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 2024-11-04.

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% 9% 3 7% 4 4 4 3 5% 7% 33%	101530
	Night	22% 10% 3 7% 4 4 4 3 5% 6% 32%	97545
Transparency	Day	28% 48% 7% 11% 6% 1	105077
	Night	29% 47% 6% 11% 6% 1	102087
Seeing	Day	27% 18% 30% 18% 6% 1	16505
	Night	27% 15% 29% 22% 6%	24299

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	16% 11% 3 7% 5% 5% 3 3 4 6% 36%	2207
	11th to 20th	Day	18% 12% 3 7% 3 2 3 2 3 4 43%	2468
	21st to end	Day	14% 9% 2 7% 5% 5% 5% 4 6% 8% 33%	3124
February	1st to 10th	Day	17% 13% 3 6% 5% 5% 4 4 6% 7% 31%	1710
	11th to 20th	Day	15% 12% 3 8% 5% 4 4 4 6% 8% 32%	1663
	21st to end	Day	12% 12% 4 8% 4 4 3 4 5% 8% 37%	1513
March	1st to 10th	Day	23% 11% 3 8% 4 4 4 3 4 5% 31%	3327
	11th to 20th	Day	17% 13% 4 7% 6% 5% 5% 4 5% 8% 27%	3480
	21st to end	Day	30% 9% 3 7% 4 4 4 3 5% 4 26%	3816
April	1st to 10th	Day	22% 11% 3 6% 5% 4 4 3 6% 6% 29%	2204
	11th to 20th	Day	21% 9% 3 6% 4 4 3 3 4 7% 37%	2442
	21st to end	Day	23% 7% 2 8% 4 4 3 3 5% 7% 33%	2470
May	1st to 10th	Day	20% 11% 3 7% 6% 5% 5% 4 6% 7% 27%	4106
	11th to 20th	Day	19% 8% 2 7% 4 4 4 4 5% 7% 37%	4318
	21st to end	Day	20% 9% 3 7% 5% 5% 4 4 6% 8% 28%	4857
June	1st to 10th	Day	24% 10% 2 7% 5% 5% 5% 3 5% 7% 28%	2850
	11th to 20th	Day	22% 8% 3 7% 4 4 3 3 4 7% 35%	2850
	21st to end	Day	30% 7% 2 6% 4 3 4 3 4 7% 28%	2850
July	1st to 10th	Day	21% 10% 3 8% 5% 4 4 4 6% 8% 27%	4760
	11th to 20th	Day	25% 10% 3 6% 4 4 4 3 5% 7% 29%	4743
	21st to end	Day	21% 10% 3 6% 4 4 4 4 6% 8% 30%	4477
August	1st to 10th	Day	25% 10% 3 7% 4 4 4 3 5% 7% 26%	4105
	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	24% 7% 2 7% 4 3 3 3 4 7% 35%	1632
	11th to 20th	Day	20% 6% 2 6% 4 4 3 3 8% 6% 39%	1520
	21st to end	Day	23% 10% 2 6% 4 3 4 3 5% 8% 32%	1520
December	1st to 10th	Day	26% 10% 2 6% 3 4 4 4 5% 7% 29%	1520
	11th to 20th	Day	24% 13% 3 8% 5% 3 3 3 4 6% 28%	1737
	21st to end	Day	24% 9% 3 5% 4 3 4 3 5% 6% 34%	2431
January	1st to 10th	Night	14% 11% 3 7% 4 5% 4 4 6% 7% 36%	4748
	11th to 20th	Night	17% 10% 4 9% 4 5% 4 3 5% 6% 33%	4486
	21st to end	Night	16% 12% 3 7% 4 5% 4 5% 6% 8% 30%	4532
February	1st to 10th	Night	19% 11% 3 6% 4 4 4 4 6% 7% 31%	2470
	11th to 20th	Night	17% 12% 3 8% 4 5% 6% 4 5% 6% 30%	2403
	21st to end	Night	16% 11% 3 8% 5% 4 5% 4 5% 5% 34%	1937
March	1st to 10th	Night	25% 10% 3 7% 4 6% 4 3 5% 4 29%	3512
	11th to 20th	Night	20% 14% 4 8% 6% 5% 4 4 5% 7% 24%	3479
	21st to end	Night	32% 10% 3 6% 4 4 4 3 4 4 27%	3816
April	1st to 10th	Night	24% 11% 2 7% 5% 5% 4 3 5% 4 31%	1974
	11th to 20th	Night	24% 8% 3 5% 4 4 4 3 5% 7% 34%	1688
	21st to end	Night	26% 8% 2 7% 4 4 4 4 5% 5% 31%	1710
May	1st to 10th	Night	21% 9% 4 6% 5% 4 5% 4 6% 7% 28%	2834
	11th to 20th	Night	20% 7% 2 7% 5% 4 5% 4 5% 7% 34%	2582
	21st to end	Night	21% 11% 5% 7% 5% 4 4 3 5% 6% 29%	2749
June	1st to 10th	Night	28% 12% 2 5% 4 4 4 3 5% 8% 24%	1338
	11th to 20th	Night	23% 8% 3 7% 4 4 3 4 4 7% 33%	1330
	21st to end	Night	33% 10% 2 6% 5% 4 4 3 4 5% 25%	1330
July	1st to 10th	Night	27% 14% 5% 8% 4 4 3 3 4 4 22%	2210
	11th to 20th	Night	28% 17% 3 6% 3 3 3 4 4 6% 23%	2210
	21st to end	Night	23% 10% 3 6% 5% 4 4 4 4 8% 29%	3044
August	1st to 10th	Night	27% 14% 4 6% 4 4 4 3 4 6% 24%	2825
	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 3 5% 5% 38%	2519
	11th to 20th	Night	21% 7% 2 6% 4 4 4 4 5% 6% 36%	2660
	21st to end	Night	21% 9% 2 6% 4 4 3 4 5% 7% 34%	2660
December	1st to 10th	Night	27% 12% 3 6% 4 3 4 3 5% 5% 27%	2660
	11th to 20th	Night	28% 10% 3 6% 4 4 3 3 4 6% 28%	3459
	21st to end	Night	23% 11% 3 7% 4 4 4 3 4 5% 32%	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	32% 38% 12% 12% 6%	2208
	11th to 20th	Day	27% 38% 5% 20% 10% 1	2468
	21st to end	Day	30% 43% 9% 9% 9%	3124
February	1st to 10th	Day	21% 65% 3 7% 3 1	1710
	11th to 20th	Day	19% 64% 4 7% 5%	1671
	21st to end	Day	16% 65% 4 9% 5% 2	1513
March	1st to 10th	Day	35% 40% 6% 11% 3 4	3331
	11th to 20th	Day	37% 44% 7% 7% 5% 1	3480
	21st to end	Day	44% 39% 3 6% 6% 1	3816
April	1st to 10th	Day	20% 65% 3 7% 4 2	2204
	11th to 20th	Day	18% 65% 4 8% 4	2442
	21st to end	Day	19% 65% 4 6% 5% 1	2470
May	1st to 10th	Day	30% 48% 8% 13% 2	4120
	11th to 20th	Day	29% 43% 12% 13% 4	4322
	21st to end	Day	32% 44% 10% 7% 7%	4857
June	1st to 10th	Day	18% 66% 4 8% 3	2850
	11th to 20th	Day	18% 65% 4 9% 4	2850
	21st to end	Day	18% 64% 4 8% 6%	2850
July	1st to 10th	Day	38% 37% 7% 11% 7%	4685
	11th to 20th	Day	37% 38% 6% 14% 5%	4662
	21st to end	Day	33% 38% 8% 16% 5%	4334
August	1st to 10th	Day	38% 39% 7% 13% 4	4092
	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	23% 58% 6% 9% 3	1632
	11th to 20th	Day	20% 60% 6% 7% 5% 1	1520
	21st to end	Day	22% 60% 5% 8% 3	1520
December	1st to 10th	Day	22% 60% 4 9% 4 1	1520
	11th to 20th	Day	35% 48% 4 7% 7%	1737
	21st to end	Day	31% 38% 8% 12% 8% 2	2431
January	1st to 10th	Night	27% 38% 10% 20% 5% 1	4748
	11th to 20th	Night	33% 38% 6% 15% 7% 1	4486
	21st to end	Night	34% 41% 5% 14% 6%	4532
February	1st to 10th	Night	20% 66% 3 6% 6%	2470
	11th to 20th	Night	19% 64% 3 8% 6%	2406
	21st to end	Night	19% 65% 2 6% 6% 2	1937
March	1st to 10th	Night	37% 41% 3 11% 6% 1	3521
	11th to 20th	Night	38% 44% 6% 7% 5% 1	3480
	21st to end	Night	44% 39% 3 7% 5% 1	3816
April	1st to 10th	Night	20% 65% 3 5% 5% 3	1974
	11th to 20th	Night	20% 65% 4 7% 5%	1688
	21st to end	Night	20% 65% 4 5% 6% 1	1710
May	1st to 10th	Night	33% 45% 10% 10% 2 1	2840
	11th to 20th	Night	28% 44% 11% 14% 3	2583
	21st to end	Night	34% 43% 10% 9% 3	2750
June	1st to 10th	Night	19% 66% 4 7% 4	1338
	11th to 20th	Night	18% 64% 5% 9% 3	1330
	21st to end	Night	21% 63% 3 7% 5% 1	1330
July	1st to 10th	Night	46% 36% 4 6% 9%	2175
	11th to 20th	Night	44% 37% 4 10% 4	2168
	21st to end	Night	33% 37% 8% 13% 8% 1	2947
August	1st to 10th	Night	43% 38% 5% 10% 3	2813
	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% 58% 6% 8% 5%	2519
	11th to 20th	Night	20% 60% 5% 8% 6% 1	2660
	21st to end	Night	22% 60% 4 6% 7% 1	2660
December	1st to 10th	Night	24% 60% 3 7% 5%	2660
	11th to 20th	Night	33% 48% 5% 9% 5%	3460
	21st to end	Night	35% 38% 7% 12% 4 3	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	29% 27% 28% 14% 1	180
	11th to 20th	Day	36% 21% 32% 8% 2	181
	21st to end	Day	21% 23% 38% 15% 3	407
February	1st to 10th	Day	29% 24% 30% 14% 3	370
	11th to 20th	Day	26% 30% 29% 13% 2 1	366
	21st to end	Day	21% 28% 34% 15% 2	355
March	1st to 10th	Day	26% 25% 35% 12% 3	460
	11th to 20th	Day	26% 22% 33% 14% 3 1	460
	21st to end	Day	32% 23% 29% 10% 5% 1	506
April	1st to 10th	Day	36% 27% 25% 10% 3	460
	11th to 20th	Day	26% 27% 29% 14% 4	452
	21st to end	Day	27% 21% 31% 14% 6% 1	460
May	1st to 10th	Day	28% 23% 32% 13% 4	463
	11th to 20th	Day	26% 18% 29% 20% 5% 1	620
	21st to end	Day	29% 18% 29% 18% 5% 1	735
June	1st to 10th	Day	30% 16% 29% 19% 7%	680
	11th to 20th	Day	27% 13% 30% 24% 6% 1	680
	21st to end	Day	34% 10% 28% 19% 7% 1	680
July	1st to 10th	Day	27% 11% 32% 22% 8%	670
	11th to 20th	Day	29% 8% 26% 25% 10% 2	664
	21st to end	Day	27% 10% 35% 22% 6% 1	532
August	1st to 10th	Day	23% 10% 30% 30% 6% 1	486
	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	28% 20% 29% 16% 5% 2	374
	11th to 20th	Day	28% 23% 28% 16% 5%	370
	21st to end	Day	32% 25% 30% 11% 2 1	370
December	1st to 10th	Day	32% 20% 29% 15% 3	370
	11th to 20th	Day	37% 29% 23% 10% 2	249
	21st to end	Day	31% 28% 29% 10% 2 1	198
January	1st to 10th	Night	27% 22% 30% 18% 3	850
	11th to 20th	Night	30% 21% 28% 17% 4	772
	21st to end	Night	21% 24% 35% 16% 4	836
February	1st to 10th	Night	27% 23% 30% 17% 2	760
	11th to 20th	Night	26% 24% 31% 17% 2	743
	21st to end	Night	25% 19% 31% 22% 4	628
March	1st to 10th	Night	25% 19% 37% 18% 2	760
	11th to 20th	Night	25% 18% 31% 21% 4	760
	21st to end	Night	25% 18% 32% 19% 6%	836
April	1st to 10th	Night	31% 16% 33% 17% 3	660
	11th to 20th	Night	28% 14% 34% 19% 4	564
	21st to end	Night	29% 14% 32% 20% 5%	570
May	1st to 10th	Night	27% 11% 32% 24% 5% 1	570
	11th to 20th	Night	29% 11% 30% 24% 6%	562
	21st to end	Night	28% 11% 34% 22% 4 1	616
June	1st to 10th	Night	34% 7% 27% 26% 7%	388
	11th to 20th	Night	26% 8% 25% 34% 7%	380
	21st to end	Night	40% 2 21% 29% 8% 1	380
July	1st to 10th	Night	29% 7% 24% 32% 9% 1	370
	11th to 20th	Night	33% 4 21% 30% 11% 1	368
	21st to end	Night	28% 6% 25% 31% 10%	593
August	1st to 10th	Night	23% 4 26% 35% 12% 1	568
	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% 28% 20% 8% 1	786
	11th to 20th	Night	27% 21% 26% 20% 6% 1	850
	21st to end	Night	29% 22% 25% 19% 5%	850
December	1st to 10th	Night	34% 18% 31% 14% 3	850
	11th to 20th	Night	32% 24% 30% 12% 2	850
	21st to end	Night	31% 22% 27% 15% 4	935

Page generated at 2024-11-01 23:47:51. Version ac07

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