Saint John
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saint John clear sky chart from 2005-11-06 to 2025-08-05.

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	21% 10% 3 7% 4 4 4 3 5% 7% 32%	125824
	Night	21% 11% 3 7% 4 4 4 3 5% 6% 32%	122366
Transparency	Day	33% 39% 7% 13% 7% 1	129357
	Night	34% 38% 6% 13% 7% 1	126920
Seeing	Day	28% 18% 30% 18% 6% 1	17520
	Night	28% 15% 29% 22% 6%	25287

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% 3 8% 6% 5% 5% 4 5% 5% 31%	3157
	11th to 20th	Day	14% 14% 5% 10% 4 3 4 3 3 5% 36%	3519
	21st to end	Day	12% 9% 3 7% 5% 5% 5% 4 6% 7% 37%	4466
February	1st to 10th	Day	17% 13% 3 6% 5% 5% 4 4 6% 6% 31%	1800
	11th to 20th	Day	15% 11% 3 8% 5% 4 4 4 6% 8% 32%	1753
	21st to end	Day	12% 12% 4 8% 5% 5% 4 4 5% 7% 37%	1590
March	1st to 10th	Day	25% 10% 3 10% 5% 4 4 3 4 5% 28%	4785
	11th to 20th	Day	21% 11% 3 6% 5% 4 5% 4 5% 7% 29%	4980
	21st to end	Day	28% 10% 4 7% 4 4 4 3 5% 5% 25%	5466
April	1st to 10th	Day	23% 11% 3 6% 5% 4 4 3 5% 6% 29%	2320
	11th to 20th	Day	21% 9% 3 6% 4 4 3 3 4 7% 36%	2572
	21st to end	Day	23% 7% 2 8% 4 4 3 3 5% 7% 33%	2600
May	1st to 10th	Day	26% 13% 3 8% 6% 5% 4 3 5% 5% 21%	5886
	11th to 20th	Day	22% 8% 3 7% 4 4 4 3 5% 6% 32%	6196
	21st to end	Day	22% 10% 4 8% 5% 4 4 4 5% 7% 27%	6983
June	1st to 10th	Day	23% 9% 2 7% 4 5% 5% 3 6% 7% 29%	3000
	11th to 20th	Day	23% 7% 3 7% 4 4 3 3 4 7% 35%	3000
	21st to end	Day	30% 7% 2 6% 4 4 4 3 5% 7% 28%	3000
July	1st to 10th	Day	20% 11% 4 9% 5% 5% 5% 4 6% 8% 25%	6820
	11th to 20th	Day	23% 11% 3 6% 4 4 4 3 5% 9% 28%	6803
	21st to end	Day	17% 9% 3 6% 4 4 4 4 7% 9% 33%	6435
August	1st to 10th	Day	25% 10% 3 7% 4 4 4 3 5% 7% 27%	4157
	11th to 20th	Day	18% 8% 2 6% 5% 4 5% 4 7% 9% 33%	4045
	21st to end	Day	13% 6% 2 6% 4 4 4 3 6% 8% 43%	4510
September	1st to 10th	Day	17% 6% 2 5% 4 3 4 4 5% 7% 44%	2269
	11th to 20th	Day	19% 6% 2 4 3 3 3 3 4 6% 47%	2090
	21st to end	Day	22% 4 2 5% 4 3 4 2 5% 6% 43%	2090
October	1st to 10th	Day	18% 6% 2 6% 4 4 4 3 5% 6% 41%	1921
	11th to 20th	Day	20% 7% 2 6% 4 4 4 3 5% 5% 40%	1900
	21st to end	Day	21% 9% 2 7% 5% 4 4 3 5% 6% 35%	2005
November	1st to 10th	Day	23% 8% 2 7% 4 4 3 3 4 7% 35%	1691
	11th to 20th	Day	21% 6% 2 6% 4 4 3 3 7% 6% 38%	1600
	21st to end	Day	23% 10% 2 6% 5% 3 4 3 5% 7% 31%	1600
December	1st to 10th	Day	23% 9% 2 6% 3 4 3 4 5% 6% 34%	2610
	11th to 20th	Day	25% 11% 3 7% 4 3 3 2 2 4 36%	2729
	21st to end	Day	22% 11% 3 4 3 3 4 3 6% 7% 36%	3476
January	1st to 10th	Night	13% 13% 4 8% 6% 5% 5% 4 5% 7% 31%	6808
	11th to 20th	Night	17% 10% 4 9% 4 5% 4 3 5% 6% 33%	6361
	21st to end	Night	13% 11% 3 7% 4 4 4 4 5% 7% 38%	6490
February	1st to 10th	Night	19% 11% 3 7% 4 4 4 4 6% 7% 31%	2600
	11th to 20th	Night	17% 12% 3 8% 4 5% 6% 4 5% 6% 30%	2533
	21st to end	Night	16% 11% 3 8% 4 4 5% 4 5% 5% 35%	2035
March	1st to 10th	Night	26% 11% 4 8% 4 5% 4 3 4 4 27%	5054
	11th to 20th	Night	21% 13% 4 7% 5% 4 4 3 5% 6% 28%	4979
	21st to end	Night	31% 10% 3 6% 3 4 4 3 3 5% 29%	5466
April	1st to 10th	Night	23% 12% 3 7% 5% 5% 4 3 5% 4 31%	2078
	11th to 20th	Night	25% 8% 3 5% 4 4 4 3 5% 7% 33%	1778
	21st to end	Night	26% 8% 2 7% 4 4 4 4 5% 5% 31%	1800
May	1st to 10th	Night	29% 11% 4 6% 4 4 4 3 5% 6% 24%	4054
	11th to 20th	Night	24% 9% 2 6% 4 4 5% 4 4 6% 31%	3711
	21st to end	Night	22% 12% 4 7% 4 4 4 3 4 6% 30%	3948
June	1st to 10th	Night	28% 11% 2 5% 4 4 4 3 6% 8% 25%	1408
	11th to 20th	Night	23% 8% 3 7% 4 4 3 4 4 7% 33%	1400
	21st to end	Night	32% 10% 3 6% 5% 3 4 3 4 5% 25%	1400
July	1st to 10th	Night	25% 13% 5% 9% 5% 5% 4 4 5% 5% 19%	3160
	11th to 20th	Night	25% 19% 3 6% 4 3 4 4 4 6% 23%	3160
	21st to end	Night	19% 11% 3 7% 4 4 4 4 4 8% 33%	4371
August	1st to 10th	Night	27% 14% 3 6% 4 3 4 3 4 6% 24%	2862
	11th to 20th	Night	20% 12% 3 8% 4 3 5% 3 6% 7% 30%	2782
	21st to end	Night	13% 10% 3 7% 4 3 4 3 4 7% 42%	3146
September	1st to 10th	Night	20% 7% 2 5% 4 3 3 3 5% 7% 41%	1909
	11th to 20th	Night	20% 8% 2 5% 3 2 3 3 4 6% 43%	2090
	21st to end	Night	22% 7% 2 5% 4 3 3 2 5% 6% 41%	2090
October	1st to 10th	Night	21% 6% 2 5% 3 4 4 3 5% 7% 40%	2258
	11th to 20th	Night	19% 7% 2 6% 4 3 4 3 4 6% 41%	2280
	21st to end	Night	23% 9% 3 7% 5% 3 4 2 4 6% 35%	2589
November	1st to 10th	Night	22% 7% 2 6% 4 3 4 4 5% 6% 39%	2607
	11th to 20th	Night	21% 8% 2 6% 5% 4 4 4 5% 6% 35%	2800
	21st to end	Night	22% 9% 3 6% 4 4 3 4 5% 7% 34%	2800
December	1st to 10th	Night	19% 11% 4 7% 4 3 4 3 5% 6% 36%	4580
	11th to 20th	Night	26% 10% 2 5% 3 3 3 3 4 5% 36%	5477
	21st to end	Night	22% 12% 3 6% 4 4 3 3 4 6% 33%	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	43% 28% 10% 14% 5%	3158
	11th to 20th	Day	38% 28% 8% 19% 7% 1	3549
	21st to end	Day	34% 30% 7% 10% 16% 4	4466
February	1st to 10th	Day	22% 62% 3 7% 4 2	1800
	11th to 20th	Day	21% 61% 4 8% 5%	1761
	21st to end	Day	18% 62% 4 10% 5% 2	1590
March	1st to 10th	Day	45% 29% 6% 9% 8% 3	4789
	11th to 20th	Day	40% 32% 11% 11% 5% 1	4980
	21st to end	Day	49% 29% 4 10% 8% 1	5466
April	1st to 10th	Day	22% 62% 3 7% 5% 2	2320
	11th to 20th	Day	21% 62% 4 9% 4	2572
	21st to end	Day	20% 62% 4 8% 5% 1	2600
May	1st to 10th	Day	46% 34% 6% 11% 3	5897
	11th to 20th	Day	39% 32% 10% 14% 4 1	6200
	21st to end	Day	41% 31% 8% 11% 8%	6983
June	1st to 10th	Day	19% 63% 5% 9% 4	3000
	11th to 20th	Day	19% 62% 4 10% 5%	3000
	21st to end	Day	20% 60% 4 9% 7% 1	3000
July	1st to 10th	Day	45% 27% 9% 12% 7%	6745
	11th to 20th	Day	40% 27% 10% 18% 5% 1	6722
	21st to end	Day	34% 28% 11% 19% 8%	6251
August	1st to 10th	Day	37% 38% 6% 14% 4	4144
	11th to 20th	Day	29% 41% 11% 14% 6%	4084
	21st to end	Day	23% 39% 9% 16% 13% 1	4510
September	1st to 10th	Day	15% 61% 6% 11% 7% 1	2269
	11th to 20th	Day	18% 61% 5% 10% 5% 1	2090
	21st to end	Day	13% 60% 5% 13% 8% 1	2090
October	1st to 10th	Day	29% 40% 7% 20% 5%	3194
	11th to 20th	Day	27% 38% 5% 23% 7%	3140
	21st to end	Day	24% 38% 12% 13% 12%	3281
November	1st to 10th	Day	25% 56% 6% 10% 3	1691
	11th to 20th	Day	23% 57% 6% 7% 6% 2	1600
	21st to end	Day	25% 57% 6% 8% 3	1600
December	1st to 10th	Day	32% 37% 11% 16% 5%	2610
	11th to 20th	Day	39% 31% 6% 10% 10% 3	2729
	21st to end	Day	35% 28% 8% 16% 11% 2	3476
January	1st to 10th	Night	38% 29% 8% 21% 4 1	6808
	11th to 20th	Night	38% 28% 9% 19% 6%	6406
	21st to end	Night	32% 30% 5% 17% 13% 3	6490
February	1st to 10th	Night	21% 63% 3 6% 7% 1	2600
	11th to 20th	Night	21% 61% 3 9% 6% 1	2536
	21st to end	Night	20% 62% 2 7% 7% 2	2035
March	1st to 10th	Night	47% 29% 3 9% 9% 3	5063
	11th to 20th	Night	42% 32% 10% 10% 6% 1	4980
	21st to end	Night	49% 28% 3 12% 8% 1	5466
April	1st to 10th	Night	22% 62% 3 6% 6% 3	2078
	11th to 20th	Night	22% 62% 4 8% 5%	1778
	21st to end	Night	22% 62% 4 6% 6% 1	1800
May	1st to 10th	Night	47% 32% 7% 9% 5%	4060
	11th to 20th	Night	39% 31% 9% 16% 4 2	3712
	21st to end	Night	41% 31% 10% 13% 5% 1	3949
June	1st to 10th	Night	20% 63% 4 9% 4	1408
	11th to 20th	Night	19% 61% 6% 10% 4	1400
	21st to end	Night	23% 60% 3 8% 6% 1	1400
July	1st to 10th	Night	53% 26% 7% 8% 7%	3125
	11th to 20th	Night	49% 26% 7% 12% 5%	3118
	21st to end	Night	37% 27% 10% 16% 10% 1	4241
August	1st to 10th	Night	43% 38% 5% 11% 4	2850
	11th to 20th	Night	33% 39% 10% 12% 4	2809
	21st to end	Night	27% 38% 6% 15% 13% 1	3145
September	1st to 10th	Night	16% 60% 5% 12% 6% 1	1909
	11th to 20th	Night	19% 59% 6% 10% 6%	2090
	21st to end	Night	16% 60% 3 14% 6% 1	2090
October	1st to 10th	Night	30% 38% 9% 15% 7% 1	3765
	11th to 20th	Night	22% 38% 7% 20% 13%	3779
	21st to end	Night	28% 37% 8% 16% 10%	4263
November	1st to 10th	Night	23% 56% 6% 10% 5%	2607
	11th to 20th	Night	22% 57% 5% 9% 7% 1	2800
	21st to end	Night	24% 58% 5% 6% 6% 1	2800
December	1st to 10th	Night	30% 37% 6% 20% 7%	4580
	11th to 20th	Night	36% 32% 5% 14% 11% 2	5478
	21st to end	Night	40% 28% 6% 14% 9% 3	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% 27% 29% 14% 1	200
	11th to 20th	Day	35% 20% 31% 9% 4	202
	21st to end	Day	20% 24% 38% 15% 3	440
February	1st to 10th	Day	28% 25% 30% 14% 3	400
	11th to 20th	Day	27% 29% 30% 13% 2 1	396
	21st to end	Day	22% 28% 34% 14% 2	384
March	1st to 10th	Day	27% 24% 34% 12% 3	500
	11th to 20th	Day	27% 21% 34% 14% 3 1	500
	21st to end	Day	32% 23% 29% 10% 5% 1	550
April	1st to 10th	Day	37% 27% 25% 9% 3	500
	11th to 20th	Day	28% 26% 28% 13% 4 1	492
	21st to end	Day	28% 21% 32% 13% 5% 1	500
May	1st to 10th	Day	29% 22% 31% 14% 4	503
	11th to 20th	Day	27% 18% 30% 20% 5% 1	667
	21st to end	Day	30% 17% 29% 17% 5% 1	790
June	1st to 10th	Day	30% 16% 28% 20% 6%	730
	11th to 20th	Day	27% 14% 30% 23% 6% 1	730
	21st to end	Day	34% 9% 30% 19% 7% 1	730
July	1st to 10th	Day	27% 11% 33% 22% 8%	720
	11th to 20th	Day	29% 9% 26% 25% 10% 2	714
	21st to end	Day	26% 11% 36% 21% 6% 1	576
August	1st to 10th	Day	23% 10% 30% 30% 6% 1	502
	11th to 20th	Day	27% 8% 29% 27% 7% 1	479
	21st to end	Day	22% 12% 29% 26% 10% 2	539
September	1st to 10th	Day	19% 11% 36% 25% 8% 1	490
	11th to 20th	Day	25% 12% 29% 21% 9% 3	490
	21st to end	Day	22% 12% 33% 21% 9% 1	490
October	1st to 10th	Day	24% 13% 28% 21% 12% 2	400
	11th to 20th	Day	24% 19% 28% 21% 8% 1	390
	21st to end	Day	25% 19% 33% 17% 4 1	429
November	1st to 10th	Day	29% 19% 30% 15% 5% 2	395
	11th to 20th	Day	31% 23% 27% 15% 4	400
	21st to end	Day	34% 24% 29% 11% 2 1	400
December	1st to 10th	Day	32% 20% 29% 16% 3	400
	11th to 20th	Day	36% 28% 24% 10% 2	272
	21st to end	Day	31% 25% 30% 10% 4	220
January	1st to 10th	Night	27% 22% 30% 18% 3	900
	11th to 20th	Night	30% 20% 28% 18% 4	813
	21st to end	Night	20% 25% 35% 16% 4	880
February	1st to 10th	Night	27% 23% 30% 18% 2	800
	11th to 20th	Night	26% 24% 31% 16% 2	783
	21st to end	Night	25% 18% 31% 23% 3	660
March	1st to 10th	Night	26% 19% 36% 18% 2	800
	11th to 20th	Night	25% 17% 32% 21% 4	800
	21st to end	Night	26% 18% 32% 18% 6%	880
April	1st to 10th	Night	31% 17% 33% 17% 2	695
	11th to 20th	Night	29% 14% 34% 19% 4	594
	21st to end	Night	30% 13% 32% 20% 5%	600
May	1st to 10th	Night	28% 11% 31% 24% 5% 1	600
	11th to 20th	Night	30% 11% 30% 23% 5%	592
	21st to end	Night	28% 11% 35% 22% 4 1	649
June	1st to 10th	Night	33% 7% 27% 26% 7%	408
	11th to 20th	Night	26% 7% 27% 34% 7%	400
	21st to end	Night	39% 3 21% 30% 7% 1	400
July	1st to 10th	Night	28% 7% 24% 32% 9% 1	390
	11th to 20th	Night	32% 4 21% 31% 11% 1	388
	21st to end	Night	27% 6% 26% 30% 10%	625
August	1st to 10th	Night	23% 4 25% 35% 11% 1	581
	11th to 20th	Night	29% 5% 23% 31% 12% 1	562
	21st to end	Night	22% 7% 25% 30% 15% 1	627
September	1st to 10th	Night	24% 4 32% 28% 11% 1	579
	11th to 20th	Night	25% 9% 22% 27% 15% 1	760
	21st to end	Night	25% 9% 27% 25% 13% 1	760
October	1st to 10th	Night	25% 9% 26% 29% 10% 2	760
	11th to 20th	Night	23% 15% 30% 21% 10% 1	760
	21st to end	Night	29% 18% 29% 22% 3	836
November	1st to 10th	Night	28% 15% 29% 20% 8% 1	815
	11th to 20th	Night	27% 21% 25% 20% 6% 1	900
	21st to end	Night	31% 21% 24% 19% 4	900
December	1st to 10th	Night	33% 18% 30% 15% 3	900
	11th to 20th	Night	32% 24% 29% 12% 2	900
	21st to end	Night	31% 22% 27% 16% 4	990

Page generated at 2025-08-02 02:32:25. Version ac07

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