Shediac
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Shediac clear sky chart from 2005-11-06 to 2026-05-02.

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	17% 11% 3 8% 5% 4 4 4 5% 6% 32%	131937
	Night	18% 12% 4 8% 5% 4 4 3 5% 6% 33%	130708
Transparency	Day	52% 5% 12% 21% 10% 1	135481
	Night	53% 4 11% 21% 10% 1	135251
Seeing	Day	24% 17% 32% 21% 6% 1	18791
	Night	25% 15% 33% 22% 6%	26451

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% 19% 5% 12% 6% 4 4 3 4 4 24%	4093
	11th to 20th	Day	15% 17% 6% 13% 5% 4 3 3 4 4 26%	4431
	21st to end	Day	8% 10% 4 9% 7% 4 3 4 5% 6% 40%	5781
February	1st to 10th	Day	15% 14% 5% 9% 5% 4 4 4 5% 5% 30%	1890
	11th to 20th	Day	16% 13% 5% 10% 5% 5% 5% 4 4 6% 29%	1843
	21st to end	Day	11% 14% 5% 9% 4 4 4 3 6% 7% 34%	1560
March	1st to 10th	Day	19% 14% 5% 13% 5% 4 4 3 4 5% 24%	5011
	11th to 20th	Day	16% 15% 4 10% 5% 5% 5% 4 6% 6% 25%	5090
	21st to end	Day	24% 16% 5% 9% 4 4 4 3 5% 5% 21%	5587
April	1st to 10th	Day	21% 12% 5% 8% 6% 4 4 3 5% 5% 27%	2496
	11th to 20th	Day	21% 11% 4 7% 4 4 4 3 5% 6% 30%	2639
	21st to end	Day	22% 11% 4 8% 4 4 4 3 4 6% 30%	2730
May	1st to 10th	Day	25% 16% 3 8% 5% 4 4 3 4 4 24%	6083
	11th to 20th	Day	22% 11% 3 7% 4 4 4 3 4 6% 33%	6318
	21st to end	Day	18% 11% 3 7% 5% 5% 5% 4 6% 8% 29%	6948
June	1st to 10th	Day	25% 9% 3 7% 5% 4 4 3 5% 7% 27%	2947
	11th to 20th	Day	19% 7% 3 7% 5% 5% 5% 4 6% 8% 32%	3000
	21st to end	Day	25% 9% 3 7% 5% 4 4 3 5% 6% 29%	3000
July	1st to 10th	Day	15% 9% 3 8% 5% 6% 6% 5% 7% 9% 27%	6820
	11th to 20th	Day	13% 6% 3 7% 5% 4 5% 4 6% 9% 40%	6687
	21st to end	Day	12% 7% 2 7% 5% 5% 5% 4 6% 9% 39%	6798
August	1st to 10th	Day	17% 9% 3 8% 5% 5% 6% 4 6% 7% 32%	4235
	11th to 20th	Day	13% 6% 3 6% 4 5% 5% 5% 7% 9% 37%	4175
	21st to end	Day	13% 5% 2 5% 4 4 4 4 6% 8% 44%	4559
September	1st to 10th	Day	15% 5% 2 6% 5% 4 5% 3 5% 8% 44%	2400
	11th to 20th	Day	16% 7% 3 6% 4 4 4 2 5% 5% 43%	2296
	21st to end	Day	17% 6% 3 5% 4 4 4 4 4 5% 44%	2155
October	1st to 10th	Day	17% 8% 3 6% 3 3 4 4 5% 7% 41%	2000
	11th to 20th	Day	19% 10% 3 7% 4 4 4 4 5% 7% 35%	2000
	21st to end	Day	20% 9% 3 8% 5% 6% 4 3 5% 6% 32%	2170
November	1st to 10th	Day	19% 12% 4 8% 5% 5% 4 3 4 6% 32%	1655
	11th to 20th	Day	20% 14% 4 6% 4 4 5% 4 3 6% 30%	1680
	21st to end	Day	18% 14% 3 7% 5% 4 4 3 6% 6% 29%	1680
December	1st to 10th	Day	17% 12% 4 8% 4 4 3 3 5% 6% 33%	2690
	11th to 20th	Day	17% 15% 4 8% 4 4 3 2 3 4 35%	2937
	21st to end	Day	16% 12% 5% 14% 5% 4 4 2 4 4 30%	3553
January	1st to 10th	Night	15% 16% 5% 10% 4 4 4 2 4 5% 31%	8831
	11th to 20th	Night	16% 17% 7% 11% 5% 4 3 3 4 4 26%	8461
	21st to end	Night	8% 12% 4 8% 6% 4 4 3 5% 6% 40%	8400
February	1st to 10th	Night	15% 14% 4 9% 5% 4 5% 3 5% 5% 29%	2730
	11th to 20th	Night	17% 14% 4 10% 6% 4 5% 3 6% 5% 28%	2663
	21st to end	Night	12% 15% 4 8% 6% 4 3 3 5% 5% 34%	2244
March	1st to 10th	Night	25% 14% 4 10% 5% 5% 4 3 3 4 24%	5049
	11th to 20th	Night	21% 15% 4 9% 5% 4 5% 4 4 5% 25%	5089
	21st to end	Night	28% 13% 3 8% 4 4 4 3 4 3 26%	5587
April	1st to 10th	Night	23% 13% 5% 8% 5% 5% 5% 3 5% 4 26%	2123
	11th to 20th	Night	23% 11% 2 8% 4 4 3 3 4 7% 31%	1929
	21st to end	Night	21% 13% 3 9% 4 4 4 2 3 6% 31%	1890
May	1st to 10th	Night	28% 13% 3 7% 4 4 4 4 5% 6% 23%	3888
	11th to 20th	Night	22% 8% 2 6% 4 4 4 3 4 6% 36%	3596
	21st to end	Night	18% 10% 3 6% 4 4 5% 4 5% 6% 34%	3948
June	1st to 10th	Night	25% 9% 2 6% 3 4 4 4 6% 6% 30%	1469
	11th to 20th	Night	20% 8% 3 7% 5% 5% 4 3 4 8% 35%	1400
	21st to end	Night	24% 10% 4 7% 5% 4 4 4 5% 5% 28%	1400
July	1st to 10th	Night	15% 8% 3 8% 6% 6% 6% 5% 7% 8% 27%	3160
	11th to 20th	Night	9% 8% 3 9% 5% 6% 6% 4 6% 8% 37%	3242
	21st to end	Night	13% 7% 2 6% 5% 4 5% 4 6% 8% 38%	4067
August	1st to 10th	Night	16% 7% 4 9% 6% 6% 5% 4 6% 7% 29%	2915
	11th to 20th	Night	10% 7% 2 7% 6% 5% 6% 4 7% 8% 37%	2872
	21st to end	Night	14% 5% 2 5% 4 4 4 4 5% 8% 47%	3338
September	1st to 10th	Night	16% 6% 1 5% 4 3 4 3 4 8% 45%	2000
	11th to 20th	Night	15% 7% 2 5% 3 3 4 3 4 6% 47%	2100
	21st to end	Night	15% 6% 2 7% 4 4 4 3 6% 5% 44%	2245
October	1st to 10th	Night	17% 7% 2 7% 4 4 4 4 4 6% 41%	2400
	11th to 20th	Night	17% 9% 3 7% 4 4 4 3 5% 6% 39%	2400
	21st to end	Night	23% 9% 3 7% 5% 4 4 3 4 5% 33%	2666
November	1st to 10th	Night	20% 10% 3 6% 5% 5% 4 4 5% 5% 34%	2863
	11th to 20th	Night	21% 12% 3 7% 5% 4 3 3 5% 6% 31%	2940
	21st to end	Night	22% 12% 3 7% 4 4 4 3 4 5% 31%	2940
December	1st to 10th	Night	15% 9% 3 7% 5% 4 5% 3 5% 6% 38%	4720
	11th to 20th	Night	18% 15% 4 7% 3 3 3 2 4 4 36%	5476
	21st to end	Night	20% 14% 5% 12% 4 4 3 3 4 5% 28%	7667

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	64% 3 10% 13% 9%	4094
	11th to 20th	Day	62% 5% 9% 13% 10% 1	4459
	21st to end	Day	46% 3 9% 21% 19% 2	5781
February	1st to 10th	Day	57% 4 11% 16% 11% 2	1890
	11th to 20th	Day	57% 6% 8% 18% 10% 1	1851
	21st to end	Day	50% 4 12% 21% 12% 2	1560
March	1st to 10th	Day	63% 5% 7% 15% 9% 2	5015
	11th to 20th	Day	58% 5% 15% 16% 5% 2	5090
	21st to end	Day	64% 4 5% 18% 8% 1	5587
April	1st to 10th	Day	60% 5% 7% 15% 11% 3	2496
	11th to 20th	Day	54% 6% 8% 20% 11% 1	2639
	21st to end	Day	55% 5% 9% 17% 12% 3	2730
May	1st to 10th	Day	63% 5% 7% 16% 8% 1	6094
	11th to 20th	Day	53% 5% 13% 24% 5%	6322
	21st to end	Day	52% 7% 11% 19% 10%	6948
June	1st to 10th	Day	56% 5% 12% 19% 7%	2947
	11th to 20th	Day	50% 6% 12% 22% 9% 1	3000
	21st to end	Day	57% 5% 11% 16% 9% 1	3000
July	1st to 10th	Day	53% 4 16% 19% 7%	6745
	11th to 20th	Day	42% 5% 16% 29% 8% 1	6606
	21st to end	Day	42% 5% 18% 28% 6%	6603
August	1st to 10th	Day	53% 5% 11% 25% 6%	4222
	11th to 20th	Day	43% 6% 14% 25% 11%	4214
	21st to end	Day	38% 4 15% 27% 16% 1	4559
September	1st to 10th	Day	39% 6% 15% 27% 14%	2400
	11th to 20th	Day	44% 4 13% 26% 13% 1	2296
	21st to end	Day	42% 4 10% 27% 15% 1	2155
October	1st to 10th	Day	46% 4 12% 29% 9%	3260
	11th to 20th	Day	46% 4 9% 31% 10%	3240
	21st to end	Day	45% 3 15% 21% 17%	3484
November	1st to 10th	Day	56% 4 11% 21% 8%	1655
	11th to 20th	Day	56% 5% 13% 15% 10% 1	1680
	21st to end	Day	56% 6% 14% 18% 6%	1680
December	1st to 10th	Day	53% 4 12% 24% 6%	2690
	11th to 20th	Day	56% 3 10% 19% 10% 2	2936
	21st to end	Day	60% 3 12% 17% 7% 1	3553
January	1st to 10th	Night	58% 2 10% 23% 6%	8831
	11th to 20th	Night	62% 4 9% 17% 7%	8508
	21st to end	Night	46% 3 9% 22% 17% 3	8400
February	1st to 10th	Night	57% 4 10% 16% 11% 2	2730
	11th to 20th	Night	57% 4 9% 18% 11% 1	2666
	21st to end	Night	52% 3 8% 21% 13% 2	2244
March	1st to 10th	Night	65% 3 5% 12% 12% 2	5058
	11th to 20th	Night	62% 4 11% 14% 8% 1	5090
	21st to end	Night	64% 3 4 16% 11% 1	5587
April	1st to 10th	Night	61% 4 8% 14% 10% 3	2123
	11th to 20th	Night	54% 4 9% 20% 11% 1	1929
	21st to end	Night	57% 3 10% 15% 14% 2	1890
May	1st to 10th	Night	62% 5% 9% 14% 9% 1	3894
	11th to 20th	Night	51% 4 14% 23% 7% 1	3597
	21st to end	Night	49% 6% 19% 18% 8%	3949
June	1st to 10th	Night	53% 5% 13% 20% 8%	1469
	11th to 20th	Night	49% 6% 10% 24% 10% 1	1400
	21st to end	Night	57% 6% 11% 16% 9% 1	1400
July	1st to 10th	Night	53% 4 13% 21% 9%	3125
	11th to 20th	Night	45% 5% 17% 25% 8%	3200
	21st to end	Night	43% 5% 18% 24% 10%	3948
August	1st to 10th	Night	53% 7% 13% 21% 6%	2903
	11th to 20th	Night	44% 5% 17% 22% 11%	2899
	21st to end	Night	36% 4 17% 27% 14% 1	3337
September	1st to 10th	Night	39% 5% 12% 30% 13%	2000
	11th to 20th	Night	39% 5% 15% 28% 13% 1	2100
	21st to end	Night	42% 4 11% 27% 14% 1	2245
October	1st to 10th	Night	50% 4 10% 27% 9%	3920
	11th to 20th	Night	39% 4 11% 33% 12%	3899
	21st to end	Night	45% 3 13% 23% 14%	4302
November	1st to 10th	Night	53% 4 13% 20% 9% 1	2863
	11th to 20th	Night	55% 4 13% 18% 9% 1	2940
	21st to end	Night	55% 5% 13% 19% 7%	2940
December	1st to 10th	Night	48% 3 14% 25% 10%	4720
	11th to 20th	Night	53% 3 10% 21% 11% 2	5478
	21st to end	Night	62% 2 11% 16% 8% 1	7667

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	32% 21% 33% 12% 1	220
	11th to 20th	Day	30% 22% 29% 15% 3	309
	21st to end	Day	19% 19% 38% 21% 3	473
February	1st to 10th	Day	24% 21% 33% 17% 4 1	430
	11th to 20th	Day	24% 25% 32% 15% 4	426
	21st to end	Day	20% 22% 38% 16% 4	358
March	1st to 10th	Day	27% 23% 35% 13% 2 1	540
	11th to 20th	Day	23% 25% 32% 16% 4	540
	21st to end	Day	31% 22% 31% 11% 3 1	594
April	1st to 10th	Day	32% 25% 30% 11% 2	540
	11th to 20th	Day	30% 21% 30% 15% 4	532
	21st to end	Day	29% 18% 30% 19% 5%	540
May	1st to 10th	Day	31% 17% 31% 16% 4	587
	11th to 20th	Day	25% 15% 31% 21% 8% 1	724
	21st to end	Day	24% 16% 35% 21% 5%	790
June	1st to 10th	Day	31% 12% 32% 19% 6%	730
	11th to 20th	Day	22% 13% 33% 25% 5% 1	730
	21st to end	Day	26% 11% 29% 26% 7% 1	730
July	1st to 10th	Day	20% 11% 35% 25% 7% 1	720
	11th to 20th	Day	16% 8% 34% 32% 10% 1	718
	21st to end	Day	18% 7% 33% 32% 10% 1	741
August	1st to 10th	Day	15% 8% 31% 34% 10% 1	526
	11th to 20th	Day	17% 8% 29% 31% 12% 2	519
	21st to end	Day	14% 15% 29% 30% 10% 2	583
September	1st to 10th	Day	13% 11% 39% 26% 9% 2	530
	11th to 20th	Day	21% 14% 30% 24% 11% 1	530
	21st to end	Day	19% 15% 33% 24% 7% 2	505
October	1st to 10th	Day	20% 14% 32% 21% 12% 1	420
	11th to 20th	Day	25% 17% 29% 20% 9% 1	420
	21st to end	Day	25% 22% 30% 17% 4 1	462
November	1st to 10th	Day	29% 22% 29% 14% 6%	425
	11th to 20th	Day	31% 21% 29% 13% 4 1	430
	21st to end	Day	29% 25% 30% 13% 2 1	430
December	1st to 10th	Day	30% 19% 34% 14% 3	430
	11th to 20th	Day	32% 29% 26% 12% 1	367
	21st to end	Day	23% 27% 35% 14% 1	242
January	1st to 10th	Night	26% 20% 34% 16% 4	950
	11th to 20th	Night	25% 20% 32% 18% 5%	933
	21st to end	Night	18% 20% 37% 19% 5%	924
February	1st to 10th	Night	25% 17% 37% 17% 4	840
	11th to 20th	Night	26% 21% 33% 16% 3 1	823
	21st to end	Night	21% 17% 36% 22% 4 1	692
March	1st to 10th	Night	25% 18% 36% 19% 2	840
	11th to 20th	Night	26% 17% 31% 21% 5%	840
	21st to end	Night	28% 16% 31% 19% 5%	924
April	1st to 10th	Night	31% 17% 29% 21% 2	653
	11th to 20th	Night	29% 15% 31% 20% 5%	624
	21st to end	Night	30% 13% 29% 20% 7% 1	630
May	1st to 10th	Night	31% 12% 29% 21% 6% 1	604
	11th to 20th	Night	26% 11% 31% 24% 8% 1	592
	21st to end	Night	20% 11% 41% 24% 4	649
June	1st to 10th	Night	29% 7% 30% 29% 6%	469
	11th to 20th	Night	22% 9% 33% 30% 6% 1	400
	21st to end	Night	26% 8% 31% 27% 8% 1	400
July	1st to 10th	Night	17% 6% 38% 29% 9%	390
	11th to 20th	Night	15% 8% 34% 32% 10%	418
	21st to end	Night	16% 6% 33% 37% 7%	656
August	1st to 10th	Night	16% 4 34% 35% 10% 1	598
	11th to 20th	Night	18% 6% 31% 32% 13% 1	592
	21st to end	Night	15% 7% 31% 35% 11% 1	660
September	1st to 10th	Night	18% 8% 39% 28% 7%	600
	11th to 20th	Night	18% 10% 28% 34% 10% 1	700
	21st to end	Night	19% 10% 34% 27% 9%	800
October	1st to 10th	Night	21% 11% 32% 26% 9%	800
	11th to 20th	Night	22% 15% 36% 20% 8% 1	800
	21st to end	Night	29% 21% 29% 18% 3	880
November	1st to 10th	Night	28% 20% 32% 16% 4	925
	11th to 20th	Night	28% 20% 30% 16% 5% 1	950
	21st to end	Night	29% 22% 31% 15% 3	950
December	1st to 10th	Night	29% 17% 34% 16% 3	950
	11th to 20th	Night	31% 22% 33% 12% 2	950
	21st to end	Night	29% 22% 29% 18% 2 1	1045

Page generated at 2026-04-29 03:21:45. Version ac07

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