Haldimand
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Haldimand 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	15% 10% 3 8% 5% 5% 5% 4 6% 7% 33%	104993
	Night	16% 11% 3 8% 5% 4 4 4 5% 7% 33%	104029
Transparency	Day	28% 45% 8% 12% 6% 1	108599
	Night	29% 44% 8% 12% 7% 1	108511
Seeing	Day	18% 11% 28% 25% 13% 5%	14623
	Night	19% 9% 29% 28% 13% 1	24212

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% 19% 7% 10% 5% 5% 4 4 4 5% 22%	2601
	11th to 20th	Day	13% 20% 8% 17% 8% 5% 4 3 4 5% 12%	2840
	21st to end	Day	22% 20% 8% 13% 6% 5% 4 3 3 4 12%	3124
February	1st to 10th	Day	17% 19% 5% 12% 7% 6% 3 4 5% 5% 18%	1710
	11th to 20th	Day	13% 16% 6% 12% 7% 5% 4 4 5% 4 23%	1663
	21st to end	Day	20% 13% 4 11% 7% 4 4 4 5% 5% 23%	1498
March	1st to 10th	Day	20% 11% 4 10% 6% 4 3 3 4 5% 28%	3432
	11th to 20th	Day	11% 17% 4 9% 6% 4 5% 4 4 6% 30%	3480
	21st to end	Day	18% 11% 3 8% 5% 5% 4 3 5% 6% 32%	3815
April	1st to 10th	Day	17% 13% 4 8% 5% 4 4 3 5% 6% 30%	2218
	11th to 20th	Day	18% 9% 3 7% 4 4 4 3 5% 8% 34%	2333
	21st to end	Day	19% 9% 3 7% 5% 4 4 4 5% 6% 34%	2470
May	1st to 10th	Day	18% 8% 2 7% 5% 5% 5% 4 5% 7% 33%	4108
	11th to 20th	Day	14% 9% 3 9% 6% 5% 5% 4 6% 8% 31%	4260
	21st to end	Day	10% 6% 2 6% 4 4 4 4 5% 8% 46%	4837
June	1st to 10th	Day	12% 6% 3 6% 4 6% 5% 4 7% 7% 40%	2660
	11th to 20th	Day	10% 6% 3 7% 5% 5% 5% 4 7% 8% 40%	2660
	21st to end	Day	12% 5% 2 6% 4 4 4 5% 7% 9% 42%	2660
July	1st to 10th	Day	8% 5% 2 6% 4 4 5% 4 7% 10% 45%	4440
	11th to 20th	Day	11% 6% 2 5% 4 5% 4 4 7% 10% 42%	4327
	21st to end	Day	7% 5% 2 6% 5% 5% 6% 5% 8% 10% 43%	4466
August	1st to 10th	Day	16% 6% 3 5% 4 4 4 4 7% 9% 38%	4104
	11th to 20th	Day	10% 7% 3 7% 5% 5% 6% 5% 8% 10% 35%	4044
	21st to end	Day	9% 5% 2 6% 5% 5% 5% 4 6% 9% 43%	4372
September	1st to 10th	Day	12% 7% 2 6% 4 4 5% 3 6% 7% 43%	2280
	11th to 20th	Day	9% 5% 2 5% 4 5% 5% 4 6% 8% 48%	2133
	21st to end	Day	15% 6% 3 7% 5% 4 6% 4 7% 9% 35%	2071
October	1st to 10th	Day	17% 8% 3 7% 5% 5% 4 3 4 7% 37%	1900
	11th to 20th	Day	19% 9% 3 8% 6% 5% 4 4 5% 6% 32%	1900
	21st to end	Day	22% 11% 3 10% 5% 4 4 3 5% 7% 25%	2090
November	1st to 10th	Day	13% 8% 3 8% 6% 4 5% 4 6% 8% 36%	1751
	11th to 20th	Day	14% 13% 3 9% 6% 4 4 4 5% 8% 30%	1600
	21st to end	Day	21% 15% 3 8% 4 5% 4 4 7% 8% 22%	1600
December	1st to 10th	Day	20% 15% 4 10% 6% 6% 6% 5% 6% 7% 14%	2600
	11th to 20th	Day	22% 16% 4 8% 4 4 5% 3 5% 5% 24%	2986
	21st to end	Day	26% 19% 5% 9% 5% 5% 4 3 4 4 15%	3960
January	1st to 10th	Night	18% 17% 5% 10% 6% 5% 4 3 4 5% 23%	4474
	11th to 20th	Night	16% 16% 6% 13% 7% 5% 5% 4 5% 5% 19%	4120
	21st to end	Night	24% 18% 6% 12% 5% 3 4 3 4 4 17%	4532
February	1st to 10th	Night	17% 17% 5% 8% 7% 6% 5% 4 5% 6% 22%	2470
	11th to 20th	Night	15% 14% 3 10% 6% 5% 5% 5% 6% 6% 26%	2403
	21st to end	Night	19% 12% 5% 10% 6% 4 5% 3 5% 8% 24%	1954
March	1st to 10th	Night	19% 10% 3 8% 5% 5% 4 3 4 5% 33%	3408
	11th to 20th	Night	16% 11% 3 7% 5% 3 4 4 5% 7% 35%	3479
	21st to end	Night	16% 8% 2 7% 4 4 3 4 4 7% 41%	3817
April	1st to 10th	Night	19% 10% 3 8% 5% 4 5% 3 5% 6% 32%	1960
	11th to 20th	Night	18% 9% 4 6% 5% 4 5% 3 5% 6% 36%	1811
	21st to end	Night	15% 8% 3 7% 6% 5% 5% 4 6% 6% 36%	1710
May	1st to 10th	Night	19% 9% 3 8% 4 4 4 3 4 6% 36%	2833
	11th to 20th	Night	11% 7% 2 9% 6% 5% 5% 5% 6% 8% 35%	2631
	21st to end	Night	11% 5% 2 6% 4 3 4 3 6% 9% 48%	2738
June	1st to 10th	Night	10% 7% 3 6% 4 4 7% 5% 7% 7% 39%	1520
	11th to 20th	Night	9% 5% 2 6% 4 5% 6% 4 7% 9% 43%	1520
	21st to end	Night	11% 6% 2 5% 5% 4 4 4 5% 7% 45%	1520
July	1st to 10th	Night	6% 5% 2 7% 5% 4 4 4 5% 10% 49%	2520
	11th to 20th	Night	9% 5% 2 5% 4 4 4 4 6% 9% 48%	2615
	21st to end	Night	7% 4 2 6% 4 4 5% 5% 6% 8% 49%	3087
August	1st to 10th	Night	10% 6% 3 6% 4 4 4 4 6% 8% 44%	2825
	11th to 20th	Night	11% 5% 2 6% 4 4 4 4 6% 8% 44%	2785
	21st to end	Night	7% 4 2 4 4 5% 5% 4 6% 10% 50%	3252
September	1st to 10th	Night	12% 8% 2 5% 5% 4 3 3 5% 7% 47%	1900
	11th to 20th	Night	10% 5% 1 5% 3 3 3 3 5% 7% 54%	2043
	21st to end	Night	16% 6% 3 7% 4 4 4 4 5% 7% 39%	2109
October	1st to 10th	Night	14% 7% 3 6% 4 4 4 3 5% 6% 43%	2280
	11th to 20th	Night	18% 8% 3 7% 5% 5% 4 4 5% 6% 35%	2280
	21st to end	Night	20% 10% 3 7% 5% 4 5% 4 6% 5% 31%	2508
November	1st to 10th	Night	15% 7% 3 6% 4 4 4 4 6% 7% 41%	2541
	11th to 20th	Night	16% 11% 3 7% 5% 4 5% 4 5% 8% 30%	2800
	21st to end	Night	19% 12% 3 8% 5% 5% 5% 4 5% 6% 27%	2800
December	1st to 10th	Night	16% 15% 5% 10% 6% 5% 5% 5% 7% 7% 20%	4580
	11th to 20th	Night	18% 19% 4 9% 5% 4 4 3 4 5% 24%	5208
	21st to end	Night	24% 18% 5% 9% 5% 4 4 3 4 5% 18%	6996

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	41% 38% 9% 5% 6%	2602
	11th to 20th	Day	49% 37% 8% 4 1	2840
	21st to end	Day	48% 41% 6% 3 1	3124
February	1st to 10th	Day	25% 65% 4 4 1	1710
	11th to 20th	Day	22% 64% 3 7% 3	1672
	21st to end	Day	19% 65% 4 7% 4 1	1498
March	1st to 10th	Day	36% 41% 6% 13% 3	3435
	11th to 20th	Day	32% 44% 10% 11% 3 1	3480
	21st to end	Day	30% 42% 5% 14% 7% 1	3815
April	1st to 10th	Day	24% 65% 3 5% 3	2218
	11th to 20th	Day	18% 66% 4 8% 4 1	2333
	21st to end	Day	19% 66% 5% 4 5% 1	2470
May	1st to 10th	Day	31% 41% 9% 11% 6% 1	4120
	11th to 20th	Day	33% 43% 12% 12% 1	4264
	21st to end	Day	22% 41% 8% 16% 11% 2	4837
June	1st to 10th	Day	16% 65% 4 8% 6% 1	2660
	11th to 20th	Day	15% 66% 5% 7% 6% 1	2660
	21st to end	Day	14% 64% 4 10% 8%	2660
July	1st to 10th	Day	23% 36% 9% 20% 11% 2	4370
	11th to 20th	Day	23% 37% 8% 24% 9%	4252
	21st to end	Day	22% 37% 12% 13% 15% 1	4324
August	1st to 10th	Day	30% 38% 10% 14% 9% 1	4091
	11th to 20th	Day	29% 39% 11% 17% 4	4083
	21st to end	Day	23% 37% 7% 24% 8%	4372
September	1st to 10th	Day	14% 61% 7% 12% 6%	2280
	11th to 20th	Day	12% 61% 5% 12% 10%	2133
	21st to end	Day	17% 61% 7% 11% 4	2071
October	1st to 10th	Day	20% 37% 11% 18% 13% 1	3160
	11th to 20th	Day	23% 37% 10% 18% 12%	3140
	21st to end	Day	28% 36% 12% 19% 6%	3428
November	1st to 10th	Day	24% 57% 7% 9% 2 1	1751
	11th to 20th	Day	22% 58% 6% 10% 4	1600
	21st to end	Day	27% 58% 8% 4 3	1600
December	1st to 10th	Day	47% 36% 11% 4 2	2600
	11th to 20th	Day	44% 32% 8% 7% 8% 1	2986
	21st to end	Day	56% 27% 6% 7% 4	3960
January	1st to 10th	Night	39% 39% 11% 8% 3	4474
	11th to 20th	Night	41% 39% 14% 5% 1	4120
	21st to end	Night	47% 40% 7% 4 1	4532
February	1st to 10th	Night	22% 65% 5% 5% 2	2470
	11th to 20th	Night	20% 64% 4 7% 4	2405
	21st to end	Night	21% 65% 4 6% 4	1954
March	1st to 10th	Night	34% 41% 7% 14% 4	3418
	11th to 20th	Night	28% 42% 12% 10% 7% 1	3480
	21st to end	Night	23% 41% 6% 15% 14% 1	3817
April	1st to 10th	Night	22% 65% 3 6% 3	1960
	11th to 20th	Night	18% 66% 3 7% 5% 1	1811
	21st to end	Night	16% 65% 5% 8% 5% 1	1710
May	1st to 10th	Night	32% 41% 7% 10% 7% 2	2840
	11th to 20th	Night	31% 43% 11% 13% 2	2632
	21st to end	Night	20% 42% 7% 15% 15% 1	2739
June	1st to 10th	Night	15% 66% 3 8% 7% 1	1520
	11th to 20th	Night	14% 65% 4 10% 6% 1	1520
	21st to end	Night	15% 63% 4 9% 8% 1	1520
July	1st to 10th	Night	24% 35% 8% 15% 14% 3	2480
	11th to 20th	Night	22% 36% 9% 23% 10%	2567
	21st to end	Night	22% 36% 12% 15% 13% 2	2988
August	1st to 10th	Night	25% 37% 9% 17% 10% 2	2814
	11th to 20th	Night	29% 38% 10% 19% 4	2812
	21st to end	Night	19% 37% 9% 22% 12%	3252
September	1st to 10th	Night	14% 60% 6% 11% 9%	1900
	11th to 20th	Night	11% 60% 5% 13% 10% 1	2043
	21st to end	Night	18% 61% 5% 10% 6%	2109
October	1st to 10th	Night	19% 36% 4 19% 20%	3800
	11th to 20th	Night	26% 36% 8% 18% 11%	3779
	21st to end	Night	21% 37% 11% 20% 11%	4120
November	1st to 10th	Night	23% 57% 6% 8% 6% 1	2541
	11th to 20th	Night	21% 57% 6% 11% 5%	2800
	21st to end	Night	25% 58% 8% 7% 3	2800
December	1st to 10th	Night	40% 36% 13% 9% 2	4580
	11th to 20th	Night	44% 32% 6% 8% 9% 1	5208
	21st to end	Night	51% 28% 8% 9% 4	6996

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	22% 25% 30% 15% 7%	203
	11th to 20th	Day	26% 21% 36% 10% 5% 1	270
	21st to end	Day	21% 21% 36% 17% 5% 1	297
February	1st to 10th	Day	24% 19% 41% 13% 3	270
	11th to 20th	Day	23% 22% 38% 16% 1	270
	21st to end	Day	26% 29% 32% 13%	234
March	1st to 10th	Day	23% 12% 34% 22% 8%	460
	11th to 20th	Day	22% 14% 38% 19% 5% 1	460
	21st to end	Day	29% 10% 32% 20% 8% 1	506
April	1st to 10th	Day	20% 15% 33% 25% 7% 1	460
	11th to 20th	Day	25% 14% 29% 19% 9% 4	452
	21st to end	Day	23% 8% 33% 27% 8% 2	460
May	1st to 10th	Day	23% 9% 29% 26% 9% 5%	463
	11th to 20th	Day	15% 8% 25% 30% 18% 4	487
	21st to end	Day	12% 7% 23% 31% 21% 6%	529
June	1st to 10th	Day	13% 8% 28% 34% 14% 2	490
	11th to 20th	Day	13% 8% 25% 32% 20% 4	490
	21st to end	Day	14% 6% 26% 35% 14% 4	490
July	1st to 10th	Day	8% 5% 19% 31% 28% 8%	485
	11th to 20th	Day	13% 6% 21% 30% 21% 10%	484
	21st to end	Day	8% 4 24% 36% 22% 6%	532
August	1st to 10th	Day	11% 4 20% 31% 23% 11%	486
	11th to 20th	Day	11% 5% 22% 31% 20% 12%	479
	21st to end	Day	10% 5% 19% 34% 20% 11%	539
September	1st to 10th	Day	14% 6% 22% 26% 21% 11%	490
	11th to 20th	Day	9% 4 17% 24% 29% 16%	490
	21st to end	Day	17% 10% 24% 27% 15% 7%	490
October	1st to 10th	Day	18% 11% 25% 23% 17% 6%	490
	11th to 20th	Day	20% 14% 32% 23% 8% 3	490
	21st to end	Day	27% 14% 29% 21% 8%	539
November	1st to 10th	Day	18% 20% 33% 19% 7% 3	318
	11th to 20th	Day	25% 21% 30% 17% 6% 3	200
	21st to end	Day	28% 17% 37% 15% 3 1	200
December	1st to 10th	Day	27% 22% 30% 17% 4 1	200
	11th to 20th	Day	29% 24% 31% 14% 3	200
	21st to end	Day	26% 20% 36% 15% 3	220
January	1st to 10th	Night	25% 16% 37% 16% 5%	785
	11th to 20th	Night	28% 15% 34% 18% 4	760
	21st to end	Night	21% 11% 39% 24% 5%	836
February	1st to 10th	Night	26% 14% 35% 23% 2	760
	11th to 20th	Night	23% 12% 36% 25% 4	743
	21st to end	Night	23% 15% 35% 25% 3	628
March	1st to 10th	Night	19% 10% 35% 28% 8%	760
	11th to 20th	Night	22% 11% 36% 23% 7% 1	760
	21st to end	Night	21% 8% 34% 27% 9% 1	836
April	1st to 10th	Night	21% 11% 33% 30% 4	760
	11th to 20th	Night	21% 9% 32% 27% 10% 1	687
	21st to end	Night	18% 7% 32% 33% 10%	570
May	1st to 10th	Night	21% 5% 27% 29% 16% 2	570
	11th to 20th	Night	15% 3 25% 40% 16% 1	458
	21st to end	Night	12% 6% 22% 36% 22% 2	411
June	1st to 10th	Night	12% 3 29% 39% 16% 1	380
	11th to 20th	Night	13% 3 24% 39% 21%	380
	21st to end	Night	14% 3 22% 43% 18% 1	380
July	1st to 10th	Night	5% 3 21% 42% 26% 2	370
	11th to 20th	Night	9% 4 21% 42% 23% 2	424
	21st to end	Night	10% 2 19% 43% 24% 2	624
August	1st to 10th	Night	8% 4 15% 40% 31% 2	567
	11th to 20th	Night	10% 2 18% 31% 35% 3	564
	21st to end	Night	9% 3 17% 37% 29% 4	703
September	1st to 10th	Night	15% 5% 18% 31% 25% 6%	760
	11th to 20th	Night	13% 3 15% 32% 31% 5%	760
	21st to end	Night	17% 7% 21% 29% 21% 5%	760
October	1st to 10th	Night	16% 8% 27% 27% 19% 2	760
	11th to 20th	Night	22% 11% 29% 28% 10% 2	760
	21st to end	Night	24% 11% 35% 25% 6%	836
November	1st to 10th	Night	19% 11% 31% 26% 12% 1	780
	11th to 20th	Night	22% 14% 33% 22% 8% 1	800
	21st to end	Night	26% 12% 36% 19% 6%	800
December	1st to 10th	Night	29% 16% 32% 18% 6%	800
	11th to 20th	Night	26% 19% 34% 17% 5%	800
	21st to end	Night	30% 12% 33% 23% 2	880

Page generated at 2025-01-04 03:24:01. Version ac07

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