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 2025-01-07.

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	18% 10% 3 8% 5% 4 4 4 5% 7% 32%	105152
	Night	18% 11% 3 8% 5% 4 4 3 5% 6% 33%	103983
Transparency	Day	52% 5% 12% 21% 9% 1	108715
	Night	52% 4 12% 21% 10% 1	108509
Seeing	Day	23% 16% 32% 21% 6% 1	17033
	Night	24% 15% 33% 22% 6%	24682

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% 13% 5% 10% 6% 4 5% 3 4 4 30%	2249
	11th to 20th	Day	13% 15% 3 10% 5% 4 4 3 4 5% 35%	2381
	21st to end	Day	12% 11% 4 9% 7% 5% 4 3 5% 6% 33%	3124
February	1st to 10th	Day	17% 12% 4 9% 5% 4 4 4 5% 5% 31%	1710
	11th to 20th	Day	16% 13% 5% 10% 5% 5% 5% 4 4 6% 28%	1663
	21st to end	Day	11% 13% 5% 8% 5% 4 4 3 6% 7% 34%	1416
March	1st to 10th	Day	22% 15% 5% 8% 5% 3 4 3 4 5% 26%	3416
	11th to 20th	Day	14% 19% 5% 12% 5% 5% 5% 3 5% 5% 21%	3480
	21st to end	Day	27% 15% 5% 8% 4 3 3 4 5% 5% 21%	3816
April	1st to 10th	Day	21% 13% 4 9% 6% 5% 4 3 5% 5% 27%	2258
	11th to 20th	Day	21% 11% 4 6% 4 4 4 3 5% 6% 31%	2385
	21st to end	Day	23% 11% 4 7% 4 4 4 3 5% 7% 29%	2470
May	1st to 10th	Day	23% 17% 3 7% 5% 4 3 3 4 5% 26%	4234
	11th to 20th	Day	17% 9% 2 7% 4 4 4 4 5% 7% 37%	4398
	21st to end	Day	16% 9% 3 8% 6% 6% 5% 4 7% 8% 28%	4836
June	1st to 10th	Day	26% 9% 3 6% 5% 4 4 3 5% 7% 26%	2799
	11th to 20th	Day	20% 7% 3 7% 5% 4 5% 3 6% 8% 32%	2850
	21st to end	Day	25% 9% 3 7% 5% 4 4 3 5% 6% 29%	2850
July	1st to 10th	Day	14% 8% 3 7% 6% 6% 6% 5% 6% 8% 31%	4760
	11th to 20th	Day	15% 6% 3 7% 5% 5% 6% 4 7% 9% 34%	4669
	21st to end	Day	12% 7% 2 7% 5% 5% 5% 5% 6% 9% 37%	4728
August	1st to 10th	Day	17% 9% 3 8% 5% 5% 6% 4 6% 7% 30%	4105
	11th to 20th	Day	14% 6% 3 6% 4 5% 6% 5% 7% 9% 36%	4045
	21st to end	Day	13% 5% 2 5% 4 4 4 4 6% 8% 44%	4419
September	1st to 10th	Day	16% 5% 2 6% 5% 4 5% 3 5% 8% 43%	2280
	11th to 20th	Day	17% 7% 3 6% 4 4 4 2 5% 5% 42%	2181
	21st to end	Day	18% 6% 2 5% 4 4 4 4 4 5% 43%	2047
October	1st to 10th	Day	18% 8% 3 6% 3 3 4 4 5% 7% 40%	1900
	11th to 20th	Day	19% 9% 3 7% 4 4 4 4 5% 6% 36%	1900
	21st to end	Day	20% 9% 3 7% 5% 6% 4 3 5% 6% 33%	2062
November	1st to 10th	Day	19% 11% 4 8% 5% 5% 4 3 4 6% 32%	1575
	11th to 20th	Day	20% 14% 4 6% 4 4 5% 4 3 6% 30%	1600
	21st to end	Day	19% 15% 3 7% 5% 4 3 3 6% 5% 29%	1600
December	1st to 10th	Day	17% 12% 4 7% 4 4 3 3 5% 7% 33%	2610
	11th to 20th	Day	18% 16% 4 8% 4 4 3 2 3 4 35%	2860
	21st to end	Day	16% 12% 5% 14% 5% 4 4 2 4 4 30%	3476
January	1st to 10th	Night	14% 12% 4 8% 4 4 4 3 5% 6% 36%	4839
	11th to 20th	Night	16% 11% 5% 9% 6% 4 4 4 4 5% 33%	4584
	21st to end	Night	14% 14% 5% 8% 8% 3 3 2 5% 6% 32%	4532
February	1st to 10th	Night	16% 13% 4 8% 5% 4 5% 3 6% 5% 30%	2470
	11th to 20th	Night	17% 14% 3 10% 6% 4 5% 3 6% 5% 28%	2403
	21st to end	Night	13% 15% 4 8% 6% 4 3 3 5% 5% 34%	2036
March	1st to 10th	Night	24% 14% 4 11% 6% 5% 4 3 3 4 23%	3424
	11th to 20th	Night	21% 18% 4 10% 5% 5% 5% 3 4 4 21%	3479
	21st to end	Night	29% 12% 3 8% 5% 4 4 4 5% 3 24%	3816
April	1st to 10th	Night	23% 12% 5% 8% 5% 5% 4 3 4 4 27%	1921
	11th to 20th	Night	22% 11% 2 8% 4 4 3 3 4 7% 31%	1743
	21st to end	Night	21% 13% 3 9% 4 4 4 2 3 6% 32%	1710
May	1st to 10th	Night	26% 14% 3 7% 4 4 4 4 6% 6% 24%	2710
	11th to 20th	Night	17% 9% 2 6% 4 4 3 3 5% 8% 40%	2506
	21st to end	Night	14% 10% 4 8% 5% 5% 6% 5% 6% 6% 31%	2749
June	1st to 10th	Night	26% 9% 2 6% 4 4 4 4 6% 6% 29%	1396
	11th to 20th	Night	20% 8% 3 7% 5% 5% 4 3 4 7% 34%	1330
	21st to end	Night	24% 10% 4 7% 5% 4 5% 5% 5% 5% 28%	1330
July	1st to 10th	Night	14% 8% 3 8% 6% 5% 5% 6% 7% 7% 31%	2210
	11th to 20th	Night	12% 8% 3 7% 5% 6% 6% 5% 6% 8% 34%	2264
	21st to end	Night	12% 6% 3 6% 5% 5% 5% 4 6% 8% 40%	2830
August	1st to 10th	Night	17% 7% 4 10% 6% 6% 5% 4 7% 7% 28%	2825
	11th to 20th	Night	10% 7% 2 7% 6% 5% 6% 4 7% 8% 36%	2782
	21st to end	Night	14% 5% 2 5% 4 4 4 4 5% 8% 48%	3236
September	1st to 10th	Night	16% 6% 1 6% 4 3 4 3 4 8% 45%	1900
	11th to 20th	Night	16% 7% 2 5% 4 3 3 3 4 6% 46%	1995
	21st to end	Night	15% 6% 2 7% 4 4 4 3 6% 5% 44%	2133
October	1st to 10th	Night	18% 8% 2 7% 4 4 4 4 4 6% 40%	2280
	11th to 20th	Night	17% 9% 3 7% 4 4 3 3 5% 6% 40%	2280
	21st to end	Night	23% 9% 3 7% 5% 4 4 3 4 5% 34%	2532
November	1st to 10th	Night	20% 10% 3 6% 5% 5% 4 4 5% 5% 34%	2723
	11th to 20th	Night	21% 12% 3 7% 6% 4 3 3 5% 6% 31%	2800
	21st to end	Night	23% 13% 3 6% 4 4 4 3 4 5% 31%	2800
December	1st to 10th	Night	15% 9% 3 7% 5% 4 5% 3 5% 6% 38%	4580
	11th to 20th	Night	18% 15% 4 7% 3 3 3 2 4 4 37%	5333
	21st to end	Night	20% 14% 5% 12% 4 3 3 3 4 5% 28%	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	57% 4 13% 18% 7% 1	2250
	11th to 20th	Day	52% 6% 6% 19% 15% 1	2381
	21st to end	Day	52% 5% 13% 15% 14% 1	3124
February	1st to 10th	Day	56% 4 11% 16% 11% 2	1710
	11th to 20th	Day	58% 6% 8% 17% 9% 1	1671
	21st to end	Day	50% 4 12% 20% 12% 3	1416
March	1st to 10th	Day	60% 6% 9% 19% 6% 2	3420
	11th to 20th	Day	63% 6% 10% 15% 5% 1	3480
	21st to end	Day	64% 5% 6% 17% 7% 2	3816
April	1st to 10th	Day	60% 5% 7% 16% 10% 3	2258
	11th to 20th	Day	52% 6% 8% 20% 11% 1	2385
	21st to end	Day	55% 5% 9% 16% 11% 3	2470
May	1st to 10th	Day	60% 6% 8% 18% 7% 1	4248
	11th to 20th	Day	46% 6% 15% 25% 7%	4402
	21st to end	Day	51% 9% 13% 18% 9%	4836
June	1st to 10th	Day	57% 5% 12% 19% 7%	2799
	11th to 20th	Day	50% 6% 12% 22% 9% 1	2850
	21st to end	Day	57% 6% 11% 16% 9% 1	2850
July	1st to 10th	Day	50% 5% 17% 18% 10% 1	4685
	11th to 20th	Day	46% 6% 16% 25% 7%	4588
	21st to end	Day	43% 7% 18% 26% 6%	4577
August	1st to 10th	Day	54% 5% 11% 24% 6%	4092
	11th to 20th	Day	44% 6% 14% 25% 11%	4084
	21st to end	Day	38% 4 15% 26% 16%	4419
September	1st to 10th	Day	39% 6% 16% 26% 13%	2280
	11th to 20th	Day	44% 4 12% 25% 13% 1	2181
	21st to end	Day	43% 4 11% 27% 15% 1	2047
October	1st to 10th	Day	46% 4 12% 28% 9%	3160
	11th to 20th	Day	46% 4 9% 31% 10% 1	3140
	21st to end	Day	44% 3 15% 21% 17%	3376
November	1st to 10th	Day	56% 4 11% 21% 8% 1	1575
	11th to 20th	Day	57% 5% 13% 15% 10% 1	1600
	21st to end	Day	57% 6% 14% 18% 6%	1600
December	1st to 10th	Day	53% 4 13% 24% 6%	2610
	11th to 20th	Day	56% 3 10% 19% 10% 2	2859
	21st to end	Day	60% 3 13% 17% 7% 1	3476
January	1st to 10th	Night	49% 4 16% 26% 5% 1	4839
	11th to 20th	Night	53% 6% 9% 22% 9% 1	4584
	21st to end	Night	54% 4 11% 21% 9% 1	4532
February	1st to 10th	Night	56% 4 11% 16% 11% 2	2470
	11th to 20th	Night	58% 4 9% 16% 11% 1	2406
	21st to end	Night	53% 4 9% 20% 13% 2	2036
March	1st to 10th	Night	66% 4 6% 16% 7% 2	3433
	11th to 20th	Night	66% 5% 7% 14% 7% 1	3480
	21st to end	Night	64% 4 5% 17% 9% 1	3816
April	1st to 10th	Night	60% 4 8% 14% 10% 3	1921
	11th to 20th	Night	53% 5% 9% 20% 12% 1	1743
	21st to end	Night	56% 3 10% 15% 14% 2	1710
May	1st to 10th	Night	59% 6% 12% 15% 7% 1	2716
	11th to 20th	Night	44% 4 18% 25% 7% 1	2507
	21st to end	Night	50% 8% 19% 16% 7%	2750
June	1st to 10th	Night	54% 6% 13% 19% 8%	1396
	11th to 20th	Night	50% 6% 10% 23% 9% 1	1330
	21st to end	Night	57% 6% 12% 16% 8% 1	1330
July	1st to 10th	Night	49% 5% 15% 20% 10%	2175
	11th to 20th	Night	47% 6% 19% 21% 8%	2222
	21st to end	Night	41% 6% 17% 24% 11%	2741
August	1st to 10th	Night	55% 7% 13% 20% 5%	2813
	11th to 20th	Night	44% 5% 17% 22% 11%	2809
	21st to end	Night	36% 4 17% 27% 15% 1	3235
September	1st to 10th	Night	40% 5% 13% 29% 13%	1900
	11th to 20th	Night	39% 5% 14% 28% 13% 1	1995
	21st to end	Night	42% 5% 12% 27% 13% 1	2133
October	1st to 10th	Night	51% 4 10% 27% 8%	3800
	11th to 20th	Night	38% 4 11% 33% 13%	3779
	21st to end	Night	45% 3 14% 23% 14%	4168
November	1st to 10th	Night	53% 5% 13% 20% 9% 1	2723
	11th to 20th	Night	56% 4 13% 17% 10% 1	2800
	21st to end	Night	56% 5% 14% 18% 7%	2800
December	1st to 10th	Night	48% 3 14% 25% 9%	4580
	11th to 20th	Night	53% 3 10% 21% 11% 2	5335
	21st to end	Night	62% 2 11% 16% 8% 1	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	31% 22% 33% 13% 1	192
	11th to 20th	Day	28% 23% 31% 15% 3	260
	21st to end	Day	18% 17% 40% 22% 4	407
February	1st to 10th	Day	26% 20% 34% 16% 4	370
	11th to 20th	Day	23% 27% 32% 15% 3 1	366
	21st to end	Day	18% 22% 39% 16% 5%	310
March	1st to 10th	Day	25% 22% 36% 14% 2 1	460
	11th to 20th	Day	20% 25% 33% 18% 4	460
	21st to end	Day	30% 20% 32% 13% 4 1	506
April	1st to 10th	Day	29% 24% 32% 12% 2	460
	11th to 20th	Day	26% 22% 31% 17% 4	452
	21st to end	Day	28% 17% 30% 19% 5%	460
May	1st to 10th	Day	31% 16% 31% 18% 5%	539
	11th to 20th	Day	23% 14% 31% 23% 8% 1	674
	21st to end	Day	23% 16% 35% 21% 4	735
June	1st to 10th	Day	32% 11% 31% 20% 6%	680
	11th to 20th	Day	22% 12% 33% 25% 6% 1	680
	21st to end	Day	26% 10% 29% 27% 7% 1	680
July	1st to 10th	Day	21% 10% 35% 26% 8% 1	670
	11th to 20th	Day	16% 7% 33% 32% 10% 1	668
	21st to end	Day	18% 7% 32% 32% 10% 1	689
August	1st to 10th	Day	16% 8% 30% 35% 9% 1	486
	11th to 20th	Day	18% 9% 29% 31% 12% 2	479
	21st to end	Day	14% 13% 28% 32% 11% 2	539
September	1st to 10th	Day	13% 10% 40% 26% 9% 2	490
	11th to 20th	Day	21% 14% 29% 24% 11% 1	490
	21st to end	Day	19% 15% 31% 25% 7% 2	467
October	1st to 10th	Day	19% 14% 31% 21% 13% 1	390
	11th to 20th	Day	24% 18% 30% 19% 8% 1	390
	21st to end	Day	24% 22% 31% 17% 4 1	429
November	1st to 10th	Day	26% 22% 30% 15% 7%	395
	11th to 20th	Day	31% 21% 30% 13% 4 1	400
	21st to end	Day	30% 24% 31% 13% 3	400
December	1st to 10th	Day	30% 19% 34% 14% 3	400
	11th to 20th	Day	32% 29% 26% 12% 1	340
	21st to end	Day	22% 27% 36% 14% 1	220
January	1st to 10th	Night	25% 20% 34% 16% 4	881
	11th to 20th	Night	24% 20% 33% 18% 5%	837
	21st to end	Night	18% 19% 37% 20% 6%	836
February	1st to 10th	Night	25% 16% 37% 18% 4	760
	11th to 20th	Night	26% 22% 34% 16% 2 1	743
	21st to end	Night	21% 17% 36% 22% 4 1	628
March	1st to 10th	Night	24% 16% 37% 20% 2	760
	11th to 20th	Night	25% 17% 31% 21% 6% 1	760
	21st to end	Night	28% 15% 31% 20% 6%	836
April	1st to 10th	Night	30% 16% 29% 22% 3	591
	11th to 20th	Night	27% 14% 32% 20% 6%	564
	21st to end	Night	29% 15% 30% 19% 7% 1	570
May	1st to 10th	Night	30% 11% 29% 22% 7% 1	570
	11th to 20th	Night	25% 10% 31% 25% 8% 1	562
	21st to end	Night	19% 11% 41% 25% 4	616
June	1st to 10th	Night	29% 7% 30% 29% 6%	446
	11th to 20th	Night	23% 7% 33% 31% 6% 1	380
	21st to end	Night	26% 7% 31% 28% 8% 1	380
July	1st to 10th	Night	18% 6% 38% 28% 10%	370
	11th to 20th	Night	15% 8% 33% 33% 11% 1	396
	21st to end	Night	16% 6% 32% 38% 8%	623
August	1st to 10th	Night	16% 4 33% 35% 10% 1	568
	11th to 20th	Night	18% 6% 30% 32% 13% 1	562
	21st to end	Night	15% 6% 30% 35% 12% 1	627
September	1st to 10th	Night	18% 8% 38% 28% 7%	570
	11th to 20th	Night	19% 9% 28% 34% 9% 1	665
	21st to end	Night	19% 10% 33% 28% 9%	760
October	1st to 10th	Night	21% 10% 32% 26% 10%	760
	11th to 20th	Night	21% 15% 36% 20% 8%	760
	21st to end	Night	29% 21% 29% 18% 3	836
November	1st to 10th	Night	28% 19% 32% 17% 5%	875
	11th to 20th	Night	28% 20% 30% 16% 5% 1	900
	21st to end	Night	30% 22% 30% 15% 3	900
December	1st to 10th	Night	30% 17% 33% 17% 3	900
	11th to 20th	Night	31% 22% 33% 12% 2	900
	21st to end	Night	29% 21% 28% 19% 3 1	990

Page generated at 2025-01-04 04:24:01. Version ac07

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