
September	1st to 10th	Night	35% 8% 14% 29% 13% 1	1900
	11th to 20th	Night	31% 7% 13% 31% 16% 1	2019
	21st to end	Night	43% 7% 13% 26% 10%	2121
October	1st to 10th	Night	36% 6% 11% 26% 21% 1	3800
	11th to 20th	Night	44% 6% 15% 23% 12%	3779
	21st to end	Night	47% 9% 15% 22% 6%	4120
November	1st to 10th	Night	50% 8% 14% 20% 8% 1	2642
	11th to 20th	Night	60% 7% 14% 13% 6% 1	2800
	21st to end	Night	64% 8% 14% 12% 1	2800
December	1st to 10th	Night	69% 8% 12% 9% 3	2737
	11th to 20th	Night	66% 9% 13% 10% 2	3288
	21st to end	Night	79% 5% 8% 6% 1	4884

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	13% 19% 36% 22% 8% 2	180
	11th to 20th	Day	19% 13% 41% 19% 7% 1	238
	21st to end	Day	23% 11% 34% 24% 6% 1	297
February	1st to 10th	Day	18% 20% 41% 14% 6% 1	270
	11th to 20th	Day	20% 18% 37% 22% 2	270
	21st to end	Day	24% 23% 32% 21% 1	225
March	1st to 10th	Day	18% 12% 40% 23% 7%	460
	11th to 20th	Day	17% 17% 34% 25% 7% 1	460
	21st to end	Day	26% 8% 35% 21% 8% 1	506
April	1st to 10th	Day	22% 14% 35% 20% 8% 2	460
	11th to 20th	Day	28% 12% 26% 18% 11% 5%	452
	21st to end	Day	24% 12% 25% 26% 11% 2	460
May	1st to 10th	Day	19% 8% 27% 27% 14% 5%	463
	11th to 20th	Day	14% 7% 25% 29% 20% 5%	487
	21st to end	Day	14% 5% 24% 31% 19% 7%	529
June	1st to 10th	Day	17% 8% 25% 28% 19% 3	490
	11th to 20th	Day	13% 6% 24% 33% 20% 4	612
	21st to end	Day	17% 7% 28% 30% 15% 4	680
July	1st to 10th	Day	9% 5% 24% 33% 23% 6%	663
	11th to 20th	Day	12% 4 23% 29% 23% 10%	484
	21st to end	Day	10% 4 20% 37% 20% 10%	532
August	1st to 10th	Day	10% 5% 19% 27% 27% 12%	486
	11th to 20th	Day	9% 4 18% 28% 26% 14%	479
	21st to end	Day	12% 4 22% 29% 22% 11%	539
September	1st to 10th	Day	13% 8% 23% 23% 23% 12%	490
	11th to 20th	Day	10% 5% 19% 25% 23% 17%	490
	21st to end	Day	14% 8% 26% 25% 21% 7%	490
October	1st to 10th	Day	17% 10% 28% 22% 14% 8%	490
	11th to 20th	Day	20% 14% 33% 23% 8% 2	490
	21st to end	Day	27% 15% 30% 22% 6%	539
November	1st to 10th	Day	20% 22% 28% 20% 9% 1	251
	11th to 20th	Day	19% 22% 38% 15% 6% 2	200
	21st to end	Day	23% 17% 42% 16% 3	200
December	1st to 10th	Day	18% 21% 35% 21% 4 2	190
	11th to 20th	Day	22% 22% 30% 21% 4 1	180
	21st to end	Day	25% 13% 44% 16% 2	198
January	1st to 10th	Night	21% 13% 39% 19% 7% 1	760
	11th to 20th	Night	23% 11% 33% 25% 6%	760
	21st to end	Night	18% 8% 34% 31% 8% 1	836
February	1st to 10th	Night	20% 11% 39% 25% 4	760
	11th to 20th	Night	18% 12% 37% 28% 5%	743
	21st to end	Night	20% 12% 37% 26% 5%	628
March	1st to 10th	Night	19% 11% 36% 29% 6%	760
	11th to 20th	Night	17% 13% 35% 28% 6% 1	760
	21st to end	Night	20% 9% 32% 28% 11%	836
April	1st to 10th	Night	23% 11% 32% 29% 5%	760
	11th to 20th	Night	21% 8% 30% 29% 10% 2	667
	21st to end	Night	22% 7% 28% 29% 13%	570
May	1st to 10th	Night	18% 3 24% 38% 16% 1	570
	11th to 20th	Night	18% 5% 25% 38% 14% 1	378
	21st to end	Night	10% 4 23% 43% 19%	411
June	1st to 10th	Night	14% 4 27% 40% 13% 1	380
	11th to 20th	Night	11% 6% 20% 47% 17% 1	380
	21st to end	Night	13% 6% 22% 41% 18% 1	380
July	1st to 10th	Night	6% 4 17% 49% 23% 1	370
	11th to 20th	Night	9% 4 24% 39% 21% 2	368
	21st to end	Night	10% 3 19% 42% 25% 1	575
August	1st to 10th	Night	10% 3 15% 41% 29% 2	567
	11th to 20th	Night	6% 2 15% 37% 36% 3	564
	21st to end	Night	13% 4 20% 34% 27% 2	689
September	1st to 10th	Night	13% 5% 20% 35% 22% 5%	760
	11th to 20th	Night	12% 3 21% 31% 25% 7%	760
	21st to end	Night	18% 8% 20% 30% 20% 4	760
October	1st to 10th	Night	19% 6% 31% 26% 17% 2	760
	11th to 20th	Night	22% 12% 30% 25% 10% 1	760
	21st to end	Night	28% 11% 30% 25% 6%	836
November	1st to 10th	Night	21% 12% 30% 26% 10% 1	780
	11th to 20th	Night	21% 15% 34% 21% 8% 1	800
	21st to end	Night	26% 14% 32% 23% 4	800
December	1st to 10th	Night	25% 16% 37% 17% 5% 1	783
	11th to 20th	Night	23% 14% 37% 21% 5% 1	760
	21st to end	Night	29% 13% 33% 22% 3	836

Page generated at 2024-12-03 06:45:11. Version ac07

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